Accuracy of implant transfer using closed tray technique with different viscosities of polyvinyl siloxane

Abstract

Statements of problem: For simultaneous making impression of implants and teeth, both dimensional and surface detail accuracyshould be considered. The purpose of this in vitro study was to evaluate and compare the accuracy of implant transfer and surface detail reproduction with different techniques and viscosities of polyvinyl siloxane (PVS) impression material. Method of study:A model with two implants (Implantium, Dentium) and three lines of 0.25, 0.50 and 0.75 mm in width was fabricated. Forty impressions with one-step and two-step putty/wash PVS using closed custom and stock trays and ten impressions with regular viscosity PVS using closed custom-trays were made. Impressions were poured and the positional accuracy of the implant replica heads in x-, y-(∆r) and angular displacement (∆θ) were evaluated using a coordinate measuring machine. Also, accurate reproduction of the lines was evaluated by a video measuring machine. These measurements were compared with the measurements calculated on the reference model that served as control, and the data were analyzed with two-way analysis of variance at α= 0.05. Results:There was more angular displacement in one-step custom-tray group compared to one-step stock-tray group (P<0.001). However, less vertical displacement using custom tray with two-step technique (P=0.003). Also, one-step technique showed less vertical and angular inaccuracies as compared to two-step one, using stock tray (P<0.05). Regular-viscosity group showed more linear displacement compared to all other groups (P<.001). The detail reproduction had no statistically significant differences (P>0.05). Conclusions:In this study both stock tray and custom tray were acceptable and the viscosity of impression material made no significant difference in surface detail reproduction.