Comparison of the accuracy of standard putty-wash impression technique with the re-putty-wash technique using Super Light material

Impression making is considered as an important step in the fixed prosthodontics.the different impression material and techniques have been supposed to be important in the dimensional changes of dies. Furthermore, the results of different studies in this regard are contradictory. The present study compared the results of two impression making techniques of putty-wash including two-step with space and double -wash using LIGHT and SUPER LIGHT viscosity.

In this experimentalinvitro study on the laboratory model, 10 impressions were made using two-step putty-wash technique with space and 10 impressions were made using double-wash techniqueby means of LIGHT and SUPER LIGHT viscosity. The impressions were poured using Velmix gypsum after 30 minutes. The height and diameter of the dies without undercut and the distance between two dies were measured 6 times while the variables were measured 3 times in the gypsum models by a blind operator using profile projector with an accuracy of micron. The mean values were calculated and the dimensions of the gypsum laboratory models were statistically analyzed by t- test.

The die height was decreased using both techniques of two-step with space and double-wash technique with LIGHT and SUPER LIGHT viscosity. The decrease was more pronounced in the double-wash technique by LIGHT and SUPER LIGHT viscosity. However, no significant differences were found between both techniques (P>0.05). Die diameter without undercut was significantly decreased in the double-wash technique by LIGHT and SUPER LIGHT viscosity (P<0.0001) while it was increased in the two-step technique with spaces. Slight distances were observed between two dies in the two-step impression technique with space. However, the distance between dies were increased using double-wash technique by LIGHT and SUPER LIGHT viscosity with significant differences (P<0.0001).

The die diameter was decreased in the impression technique of double-wash using LIGHT and SUPER LIGHT viscosity while the distance between base teeth have been increased in this technique. Therefore, the technique is not accurate and needs more assessments.