Impression Trays
- There are two major types of impression trays: stock and custom
- Stock means manufactured, pre-made basically for anybody, whereas custom
is made for a particular patient
- Stock trays are usually metal, used with
alginate for diagnostic models,
bleaching trays and repair of dentures (not so precise procedures)
- In contrast, custom trays are made for more precise procedures: such as
complete denture, partials (removable partial denture, RPD), bridge, and
implants. PVS is used as impression material
- Doctor, assistant and technician use models to make custom trays
- There are two types of metal stock trays: rounded and rectangular.
The rounded trays are for complete denture, i.e., people without teeth; the
rectangular trays are for people with full or some teeth. After losing
all of our teeth, our jaws (ridges) become rounded, whereas our teeth,
particularly molars, are rectangular
- There are different sizes of metal trays. For rectangular ones:
extra small, small, medium, large and extra large
- There are different shapes of rectangular trays: anterior (upper and
lower), quadrant (two types: one for UR, LL, the other for UL, LR)
- Paradoxically, triple tray is a stock tray, but is used with PVS to make
precise procedures such as crowns and occasionally short-spanned bridge.
To make precise impression, right size of triple tray needs to be chosen
before impression. What does triple mean? Tri- means three.
Triple tray must be able to do three types of work. What are they?
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Assistant Page
Xin Wei, DDS, PhD, MS 1st edition 06/09/2011, last revision
06/09/2011