Flexural strength of provisional crown and fixed partial denture resins

STATEMENT OF PROBLEM: Provisional prostheses are subject to flexure under function. Selection of the appropriate material for their fabrication is difficult given the limited evidence-based information on the flexural strength of provisional resins. PURPOSE: This study compared the flexural strength of 5 methacrylate-based resins and 8 bis-acryl resins used to fabricate provisional crowns and fixed partial dentures. MATERIAL AND METHODS: Bar-type specimens were fabricated according to American National Standards Institute/American Dental Association specification 27. After being immersed in artificial saliva at 37 degrees C for 10 days, the specimens were fractured under 3-point loading in a universal testing machine at a crosshead speed of 0.75 mm/min. Maximal loads to fracture in Newtons were recorded. Mean flexural strengths were calculated in MPa (n = 10 per group). Comparisons were made with analysis of variance and Duncan's multiple range test (P<.05). RESULTS: Mean flexural strengths ranged from 56.2 to 123.6 MPa. There were 4 statistically similar groups. The group with the highest strengths consisted of 4 bis-acryl materials (Provipont, Integrity, Protemp 3 Garant, and Luxatemp). CONCLUSION: Within the limitations of this study, flexural strengths were material- rather than category-specific. Some, but not all, bis-acryl resins demonstrated significantly superior flexural strength over traditional methacrylate resins.