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

Document Type : Original Article

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 based composite groups could not succeed to maintain
the repair bond strength after six months of storage, while methacrylate could maintain. 

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