Vita Complete Denture Guie

VITA shade, VITA made.

A Guide to Complete Denture Prosthetics

Date of issue 11.11

VITA shade controlVITA shade reproductionVITA shade communicationVITA shade taking

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Foreword

The aim of this Complete Denture Prosthetics Guide is to inform on the developmentand implementation of the fundamental principles for the fabrication of completedentures.In this manual the reader will find suggestions concerning clnical cases which presentin daily practice. Its many features include an introduction to the anatomy of thehuman masticatory system, explanations of its functions and problems encounteredon the path to achieving well functioning complete dentures.

The majority of complete denture cases which present in everyday practice can beaddressed with the aid of knowledge contained in this instruction manual. Of coursea central recommendation is that there be as close as possible collaboration betweendentist and dental technician, both with each other and with the patient.This provides the optimum circumstances for an accurate and seamless flow ofinformation. It follows also that to invest the time required to learn and absorbthe patient’s dental history as well as follow the procedural chain in the fabricationprocedure will always bring the best possible results.

Complete dentures are restorations which demand a high degree of knowledge andskill from their creators. Each working step must yield the maximum result, the sumof which means an increased quality of life for the patient.In regard to the choice of occlusal concept is to be used, is a question best answeredby the dentist and dental technician working together as a team.

It is essential to take into account the patient specific parameters in the decisionmaking process as there is no single answer to the question:Which is the best occlusal concept ?

It is inappropriate to think in absolute terms as there are numerous concepts whichcan be used and which will work.A successful restoration is distinguished as follows.

Correct determination and achievement of centric relation,A positive attitude and willingness on the part of the patient to accept the dentures.This means involving the patient in the procedural chain.Positional stability of the dentures (functional periphery).Cheek contact with the posterior teeth.Correct positioning of the teeth in regard to stability of the dentures.Correct mounting of the models on the articulator.Accurate remounting of the finished dentures on the articulator.

4 Foreword

If these requirements are fulfilled the result will be very close to the optimum.Given the subsequent selection of an occlusal concept appropriate to the particularcase, there is little room for error. If however the centric relation has been incorrectlydetermined, even the “best” occlusal concept will not put this right !

If the denture base will not seal due to some discrepancy in the peripheral seal, inall probability this will lead to pressure spots and other problems. The same applieswhen the second lower molar and its antagonist are set up into the ascending mandi-bular ramus and cause the lower denture to slide forward. (called – proglissement.)Painful pressure areas in the lingoanterior area are the result.In the case of occlusal interference at the second molar, short term relief is oftenattempted by selectively grinding in the affected area. While this brings instant relieffor the patient, it does not remedy the cause but merely defers the problem.

Why is it that so many dentures ultimately function in situations, which on closeexamination, do not appear to satisfy even the minimum requirements in thepublished literature and indicated by the theories ?The majority of patients in time will learn to accept or tolerate such dentures.The neuromuscular system is capable of learning and eventually finds ways to copewith the difficulties. In many cases commercially available denture adhesives playa more than significant role.

How else to explain that in Germany alone, more than 60 tonnes of denture adhesivesare sold and used annually. This is indeed food for thought and shows the need forimprovement in the teaching and the techniques applied in full denture construction.It also emphasises the great importance of thoroughly completing each step in theprocedural chain from primary impression to issue of the dentures.Finally, in this age of computer aided dental technology a high standard of manualskill is in more demand than ever

Urban Christen DD RCS

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Table of Contents

Foreword

The fabrication of complete denture prosthesis

History

1 Anatomy1.1 The anterior teeth1.2 The posterior teeth1.3 The maxilla1.4 The mandible1.5 The temporomandibular joint1.6 The tongue1.7 The musculature1.8 Arch atrophy

2 Anatomical terms of location (directional terms)2.1 The directional terms2.2 Angle's bite classification2.3 Types of bite

2.3.1 Normal occlusion2.3.2 Edge-to-edge bite2.3.3 Crossbite2.3.4 Scissor bite

2.4 The teeth of human dentition2.4.1 Anterior teeth2.4.2 Posterior teeth

2.5 Classification of cusps2.5.1 Working cusps2.5.2 Shearing (non-working) cusps

2.6 FDI tooth notation system2.6.1 Zsigmondy system of tooth notation2.6.2 Haderup system of tooth notation

2.7 Planes and lines of reference2.7.1 Frankfort horizontal plane2.7.2 Camper's line2.7.3 Occlusal plane2.7.4 Simon's orbital plane2.7.5 Median plane

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6 Table of Contents

2.8 Curves of Occlusion2.8.1 Curve of Spee2.8.2 Curve of Wilson2.8.3 Curve of Monson

3 The complete denture prosthesis according to qualitative considerations

4 Patients Dental / Medical History

5 Preparatory working steps5.1 Individual impression trays

5.1.1 Extension5.1.2 The impression tray handle

5.2 Bite registration blocks5.3 Model fabrication5.4 Mounting on the articulator5.5 The vertical dimension

6 Articulators and articulation theories6.1 Classification of articulators according to their construction

6.1.1 Arcon articulators6.1.2 Non-arcon articulators

6.2 Classification of articulators according to the type of movement that can be made6.2.1 Average value articulators6.2.2 Semi-adjustable articulators6.2.3 Fully adjustable articulators

6.3 The movements of the mandible6.3.1 Protrusion6.3.2 Laterotrusion6.3.3 Laterotrusion side6.3.4 Mediotrusion6.3.5 Mediotrusion side6.3.6 Retrusion6.3.7 Retraction6.3.8 Laterotraction (lateral retraction)6.3.9 Bennett angle

6.3.9.1 Bennett movement6.4 The Bonwill triangle

7 Model analysis

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8 Tooth selection8.1 Tooth selection based on patient's offspring8.2 Tooth selection according to nose width (Lee)8.3 Selection of anterior tooth positioning according to Gerber8.4 Selection of anterior tooth moulds according to Gysi8.5 Tooth selection according to physiognomy (Williams)8.6 Tooth selection according to constitution types (Kretschmer)8.7 Tooth selection according to the anatomical model

9 Statics and chewing stability9.1 When can a denture be said to have stability?9.2 What happens with an unstable denture?9.3 Vectors of force – what are they?9.4 The interplay of forces

10 Anterior teeth10.1 Position of the anterior teeth

10.1.1 Tooth length10.2 Setting up the anterior teeth

10.2.1 Standard setup methods10.2.2 Individual setup methods10.2.3 Overbite – overjet (overbite – sagittal overbite)

10.3 Phonetics10.3.1 Problems and appropriate solutions10.3.2 Generally accepted principles

11 Aesthetics

12 Setup and function12.1 Setup concepts – generally accepted principles

12.1.1 Lingualised occlusion12.1.2 Anterior-canine guidance with ABC contacts12.1.3 Setup according to generally accepted principles

with buccal contacts12.2 Important characteristics

12.2.1 Cheek contact12.2.2 Different bite types12.2.3 Normal bite (normal occlusion)12.2.4 Crossbite12.2.5 Edge-to-edge bite

12.3 Vertical dimension /occlusal height

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8 Table of Contents

13 The denture base13.1 Gingival shaping / contouring

13.1.1 How to reproduce naturally appearing gingiva?13.2 Peripheral (access) for unhindered functioning of ligaments13.3 Designing the denture periphery / waxing the body of the prosthesis as a whole

13.3.1 How is the denture margin correctly designed?13.3.2 Extension13.3.3 Which factors enable adhesion?13.3.4 Reducing the strain on the palatal torus13.3.5 The peripheral seal function – "all or nothing"13.3.6 Foreign body dimension, as small as possible, as large

as necessary – replacing lost natural substance13.3.7 Chimpanzee effect – designing the labial extension in the upper13.3.8 Reversible facelift effect

13.4 Palatal rugae

14 Denture processing14.1 Denture processing systems

14.1.1 Injection systems14.1.2 Packing systems14.1.3 Pouring systems14.1.4 Heat-curing polymer – self-curing polymer14.1.5 Improving adhesion / preparation of the denture teeth

14.2 Denture processing14.2.1 Relieving the cast to accommodate the palatal vibrating line post dam14.2.2 How – and where – should the cast be relieved?14.2.3 Plasted-stone separators

14.3 Grinding to adjust the occlusion14.3.1 What is the correct way to adjust the occlusion?14.3.2 Which contact points are actually necessary?14.3.3 Which movements must be free from interferences?

14.4 Finishing and polishing14.5 Seating the pentures14.6 Remounting14.7 Instructions for care

Literature references

Glossary

Imprint

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The fabrication of complete dentures (schematic procedural diagram)

The manufacture of a complete dentures (schematic procedural diagram)

Anatomical impression Anatomical models Functional impression tray

Dentist

Upper model

Pouring the impressionand completing the anatomicalmodels

Fabrication of the functionalimpression tray made of selfcuring acrylic

Functional impression Functional models Bite rims

Dentist

Upper (UJ)

Dentist

Marking the functionalbonders on thefunctional impression

Trim model upto the marking

Fabrication of the bite rims onthe functional models

Mimetic movement(muscle trimming)

Bite recording Mounting on the articulator

Occlusalheight

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A B

DentistA: in the posterior areaB: in the anterior area

Tooth selection Setup of the teeth

Waxing Investing Packing and pressing

Male

Female

According to sex, type, jaw shape and colour

Try-in by dentist

Completed wax up investedBoil out SeparatorApplications

Polymerisation Finishing Final check

issue of the dentures

Dentist

Polishing

Time Temperature

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History

The subject of restoring human dentition haslong been of interest to man. Commonly in thepast and for various reasons, people lost theirteeth while still quite young. Probably vitamindeficiency played a significant role.

As can be seen from the following photographs,aesthetics was considered important in the early

stages of human development. In many culturesit was customary for people to alter and reshape their teeth by re shaping them in variousways. Also, decorative features such as gemsto-nes were fixed to the labial of anteriors asdepicted.

Those from the upper echelons of some socie-ties even had crude prostheses fabricated forthemselves. These were mainly for cosmeticreasons and not suitable as functional dentalprostheses.

In Etruscan times a broken natural tooth wasattached to adjacent natural teeth by means ofa gold band in order form a bridge and closethe gap.

In Roman times loose teeth were secured bysplinting them to adjacent teeth with goldwire.

History

Fig. 1: Female maxillaFrom: Raudales Malpaso Dam, Chiapas/Mexico

Fig. 2: Male maxilla preclassical period,From: Tepalcates/Mexico

Fig. 4: Carved ivory “ denture” showing the separationof teeth likely accomplished with the aid of a smallfret saw

Fig. 3: A “denture” carved from ivory.

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Of all the old “dentures” in museums aroundthe world, probably the most famous is thatmade for George Washington. In 1789 at theage of 57 he became the first President of theUnited States with just one remaining naturaltooth in his head! His subsequently fabricateddental prosthesis was made of ivory, humanand hippopotamus teeth. It served to addressa cosmetic purpose.The use of such materials continued to beused for cosmetic tooth replacement untilabout the end of the eighteenth century.

Around the turn of the nineteenth century,Nicolas Dubois de Chemant, (1753 – 1824) aParisian dentist, developed the first dentalprosthetic appliance from porcelain powder.This was a significant step towards the deve-lopment of the modern denture.

Gradually the techniques developed and refi-ned and led to the introduction of single firedporcelain teeth which could be set up andfinally attached to vulcanised rubber denturebase material. Vulcanised rubber was difficultto work with, it gave off a pungent odor in pro-cessing and was not particularly aesthetic.However, it ushered in the era where fullyfunctional dentures could be made.

The pioneering work began in 1924 when VitaZahnfabrik was founded by the industrialistHeinrich Rauter and Dr Carl Hiltebrandt, a den-tist. It was located in the city of Essen in thenorth of Germany. Amongst the earliest goalsof the enterprise was to significantly improve

the aesthetic appearance of artificial porce-lain teeth as they were less than lifelike atthat time. Vita developed the famous Vitalayering scheme which revolutionised theaesthetics and manufacture of porcelain teethat the time.

Dr Carl Hiltebrandt was not only a pioneer inaesthetics but also the first to recognise thatmandibular guidance is purely neuromuscular

Fig. 7: A vulcanised rubber denture from about 1920.The porcelain teeth were retained with gold coatedmetal pins.

Fig. 5: The fitting surface contouring and finishingrequired a high degree of skill.

Fig. 6: A full upper denture in vulcanised rubber withporcelain teeth,

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and not tooth guided as was the accepted phi-losophy. He certainly can be mentioned in thesame breath as a luminary like Prof Dr Gysiand others.

In addition and resulting from his observations ofintact natural dentition, no tooth – guided excursi-ons occur at all. Hiltebrandt also noted that theindividual patient carries out small regulatory con-trol movements and if the teeth contact their ant-agonists at all during mastication, they do so wit-hout force. Dr Hiltebrandt practised prostheticsaccording to the law of form and function. ie:form adapts to functional disturbance.

Hiltebrandt was no stranger to the setting of ante-rior teeth according to the requirements of aesthe-tic and phonetic principles. In this regard he wasavant – garde – and many years ahead of his time.In the fields of both prosthetics and ceramics, newworldwide standards were set by Vita.

In 1929 Vita reported for the first time that by clo-sely studying the natural, they had identified the24 most frequently occurring tooth shades. It wasthen decided to arrange them in groups accordingto their Hue in a Vita tooth shade sample guide.

Until this time shade taking had been based onthe single parameter of lightness. With the additi-on of a second parameter, grouping shades also

according to hue, made shade determination easier.

Vita’s shade sample guide was rapidly acceptedand became a standard in dentistry and dentaltechnology. As early as the 1930’s, atmosphericfiring of Vita porcelain for producing jacket crownswas taught in a programme of Vita professionaltraining courses which were attended by dentistsand technicians.

In the same period research into the field of toothcolours and various materials resulted in the dis-covery/development of the Lumin Effect. This wasalso applied and used to further improve the aes-thetic appearance of porcelain denture teeth parti-cularly under natural and artificial light conditions.

Porcelain denture teeth traditionally and prior toHiltebrandt were made of quite opaque, mono-chromatic porcelain and had a quite different

History

Fig. 9: Dr Carl Hiltebrandt

Fig. 10:

Fig. 8: Posterior teeth fused to platinum pins fromaround 1870

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appearance under incandescent light and daylight.(Vita museum / Luminoscope Re: Mr H Rauter)The Vita production method required at least twolayers of porcelain, enamel and dentine, in orderto achieve a natural shade effect.

The VITA LUMIN shade concept of the 1930’sformed the basis for the VITAPAN classicalshade guide which was vacuum fired and intro-duced in 1956. It remains in use today.

In the 1940’s the company moved from Essen toits present location of Bad Sackingen in the farsouth of Germany close by the Swiss border. Adecade on, the Vita Lumin Vacuum Teeth andVita Lumin Ceramic were developed. With theintroduction of the Lumin Vacuum Shade Guide,the Vita A1 – D4 shades were increasinglyaccepted and became entrenched worldwidefrom the 1970’s onwards.

In the early 1960’s Vita introduced the firstEuropean developed, porcelain fused to metalsystem, VMK (Vita Metall Keramik). Around thesame period came the introduction of Vitadur, aporcelain jacket crown material with increasedstrength characteristics (due to the inclusion ofAlumina Oxide particles). These developmentswere decisive in improving the quality andrange of individual restorations.Initially the Lumin Vacuum shade guide wasused only for ceramics and porcelain toothselection. However in 1983 Vita succeeded inintegrating acrylic resin and acrylic teeth intothis one shade system. With the introduction ofthe Vitapan system, it then became possible todetermine and reproduce tooth shades withboth materials using the one shade guide.

The next milestone was the introduction if theVITA SYSTEM 3D-MASTER in 1998, which is not

based solely on the observation of tooth sha-des.

For the first time in the history of tooth shadedetermination, Dr Neil Hall from SydneyAustralia succeeded in identifying and definingthe precise three dimensional “colour space”occupied by normal human dentition from theyoung to the elderly. This made possible thedevelopment of the 3D MASTER shades whichin addition to observation of the natural, arefirmly grounded in colour science (Physics).

