Lecture 2 - Custom Tray fabrication

Question 1

Definition of Impression Trays

Answer 1

A device used to carry, confine, and control impression material while making an impression

Question 2

How does a custom tray improve accuracy

Answer 2

Maintains optimal thickness of impression materials, therefore improving accuracy by

1. Reducing stresses during removal
2. Reduces Thermal contraction

Question 3

3 different types of tray fabrication materials

Answer 3

1. Autopolymerizing Resin
2. Thermoplastic Resin
3. Photopolymerized Resin

Question 4

Limitations of Custom Trays

Answer 4

1. Nothing to physically contain the impression material on the most distal tooth resulting in pulling in crucial areas like the margin and loss of tripod effect
2. Patients cannot always repeat a consistent bite
3. Patients try to bite on the tray
4. No contralateral arch impression to use as a guide for tooth form
5. How the teeth function against one another in excursive movements

Question 5

When to use a Triple Tray (5)

Answer 5

1. Impression for direct provisional fabrication
2. Single Units only (not for implants)
3. Only if preparation is supported by adjacent teeth (Never the most distal tooth in the arch)
4. Only if a nice tight repeatable occlusion
5. Only when building the case in maximum intercuspation

Question 6

Advantages of a Triple tray

Answer 6

1. Cost (less cost than a full arch)
2. Patient comfort
3. Time (no need for a separate opposing impression or bite registration)
4. Very effective at impressing the preparation, margins and adjacent teeth