Influence of impression materials and techniques, times and pouring materials in dimensional accuracy of total casts by contact scanner and marginal adaptation of infrastructure in Y-TZP

Abstract

This study will examine the accuracy of total dental casts obtained from different impression techniques, casting times and impression's disinfection, as well as measure the cervical marginal fit of zirconia infrastructures on dental preparations for full crown. It will use a master model with preparations in the teeth 14, 16, 21 and 25, on which Y-TZP infrastructure will be made by CAD-CAM technology. Two impression techniques will be used: (T1) simultaneous mixing and (T2) reline - relief with PVC film. Half of the molds will be subjected to disinfection with sodium hypochlorite 1.0% for 10 minutes. For the impression with condensation silicone cast is poured after 30 minutes, 3 or 7 days. For the addition silicone casts are obtained after 2 hours, 3, 7 or 15 days. For each impression technique / stripping time will be obtained total 8 molds, for single calibrated operator with stock tray and condensation silicone (Speedex; Coltène / Whaledent Inc.) or addition (Express XT; 3M ESPE). The leaks will be made with plaster type IV (GC Fuji Rock EP - GC America or Zero Stone - Dentona AG). For the analysis of dimensional accuracy, the casts will be scanned by contact scanner MDX-40 (Roland, Information Technology Center - CTI, Campinas, SP, Brazil), calibrated at 0.2 mm for each stroke of the contact tip on the scanned surface. For the analysis of cervical marginal adaptation of Y-TZP infrastructure, they will be adapted passively on the preparations in plaster models, and the measurements performed in stereo. Check will be the results regarding the sample size was statistically significant power, distribution of sample and homoscedasticity data. Then statistical methods will be used to evaluate the influence of independent variables of the study, adopting a significance level of 5.0%. (AU)