Mouth Preparation

The Component PartsThe Component PartsThe Component PartsThe Component Parts

of Removableof Removableof Removableof Removableof Removableof Removableof Removableof Removable

Partial DenturesPartial DenturesPartial DenturesPartial Dentures

Five Parts of RPDFive Parts of RPD11. Rests. Rests

2. Minor connectorsMinor connectors(including proximal plates)(including proximal plates)

33 Major connectorMajor connector33. Major connector. Major connector

44. Denture base. Denture base andand Artificial TeethArtificial Teeth

55. Retainers. RetainersDirect retainersIndirect Retainers

Max. ConnectorsMan. Connectors

�� Metal framework:Metal framework: CrCr--Co alloy is mostCo alloy is mostcommonly usedcommonly used

�� Denture teeth:Denture teeth: acrylic or porcelainacrylic or porcelaindenture teethdenture teeth

�� Pink acrylic resinPink acrylic resin

Diagnosis and treatment plan

Seat and fit the RPD framework

Draw the Design of the RPD on the diagnostic chart

Survey, determine the path of insertion, and tripod

Mouth preparation and impression for the RPD frameworkMouth preparation and impression for the RPD framework

Physiologic adjustment and altered cast impressionif it is an extension base RPD

Maxillomandibular registration (obtain face bow, VDO, andMaxillomandibular registration (obtain face bow, VDO, andCR records)CR records)Tooth selectionTooth selection

Wax partial denture tryWax partial denture try--in if it is esthetic or complex casein if it is esthetic or complex case

DeliveryDelivery

Draw the Design of theRPD on the diagnosticchart. Identify the axis of. Identify the axis ofrotation due to the distalrotation due to the distalextensionextension

Sort out the proper treatmentSort out the proper treatmentsequencesequence

Design sequence:RestsRestsMinor connectorsMinor connectorsMajor connectorMajor connectorDenture base connectorsDenture base connectorsRetainersRetainers

RPD Framework Mouth preparationRPD Framework Mouth preparation

RestsRestsProximal plates/Minor connectorsProximal plates/Minor connectorsMajor connectorMajor connectorD t b tD t b t

Draw your RPD design on the study cast

Denture base connectorsDenture base connectorsRetainersRetainers

Requires tooth modificationRequires tooth modification

Dra RPD design on the cast follo ing our paper RPD designDra RPD design on the cast follo ing our paper RPD designDraw RPD design on the cast following your paper RPD designDraw RPD design on the cast following your paper RPD design

Surveying ProcedureThis may be divided into the following distinct

phases:� Preliminary visual assessment of the study cast.� Initial survey.� Analysis.� Final survey.

This stage has been described as 'eyeballing' the cast and is a usefulpreliminary to the surveying procedure proper. The cast is held in thehand and inspected from above. The general form and arrangement ofthe teeth and ridge can be observed, any obvious problems noted andan idea obtained as to whether or not a tilted survey should beemployed.

Preliminary visual assessment of the study cast

Mounted diagnostic casts withMounted diagnostic casts withproper VDO and CR recordproper VDO and CR record

Final RPD design based onFinal RPD design based onsurveying analysis and MAPsurveying analysis and MAP

Sort out the proper treatmentSort out the proper treatmentsequencesequence

View the occlusalrelationship fromthe palatal aspect

Treatment of irritated soft tissueTreatment of irritated soft tissuePreprosthetic surgeryPreprosthetic surgeryPeriodontal treatmentPeriodontal treatmentEndodonticsEndodonticsOrthodonticsOrthodontics

Flow Chart of the RPD Clinical ProceduresFlow Chart of the RPD Clinical ProceduresDiagnosis and treatment planDiagnosis and treatment plan

Pt mayPt mayrequiresrequires

OrthodonticsOrthodonticsRestorativeRestorativeTreatment partialTreatment partial

Mouth preparationMouth preparationand impression forand impression forthe RPD frameworkthe RPD framework

Treatment of Irritated Soft TissueTreatment of Irritated Soft Tissue

1.1. IllIll--fitted Existing prosthesis,fitted Existing prosthesis,

2.2. lack of positive rests,lack of positive rests,

33 Hh l iHh l i

Causes:Causes:Causes:Causes:Causes:Causes:Causes:Causes:

Lack of positive rests results in prosthesis displacement,Lack of positive rests results in prosthesis displacement,

which can destroy mucosa & periodontal attachmentwhich can destroy mucosa & periodontal attachment