The VITA Tooth guide 3D MASTER is the corre-sponding shade selection instrument. With theintroduction of the VITA Linear guide 3D-MASTER in 2008, the shade selection proce-dure was simplified even further.

With this new level of quality, tooth shadedetermination is no longer left to chance – it isa systematic procedure which when understoodand followed with use of the correspondingmaterials, produces accurate and reliable shadereproduction.

Decades of experience and expertise in toothshade determination were further augmentedwith the introduction of the digital shademeasuring device, the VITA EASYSHADE. Itssuccessor, VITA Easyshade COMPACT, offersthe user a cordless, mobile shade measuringunit and which records up to 25 differentmeasurements.

Acrylic denture base resins were developedduring the second world war. Due to their emi-nently suitable physical properties they havereplaced all other previously used materials. Intheir modern formulations they are still thematerial of choice today.

16 History

Notes

1


Anatomy

Anatomical terms of location (directional terms)

The complete denture prosthesis accordingto qualitative considerations

Patients Dental / Medical History

Preparatory working steps

Articulators and articulation theories

Model analysis

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Fig. 3: Topographical details of the interior of the maxilla1 Frontal process of the maxilla (processus frontalis)2 Anterior lacrimal crest (crista lacrimalis anterior)3 Infraorbital canal (canalis infraorbitalis)4 Infraorbital groove (or sulcus) (sulucus infraorbitalis)5 Anterior nasal spine (spina nasalis anterior)6 Infraorbital foramen (foramen infraorbitale)7 Zygomatic process (processus zygomaticus)8 Canine fossa (fossa canina)9 Alveolar foramina (foramina alevolaria)10 Infrazygomatic crest (crista infrazygomatica)11 Alveolar juga (juga alveolaria)12 Maxillary tubers (tuber maxillae)

1.3 The maxilla

The upper (maxilla) is a craniofacial bone. Itforms the floor of the eye sockets (orbits), thefloor and the side wall of the nasal cavity(cavum nasi) as well as a part of the palate,and hence the roof of the oral cavity (cavumoris proprium).

The maxilla also contains the maxillary sinuscavity.

1 Anatomy

1.1 The anterior teeth

Human dentition consists of twelve anteriorteeth (incisors), six lower and six upper. Thefunction of the anterior teeth is to bite off food.These teeth are relatively sharp, and are situa-ted in the anterior.

1.2 The posterior teeth

The posterior teeth are also referred to aschewing teeth or back teeth. These are cate-gorised into large and small posterior teeth,termed respectively molars and premolars. Thelarge molars, or back teeth, are the largestteeth of human dentition. The premolars, i.e.

the more frontal chewing teeth or small backteeth, are situated in front of the molars in thepermanent human dentition.

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Fig. 2:

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20 Anatomy

1.4 The mandible

The mandible consists of the horseshoe-shapedbody of the lower arch (mandibular corpus), andthe upwardly sloping mandibular ramus (ramusmandibulae) on either side. On these upwardsloping rami, a coronoid process is situated at

the temporal muscle insertion. Likewise situatedon both sides of the rising mandibular rami is thecondylar process with the mandibular head(caput mandibulae).

Fig. 4: Labial view of the mandible.1 Mandibular head (caput mandibulae)2 Mandibular collum (collum mandibulae)3 Coronoid process (processus coronoideus)4 Mandibular oblique line (linea obliqua mandibulae)5 Alveolar limbus (limbus alveolaris)

6 Tuberosities of the masseter (tuberositates massetericae)7 Alveolar juga (juga alveolaria)8 Mental foramen (foramen mentale)9 Mental tubercle (tuberculum mentale)10 Mental trigonum (trigonum mentale)

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1.5 The temporomandibular joint

The temporomandibular joint is situated directly infront of the outer ear canal (external auditory mea-tus). A distinction is made between the osseousand the fibrous part of the joint. This is a rotatingand sliding joint, which conveys the movement ofthe mandible in relation to the maxilla. The articu-

lating surfaces consist of the mandibular fossa(fossa mandibularis) and the mandibular head(caput mandibulae), which is located on the con-dylar process (processus condylaris) of the mandible.The mandibular fossa is situated directly in thesquamous part of the temporal bone (squama tem-poralis) and contains the articular tubercule (tuber-

culum articulare). With its posterior, downwardsslanted surface, the articular tubercle takes on theguidance of the mandibular condyle during theopening movement, and thus determines the con-dylar path.

The articular surfaces are coated with fibrocarti-lage. The articular disc (discus articularis) is loca-ted between the joint surfaces as a pressure dis-tributor consisting of the same substance. It divi-des the articular capsule into an upper and lowerjoint compartment. The articular cavity containsthe viscous, joint-lubricating (synovial) fluid, andis enveloped by the articular capsule (synovialmembrane); definition from Hoffmann-Axthelm's"Lexikon der Zahnmedizin" (a standard dictionaryof dental practice in Germany).

1.6 The tongue

The tongue is a mucous membrane-enveloped,highly mobile muscular organ, on which taste andtactile nerves are located. It is an important organfor food uptake during the process of mastication,for sucking and for the swallowing movements.

The tongue has great importance also for thespeech function, which is described in moredetail in the section on phonetics (Section 10.3).

The oral cavity is almost completely filled out by thetongue (take care when designing the denture base!).

The lingual frenulum is situated on the undersideof the tongue. This is subject to a great deal ofmovement by the chewing, swallowing andspeech functions.

For this reason, the frenulum must not be con-fined by a peripheral margin, and sufficient freespace must be left in the corresponding areas.

Fig. 5: Detailed view of the temporomandibular joint.1 Mandibular fossa (fossa mandibulae)2 Articular tubercle (tuberculum articulare)3 Articular disc (discus articularis)4 Articular capsule (capsula articularis)5 Condyle /mandibular head (condylus/caput mandibulae)6 Retroarticular process/ tympanic tubercle(processus retroarticulare/ tuberculum tympanicum)

7 Mandibular collum (collum mandibulae)

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Anatomy

1.7 The musculature

In the section entitled "Musculature" (section1.7), explanation is given only for the most ele-mentary muscles involved in the opening andclosing of the mouth and the wearing of comple-te dentures; further information can be found inthe corresponding literature.

Mouth-closing musclesThe important muscles with regard to themovement of the mandible can be classifiedinto the mouth-closing and mouth-openingmuscles.

The masseter muscle is a strong jaw-closingmuscle in the main direction of its fibres. Bymeans of its slanted fibres, it supports protru-sion and mediotrusion movements.

Due to its wide, fan like structure, the tempo-ral muscle can operate in different directionsof force. The main directions are upwards, dor-sally and somewhat anteriorally.

Mouth-closing and mouth-opening musclesThe medial pterygoid muscle, due to its identi-cal direction of operation, pulls in the samedirection as the masseter muscle. This cansupport both mediotrusion and protrusionmovements.

The lateral pterygoid muscle has two heads ofmuscle. During a closing movement, the upperhead is active. The shortening of the lowerhead causes the protrusion and/or laterotru-sive movement of the mandible.

Fig. 6: Differentiated structure of the dorsum of the tongue.1 Epiglottis2 Tongue root (radix linguae)3 Palatal tonsils (tonsilla palatina)4 Lingual tonsils (tonsilla lingualis)5 Lingual foramen caecum (foramen caecum linguae)6 Terminal sulcus (sulcus terminalus)7 Vallate papilla (papilla vallatae)8 Lingual dorsum (dorsum linguae)9 Lingual margin (margo linguae)10 Medial lingual sulcus (sulcus medianus linguae)11 Lingual apex (apex linguae)

In addition to the nerve ends responsible for thesense of, also different types of papillae bymeans of which the four different taste char-acteristics (sweet, sour, salty and bitter) can allbe perceived, are located on the underside of thetongue.

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Muscles of the floor of the mouthThe muscles of the floor of the mouth comprisethe mylohyoid and geniohyoid muscles.

The mylohyoid muscle is involved in the openingof the mouth, firmly holds the hyoid bone, and isresponsible for raising the floor of the mouthduring the act of swallowing. During this time,the tongue is able to seal off the oral cavityagainst the palate.

The geniohyoid muscle is also involved in the pro-cess of opening the mouth. It furthermore liftsand holds the hyoid bone in position.

Cheek musculature /mouth-closing musclesThe buccinator muscle is certainly an impor-tant muscle with regard to a dental prosthesis.Through the application of pressure to the

cheek, it serves to empty the vestibular area ofthe mouth.

The orbicularis oris muscle is the mouth-closingsphincter muscle that encircles the mouth.

1.8 Bone and arch atrophy

In both the upper and the lower arch, the boneatrophies following the extraction of teeth.The upper arch atrophies centripetally(inwardly), the lower centrifugally (outwardly).This not seldom leads to problems of denturestability, which can be overcome by consistentimplementation of the concept chosen for theparticular case.

Fig. 8: Diagram showing the course of arch atrophy.

Fig. 7: Musculature pertaining to the mandibular movements.1 Temporal muscle (musculus temporalis)2 Lateral pterygoid muscle (musculus pterygoideus lateralis)3 Medial pterygoid muscle (musculus pterygoideus medialis)4 Masseter muscle (musculus masseter)

U

L

upper

lower

24 Anatomy

Notes

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Anatomy





Articulation and articulation theories

Model analysis

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2 Anatomical terms of location (directional terms)

2.1 The directional terms

anterior = front, towards the front, forwardsapical = on, towards the apex (root tip),

towards the rootapproximal = on, towards the contact

surface, towards theapproximal (interdental) space

basal, basally = on, towards the (denture) basebuccal, buccally = on, towards the cheek,

cheekwardscervical, cervically = on, towards the cervix

(tooth neck), towards the cervixcoronal, coronally = on, towards the tooth crowndistal, distally = away from the centre of the

dental arch, away fromthe centre (towards the backof the dental arch)

dorsal, dorsally = towards the backfacial, facially = towards the facefrontal, frontally = towards the foreheadgingival, gingivally = towards the gingivaincisal, incisally = towards the incisal edgelabial, labially = towards the lip

lateral, laterally = towards the side,at/on the side

lingual, lingually = towards the tonguemastical = towards the masticatory

(occlusal) surfacemarginal, marginally = towards the marginmesial, mesially = towards the centre of the

dental arch, towards the centreocclusal, occlusally = refers to the masticatory

surfaces of the posteriorsoral, orally = towards the mouth, within

the dental archpalatal, palatally = towards the palateposterior, posteriorly = towards the back,

backwardssagittal, sagittally = from the front towards

the back in the direction of thesagittal suture (connectivetissue joint

transversal, transversally = running acrossvestibular, vestibularly = towards the vestibule,

outside the dental archcentral, centrally = situated in the centre

distal

mesial

palataland oral

bucc

al

facial or labial

vestibularbuccal

Upper jaw

approximal

lingual/oral

bucc

alve

stibu

lar

facial or labial

buccal

Lower jaw

Fig. 1: Directional terms in the upper arch. Fig. 2: Directional terms in the lower arch.


2.2 Angle's bite classification(Angle Classes)

Bite classification according to Angle is basedon the mesiodistal positional relationship ofthe first molars.

According to this classification, anomalieswith a neutral bite are also in Class I.

Anomalies with a distal bite belong to Class II(this has two subtypes: Class II Division 1 forcases with protruded upper anteriors, andClass II Division 2 for cases with retrudedupper anteriors or deep bite).

All other anomalies belong to Angle Class III.This classification has some disadvantages,although it is the most frequently used andmost widespread method of bite classification.

Angle Class I occlusion(Normal occlusion or neutral occlusion)The distobuccal cusp of the first lower molar issituated in the central fossa of the first uppermolar.

Angle Class II occlusion(distal occlusion)The first lower molar is positioned too far distal-ly in relation to the first upper molar.

Angle Class II/1 occlusion (syndrome: distal bite)Distal occlusion with protruded upper anteriors,mostly featuring mandibular retrusion with a nar-row maxilla, a high palate, a deep bite and anenlarged sagittal (horizontal) overbite.

Angle Class II/2 occlusion(syndrome: covering bite)Distal occlusion with steeply sloping upper ante-riors (the lateral incisors often overlap the centralincisors from an anterior), perspective mostlyfeaturing a retruded mandibular position with awide, box-shaped maxilla and a deep bite.

Angle Class III occlusion (mesial occlusion)The first lower molar is positioned too farmesially in relation to the first upper molar.Fig. 2: Angle class I occlusion.

Fig. 3: Angle class II/1 occlusion.

Fig. 4: Angle class II/2 occlusion.

29

vestibularbuccal

lingual

Fig. 5: Angle class III occlusion.

Fig. 6: Normal occlusion. Fig. 8: Crossbite.

Fig. 7: Edge-to-edge bite

Angle Class III occlusion (syndrome: progenia)Mesial occlusion with an inverted anterior over-bite (often with protruded upper anteriors andretruded lower anteriors by way of compensation);mostly accompanied by a crossbite in the poste-rior area, a large chin and a shallow mentolabialfold.

2.3 Types of bite

2.3.1 Normal occlusion

When the palatal cusps (working cusp) of themaxillary teeth bite into the fossae of themandibular teeth, this is said to be in "normalocclusion" (fig. 6).

2.3.2 Edge-to-edge-biteWhen the cusps of the mandibular teeth biteonto those of the maxillary teeth, this is refer-red to as an edge-to-edge bite (fig. 7).

2.3.3 CrossbiteWhen the buccal cusps of the lower posteriorsprotrude vestibularly beyond those of the upperjaw, this is said to be a crossbite (fig. 8).

vestibularbuccal

linguallingual

vestibularbuccal

8 7 6 5 4 3 2 1

8 7 6 5 4 3 2 1


Fig. 9: Scissors bite.

buccalvestibular

lingual

2.3.4 Scissor biteWhen the palatal cusps of the upper jaw extendbeyond the buccal cusps of the lower jaw vesti-bularly, this is referred to as a scissor bite (fig. 9).

2.4 Human dentition

2.4.1 Anterior teethCentral incisors (centrals) (1) = the middle

incisor (cutting)teeth (1)

Lateral incisors (laterals) (2) = the lateral incisor(cutting) teeth (2)

Canines (3) = the canine teeth(corner teeth) (3)

(also called cuspids or eye teeth).

2.4.2 Posterior teethFirst premolars (4) = the first posterior

teeth (4)Second premolars (5) = the second posterior

teeth (5)First molars (6) = the first chewing teeth (6)Second molars (7) = the second chewing

teeth (7)Third molars (8) = the third chewing teeth (8)(also referred to as wisdom teeth).

2.5 Classification of cusps

2.5.1 Working cuspsThe working cusps in the upper are the palatalcusps, and in the lower the buccal cusps.These are also called shearing, centric or sup-porting cusps.

2.5.2 Shearing (non-working) cuspsThe shearing cusps in the upper are the buccalcusps, and in the lower, the lingual cusps. They areresponsible for the shearing of food. The shearingcusps are also referred to as balancing cusps ornon-working cusps.

2.6 FDI tooth notation system

The following two-digit system (FDI tooth nota-tion) for the classification of the individual teethhas become established internationally. The firstdigit denotes the corresponding quadrant, 1 – 4 inpermanent, or 5 – 8 in deciduous dentition (upperright = 1, upper left = 2, lower left = 3, lower right= 4), and the second digit is the number referringto the position of each tooth in the respectivequadrant (cf. fig. 10):

Fig. 10: The names of the teeth.

31

2 3 6

5 4 2

8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8

8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8

18 17 16 15 14 13 12 11 21 22 23 24 25 26 27 28

48 47 46 45 44 43 42 41 31 32 33 34 35 36 37 38 3 4 5

2.6.1 Zsigmondy system of tooth notationThe system suggested by Zsigmondy, in whichevery tooth is numbered consecutively from thecentral incisor (1) to the third molar (8), is basedon the Zsigmondy cross to record quadrants oftooth positions. The respective teeth are ent-ered in the corresponding quadrants, with thefollowing result:

Lower right Lower left

Fig. 12: Zsigmondy tooth notation.

