Intra-oral repair of composite resin can be a conservative approach to extending the clinical life of a restoration.                                     

Objective:  The purpose of this study was to measure shear bond strength (SBS) of composite resin placed on resin prepared with simulated repair techniques.

Methods: 50 specimens of Spectrum TPH and 50 of Z-250 were incrementally placed in a cavity mold 6 mm in diameter and 4 mm deep and polymerized for 30 seconds using a light calibrated at 600 mW/cm². The resin surfaces were ground flat with 320 grit silicon carbide paper and stored in water at 37º C for 30 days. 10 bonded assemblies of each composite were prepared and polymerized using a gelatin capsule matrix after the following surface repair techniques: 1) surface roughening with a coarse Sof-Lex disk, 2) air abrasion with 50 micron alumina 3) PRODX Composit repair kit and 4) Co-jet system). A reference group for each resin was created by bonding the capsule to the air inhibited later. Specimens were debonded after water storage for 24 hours at 37°C in an Instron Model 1123 testing machine with a crosshead speed of 5 mm/minute. Data were analyzed using a one-way ANOVA and LSD test for each resin.  

Results: Mean SBS in Megapascals were:

Groups connected with like letters were statistically similar (p>0.05). Conclusion: Co-jet and composite repair generated high repair strength to TPH. Values for all methods with Z-250 generated lower values. Supported by the Health Future Foundation.