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

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 AND 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).