Comparing Fracture Resistance of Provisional Restorations of 3-Unit Fixed Partial Dentures: An in Vitro Study of CAD/CAM versus Indirect Technique

Abstract

Objective: To compare the indirect and CAD/CAM techniques and using acrylic and composites resins on the fracture resistance of provisional 3-unit fixed partial dentures (FPDs). Materials and Methods:In in vitro setting, thirty samples were divided into three groups included 10 FPDs manufactured indirectly and made of composite based bis-acryl (Protemp 4) resin, 10 FPDs indirectly milled with polymethyl methacrylate resin (PMMA) and 10 FPDs fabricated by CAD/CAM PMMA blocks. Fracture resistance was measured using universal testing machine (UTM). The master model was made of NiCr-alloy which designed using CAD/CAM technology.Results: FPDs fabricated using CAD/CAM PMMA blocks showed the highest fracture resistance values followed by Protemp 4 and then PMMA using indirect method. Statistically significant difference was found between the three groups (P=0.001). Bonferroni test was applied for pair wise comparison, in which the statistically significant difference was observed between FPDs fabricated by CAD/CAM which made of PMMA blocks and Protemp 4 and between CAD/CAM PMMA blocks and indirect/PMMA FPDs and between indirect/Protemp 4 FPDs and indirect/PMMA FPDs. Hence this suggested that PMMA significantly has minimum value of fracture resistance when compared to both CAD/CAM and Protemp 4. Conclusion:This study proved the superiority of CAD/CAM PMMA blocks for fabricating 3-unit FPDs over Protemp 4 and PMMA using indirect method, and the superiority of Protemp 4 over PMMA in terms of fracture resistance using indirect methods.