((100100% mucosal support% mucosal support))

3.3. HhyperocclusionHhyperocclusion

4.4. Bacterial and fugal infectionsBacterial and fugal infections


Irritated and traumatized soft tissueIrritated and traumatized soft tissue

resulting from a bad partialresulting from a bad partial

Tissue conditioning treatment


Solution:Solution:

Fabrication of well designpartial

Adding positive rests to control therelationship of prosthesis to mucosa

A treatment liner provides proper mucosaA treatment liner provides proper mucosa--prosthesisprosthesiscontact during the tissue treatment periodcontact during the tissue treatment period

Conditioning of Abused and irritated tissue bythe use of tissue conditioning material

Mouth Preparation

� Mouth Preparation , Follow the Preliminary diagnosis , and thedevelopment of a tentative treatment plan.

Objectives:Objectives:-� To Return the mouth , to the optimum health, and eliminate any

condition , that would be determinable to the success of theremovable partial denture.

Mouth Preparation include Procedures in three categories :-

1- Oral surgical preparation.

2- periodontal preparation .

3- preparation of abutment teeth .

Oral Surgical Preparation

1- Extraction .2- Removal of residual roots .3 Impacted teeth

- As early As Possible . long time interval Between surgery and Removable partial dentureconstruction .

3- Impacted teeth .4- Malposed tooth .5- Cyst and odontogenic tumors .6- Exostoses and tori .7- Hyper plastic tissues.8- Muscle attachment and frena .9- Bony spines , and knife edge ridges .10- Polyps , papilloma , traumatic hemangiomas.11- Hyper kera tosis, erthyroplakia , and ulcerations.12-Dento facial deformity .13- Osseo integrated device .14- Augmentation & alveolar bone .

- conditioning of abused and irritated tissue by the use of tissue conditioning material

ExtractionExtractionExtractionExtraction

Removal of Residual Roots

Impacted teeth

Malposed tooth

Enlarged tuberosityEnlarged tuberosity

Preprosthetic SurgeryPreprosthetic Surgery

Large ToriLarge Tori

Gross bone undercutGross bone undercutg yg y

Exostoses and tori

Polyps, Papilloma, TraumaticHemangiomas

Osseo-integrated device

Periodontal Preparation

Objectives11- Removal and control of all the Etiological

Factors contributing to periodontal disease .

2- Elimination or reduction of all pockets .

3- Establishment of functional non traumaticocclusion .

4- Development of personalized plaque control.

For I-bar consideration:1. Tissue quality:

2-3mm attached gingiva2. Tissue contour:

in relation to the abutment

Periodontal TreatmentPeriodontal Treatment

Free gingiva graft canFree gingiva graft canprovide attached mucosaprovide attached mucosa

in an area criticallyin an area criticallyassociated with theassociated with the

prosthesisprosthesis

Periodontal diagnosis and ttt planning

Periodontal Preparation

� Initial disease control therapy (phase 1)

� Definitive Periodontal surgery (phase 2)

� Recall maintenance (phase 3)

Advantages of periodontal therapy

Initial disease control therapy (phase 1)� Oral hygiene instructions .� scaling and root planning

Periodontal diagnosis and TTTplanning

� scaling and root planning .� elimination of local irritating factors , other thancalculus.

� Elimination of gross occlusal interferences.� Guide to occlusal adjustment.� Temporary splinting� Use of night guard.� Minor tooth Movement.

Definitive Periodontal surgery (phase 2)

Periodontal diagnosis and TTTplanning

� Gingivectomy.

� Periodontal Flap.

� Mucogingival surgical procedures

Recall maintenance (phase 3)

Advantages of PeriodontalTherapy

1- Elimination of periodontal disease --- primary

Etiologic Factor of tooth loss.

2- peridontium free of disease – much better

enviornment For successfull Restorations.

3- Response of strategic but questionable teeth, to

periodontal therapy, help to make final decision

to Exclude or include them in RPD Design.

Restorative and FixedRestorative and Fixed

Complete crowns to restore remaining teeth are often necessaryComplete crowns to restore remaining teeth are often necessaryand are contoured to coordinate and integrate with RPD treatment.and are contoured to coordinate and integrate with RPD treatment.Note positive rests.Note positive rests.

