Final impression

By Dr. Vishaal Bhat on Sunday 6 July 2008 with 0 comments



Purpose of border molding: to carry impression material to the full depth of the vestibule.

Impression techniques:

1. Definite pressure (functional)- using the same amount of pressure in the impression as during chewing. It says that occlusal loading during impression making will be the same as that during function.

2. Mucostatic (non-pressure)- sacrifices important concepts of maximum ridge coverage and border seal.

3. Selective pressure- combines the principles of both pressure and non-pressure procedures. The non-stress bearing areas are recorded with the least amount of pressure, and selective pressure is applied to certain areas of the max and mand that are capable of withstanding the forces of occlusion. The trays are selectively relieved, therefore, providing more space in some areas while at the same time, having areas in the tray that have less space. The places with less space, or relief, will transmit more pressure during the impression. Thus, greater force will be distributed during function to a more favorable part of the ridge/bone (such as the buccal shelf) and less pressure to unfavorable parts (such as a sharp ridge crest or bony spicule).

Beading and boxing: bead of adequate width = 3/8”

Adequate cast thickness = 16mm from the highest spot on the impression.


Category: Prosthodontics Notes

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