The effect of rewash on putty-wash impression technique in fixed prosthodontics∗

In the two-step putty wash impression technique after providing first impression, sometimes there are defects in the impression that can be corrected by rewash (reline), although there are different opinions regarding this technique. This study was performed by experimental method on laboratory model. In addition to ten impressions from a laboratory model with routine putty-wash technique (single wash) as control group, another ten impressions were taken with rewash (double wash) technique for evaluation. Then die stones were poured and 20 stone models were provided. Different dimensions of all stone models were compared with lab model and the results were analyzed by t – test. The height of die in the rewash impression technique comparing with control group decreased but its p-value was not statistically significant. Meanwhile in the rewash technique, there was a significant decrease in die diameter and the distance between two dies increased due to shrinkage. 1-Rewash impression technique leads to reduction in die diameter. 2- When there is an undercut below finishing line, die diameter significantly decrease in rewash technique. 3- Rewash technique is debatable because of reduction in tooth diameter, so it is not advisable.