Arrangement of teeth in complete denture

Arrangement of teeth in complete denture

HISTORY Skillfully designed dentures were made as early as 700 BC.and

Talmud a collection of books of hebrews in 352-407 AD mentioned that teeth were made of gold ,silver,and wood.

Egypt was the medical center of ancient world, the first dental prosthesis is believed to have been constructed in egypt about 2500 BC.

Hesi-Re Egyptian dentist of about 3000 BC

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Front and back views of mandibular fixed bridge, four natural incisor teeth and two carved ivory teeth Bound With gold wire found in Sidon-ancient Phoenicia about fifth and fourth century BC.3Dr Abhilash

WOODFor years, dentures were fashioned from wood .

Wood was chosen -readily available -relatively inexpensive -can be carved to desired shape

Disadvantages -warped and cracked in moisture -esthetic and hygienic challenges -degradation in oral environment4Dr Abhilash

Wooden denture believed to be carved out of box wood in 1538 by Nakoka Tei a Buddist priestessWooden dentures5Dr Abhilash

Bone

Bone was chosen due to its availability, reasonable cost and carvability .

It is reported that Fauchard fabricated dentures by measuring individual arches with a compass and cutting bone to fit the arches .

It had better dimensional stability than wood, esthetic and hygienic concerns remained.6Dr Abhilash

IVORYDenture bases and prosthetic teeth were fashioned by carving this material to desired shape Ivory was not available readily and was relatively expensive.Denture bases fashioned from ivory were relatively stable in the oral environmentThey offered esthetic and hygienic advantage in comparison with denture bases carved from wood or bone.

Carved ivory upper denture retained in the mouth by springs with natural human teeth cut off at the Neck and riveted at the base.

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Since ancient times the most common material for false teeth were animal bone or ivory,especially from elephants or hippopotomus.

Human teeth were also used,pulled from the deceased or sold by poor people from their own mouths.

Waterloo dentures

1788 A.D. Improvement and development of porcelain dentures by DeChemant.

G.Fonzi an italian dentist in Paris invented the Porcelain teeth that revolutionized the constructionOf dentures.Picture shows partial denture of about1830,porcelain teeth of fonzis design have beenSoldered to a gold backing.8Dr Abhilash

One piece porcelain upper denture crafted by Dr John Scarborough,Lambertville,New Jersey 1868.9Dr Abhilash

In 1794 John Greenwood began to swage gold bases for dentures. Made George Washington's dentures.

George washingtons last dental prosthesis. The palate was swaged from a sheet of gold and ivory teeth rivetedTo it.The lower denture consists of a single carved block of ivory. The two dentures were held togther by steelSprings. 10Dr Abhilash

In 1839 an important development took place CHARLES GOODYEAR discovered VULCANIZATION of natural rubber with sulphur(30%) and was patented by Hancock in england in 1843.NELSON GOODYEAR (brother of charles goodyear) got the patent for vulcanite dentures in 1864.

. They proceeded to license dentists who used their material, and charged a royalty for all dentures made. Dentists who would not comply were sued. The Goodyear patents expired in 1881, and the company did not again seek to license dentists or dental products. Vulcanite dentures were very popular until the 1940s, when acrylic denture bases replaced them.

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A set of vulcanite dentures worn by Gen. John J. (Blackjack) Pershing, commander of the American Expeditionary Forces in France during the First World War

Set of complete dentures having palate of swagedGold and porcelain teeth set in vulcanite.12Dr Abhilash

In 1937 Dr. Walter Wright gave dentistry its very useful resin.

It was polymethyl methacrylate which proved to be much satisfactory material tested until now.

Dentures made of polymethyl methacrylate13Dr Abhilash

DEFINITIONS

Occlusion-It is the static relationship between the incising or masticating surfaces of the maxillary or mandibular teeth or tooth analogues [ GPT 7 ]

Articulation-The static and dynamic contact relationship between the occlusal surfaces of the teeth during function is called as articulation14Dr Abhilash

Development of occlusion in complete dentures differs from that present in natural dentition due to the difference in the support system

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Differences between natural and artificial occlusion

Presence of periodontium in natural dentition

Teeth act individually in natural dentition and as a single unit on an unyielding base in a complete dentureBilateral balance is deemed necessary in artificial occlusion but not in natural dentition

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Malocclusion in natural dentition may remain uneventful but evokes severe response in artificial occlusion

Non vertical forces are well tolerated in natural dentition but traumatic in artificial dentition

Incising with natural teeth is uneventful but in complete dentures affects all teeth and the base17Dr Abhilash

