Influência de técnicas e materiais de moldagem na precisão de modelos de trabalho obtidos para a confecção de prótese fixa convencional e sobre implante

Abstract

According to the literature, all the available impression materials on the market deform after its polymerization. This distortion can affect the precision and, consequently, the marginal fit of fixed partial dentures on teeth or implants. The aim of this study was to investigate and compare, through the use of three-dimensional scanning and surface comparison software, the dimensional changes of working cast originated from different impression techniques and materials commonly used on the dental practice.. Master casts containing a maxillary central incisor and a canine prepared to receive a three-unit metal-free fixed partial denture and two external hex implant analogues were made. Groups (n=5) were divided according to the technique (dual mixture, single impression and custom tray for teeth; and direct or indirect for implants), and impression material (polyvinyl siloxane, polydimethylsiloxane and polyether). Evaluation and comparison of the surfaces between master cast and specimens were performed with a fully automated optical structured-light scanner (S600 ARTI, Zirkonzahn) and Geomagic Qualify v.13 (Geomagic Inc.) software inspection tool. The obtained results were submitted to statistical analysis, which showed that there was no significant difference between the impression techniques for both teeth and implants groups; however, in regard of impression materials, working casts obtained by polydimethylsiloxane impressions showed lower volumetric distortion than casts obtained with the other impression materials. However, the distortion values were very small and may not be clinically significant. Based on the above, it can be concluded that the dentist could choose the impression technique and material that he considers most suitable for fixed prostheses teeth or implant-borne prostheses .