The effect of the type and technique used for impression making on the accuracy of elastomeric impression materials.

The effect of the technique used for impression making on the accuracy of three types impression materials, (vinyl silicons, condensation silicons and polyether elastomers) was evaluated. Three main impression making techniques were used. Impressions were made for stainless steel master model. The impressions were poured after thirty minutes with improved stone into stone casts. Accuracy was assessed by comparing seven measurements of the master model to their corresponding on the stone case produced. A travelling microscope of 0.001 mm accuracy was used for measurements. The results of the study have shown that all elastomeric impression materials produced accurate impression but with significant difference among them. The polyether was more accurate than silicon impressions. The technique used for making the impression had more effect on the relative accuracy than the type of the material. Reference for the best technique for each type was concluded.