impression trays Flashcards
1
Q
3 functions of impression trays
A
- carrying, confining, and controlling the material
- support material during and after
- facilitate insertion/removal
2
Q
custom tray
A
- individualized
- use for final impression
- perfect adaption to record oral anatomy accurately
- shows denture-bearing area
3
Q
why do we use custom trays
A
- record most-out-of-reach anatomical landmarks
- minimize impression material distortion (uniform thickness)
- prevent tissue distortion (bc you can use less viscous materials with custom trays)
- reduced cost of impression materials
4
Q
criteria for custom trays
A
- close adaptation
- no impingement on movable oral structures
- adequate space for material
- rigidity, thickness, and fracture resistance
- handles dont interfere with oral structures
- smooth surface and flanges, no sharp corners
5
Q
preliminary impression
A
- record dimensions of edentulous arch
- stock tray
- pour diagnostic cast; construct custom tray
- use impression compound and alginate
6
Q
final impression
A
- record fine details
- custom tray
- pour master cast; make prostheses; dentures
- impression plaster material; zinc oxide eugenole; elastomers
7
Q
the border of the acrylic material is
A
2-3 mm shorter than depth of vestibule
8
Q
purpose of curing the tray while immersed in water
A
- prevent formation of air-inhibited layer
- keep wax spacer from melting during curing
9
Q
thickness space of wax
A
2-4 mm
