Aim: To evaluate shear bond strength of silorane based composite samples repaired with silorane composite with application of silane coupling agent and adhesive bond of silorane before and after thermal cycling.

Study design: Experimental study

Place and duration of study: Science of Dental Materials Department, de’Montmorency College of Dentistry Lahore from 1st January 2014 to 31st October 2014.

Methodology: Sixty composite specimens equally divided into control and experimental groups. Control group was further prepared for repair procedure after polymerization without thermal cycling while experimental group was given with 5000 thermal cycles between temperature range of 5-55oC, dwell time of 20 seconds) before testing, all samples were surface roughened with 400 grit silicon carbide strip, followed by application of silorane coupling agent and adhesive bond of silorane over the substrate and cured for 20 seconds. Repair silane based composite was applied on all substrate silorane composite samples and polymerized, before testing samples were left in distilled water (24 hour at 37oC) and tested with universal testing machine (crosshead speed 0.5 mm/min) until fracture.

Results: There is 12 (20%) adhesive, mixed 2 (3.3%) and cohesive is 46 (76.7%). The thermal cycling has no effect on bonding interface in experimental group on strength at bonding interface.

Conclusion: Silorane based composite as repair composite gave better strength with silorane based composite and can be used for repair options. Keywords: Shear bond strength, Silorane based composite, Silorane adhesive bond