Effect of Delayed Pouring of Condensation Silicone Impressions on the Dimensional Accuracy of Porcelain Fused to Metal Crown Frameworks: A Pilot Study

Abstract

Background: Condensation silicone impression materials are widely used in prosthetic dentistry, particularly for the fabrication of single crowns, inlays, onlays, and fixed partial dentures. However, the influence of delayed pouring on the dimensional accuracy of porcelain-fused-to-metal (PFM) restorations remains unclear. Aim: To evaluate the effect of delayed pouring time on the dimensional accuracy of PFM metal substructures fabricated from a single condensation silicone impression.
Materials and Methods: A standardized full-arch condensation silicone impression was made and poured with Type IV dental stone at five time intervals: 30 minutes, 24, 48, 72, and 96 hours. The resulting casts were used to fabricate removable dies, wax patterns, and cast metal substructures. Mesiodistal, buccolingual, diagonal, and finish-line dimensions were measured using a dental caliper.
Results: Dimensional variations were observed among the metal substructures produced from casts poured at different time intervals. The greatest changes were noted at the finish-line region, with reductions in metal substructure dimensions observed after 24 and 48 hours of delayed pouring. Dimensional discrepancies were detected among the evaluated measurements which might be an indication that pouring time influenced the accuracy of the resulting restorations.
Conclusions: Delayed pouring of condensation silicone impressions resulted in dimensional alterations, particularly at the finish-line region. These changes may affect the accuracy of the fabricated PFM metal substructures and potentially compromise the marginal fit and clinical performance of the final restorations.