ABSTRACT
Statement of the Problem: Mechanical properties of interim restorations are considered as important factors specially when selecting materials for long-term application or for patients with para-functional habits. Flexural strength is one of the most important components of these restorations
Purpose: The purpose of this study was to compare the flexural strength of five interim restorative materials
Materials and Method: Fifty identical samples sized 25×2×2-mm were made from five interim materials [TempSpan; Protemp 4, Unifast III, Trim, and Revotek LC] according to ADA specification #27. The specimens were stored in artificial saliva for 2 weeks and then thermocycled for 2500 cycles [5-55?C]. A standard three-point bending test was conducted on the specimens with a universal testing machine at a crosshead speed of 0.75mm/min. Data were analyzed by using one-way ANOVA and Tamhane's post-hoc tests to measure the flexural strength of temporary materials
Results: One of the bis-acryl resins [TempSpan] showed the highest, and the light polymerized resin [Revotek LC] showed the lowest flexural strength. The mean values of flexural strength [MPa] for the examined materials were as follow: Temp- Span=120.00, Protemp 4=113.00, Unifast III=64.20, Trim= 63.73 and Revotek LC=47.16. There were significant differences between all materials except Trim and Unifast III which did not show any statistical significant difference
Conclusion: Bis-acryl resins were statistically superior to traditional methacrylate and light-cured resins. Therefore, application of bis-acryl resins should be deliberated in patients with heavy occlusion and in cases that need long-term use of interim restorations