Treatment Partial Denture:Treatment Partial Denture:An acrylic resin partial dentureAn acrylic resin partial denturethat is placed on interim orthat is placed on interim ortransitional basestransitional bases

Indications:Indications:

#23 & 26: hopeless teethExtraction is recommended

11. Cases require restoration of. Cases require restoration ofvertical dimensionvertical dimension

22. Immediate esthetic &. Immediate esthetic &functional needsfunctional needs

33. Evaluation of hygiene &. Evaluation of hygiene &abutmentsabutments

44. As immediate extraction site. As immediate extraction sitebandagebandage Immediate treatment partial in placeImmediate treatment partial in place

right after extractionright after extraction

Abutment Preparation

� Correction of occlusal plane� Correction of mal-alignment .� Provision for support for periodontal weakened teeth.� Reestablishment of arch continuity.� Examination of each abutment tooth individually as to what type

of restoration is indicated.� Reshaping teeth.

- Enameloplasty.- Developing guiding planes.- Interproximal Preparation for Minor connectors.- Changing height of contour.- Enhancing Retentive undercuts- Rest seat preparation.

Correction of occlusal planeCorrection of occlusal planeCorrection of occlusal planeCorrection of occlusal plane

1- Unopposed teeth for a long period of time over Eruption.� If over Eruption is Minor Recontouring the surface of the

tooth.� If moderate cast restoration, e.g. onlays or crowns.� If Extreme Extraction.Maxillary – supraeruption accompanied by down ward migration

of tuberosity

2- Tipped molar

alignment-Correction of mal

- Tipping of teeth , facially , lingually they complicateclasping procedure, and alter the design of RPD.

Provision of support for periodontallyProvision of support for periodontallyProvision of support for periodontallyProvision of support for periodontallyweakened teethweakened teethweakened teethweakened teeth

Teeth showing decreased periodontal supportwould require splinting.

fReasons for splinting.�To provide adequate support, and stabilization for a

RPD.

Types of splinting .�Fixed splinting .�Designing of the RPDto join the teeth asa functional unit.


Fixed Splinting .� By joining teeth , with complete or partial coverage restoration .

� Fixed splinting of the posterior teeth will provide resistance toAntero posterior Forces But Not Medio lateral forces.

� To Resist Medio lateral forces, splinting

� Should include one or more anterior teeth

Advantages Resistance to applied forces.

Disadvantages Closure of inter proximal Contacts

complicates Oral hygiene measures


Splinting by using properly designed RPDSplinting by using properly designed RPDSplinting by using properly designed RPDSplinting by using properly designed RPD�Swing lock Removable partial denture leads�Swing lock Removable partial denture leads

to an even distribution of applied force.

�Extended arm Clasp.

�Kennedy bar.

�Lingual Plate.

Fixed or Removable splinting?

Reestablishment of archcontinuity

� Lone – standing tooth adjacent to an extension base area istermed a pier abutment.

� Placing a clasp on such a tooth leads to periodontal destructionand abutment loss.

� An appropriately constructed fixed partial denture is used toreestablish arch continuity.

Examination of each Abutment toothindividually

� Protection of abutment to be used in RPD construction.� Restoring canine or premolars using – veneer type

Aim

� Restoring canine or premolars using veneer typecrowns.

� Molars being restored – full cast crown.� Proximal caries, on abutment with buccal and lingual

surfaces sound gold inlay may be indicated , bestpossible support for occ. Rests.

� Most vulnerable area, is the proximal gingival area, liesbeneath the minor connector, due to accumulation ofdebris, and food susceptibility to caries.

� This area, must be fully protected, by inlay restoration,extending to beneath gingival margin.


Reshaping the tooth

� Enameloplasty

� Recountouring, But not over cutting.

Must be confined to Enamel surface , other wiseconsider the properly contoured crowns.

Recontouring

• The contours of the natural teeth mostoften require adjustments for the properq j p pplacement and functioning of the RPD.

Recontouring may be required toRecontouring may be required toRecontouring may be required toRecontouring may be required to1. Improve survey lines (improve clasp location)2. Improve clasp retention (dimpling)3. Improve the occlusal plane by grinding of the

cusp tips and incisal edges of anterior teeth.

Excessive tooth contours are reducedby lowering the height of contour so

that;

1. The origin of the circumferential clasp is placedpreferably at the junction of the middle and gingivalthird of the crown

2. The retentive terminal is placed in the gingival third ofthe crown for better esthetics and better mechanicaladvantage.

