An In-Vitro Evaluation of the influence of repeat pours of addition silicone impressions on the dimensional accuracy of resultant casts: an original research study

Abstract

Background and Aim: For miscellaneous purposes, the prosthodontists and dental laboratory technicians usually attempt repeated pouring of the impression in order to avoid expenses and curb upon the chair-side time. There are numerous factors which can affect dimensions of subsequent casts on repeated pouring. These include the process of polymerization, temperature and the material used to fabricate the replica of working cast. The sole aim of this study was to evaluate if repeated pouring of addition silicone impression would influence the dimensional accuracy of resultant casts. Materials & Methods: Addition silicone impression material along with tray adhesive were used to evaluate the influence of repeat pours on the dimensional accuracy of resultant casts at various time intervals i.e. at 15 minutes, 75 minutes, 24 hours and 7 days. Vision measurement machine was used for measurement of dimensions. A metal control model of 8*6*2 cm was made with abutments. Various dimensional markings and measurements (for inter-abutment distance & intra-abutment distance) were completed. All 80 resultant casts were along with the master model was dimensionally evaluated with “Vision Measurement Machine”. Statistical Analysis and Results: Statistical analysis was completed by SPSS (statistical package for social sciences) version 21.0 and Epi-info version 3.0. The result of this study showed that working dies obtained from Addition silicone at various time intervals i.e. 15 minutes, 75 minutes, 24 hours and 7 days exhibited insignificant dimension changes clinically. The p-value was taken significant when less than 0.05 (p<0.05) and Confidence interval of 95% was taken. Post-Hoc Bonferroni test showed no significant difference for the inter-interval comparison of mean inter-abutment distance (Line 2-3). Conclusion: Within the limitations of the study authors concluded that the addition silicone impression material could be preferred material in the field of prosthodontics for repeated pouring up-to 7 days due to its favorable qualities like dimensional accuracy and stability, elastic recovery from undercuts, low creep and moderate to high tear resistance.