Fig. 13: Notation according to a Zsigmondy cross.

Fig. 11: FDI tooth notation.

Note:The left-hand side of the patient is the right-hand side from the dentist's point of view. Theright-hand side of the patient is the left-handside from the dentist's point of view.

The diagrams of the respective tooth nomencla-ture systems are based on the dentist's point ofview.

2.6.2 Haderup system of tooth notationThe tooth notation according to Haderup de-scribes the teeth in the upper with a plus sign(+) on the mesial side, i.e. the upper left cani-ne, for instance, would be +3, and the upperright canine 3+.

In the lower a minus sign (-) is used instead ofa plus sign on the mesial side. This means that-4 denotes the first lower left premolar, and 4–the first lower right premolar.

When referring to deciduous teeth, a zero (0)is placed in front of the digit referring to thetooth.

Fig. 14: If only one quadrant is affected, only the anglerepresenting the corresponding quadrant is depicted.

Upper right Upper left

Lower left

Upper leftUpper right

Lower leftLower right

Lower leftLower right

32

1

2

3

4

1 Frankfort horizontal plane

2 Camper's plane

3 Occlusal plane

4 Simon's orbitals


• the contact point of the incisal edges of thelower central incisors (incisal point),

• the tips of the distobuccal cusps of thesecond lower molars.

This is mostly situated at the height of the lipclosure line.

2.7.4 Simon's orbital plane (4):Plane running through the orbit at right anglesto the Frankfort horizontal plane; is used fordetermining sagittal variations.

2.7.5 Median plane:Divides the body into left and right halves.

2.7 Planes and lines of reference

Definitions

2.7.1 Frankfort horizontal plane (1):A craniometrical reference plane established bythe lowest point on the margin of the right orleft bony orbit and the highest point in the mar-gin of the left or right auditory meatus.

2.7.2 Camper's line (2):An imagined plane through both tragus pointsand the spina nasalis anterior (anterior nasalspine). This runs parallel to the occlusal planeand forms an angle of 15 – 20 ° to the Frankforthorizontal plane.

2.7.3 Occlusal plane (3):This is represented by the following threepoints on the dentulous anch:

Fig. 15: Planes and lines of reference relating to the human skull.

33

2.8 Curves of occlusion

2.8.1 Curve of Spee(sagittal compensation curve)

The curve of Spree has an arch-shaped pro-gression in the sagittal direction (sagittalocclusion or compensation curve).

The imagined centre of the circle is situated inthe orbit. The radius is approx. 7 cm, andunder ideal conditions touches the anteriorsurface of the condyle. This system is used incomplete denture prosthetics under theassumption that 1. The condyle is situated onthe same circular path as the posteriors, and2. The posteriors remain in constant contactduring protrusive movement.

2.8.2 Curve of Wilson(transversal compensation curve)

The curve of Wilson is represented by a lineconnecting the cusps of the lower posteriors inthe transversal direction. Its progression isdetermined by the fact that the lingual cuspsare situated at a lower height than the buccalcusps.

2.8.3 Curve of MonsonThe curve of Monson is based on the curve ofSpee in the sagittal direction and the curve ofWilson in the transversal direction. This givesrise to a 3-dimensional spherical curvature(sphere of Monson), a spherical surface onwhich the posterior teeth are arranged.

Fig. 16: Curve of Spee.

Fig. 17: Curve of Wilson.


Notes

3


Anatomy

Antatomical terms of location (directional terms)





Model analysis

37


There are numerous ways of fabricating com-plete dentures. In order to achieve the bestsolution for the patient that corresponds to themaximum result obtainable in both aestheticand functional terms, there must be no devia-tion or error in the entire procedural chain.Objectively speaking, these boundaries arefluid. This means that the patient will, in allprobability, also manage perfectly well with75% (or maybe less, depending on the case) ofthe target 100%. How could it otherwise beexplained that all over the world, completedentures are in use, and even "function", alt-hough they do not even come close to the dif-ferent setup concepts represented, or to thecorresponding assumptions on which they arebased? This insight, however, must not lead toless care being exercised in the dental labora-tory, but rather provide the motivation toachieve a result that comes somewhat closerto the ideal 100%. In practice, however, 100%has already been achieved when the criterialisted below are fulfilled and the patient ishappy with his or her dentures.

• The patient should have unlimited ability tocomminute food.

• A well-comminuted/well-masticated foodbolus represents the first and most essen-tial stage of the digestion process.

• Complete dentures should enhance the pho-netic function.

• Both the teeth setup and the design of thegingival area should be age-related, andsuited to each individual patient.

• The patient should regain his or her originalquality of life to the greatest extent.

• The complete dentures should, if possible,match the physiognomy of the patient.

• The design should facilitate easy accep-tance of the dentures in the mouth as aforeign body.

• The dentures should by hygienic and easy tokeep clean.

• The patient's dentures should boost his or herself-confidence.

Consequently, it is impossible to fabricate com-plete dentures that fulfil the above mentionedcriteria using unsatisfactory materials. Thesame applies to each working step in the proce-dural chain, independently of whether thesesteps are carried out by the dentist or the den-tal technician. Each step makes a contributionto the success or failure of the end result. This iswhy collaboration, partnership and the clear andseamless exchange of information betweendentist and dental technician are prerequisitesfor successful treatment. To a great extent, therelative importance of complete denture pros-thetics is not sufficiently appreciated. Com-plete dentures require a particularly highdegree of professional skill on the part of den-tist and dental technician alike. The patienthistory serves as a guideline for the key aspectsof treatment. Careful implementation is decisi-ve for the peripheral fit of the finished dentu-res. Denture wearers who present for treat-ment with several poorly fitting dentures are anotable indication of existing problems. Sowhat is stopping us from acting on this evi-dence?

The correct functional design of the individualimpression trays is essential for a successfulrestoration. The correct determination of thecentric relation is a further essential criterion.Without the correct centric position, the willresult be among other things, in unstable den-tures.


Each case requires careful analysis; this deter-mines the setup concept most appropriate to thecase. For more details, please refer to section12.1 "Setup concepts".

An essential factor is the alignment of the waxbite rims with reference to Camper's plane, andthe indication of the position and length of theanterior teeth. In addition to this, the midline,the smile line and possibly the canine line (cen-tre of the canines) must also be marked on themodel. The vestibular expansion for cheek con-tact can be formed with wax.

This gives the technician, in addition to thefunctional impression, all the necessary informa-tion in order to obtain faultless dentures.

The implementation of this information by thedental technician is essential. In this respectnothing should be left to chance, as it is not pos-sible to later rectify such omissions.

The quality of the restoration is a result of theconsistent implementation of every individualworking step.

39

Notes


Notes

4


Anatomy






Model analysis

43

4 Patients Dental / Medical History

Which criteria are importantfor the dental technician?

With regard to the patient input, it is worth in-vesting more time in this than is generally thecase. A great deal of important information isrevealed by patients themselves; the attentivedental practitioner takes note of this. It is oftenthe little things that can make the differencebetween success and failure. When the patientcomplains, for example, that his old dentureshampered him in some way or another, this canbe taken into account and improved accordin-gly in the making of the new denture. In thisway, one thing leads to another. What mattersis that the patient is able to "experience" orfeel this progress.

The information communicated by the dentistto the dental technician should include the fol-lowing:• Surname and first name of patient• Date of birth• Length of anterior teeth, measured with thepapillameter (ideally before fabricating thewax rims)

• Lip length, measured with the papillameter(ideal before fabricating the wax rims)

• Current position of the central incisors in

relation to the incisal papilla (e.g. too fartowards anterior? Too far towards posterior?)

• Width of the nasal wings (determination ofanterior width according to Lee)

• Appropriate tooth characteristics• Tooth shade• Contour of the nasal base line• Skeletal jaw situation• Information on phonetics (e.g. difficulty inpronouncing the "s" sound, etc.)

• Statements/information given by patient• Additional information on the patient• Further comments• Description of patient's general state ofhealth

If, for instance, a patient has muscular hyper-activity, it is essential to take this into accountin the prosthetic planning of the occlusion con-cept and the posterior tooth selection withregard to the occlusal design.

The better the collaboration between patient,technician and dentist, the more satisfactory theend result will be for the patient. And in turn,successful teamwork motivates all involved.

44 Anamnesis

Notes

5


Anatomy






Model analysis

47

5 Preparatory work steps

5.1 Custom made impression trays

Impressions taken with custom made traysserve to fine tune the primary impressionstaken using stock impression trays. During thesecondary impression taking, it is important toreproduce as precise an impression of thepatients tissues as is possible. Care must betaken in regard to registration of the variousmuscle ligaments and maintaining as uniformthickness of impression material as possible.The customised tray must extend only to thoseparts of the mucosa which provide osseoussupport.

The aim of the functional impression is to maxi-mize the rest area of the denture base takingthe musculature functions into consideration. Itis also essential to obtain retentive suction bet-ween the denture base and mucosal tissue.This is achieved by means of cohesive andadhesive forces acting within a peripherallysealed border. In order to maintain this suctioneffect during speech and masticatory function,it is necessary to have a well muscle trimmedperiphery to provide the necessary seal. Prior tosecondary impression taking the denturebearing tissue must be in a” recovered “ state,ie: the previous denture must not have beenworn for at least 24 hours.

Prior to making custom impression trays on theprimary models, the dental technician shouldbe informed concerning the viscosity and / or,flowability of the impression material to beused, so that he can provide relief in particularareas of the model or a spacer if considerednecessary.

Materials with low viscosity require an accura-tely fitting tray and materials with a high visco-

sity may require a spacer between the tray andmodel on which they are made.

Most important is that the tray be rigid and notat all flexible.

Note:Be careful with impression tray materials thatmay be dimensionally unstable and not suffi-ciently rigid !

5.1.1 ExpanseThe expanse of customised trays should besmaller than the future denture bearing area.Sufficient clearance for muscle trimming mustbe left around the lip, cheek and tongue tendons.

The borders of the tray are trimmed so as not toextend quite as far as the final periphery of thefinished denture.

In the post dam area the tray should extend 2 mmbeyond the subsequent finish line of the denture.

The borders of custom trays should have a uni-form thickness of about 2 mm.

Fig. 1: Upper and lower custom trays on primary models

48 Preparatory working steps

5.1.2 Impression tray handleImpression tray handles must provide lip sup-port during impression taking but must nothinder lip and tongue function.

Handles must be designed symmetrically andserve as a locating guide for the dentist to cor-rectly position the tray in the mouth. The handle

must be grippable so that the impression canbe easily removed from the patients mouth.

The lip and cheek tendons are exposed in sucha way that they are not distorted by theimpression tray (see Fig. 5 + Fig. 6).

During the secondary impression taking proce-dure the periphery of the tray is lined with athermoplastic reversible but rigid material(Compound/greenstick). This facilitates themuscle trimming procedure and is the firststage in establishing the peripheral seal. This

muscle trimming is progressively carried outuntil the entire periphery is completed. Finallythe impression material is added to the trayand the final impression is obtained. This finalperiphery must be maintained throughout theremaining denture construction procedures asit provides the seal for the suction which isessential for retention of the denture.

5.2 Bite registration rims (bite blocks)

Bite blocks are necessary for the dentist to esta-blish the upper and lower centric relationship.Preferably they should be made of an acrylicbase with attached wax rims. The wax should beof a firm consistency.

It is also possible to use a wax instead of anacrylic base but this is recommend against as arigid, well fitting base of acrylic provides muchgreater stability and also significantly more con-trol for this most important procedure.

The peripheral border is most important. It mustnot be over extended nor have any sharp edges.The wax bite rim should be positioned on thecentre of the alveola ridge. The occlusal planeruns parallel with the upper alveola ridge. Thesame progression is limited in the lower by theupper third of the retromolar triangles.

In both upper and lower anterior areas both biteblocks can be bulked out by the dentist to obtainthe desired degree of lip support.

The height of the individual bite rims – measu-red from the mucolabial fold – is reduced toobtain a measurement of, 20 – 22 mm for theupper and 18 – 20 mm for the lower.

Fig. 2: Oral view of impression tray handle.

Fig. 3: Labial view of impression tray handle.

49

Research has demonstrated that these are theupper limits. Dentists generally prefer to remo-ve rather than have to add wax.

The most important points are as follows:

• The anterior regions of bite rims are notbulky and allow for maximum tongue space.

• The design of the bite block periphery mustaccommodate the functional muscles.Tendons and muscle attachments must beexposed.

• The labial and buccal extensions shouldcorrespond with that of the finished dentu-res. The width of the wax rims should beabout 6 mm in the bicuspid areas and about8 mm in the molar areas.

• The wax rims should be positioned on thecentre of the alveola ridge. An exception canbe made in the upper anterior region wherethe wax rim is positioned to accommodateaesthetic considerations. The bite rim canbe more towards the anterior to provide lipsupport corresponding with the anteriortooth set up.

• The incisal edge of the upper centrals shouldbe situated aprox 7 mm anterior of the inci-sal papilla (See fig 8).

Fig. 8: Upper bite block.

Fig. 4: Labial view of upper and lower bite blocks.

Fig. 7: Buccal view of upper and lower bite blocks.

Fig. 5: Upper base plate.

Fig. 6: Lower base plate.

50

• The height of the upper wax rim should beapprox 20 – 22 mm measured from themucolabial fold in the area of the lip tendon,to the upper limit of the wax rim.

• The height of the lower wax rim should beapprox 18 mm measured from themucolabial fold, in the area of the liptendon, to the upper limit of the wax rim.The distal height of the upper and lower canbe adjusted by softening of the bite rim witha rim former.

• The distal height should correspond with theupper third of the retromolar triangle.

• The flattened wax surface of the upper andlower bite rims should fit neatly together.

• The total height of the bite blocks should notexceed 40 mm.

Final countouring of the bite rims is usuallycarried out by the dentist in the patientsmouth.

The dentist aligns the occlusal plane to thepupil line and Camper's plane using the bitefork. He also builds up the buccal area withwax until optimum cheek contact is reached.

All such information is required by the dentaltechnician and can be recorded by means of aplaster or silicone key. This enables continuouschecking during the setup as to whether cheekcontact according to the wax bite record is cor-rect or otherwise.

Dentist markings on the bite registrationblock.

Midline, middle of faceThis line is not necessarily identical to theupper and lower lip tendons or the midline ofthe model.

Canine lineThis determines the width of the upper ante-riors, also where the tips of the canines are tobe positioned. Also, their positioning can bedetermined on the basis of the corners of themouth or a vertical extension of the outer nasalwings.

Smile lineThis is decisive for the length of the upperanteriors. The tooth necks should normally beabove this line.

Occlusal planeIt follows the upper edge of the lower wax biterim. ie: between the lower incisal edges in theanterior area and the distobuccal cusps of thelower second molar. It intersects the midlinewhich is the fix point for the incisal pin, andruns parallel with Campers line.

Fig. 9: Lower base plate with wax bite rim.


51

5.3 Model fabrication

For full denture secondary models we use aclass 1V hard stone. In a case with severeundercuts in the alveola ridge, a class 111 hardstone can be used. Regardless, it is essentialthat the functional periphery area of themodels remain intact.

For this purpose we attach a strip of adhesivewax to protect the peripheral area.

In order to maintain the stone’s physical pro-perties, it must be mixed under vacuum in theprescribed water powder ratio. The pouring ofthe model must be bubble free.

The functional periphery area shows:

In the upper:• The mucolabial fold• The alveolar ridge with the areas of themaxillary tuberosities and palate

• The transition from hard to soft palate and(post dam area)

• The lip and cheek tendons

Lower:• The alveolar ridge with the areas of theretromolar triangle

• The mucolabial fold and sublingual areas• The muscle and tendon insertionsof the tongue and cheek musculature

• The lip and cheek tendons

When manufacturing the functional models, itis essential to ensure that the functional mar-gins remain completely intact. This is becausethe functional margins form the valve borders(marginal seal) of the area in which a suctioneffect between the denture basis and the oralmucosa is created.

