effect of polyvinyl siloxane viscosity on accuracy of dental implant impressions

objectives: the aim of this study was to compare the accuracy of dental implant impressions obtained by a combination of different impression techniques and viscosities of polyvinyl siloxane (pvs). materials and methods: four parallel fixtures were placed between mental foramina in a master model of lower dental arch. three different viscosities (putty/light body, medium body/light body, and monophase: heavy body) and direct and indirect techniques (six groups) were used, and seven impressions were obtained from each group (n=42). to measure the accuracy of impressions, drift, horizontal, and vertical angles of the implants, as well as the hex rotation of the implants in casts were evaluated using a digitizer device (1μm accuracy), in comparison with master arch. data were analyzed using five-factor two-way anova and tukey’s post-hoc test. results: the accuracy of impressions was assessed and the results showed that direct technique was not significantly different from indirect technique (p>0.05). also, there were no significant differences between the mentioned viscosities except for the horizontal angle (p=0.006). conclusions: viscosity of impression materials is of high significance for the accuracy of dental impressions. keywords: dental materials; dental implants; dental impression technique; viscosity; vinyl polysiloxane; dimensional measurement accuracy