In natural dentition second molar is favoured for mastication but in a complete denture it is the first molar and second premolar which are favoured for mastication

Proprioception present in natural dentition but absent in artificial occlusion

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Preliminary selection of Artificial Teeth Anterior teeth Esthetic requirement Posterior teeth Masticatory functional requirement Compatibility with surrounding oral environment Preliminary selection is based on:

Size Form Color

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SIZESelection of Anterior teeth Size of the face Size of Maxillary arch Incisal papilla and the cuspid eminence Maxillomandibular relations Vertical distance between ridges

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Selection of Posterior teeth Functional harmony with musculature Less buccolingual dimension Anteroposterior dimension21Dr Abhilash

FORM Conform to the general outline of face Facial forms Square Square tapering Tapering Ovoid

Sex

Ageing

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Form of Posterior teeth Occlusal surface primary concern Balanced in centric and eccentric positions cusp form Disocclusion in eccentric position Cusp or monoplane Balanced in centric position only Monoplane Arrangement of artificial posterior teeth for functional harmony depends on a thorough understanding of occlusion23Dr Abhilash

SHADE Harmony with color of skin, eyes and hair Shade of posterior teeth should harmonize with shade of anterior teeth Bulk influences the shade . . . . 24Dr Abhilash

Horizontal orientation of Anterior teeth Insufficient support of lips

Drooping of corner of mouth Deepening of nasolabial groove Deepening of sulci Reduction in prominence in philtrum Reduction in visible part of vermilion border

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Excessive support of lips

Stretched appearance of lips Elimination of contour of lips Distortion of lip and sulci Tendency of lip to dislodge the denture

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Incisive papillae

Midline of upper denture27Dr Abhilash

Buccolingual position of posterior teeth Mainly determined by Neutral zone

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If teeth located lingually . . .

If teeth located buccally . . .

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Vertical orientation If the upper lip is relatively long . . .Anterior teeth

. Length and movement of upper lip30Dr Abhilash

Lower lip is a better guide Cusp tips of canine and I premolar are even with lower lip- If lower anterior - above this level

- If lower anterior

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Maxillary anterior teeth are arranged according to phonetics

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Posterior teeth Two basic anatomic guide - Orifice of Stensons Duct - Retromolar pad If occlusal level is too low If occlusal level too high Character of residual ridge

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Inclination of teeth Labial surface of bone

Profile form of the patient

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Anteroposterior curveMediolateral curve

Compensatory Curves35Dr Abhilash

ARRANGMENT OF TEETHThe four principal factors that govern the positions of the teeth for complete dentures are

(1) the horizontal relations to the residual ridges, (2) the vertical positions of the occlusal surfaces and incisal edges between the residual ridges, (3) the esthetic requirements, and (4) the inclinations for occlusion

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Guidelines for horizontal Placement of Anterior Teeth

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Dr Abhilash38Role of incisive papilla & mid palatal sutureIt is found in Lingual embrasure b/t Maxi.C.I.Labial surface of maxillary incisors is approx. 8 to 10 mm anterior to incisive papilla.A transverse line bisecting the middle of I.P. passes through the tip of canine.

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Dr Abhilash39Cuspid eminences When cuspid eminences are visible on cast, a line marking the distal of eminences co-incide with distal margin of cuspids. Relation to residual alveolar ridge

Max. Anterior teeth are placed anterior to residual ridge, depending upon amount of resorption.

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Dr Abhilash40Arch Form And ShapeSquare arch C.I. in line with the canine

Tapering arch C.I. at a greater distance forward than canine

Ovoid arch - in between

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Dr Abhilash41EstheticsVermilion border of upper lip.

Mento-Labial & Naso-Labial groove.

Everted upper lip.

Corner of mouth (no drooping appearance)

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RELATION WITH THE UPPER LIP

If set too far posteriorly Lip looks unsupported.Vermilion border would not be visible.If set too far anteriorlyLip would taut & stretch.Nasolabial fold may fill out.

Incisal two-thirds of labial surface of teeth supports the lips.

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Dr Abhilash43MEDIO- LATERAL POSITIONMidline midline of face passes between 2 upper & lower central incisors.

Ala of nose line dropped from the Ala passes through tip of canine.

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Guidelines for vertical Orientation of Anterior Teeth

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Dr Abhilash45Role of upper lipVisibility of upper anterior teethIncisal edges are visible by 1 to 2 mm below the upper lip at rest.