Fig. 10: Dentist’s markings on the models and bite rims. Fig. 12: Lower stone model.

Fig. 11: Upper stone model.

Smile line

Occlusal plane

Canine line

Midline


5.4 Mounting of models in the articulator

Correct determination of the centric relations-hip of the upper and lower arch is essential forthe functional success of complete dentures.

It is the method for the three dimensionaldetermination of the positional relationship ofupper and lower arches. It is achieved bymeans of the bite blocks and the resulting biterecords.

For this purpose, the condylar joints should bein their cranial and not their laterally shiftedpositions in the articulator fossae.

A distinction is made between:

1. The relationship of the lower to theupper (maxillomandibular relationship)This refers to the definition of the transver-sal and sagittal relationship.

The vertical dimension ( occlusal height) isgenerally 2 – 5 mm less than the interocclu-sal distance between the upper and lower.The transversal and sagittal relationship isdetermined with the aid of a gothic arch orby manual bite taking.

2. Position with reference to a cranialplaneCorrect determination of the upper andlower arch relationship is essential for themounting of the models on the articulatorwith reference to a cranial plane. The cra-nial orientation of both upper and lowermodels is transferred to the articulator bymeans of a face bow. If a face bow readinghas not been taken, an elastic band can be

used to represent the Camper’s line andBonwill triangle for the purpose of mountingof the models. For this purpose the dentistmust first intraorally align the wax bite rimsto the Camper’s line.

5.5 The vertical dimension

The vertical dimension is determined chairsideby the dentist. Any modification to this dimen-sion can have significant consequences. If inany doubt however, it is preferable to reduce thevertical dimension rather than increase it.

The vertical dimension naturally has a greatinfluence on the function and the Freway Spaceof the prostheses.

A patient with Angle Class 2/Division II occlu-sion will certainly require more Freway Spacethan a patient with Angle Class 1. In figures, theapproximate values for the speaking distance(e.g. for the pronunciation of "s" sounds) is asfollows:

Overbite: 2 – 3 mmEdge-to-edge bite: 1 mmCover-bite: 4 mm

53

Notes


Notes

6


Anatomy


The complete denture prosthesis accordingto qualitative criteria




Model analysis

57

In order to produce complete dentures, it isnecessary to have a device which simulates theopening and closing movements of the mouth,the lateral and protrusion movements as well asthe retrusion movements. A device which carriesout such movements is described as a chewingsimulator, or, an articulator.

6.1 Classification of articulatorsaccording to their design

6.1.1 Arcon articulatorsAn arcon articulator is a mechanical devicewhich imitates the natural temporomandibularjoint.

The condylar casings are situated – similarly tothe TMJ – on the upper part of the articu-lator,and the condyles are attached firmly to thelower part of the articulator. The advantage ofthis type of articulator is the unidirectionalmovement, as with natural chewing apparatus.

Examples: Denar, MarkII, New Simplex,Panadent, Protar, Quick-Perfekt, SAM, Stuartetc.

6.1.2 Non-arcon articulatorsIn contrast to the arcon articulator, the condylarcasings are situated on the lower part of the arti-culator and the condyles on the upper part. Allmovement sequences are made in the oppositedirection to the natural temporomandibular joint.

Examples: Atomic, Atraumatik, CandulorArticulator, Dentatus, Condylator, Mastikator,Rational.

6.2 Classification of articulatorsaccording to the type of movementthat can be made

6.2.1 Average value articulatorsThese articulators correspond to Bonwill's tri-angle, and the inclination of the condylar pathis taken to be a fixed value. Masticatory move-ments can therefore only be carried out on anaverage value basis.

Average value inclination of condylar path: 34°Average value Bennett angle: 15°

6.2.2 Semi-adjustable articulatorsThese allow different values to be set such asthe inclination of the condylar path, theBennett angle and in some articulators, theintercondylar distance.

6.2.3 Fully adjustable articulatorsThese articulators reproduce individual valuesobtained using an extraoral or an intraoral regi-stration procedure.

The aim of articulation theory is to interpretthe existing anatomical conditions of the eden-tulous patient with the physical and mechani-cal conditions of the dynamic chewing systemin such a way that feasible solutions for thepractical fabrication of complete dentures canbe developed.

Literature on the subject offers various exam-ples with explanation's as well as practicalworking instructions.

6 Articulators and articulation theories

58

6.3 The various movements of themandible are defined as follows

6.3.1 ProtrusionSymmetrical Anterior movement of the lowerjaw out of the position of maximum intercus-pation towards anterior.

6.3.2 Laterotrusion (working movement)The mandible moves sideways (laterally) out ofthe position of maximum intercuspation.

6.3.3 Laterotrusion side (working side)Moves away from the centre during lateralmovements.

6.3.4 Mediotrusion (balancing movement)The mandible moves out of the position ofmaximum intercuspation towards the centre.

6.3.5 Mediotrusion side (balancing side)The side of the mandible which is movedtowards the centre during lateral movements.

6.3.6 RetrusionThe mandible is moved backwards anddownwards (posteriorly and down) out of maxi-mum intercuspation.

6.3.7 RetractionMovement of the mandible out of the protru-sion position back into maximum intercuspation.

6.3.8 Laterotraction (lateral retraction)Movement of the mandible out of laterotrusioninto maximum intercuspation.

6.3.9 Bennett angleThe Bennett angle is formed by the condylarpath of the mediotrusion side (fig. 1, from M1

to M2) and a line parallel to the median planeduring lateral movement. It varies between 10°and 20°. Average value 15°.

6.3.9.1 Bennett movementThe lateral and spatial shifting of the laterotru-sion condyle in an outward direction. Duringlateral movement: fig. 1, from L1 to L2.

The mediotrusion condyle accordingly movesmore towards the centre. The lateral move-ment of the working condyle normally variesbetween 0.6 mm and 1.5 mm (Lundeen et al.1978, Wirth 1996).

Diagrams show that the working condyle is notonly moved in the lateral direction; its move-ment can also include a superiorly, inferiorly,anteriorly or posteriorly directed component.

The condyle can here carry out movements inthe following directions:

superior = sideways (laterally) and upwards(laterosurtrusion)

inferior = sideways (laterally) anddownwards (laterodetrusion)

anterior = sideways (laterally) and forwards(lateroprotrusion)

posterior = sideways (laterally) and backwards(lateroretrusion).

In the absence of further information from thedentist, the average value for dentulouspatients is taken to be 15° and for edentulouspatients 20°.

The size of the movement has an influence onthe Bennett angle.


α L1 L2

M1M2

59

Fig. 2

Fig. 1

Fig. 4: An elastic band is used to form the boundary of theBonwill triangle. This corresponds to the occlusal plane.

Fig. 3: Boundary of the Bonwill triangle.

6.4 The Bonwill triangle

The Bonwill triangle is represented by an equi-lateral triangle that runs from the mandibularcentral incisal point to the centre of the rightand left condyles (fig. 2).

The intercondylar distance is consequently equal tothe distance from the condyle to the centre of thelower central incisors (incisal point). The length ofone side of the triangle is approximately 10.5 cm(fig. 3).

Mounting the models in the articulatorPreparation: Locating grooves are made in thebase of maxillary and mandibular models witha plaster cutter, so they can be remounted afterthe dentures are completed. There are manydifferent systems which available for this pur-pose.

The ideal is to use a Split Cast, which enableseven the most minor deviations to be recognisedafter completion of the denture, and to rectifyor correct these accordingly.

If a face bow is not used for mounting, themodel pairs can be placed according to avera-ge values in the Bonwill triangle.

This requires an elastic band and an incisal pin(fig. 4).

60 Articulators and articulation theories

Notes

7


Anatomy


The complete denture prosthesis accordingto qualitative criteria




Model analysis

4

12

6

7

3

5

1

3

5

4

2

6

63

The purpose of model analysis is to assess theprosthetic situation.

No human being is symmetrical. This meansthat the goal cannot be to achieve maximumsymmetry in the model analysis markings.Instead, each side must be assessed independ-ently of the other and marked or characterisedby means of the lines sketched on the model.These lines serve as a guideline for the sub-sequent wax setup of the denture teeth.

From the point of view of statics however,functional stability is not automatically gua-ranteed in the resulting setup. These linesrepresent a guideline. Every complete denturemust be checked intraorally for chewing sta-bility by the dentist.

The dentist's markings on the model show• the centre of the alveolar ridge, transferredto the margin of the model with the aid of aset square,

• the progression of the alveolar ridge withthe aid of a pair of compasses on the modelbase,

• the retromolar triangle on the mandibularmodel.

Fig.1: Upper jaw1 Incisal papilla (papilla incisiva)2 Large palatal ridge3 Centre of alveolar ridge4 Midline of model5 Maxillary cusp (tuber maxillaris)6 Palatal vibrating line7 Canine point

Fig. 2: Lower jaw1 Retromolar triangle (trigonum retromolare)2 Centre of alveolar ridge, front3 Centre of alveolar ridge, lateral4 Midline of model5 Border line (setup limit) for the distal sides of the last molarsThe deepest point in the posterior area is also markedon the model base.

If the height of the occlusal plane is not given,this can be calculated as an average value bymeasuring the distance between the deepestpoint of the mucolabial fold in the upper andlower jaw, and halving this value.

The final setup line is determined by determi-ning the alveolar ridge markings and transfer-ring these to the outer margin of the model atthe front and back. These form the outer limitof the static field.

Furthermore, the following values which thedentist indicated on the bite template aretransferred to the models: midline, canine line.

7 Model analysis

64

1

23

4

5

Stopp-Linie

Tiefster Punkt =Position der größtenKaueinheit

Model analysis

If the inclination of the interalveolar line to thehorizontal plane (4) is over 80°, a neutral biteshould be set up; if it is under 80°, a cross-biteshould be set up (Gysi).

Behind the border line for the distal sides of thelast molars begins the steep upward slope ofthe mandibular ramus. No more teeth should beset up here, as this would result in the pros-thesis slipping forwards (proglissement).Constant forward sliding of the mandibularprosthesis would result in age-related mandibu-lar protrusion. In the case of flat alveolar ridges,the setup of the teeth ends at the mesial of theretromolar triangle.

Fig. 3:1 Centre of alveolar ridge of upper jaw2 Interalveolar line (alveolar ridge connecting line)3 Occlusal plane4 Maximum innermost setup limit for lower teeth5 Centre of alveolar ridge of the upper

Fig. 4:

Border line (setup limit) for thedistal sides of the last molars

Deepest point = Position ofthe largest chewing unit,(i.e. pair of molar antagonists).

65

Notes

66 Model analysis

Notes

8


Tooth selection

Functional stability

Anterior teeth

Aesthetics

Setup and function

Facts on the denture base

Denture finishing

69

8.1 Tooth selection based on patient'soffspring

Tooth selection based on the teeth of thepatient's descendants or children has often pro-ven helpful. If, for example, a female patientcomes to the practice with her daughter, or a

8 Tooth selection

Fig. 2: Father and son.Fig. 1: Mother and daughter.

male patient with his son who has his/her ownnatural teeth, this is an excellent opportunity todetermine the tooth shape for the parent.Patients often comment on the fact that theirteeth used to look just like this or that.

70

8.2 Selection of anterior teeth widthaccording to Lee

When selecting teeth according to Lee, the dis-tance between the nasal wings is measured.This generally corresponds to the distancefrom the midline of one canine to the midlineof the other canine.

8.3 Selection of anterior toothpositioning according to Gerber

The contour of the nasal base line serves as aguideline.

Tooth selection

Fig. 3: Definition according to Lee. Fig. 4:

Fig. 5:

Fig. 6:

71

Fig. 11:

Fig. 12:

8.5 Tooth selection according tophysiognomy (Williams)

For many dental practitioners, the selection of thetooth mould according to Williams is an establis-hed method for determining the tooth mould cor-responding to the shape of the patient's face ortype. In addition to this, the classification accord-

ing to the four different types of facial shape ismore or less an international standard. This clas-sification, however – and likewise the classifica-tion according to Kretchsmer – originates morefrom the early days of dental prosthetics.

Fig. 10:

8.4 Selection of anterior tooth mouldsaccording to Gysi

The tooth shape results in facial harmony.

Fig. 7:

Fig. 8:

Fig. 9:

72 Tooth selection

Fig. 13: Pyknic type – oval tooth shape

8.6 Tooth selection accordingto constitution types (Kretschmer)

The three constitutional types – athletic, lepto-some and pyknic – form the basis for toothselection according to Kretschmer.

Fig. 14: Leptosome type – triangular tooth shape

Fig. 15: Athletic type – angular, almost square tooth shape

73

8.7 Tooth selection accordingto the anatomical model

When no tooth selection information is avai-lable from the dentist, the maxillary alveolarridge can also be taken as a basis for selectingthe anterior tooth shape.

Fig. 16:

Oval alveolar ridge Pointed alveolar ridge Square alveolar ridge

oval anterior tooth shape triangular tooth shape square anterior tooth shape

74

Notes

Tooth selection

9


Tooth selection


Anterior teeth

Aesthetics

Setup and function


Denture finishing

77

9.1 When can a denture be said to bestable?

When functional forces are applied to the den-ture in the mouth and the denture remains unmo-ved by tilting or displacement it can be said to bestable. ie: positionally stable under masticatoryforces.

9.2 What happens with an unstable denture.

An incorrectly designed denture will be unstablewhen:

• The denture teeth are incorrectly positioned.Due care has not been taken in regard toTHE EXTENT OF THE DENTURE BASE theextent of its borders and design of its peri-phery.

The functional requirements of providing suffi-cient clearance for lip and muscle tendons aredeficient.

Such shortcomings lead to “lifting” and displa-cement of the denture from the alveola ridgeduring speech or other functions. They will alsocause the development of pressure spots onthe mucosa.

9.3 Vectors of force – what are they?

The multidirectional forces which act onfunctioning denture and teeth are referred toas vectors of force.

A vector of force represents the characteristicsof a force. In Fig 1, forces are indicated byarrows which also indicates a range of forces

which may be in action during masticatoryfunction. In order to overcome such problems itis necessary to understand what occurs whena denture tooth is ground in the pursuit ofelimating such a problem and what consequen-ces may follow.

9.4 The interplay of forces

In order not to be helpless in overcoming theseforces the following should be kept in mind.All vectors of force acting on a denture shouldcancel each other out. ie: the sum of all vectorsof force acting on a denture should be zero.I as far as possible all vectors of force mustmeet the alveola ridge at right angles.

In this way the various forces acting on themandibular denture help to centre the denturesquarely on the alveola ridge.

9 Functional stability

Fig. 1: Vectors of force meet the alveolar ridge at right angles.

78

Fig. 3: Proglissement caused by the force acting on the denture.

If the setup ends at the distal of the firstmolar, the remaining gap is built up in denturebase acrylic towards the retromolar pad. It isdefinitely out of occlusion and slopes awaylingually and buccaly towards the periphery ofthe denture. This configuration prevents foodaccumulation.

It is for this reason that the second molar issometimes omitted from a set up as it wouldotherwise have to be positioned on the steepslope of the mandibular ramus. This would becontrary to the vectors of force principles des-cribed and not in harmony with the alveolaridge. If set, the second molar would causefunctional displacement of the denture.

In this way the denture is prevented from beingpushed down and forward on a sloping plane.

Statics and chewing stability

Fig. 2: Incorrect positioning of the second molar.

79

Notes

80

Notes

Statics and chewing stability

10


Tooth selection


Anterior teeth

Aesthetics

Setup and function


Denture finishing

7mm

83

Fig. 2: CPC line (canine, papilla, canine).Fig. 1:

10.1 Positioning of the anterior teeth

It can generally be assumed that in a normalocclusal situation the upper anteriors aresituated at a distance of about 7 mm anterio-rally of the incisal papilla (Fig 1).

With a close bite the distance is about 6 mmand a protrusive bite about 9 mm.

The anterior teeth are positioned according toanatomical, functional, aesthetic, and phoneticrequirements.

