An accurate method for occlusal registration and altered-cast impression for removable partial dentures during the same visit as the framework try-in (original) (raw)

1998, Journal of Prosthetic Dentistry

In recent years, a number of reports have proposed procedures for registering jaw relation and making the altered-cast impression during the same visit as the framework try-in. 1,2 By minimizing the number of visits, such an approach reduces both the cost of the treatment and inconvenience to the patient. To make an altered-cast impression 3 correctly requires that the framework remain in exactly the same position as during the try-in. Problems often arise because the impression material placed between framework and mucosa may cause the framework to lift away from the mucosa; subsequently, during flasking, the framework will depress again, producing inaccuracies in the prosthesis. An attempt can be made to counter this problem by pressing down on the framework with the fingers while making the impression; however, this may not give acceptable results, because it is difficult to judge how much pressure to exert; in addition, the act of pressing down may itself cause slight displacements. An alternative approach is to take the altered-cast impression first, and then to obtain a jaw relation record in silicone. 2 This procedure has 2 major disadvantages: (1) It is difficult to ensure that the framework will remain in the correct position, and (2) the impression material used for obtaining the jaw relation record may be displaced slightly, leading to inaccuracies in the final structure. Another possibility is to use the framework as record base 3,4 ; however, this procedure is also sometimes inaccurate. This article describes an accurate procedure for registering the jaw relation and making the altered-cast impression during the same session as the framework try-in for the removable partial denture (RPD).