The influence of impression trays on the accuracy of stone casts poured from irreversible hydrocolloid impressions.
An investigation was conducted to determine which of four commonly used impression trays yields the best results when making irreversible hydrocolloid impressions. This objective was achieved by evaluating the comparative accuracy of stone casts obtained from irreversible hydrocolloid impressions made with trays of different characteristics. The following conclusions are drawn from this study. Some kind of distortion can be expected in irreversible hydrocolloid impressions with the use of any of the tested impression trays. The perforated trays (B and D) reproduce more accurately the distances along the length and the width of the arch than the nonperforated trays (A and C). The depth of the palatal vault (distance f-g) is reproduced most accurately by the Rim-lock nonperforated tray (A) followed closely by the stock perforated (B) and the custom nonperforated (C) trays. Under the conditions of this study, all the impressions had a tendency to be oversized except the impressions made with the stock perforated tray (B). Those impressions were slightly undersized for all but two measured distances. Clinically significant inaccuracies produced by any of the four tested impression trays were not found in this study.
D002133:Calcium Sulfate; D003102:Colloids; D003760:Dental Impression Materials; D003761:Dental Impression Technique / Q000295:instrumentation*; D004867:Equipment Design; D003765:Models, Dental; D013499:Surface Properties
D003102:Colloids; D003760:Dental Impression Materials; D002133:Calcium Sulfate