The following points should be heeded:

• The denture teeth should be incorporated inthe wax rim in such a way that they continuethe contour of the wax rim.

• Both mesial interdental surfaces of theupper central incisors and the mesial inter-dental surfaces of the lower central incisorsshould correspond to the midline markingson the model (Refer to diagram in section5.2.)

• The midlines of the upper canines corre-spond to the position of the canine line mar-kings on the model ( Refer to diagram in sec-tion 5.2.)

• The length of the upper anteriors corre-sponds to the distance between the lipclosure line and the smile line.

• The line connecting the tips of both upperCanines runs through the centre of the inci-sal Papilla (CPC Line).

10.1.1 Tooth lengthThe incisal edge of the maxillary central incisorsshould be aprox., 0.5 – 1.00 mm longer than thelower edge of the upper lip, when the upper lipis passive (for men, 1.0 mm longer and forwomen, 2.0 mm longer).

These values concerning anterior tooth length areapproximate and serve as a starting point. If follo-wed, they will often deliver satisfactory results.

10 Anterior teeth

ca. 10 mm

84

approx. 10 mm

Anterior teeth

Fig. 3:

Fig. 4:

Fig. 5:

10.2 Setting the anterior teeth.

10.2.1 Standard setup methodsThe anterior teeth, as explained following, canbe set according to a standardised method.This is intended only as a guideline which canand should be modified to suit the individualpatient case.

Upper• The incisal edge of both upper centralincisors are situated +/- 1 mm above theocclusal plane.

• The incisal edge of each lateral incisors issituated +/- 0.5 mm above the occlusalplane.

• The incisal edged of each incisor runsapproximately parallel with the occlusalplane.

• The tips of both canines are positionedapproximately at the level of the occlusalplane.

• The tips of both canines are situated at anapproximate distance of 10 mm from theend of the first pair of palatal ridges (Fig 3).

Lower• The incisal edge of each lower central inci-sor corresponds precisely to the contour ofthe occlusal plane.

• The incisal edge of each lower lateral inci-sor runs approximately parallel with theocclusal plane.

• The tips of both canines are positionedslightly above the occlusal plane.

The labial surfaces of the upper anteriors sup-port the upper and lower lips (Fig 4).

A standard positioning of the upper anteriors isachieved as follows (Fig 5 / labial view).

• The central incisors are straight and upright.• The lateral incisors are inclined cervicallyand slightly laterally.

• The canines are more upright with the neckslightly towards the labial.

• The central incisors and canines are parallelto the pupil line and correspond to the posi-tive smile line in the arch.

85

Fig. 6:

Fig. 7: Inclination of the central incisor, lateral incisor and canine.

A standard lower anterior set up viewed fromthe labial perspective is as follows (Fig 6).

• The central incisors are straight and upright.• The lateral incisors are slightly mesiallyinclined.

• The canines are also mesially inclined andthe distal facet inclined in the direction ofthe molars.

Approximal inclinations:• All anterior teeth are positioned with thebody of the tooth on the centre of thealveola ridge.

• The central incisor is labially inclined.• The lateral incisor is upright.• The canine is lingually inclined.

At this point and as a general rule of thumb,the expression of, “on – at, -outside of”applies to the central and lateral incisors andcanine. It concerns the position of the neck of

the tooth in relation to the alveola ridge andwill generally produce an aesthetic set up. Thelower canines have a slightly inward tiltedposition. It would be a disadvantage bothfunctionally and aesthetically if the tips of thecanines were positioned too far labially or thenecks, too far towards the alveola ridge.

10.2.2 Individualised setupsIndividualisation of the setup is best carried out atthe try in. If for example the patients mid line isoff centre, the setup can be adjusted at the try instage to avoid a lopsided appearance. Incisal inci-sal edges can be harmonised with the nasal baseline and individual teeth can be slightly rotated ontheir axis. These modifications to the set – up canalso be done in the absence of the patient butthey are best completed and finalised at the try instage with the agreement of the patient.

86

Examples of individual anterior setups

Anterior teeth

Fig. 8.1: VITA MFT T46 – the teeth are rotated slightly

around their vertical axes, a labial view.

Fig. 8.2: ... and from an incisal viewpoint.

Fig. 9.1: VITA MFT S47 – the pronounced anterior

positioning of the central incisors. The labial view ...

Fig. 9.2: ... and the incisal view shows this very nicely –

note the slightly retruded lateral incisors.

87

Fig. 10.1: VITA MFT T46 – typical for class II/2,

pronounced incisal retrusion.

Fig. 11.1: VITA MFT R42 – not too conspicuous in the

labial view ...

Fig. 10.2: The incisal view is a good example –

the butterfly position of the central incisors in combination

with the typical positioning of the lateral incisors.

Fig. 11.2: ... the slightly retruded central incisors and more

conspicuously protruding lateral incisors.

88 Anterior teeth

Fig. 12.1: VITA MFT L37 – individual anterior positioning in

the lower is a good aesthetic solution ...

Fig. 12.2: ... most clearly visible in the "broken arch" form.

Setups of this type are refined with correspondingly

abraded facets caused by protrusive movements.

Fig. 13.1: VITA MFT L34 – Example of a moderately

individualised setup.

Fig. 13.2: A rather even contour despite slight tooth

rotation around the vertical axis.

89

Recouvrement

Sur-plomb

ÜB

VB

Fig. 14:

10.2.3 Overbite – overjetOverbite – sagittal (horizontal) overbite

An overbite is a vertical anterior overbite. Thiscan have a dimension of up to 2 mm aprox. Theterm overbite, refers to the sagittal anterioroverbite, horizontally of up to 2 mm aprox. As ageneral rule it is assumed that “overbite equalsoverjet” (Fig 14).

This usually has a dimension of 1 mm whichmeans that the overbite and overjet should cor-respond precisely if balancing of the mandibu-lar movements is intended.

10.3 Phonetics

10.3.1Problems and the appropriate solutions

To enable a complete denture patient to speakproperly, consideration should be given to set-ting up in phonetic balance.

In order to be able to begin with the restora-tion of lost dentition, it is necessary to beaware of the function of the various oral seg-ments (ie: tongue, palate, lips etc and theirrespective functions).

In this respect, nature itself shows the way. Innature, we can observe how the oral cavity isdivided into sections in order to ensure fault-less phonetics.

We also recognize the interconnection of den-tition with speech and phonetic function.These develop during growth of the primarydentition and continue during development ofthe permanent dentition.

Once this speech / phonetic function has beenlearned during development, it is stored in thebrain and will remain for life.

If the denture teeth are wrongly positioned, thepatient will likely be able to reach only anapproximation of their original speech pattern.However, every complete denture wearer deve-lops phonetic tricks in order to overcome short-comings and speak reasonably well.

If by comparison with the previously describedexample, the teeth are correctly positioned,the patient; even after wearing a denture withpoor phonetics for 20 years, will regain phone-tic function and revert to their original speechpattern.

How can this be achieved and how to correctlyposition the teeth in the first place ?It is necessary to explore the patient’s, “storedphonetic speech pattern” and set the teethphonetically (so to speak).

Overjet

Overbite

90 Anterior teeth

10.3.2 Generally accepted principles.The oral cavity forms a resonating cavity which,depending on the position and orientation of thetongue, the teeth, the various muscles involvedand the lips, convert an air stream into phoneticsound. The same occurs when a musician playinga trumpet or trombone, reduces the volume of theresonance chamber in order to produce highernotes or enlarges it to produce lower notes. Thesmaller the aperture through which the air passesthe more the air stream accelerates and the lar-ger the aperture, the slower the flow of the air-stream.

The phonetic articulation is limited to twobasic types.• Fricative consonants.ie: produce a rubbing sound.Fricatives are consonants produced by for-cing air through a restricted opening.eg: the letters “f and v” are formed by thelower lip against the upper incisors.

• Explosive consonants.The respiratory stream is interrupted at one ofthe four places of formation and immediatelyreleased.

There are two categories of explosives.Unvoiced explosives such as p, t, k.Voiced explosives such as b, d, g.

Beginning with the Fricatives. These are calledlabio dental consonants such as f, v and w.

The tongue plays a passive role in the formati-on of these sounds. They are formed by theanterior incisors contacting the lower lip at thewet dry line.

In order to form these sounds, the upper inci-sors must be in the correct position.

To form the “s” fricative, the tongue touchesthe posterior teeth and part of the upper ante-riors. The tongue does not contact the middleof the upper anterior as this channel remainsopen for the air stream. The tip of the tongue isgenerally in contact with the lower anteriorswhen forming the “s” sound.

In order to form these sounds, the lower inci-sors must be correctly positioned.

If they are situated too far lingually, the “s”sound will be distorted and become similar tothe “th” sound of the English language. If thelower anteriors are positioned too far labially,the “s” sound will bear more resemblance tothe “sh” sound.

In order to produce the “sh” fricatives, thetongue is supported in the palatal, dental andalveola directions.

The tongue presses against the palate and inthis way controls the air stream.

In order to form these sounds, the patientrequires tongue support from the oral struc-tures in the palatal area.

Fig. 15: Contact areas of the tongue when pronouncingthe "s" sound.

91

Failing this, the patient can only improvisethese sounds with difficulty by shifting thelocation of articulation posteriorally. The resultwill then be an approximation, similar to theScottish pronounciation of the word, “loch.”

Explosive consonants p, t, k, b, d, g are formedwhen the air stream is sealed off anteriorally bythe tongue, lips, or other parts of the mouth andthen rapidly released.

The correct positioning of the upper incisors isessential for the formation of the consonants tand d and in the case of consonants k and g,the positioning of the posteriors and corre-sponding palatal support is important.Consonants b and p are formed purely labially.

Description of facial / oral positions andmovements in formation of consonants m, band p.

What can we see?• When pronouncing “m,” complete lipclosure can be observed.

• In the case of b, the lips are releasedslightly.

• With P, the lips move apart rapidly and thecheeks swell slightly.

• The chin does not move when m, ispronounced.

• The chin moves slightly downwards when bis pronounced.

• The chin shows a sudden downwardsmovement when p is formed.

What we cannot see• The teeth have only a slight inter-occlusalseparation (freeway space).

• The tip of the tongue lies on the lowerincisors.

• The underside of the tongue lies flat asduring the formation of the "a" sound.

Classification according to placeof articulation:• Labial (Latin: labium = lip)p, b, m, f, v, ph, w, pfThe lips form a more rounded-elongatedaperture.

• Dental (Latin: dens = tooth):sh, t, d, tz, s, z, nThe upper incisors articulate against theinner edge of the lower lip. The tip of thetongue articulates against the inner edge ofthe upper incisors.

• Palatal (Latin: palatum = palate)n, l, "ch" as in "chew"The Palatal consonants result when the tipof the tongue articulates against the ante-rior palate.

• Velar (Latin: velum = sail):k, g, ng, nk, q, ch, j, or ch as in theScottish pronounciation of “loch.The place of articulation is between theposterior portion of the tongue and the softpalate.

Fig. 16: Contact areas of the tongue when pronouncing

the "sh" sound.

92

Notes

Anterior teeth

11


Tooth selection


Anterior teeth

Aesthetics

Setup and function


Denture finishing

95

11 Aesthetics

How do we define aesthetics? Aesthetics areoften associated with beauty.

“Beauty is in the eye of the beholder.”

The word, aesthetic, can also be described asbeing “pleasing to the eye,” an impression isperceived by the eye and conveyed to thebrain.

A varying play of light colour and form can givevarying emphasis to a motif and highlight cer-tain details.

Aesthetics in nature does not mean symmetryand regularity, but a harmonious mix of irregu-larity and asymmetry.

When speaking of aesthetics it is inappropri-ate to speak of aesthetics being correct orincorrect as aesthetic concepts are very flexi-ble. Generally a dental restoration can be des-cribed as having a natural appearance or isclose to natural. If for example we produce adental restoration or a crown which closelyresembles the natural, we say it has an aesthe-tic appearance.

To this purpose, it is essential to look closelyand observe the effects evident in differentsurfaces. For example the texture of a surfacesuch as gingival tissue or that of a tooth whichcauses reflected light to diffuse under varyinglighting conditions.

Of course shape, value and colour are alsoimportant.

A crown which differs very slightly in colourfrom the ideal but which has excellent shape,texture and value will be significantly less of adisturbance to the oral harmony of the patientthan a shade perfect crown that has an inap-propriate shape and texture or value.

Regarding complete dentures, not only toothform and positioning are important aesthetical-ly, but the gingiva also must appear as a repro-duction of the natural gingiva.

96

Notes

Aesthetics

12

Tooth selection


Anterior teeth

Aesthetics

Setup and function


Denture finishing


99

12 .1 Setup concepts

Generally accepted principles.When setting up posterior teeth stability of thedenture is a major goal applicable to all den-ture prosthetics. This should be kept in mindwhen addressing and overcoming the range ofclinical difficulties encountered daily in den-ture construction.

Regardless of which concept is to be used, cor-rectly determined centric relation is an essenti-al and fundamental base from which to beginthe work. The only possible exception may bewhen using teeth with zero degree cusps.

It makes no sense to try to conform to a singletheoretical concept at any price without beingaware of the practical consequences. Thismeans that the suitability of a particular con-cept must be determined for each particularcase.

Three concepts are described in the followingand which can be utilized in virtually all cases

12.1.1 Lingualised occlusion

VITAMFT®

The principle of lingualised setup.In lingualised occlusion the lingual workingcusps of the upper posterior teeth occlude intothe central fossae of the lower posteriors.

The buccal cusps are out of contact. The lowerposteriors are set up according to the alveolarridge and curve of Spee in order to obtain den-ture stability. Their occlusal surfaces appearhorizontally aligned from a labial perspective.

The upper and lower posteriors are broughtinto contact in such a way that they articulateanatomically and functionally. Note: there isalways a free space left between the upperand lower buccal cusps.

VITA MFT teeth are generally set up in a toothto tooth relationship. Should it be necessaryfor some reason to set the teeth in a tooth - to– two – teeth relationship this is quite accep-table.

Advantages of lingualised occlusion.The aim of lingualised occlusion is to stabilisethe dentures while providing maximum spacefor the tongue.

The occlusal forces transferred to the oralmucosa and the underlying bone substance arethereby minimised.

This generally reduces the strain on the dentu-re bearing area and can be an essential ingre-dient in the survival of implant cases.

12 Setup and function


Procedure:1. Setup beginning with the first uppermolarPlease note: with lingualised occlusion, thelower posteriors are set up vertically, i.e. are notlingually inclined (fig. 1). The dominant mesio-lingual cusp of the first upper molar bites into

the fossa of the first lower molar (fig. 2). Thedistolingual cusp comes into contact with thedistal marginal ridge of the first lower molar.The second upper premolar is then brought intocontact with its antagonist. The palatal cusp ofthe latter should come into contact with thefossa of the second lower premolar (fig. 3).

Fig. 1:

Fig. 2:

Fig. 3:

101

The palatal cusp of the first upper premolarshould now bite into the fossa area of the firstlower premolar (fig. 4). Finally, the secondupper molar is set up. The palatal cusps gripinto the fossa area of the second lower molar(fig. 5).

The buccal cusps of all upper posteriors aresituated slightly higher than, and out of con-tact with the buccal portions of their antago-nists (fig. 6).

Fig. 6:

Fig. 5:

Fig. 4:


2. Setup beginning with the first upperpremolarPlease note that in lingualised occlusion, thelower posteriors are first set up horizontally,i.e. not lingually inclined (fig. 7). The lingualcusp of the first upper premolar should now

bite into the fossa area of the first lower pre-molar (fig. 8). The second upper premolar isthen brought into contact with its antagonist.The lingual cusp of the latter should grip intothe fossa of the second lower premolar only(fig. 9).

Fig. 8:

Fig. 7:

Fig. 9:

103

The dominant palatal cusp of the first uppermolar bites into the fossa of the first lowermolar. The distolingual cusp meets the distalmarginal ridge of the first lower molar (fig. 10).Finally the second upper molar is set up.