Short or long or incompetent lip influences the amount of teeth visibility.Some racial types have fuller lips, others have thinner.

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Dr Abhilash46Effect of agingIn young pt, Incisal edges are visible by 1 to 2 mm below the upper lip at rest.

While smiling or during speech,incisal & middle 1/3 are visible in normal person.

With aging, tone of upper lip decreases, lesser amount of maxillary teeth visible and more of mandibular teeth become visible.

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Dr Abhilash47Relationship of lower lip to anterior teeth Lower canine & Ist premolar should be even with lower lip at the corner of mouth.If lower teeth are high-Anterior plane of occlusion may be too high-excessive VDO-Excessive vertical overlap reverse is true if mandibular teeth are below lower lip at corner of mouth.

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Guides to position of posterior teeth

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Dr Abhilash49Retromolar padThe maximum extension posteriorly of any artificial tooth is anterior border of Retromolar pad. to avoid having a tooth over an incline which results in denture sliding.

Sometimes space is available for only 3 mandibular posterior teeth, then drop Ist premolar.

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Dr Abhilash50Retromolar pad

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Dr Abhilash51Maxillary TuberosityTeeth should not be set on the Tuberosity as it can lead to lever imbalance and might lead to cheek bite in posterior region.

When space permits,4 maxillary posterior teeth can be placed opposing 3 mandibular posterior teeth, to provide support to cheeks

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Dr Abhilash52OCCLUSAL PLANE Anterior occlusal plane parallel to interpupillary line & at the level of commissure.

- posterior occlusal plane should be at the level of 2/3 the height of retromolar pad

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Dr Abhilash53 Stensons duct it exits at Bu mucosa in the region of 2nd Molar. Occlusal plane is located of 1/8 of an inch below this.

With these anterio-posterior guidelines,occlusal plane is made parallel to lower mean foundation plane and Ala-Tragus plane.Height of occlusal plane is also influenced by- -length of lips-Ridge height-Amount of maxillomandibular space available

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Dr Abhilash54Relationship with tongue

Occlusal plane should be located in relation to lateral surface of tongue near demarcation zone b/w Dorsal keratinized mucosa & ventral nonkeratinized mucosa.

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Dr Abhilash55Buccal LimitTeeth should not be set too far off the ridge.Placing too far Buccally can cause:Cheek Biting Esthetic problems due to obliteration of Buccal corridor. Denture instability due to lever imbalance & muscle function.

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Dr Abhilash56Lingual LimitLingual cusps of molars are in alignment with Mylohyoid ridge.Placing too far lingually can cause Crowding of tongue. Tongue biting. Imbalance due to tongue function.

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Dr Abhilash57Overjet & OverbiteClass I Normal , Class II Retruded , Class III - Protruded

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Dr Abhilash58Canine & Molar RelationshipMesial slope of cusp of upper canine opposes the distal slope of Lower canine cusp. ORDistal surface of lower canine is in line with tip of upper canine.

M.B cusp of upper 1st molar opposes the Buccal groove of lower 1st molar.

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Dr Abhilash59Buccal CorridorSpace b/w buccal surface of posterior teeth & inner surface of cheeks.Excessive buccal corridor results when posterior teeth are set too far ligually.Resulting dark space appears excessive & unaesthetic. Inadequate buccal corridor occurs when posterior teeth are placed too far buccally, causing obliteration of buccal corridor.

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Dr Abhilash60Canine-retromolar Pad Reference Line

From tip of Canine to center of Retromolar pad. This designates centre of mandibular Ridge.Central fossae of mandibular Posterior teeth should coincide with this line ORThis in turn corresponds to maxillary palatal cusps .

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Individual orientation of maxillary teeth

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ARRANGING TEETH FOR COMPLETE DENTURE OCCLUSIONMaxillary Central Incisor:

The long axis of the tooth is perpendicular to the horizontal (labiolingual inclination)Its long axis slopes towards the vertical axis ( mesiodistal inclination)

Slopes labially about 15 degrees when viewed from the side.Incisal edge is in contact with the occlusal plane.

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Teeth is set on the occlusal rim63Dr Abhilash

Maxillary Lateral Incisor:

Long axis slopes rather more towards the midline

Inclined labially about 20 degrees when viewed from the side

The neck is slightly depressed

The incisal edge is about 1mm short of the occlusal plane.

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Maxillary Canine :Its long axis is parallel to the vertical axis when viewed from both the front and side or it may be slightly to the distal.

The bulbous cervical half of the tooth provides its prominence.

