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Dental Lab Step #4
Denture Processing and Denture Finishing Denture Processing - Suggested Quality Procedures
  1. Read and understand the prescription before starting procedure.
  2. Make sure the denture wax-up accurately represents the proper gingival and arch form, following guidelines for accepted oral anatomy (Figure 7a). Wax the denture to the full contour and properly seal it to the master model.

    Figure 7a
  3. Lubricate the models properly with petrolatum or separating agent to assist in cleaner, easier devestment and less finishing labor..
  4. Vacuum mix investment stone for best results or mix hydrocolloid to manufacturer's recommendations.
  5. Pour investment properly to minimize bubbles by filling the flask from one side to the other allowing air to escape. This is the same technique as pouring an impression.
  6. Thoroughly boil-out and flush wax residue from invested case with clean boiling water. This prevents contamination of the processed denture base resin (Figure 7b).

    Figure 7b
  7. If mechanical retention is desired to secure teeth, prepare the teeth after removing wax and cleaning the denture mould. Use minimal drilling and grinding to minimize weakening of teeth. A chemical bonding agent may be used on plastic teeth if desired.
  8. Whether packing, pouring, injecting, or microwaving, prepare and process the acrylic resin exactly to the manufacturer's directions for use. Thorough cleanliness is essential during the mixing and packing of the acrylic resin.
  9. When injecting acrylic, position sprue according to the manufacturer's technique (Figure 7c and 7d).

    Figure 7c
    Figure 7d
Denture Processing - Quality Standards
  1. Processed denture base is free of porosity and contaminants such as investment debris (Figure 7e).

    Figure 7e
  2. Processed dentures do not have excessive increase in vertical dimension as confirmed when remounted on the articulator.
  3. Processed dentures are free of visible flaws or defects.
Denture Processing - Quality Failures
  1. Processed denture has internal porosity and/or large voids (Figure 7f).

    porosity
    large void
    Figure 7f
  2. Processed denture has excessive increase in vertical dimension (more than1.5-mm).
  3. Tooth movement causes improper articulation.
  4. Excess melting of wax during boil-out penetrates investment making devesting difficult or discoloring acrylic.
  5. Note: There are no ways to check for 'disasters' during pack, pour, or injection procedures. Following the directions for use is the best way to avoid remakes.
Denture Finishing
Denture Finishing - Suggested Quality Procedures
  1. Use care when removing investment from the restoration, especially when using power devices (Figure 8a). Remove investment starting at the posterior section and moving toward the anterior section. Avoid using force.

    Figure 8a
  2. If available, use walnut shell abrasive to remove gross investment. If not, use ultrasonic stone and plaster remover in an ultrasonic unit for thirty (30) minutes.
  3. Use light pressure on the restoration when using a lathe or handpiece.
  4. Use coarse abrasives and burs first, if needed for gross reduction. Use finer abrasives to finish.
  5. Check for flash on the teeth, but do not over-polish acrylic denture teeth.
Denture Finishing - Quality Standards
    ACRYLIC APPEARANCE

  1. Denture base is clean without traces of investment or polishing media present on denture base surface.
  2. Contours mimic nature and follow the desired criteria of the restoring clinical professional and patient.
  3. All edges are rounded and smooth, but not over-polished.
  4. Stippling and festooning, if desired, is subtle and follows accepted criteria for appearance and contour (Figure 8b).
    Figure 8b
  5. Tissue bearing surface of denture base must be free of sharp edges and positive or negative defects (bubbles and voids).
    OCCLUSION / TEETH

  1. There should be minimal pin opening on the articulator when the restorations are remounted.
  2. The appliance should have even contact on all occlusal surfaces.
  3. Premature tooth contacts are removed carefully with selected grinding procedures; using care to maintain an aesthetic tooth appearance.
  4. Labial, buccal and lingual surfaces of denture teeth should not require polishing.
Denture Finishing - Quality Failures
  1. Denture breaks when investment is removed.
  2. An over-polished tooth surface shows loss of labial, buccal and lingual anatomy.
  3. Tissue surface of denture wax inadvertently polished, creating loss of retention and fit.
  4. The denture base is burned or discolored from heavy pressure or extended polishing with a lathe and/or handpiece. (Figure 8c)

    Figure 8c
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