The lingual cusps bite into the fossa area ofthe second lower molar (fig. 11). The buccalcusps of all upper posteriors are always situ-ated slightly higher, and out of contact with thebuccal portions of the antagonists (fig. 12).

Fig. 12:

Fig. 11:

Fig. 10:


Contact pointsThe red dots mark the centric contacts. Exceptin special cases, no occlusal grinding should becarried out before transferring the wax setupto acrylic resin.

Before removing the acrylic resin denture fromthe model, the articulation and occlusion canbe perfected by grinding where necessary inthe areas of the lower fossae and the cuspalridges.

Due to the functional design of their occlusalsurfaces, VITA MFT posteriors require only aminimal amount of occlusal adjustment in excur-sion movements. Where necessary, the excur-sion movements can be carried out according tothe following diagram.

• Centric relation• Protrusion• Laterotrusion /working side• Mediotrusion / balancing side

Fig. 13: Lingualised setup – centric contacts. Fig. 14: The pattern of excursion movements.

105

A

B

C

OK

UK

12.1.2 Anterior-canine guidancewith ABC contacts

Dr Karl Hiltebrandt, one of the founders of Vitain the early 1920’s, was somewhat of a visio-nary and some say, ahead of his time. DrHiltebrandt concluded that a “normal” bite isdriven by neuromuscular guidance rather thantooth guided movement as was thought to bethe case at the time.

When constructing full dentures for edentulouspatients the clinician is presented with a seriesof problems which must be overcome if stable,comfortable and functional dentures are toresult.

Two of the most common problems to overco-me are divergent atrophy of both maxilla andmandible and the fact that the lower denturesits partially on a sloping incline (see section1.8 / Bone / arch atrophy).

This situation is not as nature intended and thereason the patient is in need of a “replace-ment.” All the various forces acting on the den-tures, particularly those occurring duringmasticatory movements, must be balanced outagainst one another.

This does not mean grinding the occlusion inorder to obtain excursion movements but, as itwere, “entry lanes”, with corresponding canineguidance which culminate in group guidance.The dentures can therefore be returned tocentric position from every dislocated positionsimply by clenching the teeth together.

Necessary posterior antagonist contactsto achieve occlusal stability.

Contacts with the opposing teeth (antagonistcontacts) are generally classified into threetypes of positional relationships:

"A" contacts:Buccal cusps – upper and lower contacts. Theshearing (non working) cusps of the upper teethare in contact with the working cusps of thelower teeth (Fig 15).

"B" contacts:Lower buccal cusps contact with lingual cuspsof the upper. The working cusps of upper andlower are in contact (Fig 15).

"C" contacts:Upper and lower lingual cusp contacts. Theworking cusps of the uppers and the shearing(non working) cusps of the lowers are in con-tact. As a rule,either A and B, or C and B con-tacts are sufficient. They provide stable occlu-sal and axial loading of the teeth.

A, B and C contacts can be present at the sametime and this is fine. What is important is theiruniform distribution.

Fig. 15:

Upper

Lower

A

B

C

A

B

C

OK

UK

A

B

C


In order to stabilise both the mandibular andthe maxillary dentures, an A contact and a Bcontact, or a B contact and a C contact arerequired (see fig. 16).

Fig. 16:

Fig. 17: Individual distribution of the ABC contacts.

Upper

Lower

107

12.1.3 Setup according to generally acceptedprinciples with buccal contacts

After the anterior teeth have been set uptaking the sagittal overbite (overjet) intoaccount as described in chapter 10.2, theposterior teeth can be set in position.

The following applies to the setup of alllower posteriors:• They are generally positioned on the centreof the alveolar ridge.

• The central fissures should be in a straightline which runs between the tips of thecanines and the centre of the retromolar tri-angle.

• The buccal cusps are situated on the tan-gent of the Bonwill circle, which reachesfrom the buccal limit of the first premolar tothe buccal limit of the retromolar triangle.

• The lingual cusp tips are situated onPound's line.

• The posteriors lingually inclined => toothinclination increasingly towards the distal.(axial inclination of tooth crowntowards the lingual in relation to axial incli-nation of tooth root, a characteristic ofmandibular teeth).

The following applies to setting of the upperposteriors:• If possible, they are positioned on the centreof the alveolar ridge.

• The central fissures are situated on an ellip-tical connection line between the tips of thecanines and the tubera maxillae.

• Viewed from in front, less and less of thebuccal surface can be seen from the first pre-molar to the second molar; this gives rise tothe "buccal corridor".

• They are buccally inclined.• The first lower premolar is set up.The buccal cusp tips touch the occlusal plane.

• The second premolar is set. It is situatedapprox. 1 – 1.5 mm below the occlusal plane.

• The first lower molar must be set up in thearea of the lowest point of the alveolar ridge.Taking into account the sagittal and transver-sal compensation curves.

• The buccal cusp tips are approx. 2 mm belowthe occlusal plane, rising towards the distal.If there is no danger of proglissement (lowerdenture forward displacement), the secondlower molar can also be set up. Otherwise thesagittal progression of the curve in the area ofthe first molar should be compensated, i.e.distally raised.

• The first upper molar is brought into optimumintercuspation. Subsequently the secondupper premolar and then the first upper pre-molar are inserted into the available space.

• If, as previously described, it is possible toset the second lower molar, the upper anta-gonists can then be added, and brought intointercuspation.

In the lower, the distobuccal cusps of the se-cond molars touch the occlusal plane. If spaceis limited, premolars can be substituted in-stead. What is important ultimately is that nomore teeth are not beyond the setup limit, i.e.no teeth are set up into the steep upward slopeof the mandibular ramus – otherwise there is arisk of proglissement (lower denture forwarddisplacement)!

In order to achieve a balanced occlusion, pro-ceed as described in chapter 14.3.3.


Fig. 17: Mesal view of setup.

Fig. 18: Lingual view of setup.

Fig. 19: Mesal view of setup.


109

Fig. 21: Buccal view of second upper premolar and first upper molar.

Fig. 22: Lingual view of first and second upper premolar and first molar ...

Fig. 23: ... and the buccal view.



Fig. 25: Buccal view of setup.

Fig. 26: Setup with buccal contacts according to generally

accepted principles.

111

12.2 Important characteristics

12.2.1 Cheek contactWhat is the purpose of cheek contact, and whyis it so important?

In order to have the patient feel that their den-tures are stable and comfortable it is necessa-ry that the posterior teeth have contact withthe cheeks.

It is also of key importance that the posteriorsare positioned correctly on bone supportedmucosa, preferably on the alveola ridge. (Thisis not always possible.) What remains impor-tant however is, osseous support of the muco-sa.

The dentist should build out the wax flanges,until cheek contact is achieved. This assists instabilising the wax up to some degree byhaving cheek contact on both left and rightsides. It also contributes to centric stability.

Additionally, during mastication, the food bolusis automatically maintained on the posteriorocclusal table until it is ready to be conveyedfurther. Without cheek contact the denture isless stable and the food bolus will accumulatebetween the cheek and denture which subse-quently requires removal with the tongue orthe finger.

The importance and function of cheek contactis commonly underestimated.

12.2.2 Different types of biteIn order to produce functionally stable dentu-res, the skeletal and dental parameters of eachcase must be considered. Such informationmust be accounted for in the planning andimplementation of complete dentures.

For example,an unfavourable progression ofbone atrophy makes it more difficult to producea denture that is positionally stable undermasticatory pressure.

By selecting the appropriate type of bite, dentu-re stability problems caused by difficult skeletalconditions or unfavourable progression of boneatrophy can be overcome.

12.2.3 Normal biteWhenever possible teeth should be set up in anormal bite, but not at any price!

If unfavourable interalveolar conditions pre-sents, a cross bite or edge to edge bite is used,particularly in regard to partial dentures.


12.2.4 CrossbiteAs already described in section 7 on modelanalysis, when the inter – alveola connectionline has an angle of less than 80 degrees, theteeth are set in a cross bite in order to avoid orminimise problems of instability.

To this purpose the maxillary buccal cusps (ie;the shearing non working cusps) become wor-king cusps which bite into the fossa of thelower posteriors. As a rule, the first premolar isset in neutral occlusion, then the second pre-molar is set in an edge to edge bite. (to thispurpose the cusps must be ground) This isfollowed by the first or second molar which isset in a cross bite position.

12.2.5 Edge to edte biteAn edge to edge bite is normally not used inthe posterior of a set up. An exception can bea “transitional tooth” such as a second premo-lar in a cross bite, which has been ground intoan edge to edge bite relationship (refer section12. 2. 3).

It is also possible to achieve an edge to edgebite with posteriors that have a flat occlusaltable and without a definite centric position.This is not recommended however as the patientmay experience a tendency towards “cheekbiting.’ In this circumstance a cross bite or anormal bite is usually possible.

Partial dentures can also present an exceptionto this but, depending on the particular situa-tion a suitable compromise can be found.

Edge to edge bite relationships are most com-monly found in the anterior region.

12.3 Vertical dimension /occlusal height

Determination of the vertical dimension is nota simple matter.

When the vertical dimension has not beendetermined correctly the patient’s denturesmay cause a clackety – clacking sound whenspeaking. This is usually more pronounced withceramic teeth than with acrylic teeth. The cera-mic however is not the cause of the sound butrather an incorrectly set vertical dimension. Inyears past, instead of correcting the verticaldimension the ceramic teeth were sometimesreplaced with acrylic teeth. This resulted in alower volume of the sound but did not elimina-te the cause. It was commonly thought by thegeneral public that “crockery teeth” as theywere known were the cause of the problem !

On the other hand, if the vertical dimension isinsufficient, the effect will be less pronouncedbut the aesthetics will be poor.It is essential the vertical dimension be correct.

113

Notes

114

Notes

Setup and function

13

Tooth selection

Funtional stability

Anterior teeth

Aesthetics

Setup and function


Denture finishing


117

Fig. 2

Fig. 3Fig. 1: Prosthesis ideally modelled in wax.

13.1 Gingival contouring

How is natural gingival structured and howshould it be reproduced? Natural gingival con-sists of marginal gingiva and gingival papillae.

There is no clear cut boundary between themarginal gingiva and the attached gingival buta gradual transition between the two. The mar-ginal gingival covers the osseous alveola pro-cess, is keratinised and has a pitted orangepeel texture (surface stippling).

The mucogingival junction forms the transitionbetween the attached gingival and the alveolamucosa. This is distinguishable and easilyrecognised, as the gingival mucosa is darkerand thinner than the attached gingival.

13.1.1 How can naturally appearinggingival be reproduced?

An appropriate expression might be that “less ismore.” Exaggerated carving and over contouringin the gingival margin area is painstakingly diffi-cult to trim and also can be difficult for thepatient to keep clean.

If we observe natural healthy gingiva, it can beobserved that the transition from tooth to gingivaoccurs at a very flat angle precisely in the vicini-ty of the gingival margin.

It can also be observed that this very thin gingi-val tissue is opaque and as a consequence, theunderlying tooth neck / root is not visible.

It is for this reason we use and recommendopaque acrylic for dentures where we want thebest possible aesthetic result. It is our opinionthat transparent acrylics are aesthetically unsui-table for use as denture base material. A keyarea of gingival contouring is the design of theinterdental papillae. The papillae should have theform of a droplet (see Fig 1) and be oriented to-wards the approximal. The papillae always finis-hes well short of the incisal edge and occlusalsurface.

The simplest and best way to reproduce natu-rally appearing gingival is with pink sheet waxsheet and the use of wax carving instruments(Figs 2 and 3).

13 Facts on the denture base


The transition of the gingival to the teethshould be flat. ie: must taper at a flat angle.

Excessively pronounced contouring such asgingival neoplasms, periodontal pockets etc.are seldom attractive to a patient, they can bedifficult to keep clean and are best avoided.

Ultimately, moderate contouring has a numberof advantages:It has a natural appearance, simpler to produ-ce, easier to polish, and easier for the patientto keep clean.

After the wax up and wax contouring are com-pleted a “brush” flame is used carefully tosmooth the surface of the wax.

After the wax has slightly cooled any wax onthe teeth at the gingival margin is removedwith a suitably shaped instrument.

Fig. 4: Wax up ready for investing and processing is

completed.

Fig. 5

119

The edge created as a result of exposing the cer-vical area is bevelled, the angle as previouslydescribed should be flat.

These steps enable a good basic gingival struc-ture to be achieved by simple means.

After removing wax carving residue, the con-tours can be smoothed and rounded off using asoft and not so hot flame of an alcohol torch. Aclean methodical way of working is essential.

Next the tooth/gingival transition is definedand any excess wax on the teeth removed (fig. 9).

FIg. 6

Fig. 7

Fig. 8: Smoothing the wax with alcohol flame.

Fig. 9

120

An essential part of a good, naturally appearinggingival reproduction is the papillae.As can be seen in the above photograph, the tipof the papillae is removed and shortened usingan arrow headed instrument (fig. 10).

The dental technician next decides on thedegree of wax contouring in order to obtain anaturally appearing gingiva (fig. 11).

The remaining tip of the papillae and the smallamount of wax carving are slightly rounded so thatthere are no angles and the wax gingiva appearsto flow interdentally. Finally, the interdental gingi-va can be smoothed very carefully using a softflame such as that of an alcohol torch (Care mustbe taken, not to apply the flame to the teeth).

In a situation where the patient has a big smileand shows a lot of gum when they laugh,thoughtful contouring of the lip tendon area canserve to enhance the natural appearance of thegingiva (Superior labial frenulum) (fig. 13).

Fig. 10

Fig. 11

Fig. 12

Fig. 13


121

13.2 Passage – ways for unhinderedfunctioning of the ligaments.

In order to ensure retention of complete dentu-res, the muscle / ligaments in the sulcus whichhave been carefully recorded in the functionalimpression must have unhindered freedom ofmovement. If not sufficiently accommodated inthe periphery of the denture, they will inhibitachievement of the suction required for retenti-on of the denture. Also, if the periphery of thedenture is on top of the sulcus ligament it willcause displacement of the denture in functionand cause irritation to the ligament and painfulpressure areas.

The correct design and execution in acrylic ofthese functional passage ways is an essentialfactor which directly affects stability of thedenture and avoidance of pressure spots.These passage- ways must be correctly dealtwith from the functional impression onwards.This means that they must not be trimmed withburs but only lightly refined using a sandpapermandrel in preparation for polishing. No fur-ther activity in regard to these areas is neces-sary until they are lightly polished, otherwisethe peripheral seal and retentive suction maybe jeopardised.

13.3 Determining the borders of the denture.

13.3.1 How is the border / periphery of thedenture determined.

This is determined by the limits of the functio-nal impression and is of key importance for thecompleted dentures.

The thickness of the periphery must not be alte-red or randomly reduced, it should retain theexact dimensions determined by the dentistwhen taking the functional muscle trimmedimpression. Only in this way can the outer peri-pheral seal be obtained.

The periphery of the denture must reach boththe attached and mobile mucosa circumferenti-ally around the denture. Optimum adhesionrequires the denture base to extend into themobile mucosal areas which does not moveduring functional activity. Between the innerperipheral sea and the mobile mucosa there isan ‘inner’ seal. Between the outer edge of thefunctional border and the mobile mucosa whichrests on top of this, there is an outer seal on thesuction area.

With many dentures a frequent short coming isthe design of the post dam. For further detailsrefer to the chapter 14.2.1 –“Insertion of thepost dam.”

Another important area that requires attentionis that of the tuberosity cheek pouch. This isoften waxed too thinly with the result that theouter peripheral seal is lost. It must be precise-ly waxed so that it has the correct peripheralthickness and will not interfer with the coronoidprocess in extreme lateral movement (coronoidprocess /where the temporal muscle begins).

Fig. 14: The wax up ready for try in.

122

be kept intact in order not to compromise orlose the suction effect.

In the sublingual area this runs in the dorsaldirection, after the transition from the attachedto the mobile mucosa in front of the caruncu-lae, i.e. approx. 2 mm below the mylohyoidcrest along to the tubera retromoleria.