Its cusp is in contact with the horizontal plane.. The neck of the tooth must be prominent

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Remaining maxillary teeth are arranged on the other side of the arch to complete the anterior set up.

To maintain the set teeth in position, the wax supporting the teeth must be heated and sealed both to the teeth and to the record base.

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First premolar:

Long axis is parallel to the vertical axis when viewed from the front or the side.

Its palatal cusp is about 1mm short of, and its buccal cusp in contact with, the occlusal plane.

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Second premolar:

Its long axis is parallel with the vertical axis when viewed from the front or the side.

Both buccal and palatal cusps are in contact with the occlusal plane.

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First molar:Long axis slopes buccally when viewed from the front, and distally when viewed from the side.

Only mesiopalatal cusp is in contact with the occlusal plane.

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Second molar:

Long axis slopes buccally more steeply than the first molar when viewed from the front, and distally more steeply when viewed from the side.

All four cusps are clear of the occlusal plane, but the mesiopalatal cusp is nearest to it.

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Maxillary teeth set checked on occlusal plane76Dr Abhilash

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Orientation and arrangement of mandibular teeth

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Arranging the Mandibular Teeth

Mandibular central incisor:

Long axis slopes slightly towards the vertical axis when viewed from the front.

Slopes labially when viewed from the side.

Incisal edge is about 2mm above occlusal plane

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Mandibular lateral incisor:

Long axis inclines to vertical axis when viewed from the front

Slopes labially when viewed from side but not so steeply as the central incisor.

Incisal edge is about 2mm above occlusal plane

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Mandibular canine:

Long axis leans very slightly towards the midline when viewed from the front.

Leans very slightly lingually when viewed from the side

Neck is slightly prominent and the tooth is tilted to the distal

Tip at same level as incisors.

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Teeth arrangement checked in patient mouth86Dr Abhilash

The retromolar pad is exposed and points are marked on pounds lines joining the cannine to retromolar pad. 87Dr Abhilash

First molar:

Long axis leans lingually when viewed from the front and mesially when viewed from the side.

All cusps are at a higher level above the occlusal plane than those of the second premolar.

The buccal and distal cusps are higher than the mesial and lingual.

The mesiobuccal cusp occludes in the fossa between upper second premolar and first molar.

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Dr Abhilash89Mandibular 1st MolarFacial: Long axis leans mesially, when viewed from side.Proximal : Long axis inclines Lingually, when viewed from front.Occlusal: Buccal cusps are higher than Lingual cusps.Distal cusps are higher than Mesial cusps.

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Second premolar:

Long axis is parallel to the vertical plane when viewed from both the front and the side.

Both cusps are about 2mm above the occlusal plane.

The buccal cusp contacts the fossa between the two upper premolars.

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Dr Abhilash92Mandibular 2ed PremolarFacial & Proximal : Long axis is vertical from both views.Occlusal : Both cusps are about 1-2mm above Occlusal plane

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First premolar:

Long axis is parallel to the vertical plane when viewed from the front and the side.

Its lingual cusp is below the horizontal plane

Its buccal cusp about 2mm above it as it contacts the mesial marginal ridge of the upper first premolar.94Dr Abhilash

Dr Abhilash95Mandibular Ist PremolarFacial : Long axis is parallel to vertical plane.Proximal : Long axis is parallel to vertical plane.Occlusal : Bu cusp is above the occlusal plane, whereas Li cusp is below occlusal plane.

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Second molar:

Lingual and mesial inclination of the long axis is more pronounced than in the case of the first molar.

All the cusps are at a higher level above the occlusal plane than those of the first molar, the distal and buccal cusps more so than the mesial and lingual.

The mesiobuccal cusp contacts the fossa between the two upper molars.

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Dr Abhilash98Mandibular 2nd MolarFacial : Mesial inclination is more than 1st molar.Proximal : Lingual inclination is slightly more than 1st molar.Occlusal : Buccal cusps are higher than Lingual. Distal cusps are higher than Mesial.

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Key of occlusionCannine key of occlusionThe distal arm of the lower cannine should align with the mesial arm of the upper cannine.

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Molar key of occlusionThe mesiobuccal cusp of the maxillary permanent molars should coincide with the mesiobuccal groove of the mandibular permanent molar

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Overjet & overbiteOverjet denotes the distance between the upper & lower incisor measured in horizontal plane - 2mmOverbite denotes the vertical overlap of the maxillary and mandibular anterior 2mm103Dr Abhilash

Overjetoverbite104Dr Abhilash

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Dr Abhilash107 THANK YOU

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