Comparative Evaluation of the Dimensional Accuracy of Silicone-Based Putty Reline Impressions with Different Spacer Acquisition Techniques in Fixed Partial Dentures

Abstract

Background: A tooth preparation’s clinical requirements and geometric configurations should take precedence over material characteristics when advocating for putty reline impression techniques for permanent restorations, since they require a technically sensitive spacer for light body elastomer. We evaluated the linear dimensional accuracy of vinyl polysiloxane-based putty reline impressions with different spacer acquisition techniques in short-span and long-span fixed partial dentures (FPD). Material/Methods: A typodont tooth set simulated a 3-unit (short-span) and a 5-unit (long-span) FPD. Between respective prepared abutments, 31 coordinates were identified and measured based on angles (line/point) and surfaces (curved/flat). Sixty impressions (dual stage 2-step putty reline technique) were divided into 5 groups (n=12/group): group PP (pre-preparation putty), group GP (gouging putty), group PS (polythene spacer), group CT (conventional temporary), and group MT (modified temporary), depending on spacer acquisition method. Coordinates measurements were conducted using a measuring microscope. Descriptive and inferential statistical tests (ANOVA, post hoc Tukey) determined between-group and within-group differences, at P≤0.05 significance level. Results: In short-span FPD, compared with control, the number of significantly different coordinates group-wise were GP (4 coordinates), PP (2 coordinates), and PS, CT, and MT (1 each). In long-span FPD, compared with control, the number of significantly different coordinates group-wise were group GP (12 coordinates), group PP (10 coordinates), group PS (5 coordinates), and group CT and group MT (4 each). Conclusions: Different spacer acquisition methods produce varied thickness of spacers for relining of putty. CT and MT, when used as spacers, provided maximum accurate coordinates for angles (line/point) and surfaces (curved/flat).