13.3.3 What factors enable good adhesion?The secret of good adhesion of complete den-tures lies in the body of the prosthesis beingpositioned congruently on the mucosa, the cor-rect expanse of the denture base and the per-fect design of the prosthesis margins with thesuction area sealed off internally (inner valvemargin) and externally (outer valve margin) inconjunction with a faultless occlusion.

13.3.4 Reducing the strain onthe palatal torus

Reducing the strain on the palatal torus by meansof tin foil, etc., is a rather controversial matter.

The general rule applies that, in order to re-duce the strain on the palatal torus, materialmust not simply be removed from the denturebase in a freehand manner, and with a more orless arbitrarily determined limit.

Reducing the strain in this manner counteractsthe salivary (adhesion) film necessary for theretention of the maxillary prosthesis, since thedenture base is no longer seated congruentlyon the gingiva.

The strain on the palatine torus must be re-duced only by partial adjustments made by thedentist. This should only be done, howeverwhen a hypomochlion occurs on the torus.

ie: to the distal of the tubera (tuberosity), theperiphery must reach the area of mobile muco-sa which lies between the tuberosity and thepterygoid hamulus.

The lower denture periphery thickness shouldnot exceed 2 mm in the area of the mylohyodline. At this point there is no permanent outerseal, only an inner seal.

The periphery extends aprox 2mm below themylohyd crest (crista mylohoyoidea). The borderof the linguo-anterior area remains as given bythe functional impression.

13.3.2 Peripheral sealing mobile mucosaThis runs circumferentially around both upperand lower denture bearing area.

The expanse of the upper comprises the maxil-lary tubers in the dorsal direction, reachinginto the soft tissue area between thetubera and the pterygoid hamulus, and fromhere in the vestibular direction – correspond-ing to the functional impression – reaching tothe tubera of the other side.

In the area of the palatal vibrating line, theexpansion continues into the area which justbegins to vibrate during the formation of the"a" sound.

In the lower the retromolar tubers must becorrectly incorporated. The expansion of thedorsal limit of the prosthesis extends into thearea of the mobile mucosa slightly distally ofthe tubercula retromolaria.

In the vestibular area the expanse is deter-mined by the functional impression. This must


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13.3.5 The sealing function of the dentureperiphery – all or nothing –

In both the upper and lower dentures the enti-re circumferential periphery provides a sealsimilar to that of a suction pad.

A general distinction is made between an innerand outer peripheral seal. Some areas on thedenture such as the palate post dam / finishline have no permanent outer peripheral seal.Nor does the mylohyoid line in the linguo-ante-rior region.

In these areas which have only the permanentinner peripheral seal and no permanent outerseal, the expression “all or nothing” can beapplied. In other words, if the seal fails in oneplace the retentive suction effect is lost forthe entire denture. This is in contrast to otherareas in which both an inner and outer sealexists. If for whatever reason the inner sealdoes not function, the denture will still beretained because of the retention provided bythe outer seal. This means that in extremecases there are two sealing functions whichwork together alternately. This also meansthat in the case of an incorrectly designed postdam / palatal finish line there will be no reten-tion at all.

13.3.6 Foreign body in the mouth sensation.“as small as possible as large asnecessary”

Periodically there is a tendency towards flimsydesign of full dentures. This is understandableas a patient who is new to dentures may feelthey have more than a “mouthful!” Such dentu-res are often found by patients to be somewhatunstable with problems conveying the mastica-

ted food bolus from the anterior to the posteriorregion (food bolus remaining in vestibularareas/see section 12.2.1, “Cheek contact”).

It is no doubt correct as well as logical todesign immediate dentures with as gracefuldimensions as possible. Immediately aftertooth extraction, resorption of the alveola ridgehas not occurred and any increase in dimensionis too much. In such circumstances the patientis sure to comment in regard to the sensation ofhaving a foreign body in the mouth.

After resorption of the alveola ridge, the redu-ced volume must be restored by means of addi-tional denture base acrylic etc in order to per-mit normal food uptake and mastication. It isalso necessary for the restoration of phonetics.

This results in dentures which have a somewhatawkward appearance when compared withthose purposely given a more graceful design.The patient will come to appreciate and mana-ge better with the more robust dentures.

When it comes to restoring lost tissue, thedimensions of that tissue must be accommoda-ted in the design of the dentures.

13.3.7 Designing the upper labial acrylicflange.

It can sometimes be observed that a personwearing an upper full denture appears to have apuffed out area immediately below the nose andextending from canine to canine. This gives achimpanzee like appearance.

This is caused by an excessively thick borderarea of the denture and / or, over bulking of theanterior flange of the denture.


In regard to bone atrophy it must be noted thatthe bone immediately beneath the nose under-goes virtually no loss of dimension. If, howevera thick denture border is added to this “zeroshrinkage“ area it makes it appear as if thepatient is blowing air under the upper lip. Thisis obviously detrimental to the aesthetics.

13.3.8 Face lifting effectThis refers to the bulking out of the denturebase to restore the facial contour which mayhave lost its support due to atrophy of themaxilla.

This bulking out of the denture base contour isbest done at the try in. Care must be taken notto subject the lip to excessive pressure frombulking out of the wax up.

The corrected contouring is subsequentlytransposed to denture base acrylic.

13.4 Palatal rougae

The subject of palatal rougae is some whatcontroversial. It has occurred on occasion thatfor whatever reason, rougae incorporated in adenture palate has had to be removed and thepalate trimmed and polished to a smoothfinish. Not an experience one would wish torepeat.

A patient who has worn a denture with asmooth palate for an extended period will pro-bably find it more difficult to become accusto-med to palatal rougae. Even more so if thepatient is insufficiently informed of its purpo-se.

Experience however shows that patients whoare well informed about the purpose of rougaeusually become accustomed to the palataldesign within days.

Palatal rougae is conducive to phonetic functi-on. It is also helpful for turning over food andmay even contribute to an improved sense oftaste. This is because the tongue encounters asurface that provides friction and the papillaeon the tongue is stimulated by the contactwith the rougae and enveloped in flavouringsubstances. This effect is less pronouncedwith a smooth palate.

Fig. 15: Palatal rougae.

125

It is not uncommon for palatal rugae to beincorporated in an upper denture for aesthe-tic,and functional reasons.

Excellent, prefabricated, reusable and flexiblerougae patterns are commercially available andwhich can be incorporated into a denture waxup. These patterns are reproduced in the pala-te of the denture base acrylic. Care when poli-shing must be exercised when polishing tomaintain the reproduced rougae pattern.

Fig. 16: Indistinguishable from the natural.


Notes

14

Tooth selection


Anterior teeth

Aesthetics

Setup and function


Denture processing


129

14 Denture processing

14.1 Denture processing systems

Differences of opinion exist in regard to dentureprocessing systems. It is up to the individual tochoose a preferred method of working. The fol-lowing describes some of the advantages anddisadvantages of the various procedures.

14.1.1 Injection systemsInjection systems with different equipment forusing both self curing or heat curing polymershave yielded good results and enjoy a highdegree of popularity. An advantage of closedinjection systems is that the bite is not raisedwhich enables fabrication of dentures with ahigh degree of occlusal accuracy.

14.1.2 Packing systemsPacking systems using flasks and presses andusing both heat curing and self curing polymersare widely used and when correctly used, deli-ver good results.

In order not to raise the bite, a certain amountof practice / experience in handling flasks andhydraulic presses is required.

14.1.3 Pouring systems.Acrylic pouring systems which use self curingacrylics are inclined to increased shrinkage ofthe material due to their greater fluid content.Generally it can be said that the more fluid, thegreater the shrinkage.

There is also the possibility that when usingpour systems liquid will be unable to escapefrom the mould resulting in incomplete fillingof the mould.

The time intended to be gained by using a pourtechnique may well be a mirage if work mustbe repeated resulting from sensitivities in theuse of this system. With pour systems the resi-dual monomer content in the acrylic is highest.It is unrealistic to describe pour systems asbeing capable of delivering high qualityresults.

14.1.4 Heat Curing Acrylic versusSelf Curing Acrylic

Heat Curing Acrylics (thermo-polymers) havesuperior long term characteristics comparedwith Self Curing Acrylics:They have a lower content of residual monomer;are more dense; are more dimensionally stable;they are easily polished to a high lustre andmaintain the lustre indefinitely. To achieve re-liable and consistent bonding between the den-ture base acrylic and the teeth, the followingprocedure is recommended.

14.1.5 Improving adhesion / preparationof the denture teeth.

Bonding agent for acrylic teeth and den-ture base.With so many brands of denture acrylic avai-lable it is difficult for the Dental Technician todetermine as to the quality of the “bond” bet-ween the particular teeth and the selecteddenture base acrylic. With correct use of VITA-COLL combined with good packing associatedand processing procedures, good bonding isassured.

130

Incorrect!

Denture processing

1. The base of each tooth should be roughenedusing a shallow groove cutting bur (No 108),A coarse toothed steel or carbide bur mayalso be suitable. Any type of retention holesor dove tails are strongly recommendedagainst. During the flask packing and pres-sing procedure, air can be trapped in such“retention holes” impairing the bond. Dovetails serve only to weaken the body of eachtooth and increase the likelihood of fractureincluding at low levels of loading (Fig 1).

2. The teeth must be free of wax residue andplaster separator. It is also preferable thatthe mould / flask be cool rather than hot.VITACOLL is recommended for use with HeatCuring acrylics and mandatory when usingSelf Curing acrylics. VITACOLL acts on theclean cut surface of the denture teeth andmodifies the chemistry of the surface toaccommodate the chemistry of the denturebase acrylic. A strong chemical bond results.Some denture base materials are availablewhich cannot otherwise form a bond withmodern high quality acrylic denture teeth.

THE PROCEDUREVITACOLL is applied to the roughened base ofeach tooth with a small brush. It must be allo-wed to stand to take effect for a minimum of 5minutes. If after 5 minutes the surface appearsdry and not shiny-wet, VITACOLL should againbe applied.

After another 5 minutes has elapsed, packingof the denture base acrylic can begin. Packingof the denture base acrylic should begin within10 minutes of the end of this 5 minute holdingtime. If not, the bond enhancing effect of theVITACOLL may be lost.

Further procedural instructions.When contouring, carving and refining the gingi-val wax up of dentures, one must be carefulwhen using a flame to smooth the finally con-toured gum areas. A flame in contact with theteeth will scorch the high points of the teeth andcause whitish discolouration which may not beimmediately evident (Points of cusps/ ridges/ in-cisal edges). During processing of the denturebase these scorched areas which are microsco-pically porous, absorb moisture emanating fromthe plaster mould. In a short amount of time inthe mouth they will discolour and can be seenclearly. When smoothing with a brush flame, theflame should be small and soft and care must betaken that the more prominent areas on theteeth are not scorched by the flame.

14.2 Denture Processing

14.2.1 Inserting the Post Dam.(Distal Palate Vibrating / Finish line)

The scraping of the upper model across thedistal of the palate to provide a post dam anddenture finish line is essential for obtainingretentive suction of the denture.

If not done correctly the retention of the dentu-re is put at risk and will have to be corrected.

Fig. 1: Loading of the body of the tooth.

131

•• ausla

•• abge

t=0,5mm

t=0,5mm

t=0,5mm

t=1,0mm

t=1,0mm

10mm

0,5mm

10mm

Fig. 2

Full upper dentures are commonly over orunder extended in this area and / or, improper-ly dammed. The palatal finish line should beplaced in the mucosal area which begins tovibrate when forming the sound of the letter“a.”

14.2.2 How – and where – should the distalpalate of the model be trimmed?

The dental care provider should mark the finishline and palatal post dam area on the model forthe technician or, personally prepare the modelwith both finish line and post dam.

A fairly standard example follows:

The green dotted line indicates the extremity ofthe palatal reduction from the red dotted, pala-tal finish line. The depth of palatal reduction ofthe model at the red finish line is usually 0.5 -1.0 mm and tapers anteriorally to the greenline.

14.2.3 Plaster /stone separators(cold mould seal)

In order to prevent adhesion of acrylic and pla-ster / stone during polymerization procedures,alginate based “plaster separator liquid” isused (cold mould seal). It is important to usethese separators correctly to obtain the best

possible surface on the acrylic after the pro-cessing is completed (as follows).

Immerse the model or flask halves in hotwater for a few minutes. Remove from thewater and remove remaining water with com-pressed air.

Generously apply the plaster / stone separatorwith a brush and massage it onto the plaster /stone for 50 – 60 seconds. Excess is thenremoved by rinsing with a fine jet of warmwater. Next the models / flask halves are pla-ced in a sealed container where they remainfor 15 or 20 minutes. After removal, packing ofthe acrylic can begin.

This procedure results in the subsequentlypacked and processed acrylic having a denseand glass like surface.

Using this method it is also possible to delaypacking of the acrylic for some time, withouthaving the separator becoming too dry.

On the other hand, if separator is applied todry un-warmed models, it does not penetrateand dries out very quickly. This allows moistu-re to escape from the model / mould duringpolymerisation and diffuse into the acrylic.This results in whitish areas on the surface ofthe acrylic which indicates a reaction hastaken place between the moisture and acrylic.There is not much sense in repeatedly apply-ing separator to attempt to prevent such a pro-blem. Better to apply separator just once, butcorrectly, as indicated.

t=0.5mm

t=1.0mm

t=0.5mm

t=1.0mm

t=0.5mm

model tapering

model with clearboundary

10 mm

0.5 mm

10 mm


14.3 Occlusal Contact Adjustment

The ideal point at which to adjust the occlusionis after the dentures have been transferred fromwax to acrylic. Regardless of the preferred setup method, a balanced centric occlusion isessential. The dentist must decide which con-cept is appropriate for the particular case.

1. If a patients dentures are constructed accor-dingly to the mandibular neuromuscular gui-dance philosophy of Dr Karl Hiltebrandt, asopposed to tooth guided movement, the resul-ting centric support will be sufficient.

2. If a fully balanced occlusion is the goal,occlusal adjustments are made as follows.

14.3.1 What is the correct method to followwhen adjusting the occlusion of fulldentures?

Occlusal adjustment of full dentures by bilate-ral balancing.

Prerequisites:• Correctly set teeth with interdigitation of thecusps and fissures.

• Taking into account the sagittal and if appro-priate, the transverse compensating curve.

• Sagittal overbite (overbite – overjet) as arule by 1 – 2 mm.

Basic rules:• The palatal cusps of the maxillary teeth 4, 5,6 and possibly 7, and the buccal cusps of themandibular teeth 4, 5, 6 and possibly 7 securethe occlusion. They must always be con-served when determining the occlusion.

• When adjusting the occlusion of the ante-riors, cosmetic factors should also be takeninto consideration.

Adjusting the occlusionThe palatal cusps of the upper posteriors 4, 5, 6,and possibly 7 should have homogeneous contactin the fossae of the lower posteriors. Likewise,the lower posteriors 4, 5, 6 and possibly 7 shouldhave good contact with their antagonists. Thesupporting cusps must not be shortened, butshould be adjusted to fit into the fossa of the ant-agonist.

14.3.2 Which contact points are actuallynecessary?

Different contact points will be required, depen-ding on which occlusal concept is selected forthe patient in question. If the concept of lin-gualised occlusion is used, the following con-tacts are required in the centric position:

Fig. 3: Lingualised occlusion.

133

If the teeth have been set up according to theconcept of canine guidance with ABC contacts,possible combinations of contact points aredepicted in the following diagram. These arepositioned individually, but usually in pairs. Asalready described in section 12.12 the A and B orB and C contacts, and sometimes also A and Band C contacts, which will provide stability.

14.3.3 Which movements must be freefrom occlusal interference ?

If at the outset we do not wish to work accor-ding to the described principles and grind theocclusion to enable excurson movements, or, ifanother approach is necessitated by the parti-cular case, we can proceed as follows.

Occlusal adjustment to facilitate excursivemovement as per generally accepted prin-ciples.As a rule, the occlusion supporting cusps of theposterior, 4 ,5, and 6 must not be ground in anyway during occlusal adjustment procedures.They must be preserved in all circumstances.

