Selection _ Arrangement of Teeth for RPD by cuiliqing

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									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 & 94 - 99
             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:    Selected 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
            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.
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