Complete Dentures: Tray Design

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Complete DenturesTray Design Border Molding
for Final Impressions
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Fabrication of Custom Trays
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Why Use Custom Trays?

• Gordon J. Christensen, D.D.S., M.S.D., Ph.D-JADA,
  May 1994
• Custom trays provide anatomically correct
  extension of denture impressions.
• Allow homogeneous thickness of impression
  material.
• Provide optimum accuracy and stability.

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Economic Factors

• Stock trays require 3x to 4x the impression
  material as custom trays.
• At 14 cents to 45 cents/cc, the cost savings can
  be 2 to more than 10 per full arch impression.
• Reduced number of remakes due to distortion or
  under-extension.

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Identify Denture Extensions

• Mark the anticipated final extension of the
  denture in red pencil on the cast

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Mark Tray Extensions

• Mark the tray extension in blue pencil about two
  mm shorter than red pencil line except
• Coinciding with red line in hamular notch
• If you did not get a good transfer of your
  posterior palatal seal, make the tray longer in
  this area, mark in the mouth, and shorten to the
  correct extension

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Adapt Baseplate Wax to Blue Line on Cast
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Tray Design

• A. Tray to extend to blue lines on casts.
• B. Lower handle no longer than the lower teeth
  would be.
• C. Upper handle approximately 20 mm to clear lip.
• D. Do not place vent holes at this time.

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Adapting Tray Material
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Handle Design
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Cured Tray With Wax Inside
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Trimming Tray
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Completed Trays
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Evaluating Trays

• Try tray in patients mouth tray should stay in
  place passively when mouth is at rest
• Remove any pressure areas/sharp spots
• Reduce any areas that cause the tray to lift when
  lips, tongue, or cheeks are moved
• Evaluate and correct posterior palatal seal
  length of upper tray
• Evaluate frenum areas

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Pretty Good Rule 1

• You cannot make an over-extended tray shorter by
  adding border molding compound.

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Set-up for Border Molding

• Hot water bath
• Ice bath
• Hanau torch and bunsen burner
• Scalpel
• Indelible ink sticks
• Acrylic burs for slow speed handpiece
• 2 X 2 gauze

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Border Molding

• Cut away pink wax in the segment you are border
  molding
• Heat green stick compound until soft, then stroke
  it onto the tray
• Flame with Hanau torch
• Temper in water bath

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Border Molding

• Rotate tray into patients mouth
• Manipulate tissue to adapt green stick compound
  to form final extensions of tray

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Pretty Good Rule 2

• The tray is already wide enough, so most of the
  green stick compound should go on the edges and
  the inside of the tray.

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Goals of Final Impressions

• 1.Maximum coverage of denture bearing areas-less
  force/unit area less trauma
• 2.Stabilization of dentures-bracing against
  vertical portion of ridges
• 3.Retention
• Adhesion by contact
• Border seal

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Prepare Trays for Impression

• Remove slight amount of compound from every
  surface, slightly more in frenum areas
• Remove minimal amount from undercuts that will
  still allow for tray seating
• Remove remaining pink wax spacer
• Use round bur to place vent holes
• Coat tray and compound with adhesive

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Impression Material

• Add enough light-bodied PVS to tray so it is
  slightly thicker than the pink wax spacer that
  you have removed
• Use cement spatula to coat the tray evenly, as
  well as over green compound borders
• Rotate tray into mouth and seat to place

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Impression

• Go through border molding movements, hold tray in
  place until PVS is set
• For mandibular impression, start with the lingual
  movements, finishing with the posterior buccal
  movements
• Have patient close to a relaxed position while
  mandibular impression sets

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Verify Results

• Trim away excess PVS, re-seat impression in the
  patients mouth
• Evaluate stability, retention, patient comfort
• Re-mark vibrating line, if needed
• Box and pour impression

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Trimmed Model
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