LaterotrusionIn Laterotrusion on the working side contactsshould be created both frontally and betweenthe buccal cusps of the posteriors. For cosmeticreasons, anterior grinding in laterotrusionshould be carried out, if possible, only on thelowers. Posterior occlusal adjustments aremade only to non occlusion supporting cusps.Prior to this, the occlusion supporting occlusalcontacts should be marked as they must bepreserved in all circumstances.

MediotrusionIn mediotrusion on the balancing side, antago-nist contacts are required on at least twoposterior teeth between the upper lingual cuspand the lower buccal cusp.

Fig. 4: ABC contacts – this concept does not have the aimof balancing.

Fig. 5: When adjusting the occlusion, the red arrows indicatethe occlusion supporting cusps which must not be ground.


Protrusive adjustment:Bennett angle set at zeroIn protrusion, when the upper and lower inci-sors are “edge to edge,” bilateral occlusal sup-port is required distally in the posterior area.

14.4 Finishing and Polishing

A high quality polish is a must in order to pro-vide comfort and hygiene for the patient.Light curing glaze varnish is no substitute for asparkling polish The working steps towardsachieving a good polish are simplified andshortened by careful waxing, wax contouringand carving, investing and the correct use ofacrylic / plaster separators both alginate basedand silicone. Theories regarding the addition ofbulked out gum areas which can be carved or

removed as required with trimming burs afterprocessing of the denture acrylic are very inef-ficient as they require a great deal of both timeand experience. The time is far better spentwith careful wax contouring, wax carving andpreserving this with thoughtful use of thevarious wax / plaster separators available. Ifthe various working steps are diligently carriedout, the denture finishing and polishing timeand work is minimised and results in a qualityfinish for the dentures. After removal of theprocessed dentures from the flask/ mould isthe trimming of the acrylic ‘flash.’

Do not trim or remove any of the bulk of thedenture border / periphery as this is a repro-duction of the muscle trimmed, functional

impression which was painstakingly obtainedby the Dentist. These borders are important asthey contribute towards the seal of the dentu-res with the tissue which is necessary forretention of the dentures. Additional trimmingwill diminish or even eliminate the retention.

The palatal finish line and post dam areas arenormally clearly visible on the processed den-ture. The acrylic ‘flash in this area is first remo-ved and the finish line trimmed.

Fig. 7: Optimally balanced posteriors. Fig. 8: Remove only the acrylic ’flash’.

Fig. 6: In this case it is necessary to grind the fossaof the antagonist. As indicated.

135

The thickness of the post dam / finish line areaof the denture palate can be reduced to a fea-sible minimum in order to maximise comfort forthe patient and avoid nausea.

With a sandpaper mandrel and a suitably finegrade of sandpaper, the lightly trimmed surfa-ce of the exposed periphery and reduced postdam / finish line areas can be refined.Further surface refining can also be accomplis-hed with the use of rubber polishers beforefinally using pumice.

In regard to the use of abrasives in refining thecut of a surface to be polished, the basic rule isto work from a larger coarser grain progressi-vely towards a finer smaller grain size. Thiswill always give the best possible surfacefinish and ultimately the best polish.

When beginning the refinement of the denturesurface start with the relatively coarse grainabrasive and use on all necessary surfaces ofthe denture before moving on to a finer grainabrasive. Chopping and changing from coarseto fine and fine to coarse is time consumingand will compromise the surface finish. Itmakes sense to develop a systematicapproach to denture finishing in order to acqui-re the necessary experience and obtain consi-stent results.

Particular areas of some dentures are not veryaccessible to the large polishing brushes mopsor felt cones normally used on a polishinglathe. These include the areas immediatelyaround the teeth and very high palates. Suchinaccessible areas are best polished at thework bench with the use of small handpiecemounted polishing implements. (brushes, mopsand felt cones.)

The gingival area of a denture wax up requiresspecial attention as the finishing of the junc-tion of teeth and denture base material mustbe accomplished without damaging the acrylicteeth. Picking around the gingival with a sharpinstrument in order to remove any ‘pink acrylicflash’ will inevitably cause damage to the sur-face of the teeth. This whole procedure can beavoided with the use of a silicone protectionlayer which is applied to the carefully waxedand carved gingival area immediately prior tothe pouring of the second (top) half of thedenture flask during the investing procedure(“Vitafol–H”). Use of such products greatlysimplify the gingival finishing / polishing pro-cedures and eliminate completely, the other-wise inevitable damage to the surface of theteeth while finishing. Final pumice polishing ofsuch a well finished area is minimised and thedanger of over polishing of fine contouring andcharacterization, eliminated.

A sparkling glaze like surface can be obtainedwith polishing mops using a good high shinepolishing paste the selection of which is one ofpersonal preference. There are many suchpolishing materials available and a discussionof the pro’s and con’s of each would probablyyield sufficient material for a separate publica-tion on the subject.

For those who may be accustomed to workingprocedures and sequences different from thosedescribed, it will likely take time and someeffort to ‘change their ways!’ If however theychoose to do so, they will be rewarded withincreased productivity and above all the highquality of their work will be obvious to theirDentist client’s, patients and most importantly,themselves.


14.5 Seating and issue of the dentures.

In the entire sequence of the various workingsteps, the seating and issue of the dentures isundoubtably the most important moment for allinvolved. Checking the retentitiveness of thedentures, their functional stability and their aes-thetics are the penultimate steps in this proce-dural chain.

14.6 Remounting the dentures.

Patient aftercare is an integral part of treat-ment. Remounting of the dentures after a shorttime in the mouth is essential and should bedone after the dentures have been worn forabout 24 hours.

For this purpose, newly fabricated models anda new bite are used to remount the dentures onthe articulator. It is important that the bite rec-ording medium not be perforated as this wouldproduce an un-physiological bite relationshipwith possible pathological consequences. It isalso most important that the remounting not bedone on the “used” models. Polymerisation willhave caused volumetric change and if used forremounting would subject the dentures toharmful stresses.

For the purpose of model remounting, the useof split – cast models or mounting plates areuseful along with the indispensible use of arti-culation Shimstock foil

This particular step should be carried out withmuch care in order to obtain the optimum occlu-sal comfort for the patient. If not done withcare it would seem so to speak that the cake isbeing delivered without the icing.

14.7 Instructions for care

Caring for dentures.

• Using toothpaste and hard bristle tooth-brushes are not recommended.

• Dish washing liquid and a SOFT brush areexcellent for the purpose.

• Any tartar can be removed by immersion invinegar.

• The occasional immersion in water with adenture cleansing tablet is also helpful.

137

Notes

138

Notes

139

Literature references

Carl Hiltebrandt, Die Arbeitsphysiologie des menschlichen Kauorganes

Hofmann-Axthelm, Lexikon der Zahnmedizin

Hohmann-Hielscher, Lehrbuch der Zahntechnik, Quintessenz Verlag 2001

Stuck /Horn „Zahnaufstellung in der Totalprothetik“

Parsche E., Funktionslehre/Biomechanik Graz 2006

Gründler, H. /Stüttgen, U., Die Totalprothese, Verlag Neuer Merkur GmbH 1995

Linke u.a., 2001

Tschirch, 1966

140 Glossary

Aadequate

adhesion

anamnesis

anatomy

anomaly

antagonist

anterior

apical

approximal

articulator

aesthetics

atrophy

Bbasal

bolus

buccal

appropriate, fulfilling requirements

the state of adhering to; sticking to

the recording of the patient's history

the science and teaching of the structureof the human, animal or plant body

a congenital or subsequent developmentirregularity of an organ

opposing tooth

front

at, on, towards the apex (root tip)

at, on, towards the adjacent(mesial or distal) tooth

apparatus for simulatingthe jaw movements (chewing simulator)

the nature, expression and appreciation(sensory perception) of beauty; used informallytoday to refer to an attractive appearance

the wasting or loss of tissue

at, on, towards the base

mass of food formed in the mouthafter thorough chewing (food bolus)

at, on, towards the cheek

Glossary

141

Ccanines

carunculae salivariae(salivary caruncles)

central

cervical

cohesion

condyle

coronal

crista mylohyoidea(mylohyoid crest)

Ddentition

diffusion

distal

divergent, diverging

dorsal

corner teeth, eye teeth (plural cuspids)

small eminences on the efferent ductsof the salivary glands on both sides of thetongue tendon on the transition to thefloor of the oral cavity

forming the midpoint, med. also usedpertaining to the central nervous system

at, on, towards the tooth cervix/neck

holding together; also referred to asthe "force that holds together"

articular head

towards the crown, pertaining to the crown

soft, osseous ridge, also called lineamylohyoidea (mylohyoid line): area of themylohyoid muscle attachment on theinside of the lower jaw

the natural teeth in the dental arch;tooth eruption

the process of becoming mixed throughor widely spread (until particles are evenlydistributed)

away from the centre

deviant, moving apart

at, on, towards the back

142 Glossary

Eeugnathic

excursion movement

explosives

extraction

Ffacial

fissures

food bolus

fricatives

frontal

freeway space

Ggingival mucosa

gingival

Hhamulus pterygoideus(pterygoid hamulus)

hygiene

normal, corresponding to the rule

every movement of the mandible outof the centric position on any side

stop consonants (phonetic term)

removal, e.g. of a tooth

at, on, towards the face

gap, crack, pit with regard to the occlusion(occlusal valleys)

food mass which has been processed by chewing

fricative consonants, i.e. which make"rubbing" sounds (phonetic term)

at, on, towards the front or the forehead

the interocclusal distance between

alveolar mucous membrane

on, towards the oral mucosa,relating to the oral mucosa

hook-shaped process forming the inferiorextremity of each medial pterygoid plateof the sphenoid bone

the theory or practice of the preventionof infectious diseases

143

hypomochlion

Iimmediate prosthesis

incisal, incisally

incisors

inferior

interalveolar line

intercuspation

Jjaw atrophy

Llabial, labially

lateral, laterally

lateroretraction

laterotrusion

pivotal point of a lever which makesa decisive contribution to the leverage

immediate denture, prosthesis generallyseated directly after extraction of teeth

pertaining to the incisal edges; at, on,towards the incisal edges

incisor teeth

lower

also interalveolar connection line; is theimaginary connecting line between the centreof the alveolar ridge of the upper jaw andthe centre of the alveolar ridge of the lowerjaw in the posterior area

interdigitation of the upper teethwith the lower teeth

loss or wasting of the jaw / bone

pertaining to the lip; at, on, towards the lip

at, on, towards the side, pertaining to the side

movement of the lower jaw out of the lateralposition back into the position of maximumintercuspation

lateral movement of the mandible outof the position of maximum intercuspation

144

laterotrusion condyle

laterotrusion side

ligament (pl.: ligaments;Lat ligamentum, pl. ligamenti)

linea mylohyoidea (mylohyoid line)

lingual

Mmandible

marginal

mastical

maxilla

mediotrusion

mediotrusion condyle

mediotrusion side

mentolabial fold

condyle of the side which moves awayfrom the centre during lateral (sidewards)movements (working condyle)

segments of the mandible which move awayfrom the centre during lateral movements

elastic, fibrous chord of connective tissue

soft, osseous ridge, also crista mylohyoidea,giving attachment to the mylohyoid muscleon the inner surface of the mandible

towards the tongue, pertaining to the tongue

lower jaw

belonging to the margin,situated at the margin

oriented towards the occlusal surface

upper jaw

lateral movement in the non-working sidetowards the centre

condyle of the mediotrusion side (balancingcondyle), which moves towards the centreduring the lateral movement (swinging condyle)

segments of the lower jaw which movetowards the centre during a lateral movement

fold of the mouth running from the cornerof the mouth in the direction of the chin

Glossary

145

mesial, mesially

molars

morphology

mucoginival boundary

musculus temporalis (temporal muscle)

Oocclusal, occlusally

occlusal plane

occlusion concept

opaque

oral

Ppalatal, palatally

palatal vibrating line

papilla incisiva (incisal papilla)

papilla

towards the centre, pertaining to the centre

large posterior teeth

theory of the structure and shape of organisms

clearly defined boundary betweenthe attached gingiva and the mobile oralmucosa (gingival mucosa)

temple muscle

at, on, towards the occlusal surface

plane in space, on which the teethof the upper and lower jaw meet

interpretation of the way in whichthe rows of teeth of the upper and lowercorrespond to one another

cloudy, impenetrable by light,not transparent or translucent

pertaining to the mouth

at, on, towards the palate

the transition from the soft to the hard palate

the interdental papilla of the incisal teeth

round protuberance

146

pharynx

phonetics

physiognomy

posterior

premolars

pressure area

processus coronoideus(coronoid process)

proglissement

prognathism, mandibular (progenia)

prognathism, maxillary

protrusion

pupil line

Qquadrant

mucosally enveloped connective tissue-likemuscular tube which runs from the outersurface of the base of the skull to the entranceto the laryngeal inlet

branch of linguistics comprising the studyof the sounds of human speech; analyses thephysical properties relating to speech sounds

external appearance of a person,especially characteristic facial features

the back / behind

small posterior teeth

raised point on a prosthesiswhich causes gingival irritation

front process on the rising mandibular rami,on which the temporal muscle begins

forward displacement of a mandibular pros-thesis due to the effect of occlusal forces

protrusion of the mandible (inverted anterioroverbite)

protrusion of the maxilla (protrusionof the body of the upper jaw as a whole)

to push forwards; forwards movement

an imagined straight, horizontal line runningthrough the centres of the pupils of both eyes

quarter-circle, one of four parts into whicha plane /a structure is divided by two real orimaginary lines that intersect each otherat right angles

Glossary

147

Rremounting

resorption

retraction

retromolar

retrusion

rim-former

rugae palatinae (palatal rugae)

Ssagittal

skeletal

statics

stippling

sublingual

superior

TTexture

torus palatines (palatal torus)

remedying the occlusion on the articulator

absorption, dissolution (also of bones atrophy)

shrinkage, shortening, recession

behind the molars

to force backwards; backwards movement

instrument for forming wax bite rims(to reduce and shape the vertical height)

palatal ridges, folds

in the direction of the sagittal suture(connective tissue joint along the midline,between the two parietal bones of the skull)

pertaining to the skeleton

theory of the conditions under whichbalance occurs (stability)

creating an orange-peel like texture/structure,especially in the area of artificial gingiva

beneath the tongue

upper

quality, structure or compositionof elements in the dental world, oftenused for the surface quality

bony growth on the palate

148

transversal

trigonum retromolare(retromolar triangle)

tuber maxillaris (maxillary tuber)

tubera, tubers

tuber-cheek pouch

Vvalve border (marginal seal)

vector of force

vestibular

Wworking condyle

running across

triangular, osseous area posteriorto the last lower molar

ridge or eminence on the surfacebehind the upper jawbone

plural of tuber

area between the tuber and the cheekincluding the mucolabial fold

functional margin which sealsthe suction area of a prosthesisin the area of the mucolabial fold

direction of force

towards the vestibule of the mouth

the condyle of the laterotrusionside /working side; (resting condyle);see also laterotrusion condyle

149

Imprint

Author:Urban Christen

Co-Author:Eva Kerschensteiner

Title:A Guide to Complete Denture ProstheticsArt. No. 027 XXXISBN:

Copyright by Christen/KerschensteinerXXXX 1, 72336 XXXX

This instruction manual is protected by copyright. All rights remain reserved, includingthose of translation, reprint and reproduction of this manual or parts thereof.

No part of this instruction manual may be reproduced in any form (photocopy, microfilmor any other procedures) without written consent from the authors, neither may itbe reproduced, processed, replicated or distributed by electronic means; this appliesalso to its use for teaching and training purposes.

All information contained in this instruction manual was compiled to the bestknowledge of the authors, and the content checked with due care. This, however, doesnot constitute an absolute guarantee against errors. For this reason, the informationfeatured in this product is not subject to any obligation or guarantee of any nature.Furthermore, neither the authors nor VITA Zahnfabrik H. Rauter GmbH & Co. KGshall assume any responsibility or liability arising therefrom.

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