Presentation on theme: "Selection & Arrangement of Teeth for RPD & The Denture Base McCracken’s RP Prosthodontics, Chapter 9; pages 161 – 164 Stewart’s Clinical Removable Prosthodontics,"— Presentation transcript:
Selection & Arrangement of Teeth for RPD & The Denture Base McCracken’s RP Prosthodontics, Chapter 9; pages 161 – 164 Stewart’s Clinical Removable Prosthodontics, pages 384 – 394 &
Selecting the Artificial Teeth While selecting the replacement teeth, the clinician must carefully consider the esthetic and functional requirements of the patient, the structural requirements of the RPD and the materials to be used in prosthesis construction.
Types of Replacement teeth Commercially available acrylic resin teeth (Ant. & Post.) Commercially available porcelain teeth (Ant. & Post.) Commercially available composite resin teeth (Ant. & Post.)
These are usually used with acrylic resin denture bases. Tube teeth / braided posts (small Posterior spaces) Metal pontics with / without facing (limited inter-arch Posterior space)
Selecting the Anterior Denture Teeth The artificial denture teeth are available in any shape or size and color.
Selecting the Anterior Denture Teeth These can also be individualized to improve esthetics by staining and by placing restorations.
Selecting the Anterior Denture Teeth ‘the material’ Because of their greater ease of placement, acceptable esthetics, and decreased danger of fracture, acrylic resin teeth are commonly used in RPD service than the porcelain teeth.
Selecting the Anterior Denture Teeth Contra-indications for Acrylic resin Tooth: Single tooth replacement on an RPD.
Mold & Shade Selection Shade selection : Guide is always provided by the manufacturer Guide should be moistened before using..
Selection should be made under natural light where possible. Match the shade to the remaining natural teeth. Obtain the shade as quickly as possible
Mold & Shade Selection Mold Selection: S elected as close to the remaining natural teeth as possible and then modified to match by selective grinding. For all anterior missing teeth - Use C.D guidelines
Guidelines for Setting Anterior Teeth 1. Replace the acrylic resin record base attached to the framework with the base-plate wax base.
Guidelines for Setting Anterior Teeth 2. Set the Central Incisor first if the teeth are missing across the midline to reestablish the midline. 3. If required – reshape the ridge lap portion of the artificial tooth without shortening the clinical crown length substantially.
Guidelines for Setting Anterior Teeth 4. Place the teeth as nearly as possible where the original natural tooth was located.
Guidelines for Setting Anterior Teeth 5. Proximal surface of the artificial tooth may need to be recontoured for better adaptation to the adjacent natural tooth, without loosing its morphology.
Guidelines for Setting Anterior Teeth 6. The denture base flanges should be carefully contoured & smoothed. Remove the excess wax from the teeth and the framework.
Some Problems Encountered while Setting the Anterior Teeth
Anterior Denture Teeth Set-up Problem: Narrow Space Mesio-distally. Cause: Tilting or drifting of the adjacent teeth into the space. Solution: 1. Avoid this situation by immediate replacement dentures. 2. Regain the original width by reshaping the proximal surfaces of adjacent natural teeth.
Anterior Denture Teeth Set-up Problem: Narrow Space Mesio-distally. 3. Overlap arrangement of the artificial teeth of proper size. 4. Use narrower teeth than the adjacent teeth - with poor esthetics.
Anterior Denture Teeth Set-up Problem: Excessive Loss of Residual Ridge. Cause: Poor surgery at the time of tooth extractions or enhanced ridge resorption. Solution: Place the artificial teeth in their natural position. Acrylic resin flange should be built to the desired thick- -ness to support the artificial teeth and to restore symmetry and contour of the lips.
Anterior Denture Teeth Set-up Problem: Bulbous, too full, large edentulous ridge. Cause: Naturally bulbous ridge, poor surgery, or minimal resorption of the alveolar process post extraction. Solution: Artificial tooth is butted directly over the ridge. No labial flange is added to avoid plumping the lip and affect esthetics.
Posterior RPD Teeth Selection & Arrangement
Mold Selection for the Posterior teeth The tooth size, or mold, is generally dictated by the size of the edentulous space, however, following guidelines may be followed, For an RPD replacing all posterior teeth, complete denture guidelines should be applied for the selection of posterior teeth, e.g., distance from the distal surface of the natural Canine to the upward incline of the ramus or mesial aspect of maxillary tuberosity.
