In Vitro Assessment of Linear Dimensional Accuracy of Polyvinyl Siloxane-Based Computer-Aided Design and Transparent Interocclusal Record Materials at 3 Different Storage Times.

BACKGROUND Recent interocclusal registration (IOR) materials require scientific data that verify manufacturer claims of using them for an extended period. This study aimed to evaluate the time-dependent (1, 3, 7 days) linear accuracy of polyvinyl siloxane (PVS)-based computer-aided design (CAD) and transparent IOR materials. MATERIAL AND METHODS Three commercial brands of CAD and transparent PVS-based IOR materials were divided into 24 groups based on time intervals of 1 h and 1, 3, and 7 days, with the 1 h subgroup serving as control. A total of 360 IOR specimens (n=15 each group) were standardized following modified ADA specification 19. Using horizontal distances between 2 perpendicular intersecting lines at 3 different locations, linear measurements were observed under stereomicroscope. Derived mean values were tested for group differences using one-way ANOVA and within-group differences using the Tukey-Kramer test. Statistical significance was determined at P value ≤0.05. RESULTS Mean linear dimensions varied in the range of -0.06 (-0.24%) to -0.15 (-0.60%) mm and -0.06 (0.24%) to -0.10 (0.40%) mm for CAD and transparent IOR materials, respectively. Virtual CADBite and Maxill Bite showed least linear discrepancy at 1 h, but both showed significant changes at 7 days. Flexitime Bite (CAD) was the only material that showed linear accuracy (0.13 to 0.15, -0.52% to 0.60%) beyond the clinically acceptable threshold. CONCLUSIONS All materials showed a reduction in linear dimensions, indicating linear shrinkage within specimens. All IOR materials except Flexitime Bite (CAD) were clinically accurate till 7 days. Virtual CADBite and Maxill Bite showed significant changes between 1 h and 7 days.