Estudo comparativo de troquéis obtidos pela técnica convencional e correção

Abstract

The purpose of this research was to study the practicability of a reline impression technique in individual impressions using polyether, polysulfide and addition silicone, regular consistency. A stainless-steel master die simulating a complete crown preparation was used. The assessment of the adaptation was made using a metallic crown fitted to the master die. A special device was developed to standardize the steps to obtain the impressions. Individual custom trays were constructed with acrylic resin and a 2mm relief for the elastomers. The Group I impressions were made using a conventional technique. Before doing the impressions for the Group II, a standardized piece of copper wire was put, always at the same place, on the master die to simulate a defect. After doing the impression, the defect was removed and a new portion of impression material was manipulated and a relining impression was done. All elastomers were proportioned by length and handily manipulated. The setting time was according to the manufacturers instruction. A type IV stone was poured into the impressions. The impressions and the pouring were made at controlled room temperature (23 ± 1°C). The metallic crown was used to compare the marginal discrepancy between the ring and the stone die. A comparator microscope (Mitutoyo TM) was used to make the measurements. The mean discrepancy in the Group I was 73,1 ± 19,6ìm (polyssulfide), 41,3 ± 21,4ìm (polyether) and 37,3 ±18,1 (addition silicone). The mean discrepancy in the Group II was 25,0 ± 9,7ìm (polysulfide), 21,4 ± 10,5ìm (polyether) and 26,9 ± 14,2ìm (addition silicone). After statistical analysis, it was conclude that the impressions obtained by the reline technique were more accurate The addition silicone showed the best results followed by the polyether and polysulfide.