Mold Selection for the Posterior teeth Occluso-gingival height of the denture tooth should match with the adjacent natural tooth for good esthetics. Re-contouring the ridge lap portion of the tooth can be done so that a thin veneer of plastic tooth at the gingival margin remains that can be butted against the edentulous ridge.
Posterior Denture Teeth 1. should fit into the available edentulous space. 2. should be harmonious in composition, size, and occlusal anatomy with the opposing teeth. Adjacent teeth should guide the artificial teeth in their correct bucco-lingual position.
Posterior Denture Teeth 3. the type or number of artificial teeth may differ from the type and number of missing teeth – if drifting of abutment teeth has occurred.
Posterior Denture Teeth 4. acrylic resin teeth are commonly used due to their ease of reshaping and adjusting occlusion without weakening. These can oppose enamel & gold surfaces without abrading them.
Posterior Denture Teeth Alternatively, gold occlusal surfaces can also be fabricated.
Posterior Denture Teeth 5. The use of Porcelain teeth in RPD construction is rare as these must only oppose porcelain surfaces.
Setting Posterior Teeth Guidelines As a rule – achieving classic pattern of intercuspation of opposing teeth should be attempted. In order to duplicate the occlusal anatomy of the opposing natural teeth, set the posterior denture teeth slightly higher in occlusion (by opening the incisal pin by 0.5 mm) and then re-establishing the OVD by selective grinding.
Setting Posterior Teeth Guidelines Positioning the denture tooth adjacent to the abutment having a clasp or a Minor Conn. usually requires, a. trimming of the proximal surface and the ridge lap portion of tooth carefully - Not to over-reduce the height of the buccal surface for esthetic reasons.
Setting Posterior Teeth Guidelines b. The tooth should first be adjusted to fit the cast without framework and then readjusted after placing the framework on the cast.
Setting Posterior Teeth Guidelines The remaining teeth should then be positioned in maximum intercuspation. Some occlusal adjustment or leaving small spacing between two denture teeth may be necessary.
Setting Posterior Teeth Guidelines For the mandibular posterior teeth, central groove should be placed over the crest of the ridge.
Setting Posterior Teeth Guidelines The use of non-anatomic teeth for RPDs is seldom indicated.
Setting Posterior Teeth Guidelines After establishing good centric occlusal contacts, lateral and protrusive contacts of the posterior teeth during function should also be developed by moving the semi-adjustable in use.
Setting Posterior Teeth Developing Functional Contacts The desired occlusal contacts for RPD vary according to the class of partially edentulous arch, e.g., Simultaneous bilateral occlusal contacts in C.O or C.R on artificial as well as the natural teeth for all types of RPD.
Setting Posterior Teeth Developing Functional Contacts For class III RPDs, existing canine protected occlusion should be maintained. Group function occlusion can be provided if the remaining teeth exhibit this occlusion.
Setting Posterior Teeth Developing Functional Contacts For an RPD opposing a CD, bilateral balanced occlusion in centric and all eccentric positions is desired.
Setting Posterior Teeth Developing Functional Contacts For bilateral distal extension RPD (class I), both working and nonworking side natural and artificial teeth should contact simultaneously during function. Whereas, for a class II denture only working side contacts are desired.
Setting Posterior Teeth Developing Functional Contacts For a class IV RPD, no or light contact of opposing natural teeth should be provided only in C.O either on acrylic resin teeth or denture base.
Waxing-up RPD for Wax Try-in
The denture flanges should be contoured and smoothed to provide a pleasing appearance. The distal extension saddle areas should be maximally covered for better soft tissue support.
Waxing-up RPD for Wax Try-in The waxed up denture flanges should not be extended into the soft tissue undercuts.
Waxing-up RPD for Wax Try-in The gingival contouring should harmonize with the adjacent natural teeth and should be self cleansing.
Waxing-up RPD for Wax Try-in Excess wax should be removed from the cast and the framework.
Attaching Artificial Teeth to the Framework Types of RPD Bases Acrylic resin Base Metal Base
Attaching Artificial Teeth to the Framework Types of RPD Bases Acrylic resin Base: where the future need for relining or rebasing is anticipated, i.e., Kennedy’s class I & II or h / o recent extractions.
Attaching Artificial Teeth to the Framework Types of RPD Bases Metal Base: Kennedy’s class III & IV or small edentulous areas.