1. The tray should be rigid and strong but not
2. The tray should simulate the finished denture
in size and shape.
3. The border extension of the tray should be
2mm short of the vestibular depth with no
interference with muscle or frenal
Requirements Of Impression Trays
4. The entire borders of the tray should be
smooth and rounded.
5. The tray should retain its shape throughout
the impression procedure and pouring of
6. The handle of the tray should be angulated.
Types of stock trays
A. Metallic it can be aluminum or stainless steel.
B. Non metallic:
1. Plastic tray which can be sterilized.
2. Disposable plastic trays.
1. Perforated trays (used
2. Non perforated or plain
trays (used with
Mode of stock trays
• 3. Sizes : small, medium, large and extra large
Adhesives & Perforations
• t is essential that impression
materials adhere firmly to the
impression trays. This can be
achieved by either perforations
or by the use of adhesives.
Adhesive solutions are needed
for alginates, polysulphides and
silicones. Adhesives for alginates
are solutions of resins in alcohol,
they are supplied in a bottle with
a brush or an aerosol spray.
Tray adhesive being applied to a
metal stock tray for an alginate