Methacrylate versus Ormocer - Based Composites: Impact of Preheating on Repair Bond Strength

Abstract

: Objective: To evaluate and compare the impact of preheating on the repair bond strength of Methacrylate and Ormocer based composite. Materials and Methods: A total number of 24 standardized cuboid composite blocks were fabricated with the aid of teflon split mold (25×4×4) mm dimensions. Half of these composite blocks were made from a universal nanohybrid methacrylate-based composite and the other half was made from a universal nanohybrid Ormocer based. The top surfaces of all mounted specimens were surface treated with sandblasting, silane coupling agents, and universal adhesive of the same brand of composite. Four cylindrical composite rods (2 mm height, 3 mm internal diameter) were built over each composite block and filled with the repair composite from the same material with the aid of tygon tubes. Composite blocks of both groups were divided into two sub-groups according to the previous treatment of repairing materials (preheated or not preheated). Then half of the blocks with their attached repair materials were stored for 24 h to evaluate the immediate bond strength and the other half was stored in distilled water for 6 months to evaluate the bond durability. Shear bond strength was measured using a universal testing machine (Instron), and the collected data were statistically analyzed with three-way ANOVA and post-hoc Tukey test. Results: The outcome of three-way ANOVA revealed that there was a statistically significant difference between the repair bond strength of Methacrylate & Ormocer groups immediately and after 6 months of storage (p=0.03). No statistically significant difference was found between the repair bond strength of the preheated and non-preheated immediately and after 6 months of storage (p=0.7). Conclusions: Immediate and delayed repair bond strength of methacrylate-based resin composite was superior to Ormocer based composite within the preheated group. Preheating of both methacrylate and Ormocer composite did not affect immediate and delayed repair bond strength. Ormocer