The influence of five impression techniques on the dimensional accuracy of master models.

A high-grade steel model with different preparation angles of 3 degrees, 7 degrees and 11 degrees in one- and two-step impression techniques were made for the determination of the influence of the preparation angle on the dimension loyalty of the resulting master casts. Using a 3-D-measuring instrument, analysis of the data showed that with the correction technique the model abutments led to a reduction in dependency on the preparation angle. The general reduction in stump height of the abutments was independent of the preparation angle. The double-mix technique showed decent increased abutments and is thus recommended for impressions of supragingival preparations.