ABSTRACT
The objective of this invitro study was to compare shear bond strength of methacrylate based composite repaired with Silorane composite using intermediate layer of silane coupling agent and Silorane adhesive bond with or without thermocycling. A total of 60 composite samples were prepared with 30 samples of silorane based and 30 samples of methacrylate based divided into control and experimental groups. Control group was processed immediately after photo-curing, while experimental group was thermal cycled [5000 cycles, 5_55°C, dwell time 20 seconds] followed by surface roughening with 400 grit silicon carbide, applied with silane coupling agent and relevant adhesive bond over the corresponding substrate and cured for 20seconds. Repair composite was placed on substrate samples of both groups and photo-cured, all samples were stored in distilled water for 24 hour at 37°C before testing with universal testing machine at crosshead speed of 0.5mm/min until debonding. Type of fracture was analyzed under light microscope at 40x magnification and was categorized as cohesive, adhesive or mixed failure. Silorane composite overall showed better shear bond strength and can be used with Methacrylate based composites in repair options using silane coupling agent and its silorane adhesive bond. Thermal cycling did not affect the shear bond strength before and after aging in both groups