3. The reciprocal clasp is placed above the height ofcontour, but not higher than the cervical portion of themiddle third of the crown.


Developing guiding planes.�Guiding planes : they are�Guiding planes : they are

surfaces on proximal or lingualsurface of teeth, that are parallelto each other, more importantparallel to the path of insertionand removal.

�Guiding plane adjacent to a toothsupported segment should be 2to 4 mm in height

• Guiding plane of tooth adjacent todistal Extension Edentulous space

i li htl h t it’ 1 5 2– is slightly shorter it’s 1.5 – 2 mmin height

- Decreased height results in decreasedcontact with the minor connector, and sopermits greater movement of RPD sodamaging torque forces on Abutment

1- Properly Prepared guiding Plane Permits contactbetween the reciprocal element and Abutment so

Guiding Plane on lingualsurface of Abutment

between the reciprocal element and Abutment soPrevent lateral forces.

2- Minimize the number of Pathways by which theProsthesis May enter and exist

3- Reciprocal clasp arm With lingual guiding planeEffective Reciprocation

� Guiding the prosthesis during insertionand removal.

Advantages ofAdvantages ofAdvantages ofAdvantages of Guiding Planes

� Enhance Stabilization

� Undesirable space Between Prosthesisand Abutment

� Retention -- Frictional Resistance

Changing the height of contour

Enhancing Retentiveundercuts

Rest seat Preparation

� Any unit of the partial denture that rests on atooth surface, to provide vertical support is

ll d tcalled a rest.� The prepared surface of the abutment to

receive the rest called rest seat.� Primary purpose of a rest to provide vertical

support they would transmit vertical forces tothe abutment, and direct forces along long axisof the roots.


� Form of occlusal Rest and Rest seats

1- Outline– Triangular with deepest Part of occlusal RestPreparation should be inside lowered marginalridge( reduction app. 1.5mm )

2) Floor: Should be concaveor spoon shape. To preventtransferring of horizontal


transferring of horizontalstresses to the Abutment

3) Angle Formed by occlusal rest and minorconnector Should be less than 90 to direct theforce along axis of Abutment.

a- slippage of the prosthesis away fromthe abutment orthodontic like force

If the angle Formed by occlusal rest andminor connector is greater than 90, this willlead to::::

the abutment orthodontic like force –leading to Movement of tooth

b- Torque on the abutment.

Rests can be placed on :-) S d E l

Support for Rests

a) Sound Enamelb) Any restoration, that proven to

resist fracture or distortion, whensubjected to forces.

- Secondary occlusal Rest

Severely Tilted Abutment

- Extended occlusal Rest- Onlay to Restore occlusal plane

� To Minimize Further tipping of theabutment and Direct Forcestowards the long axis of tooth

Interproximal occlusal Rest seat

- Prepared as Individualocc Rests Except that itocc. Rests, Except that itmust be extended furtherlinguallyused – to avoidinterproximal wedging byframework.

RPD totally tooth supported by means of cast retainers on all abutments,use internal occlusal rest seat for :-

1- Occlusal support-------- derived from the floor of the rest seat

Internal occlusal Rests

1- Occlusal support-------- derived from the floor of the rest seat2- Horizontal stabilization -------near vertical walls of this type of rest seat

- Should be parallel to path of insertion- Tapered occlusally, and dove tailed to prevent dislodgment

proximallyAdvantages of internal rest seats:-

1- elimination of visible clasp2- location of the rest seat in a more Favorable position in relation

to the tipping axisIndicated only for tooth supported RPD

Cingulum rest

� Canine rest more preferable to an incisal rest

Lingual Rests on canines andIncisor teeth

Cingulum rest- Confined to maxillary canines- Rounded inverted v- shaped.

� At junction of gingival marginand middle 1/3

Fl h ld b t d th

Lingual Rests on canines andIncisor teeth

� Floor, should be toward thecingulum rather than the axialwall

� For mandibular canines ------contraindicated due to lack ofthickness of enamel to prepare aretentive rest seat

� Most satisfactory cingulum rest from the support point of view --- that prepared on cast restorations

On incisal Angles of Anterior teethOutline: Rounded notch at incisal angle, deepest

Incisal rests and rest seats

portion of preparation, apical to incisal edgeNotch: Should be beveled lingually and labially

- They are used predominantly as Auxiliary rests for indirect retainers

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own name.

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Mouth Preparation