Method: Materials and Methods: A total of 32 Filtek P90 substrate specimens (2mm diameter and 4mm height) were made using a specially constructed split Teflon mold. Substrate specimens were grouped according to the period prior to repair into four groups (n=8/group), immediately (15-30 min), after 24 hours, one month or three months. For each pre-aging period, specimens were subdivided into two subgroups according to the repair material used (n=4/subgroup) Filtek™ P90 + P90 System Adhesive (3M ESPE/USA), or Tetric® N-ceram + AdheSE® One F (Ivoclar Vivadent/Lichtenstein). Additional 16 specimens were made from each resin composite material and stored according to the aging periods (n=4/each pre-aging period) to study their cohesive strength. Pre-aged specimens were removed from the artificial saliva and thoroughly rinsed with water and blotted dry with tissue. Substrate surface was ground flat using a diamond stone and was etched using the Scotchbond™ phosphoric acid etchant (3M ESPE/USA) for 30s, rinsed and dried with air for 15s prior to be repaired. The intermediate adhesive system of each resin composite material was applied and light cured according to the manufacturer’s instructions. Repair resin composite was built up in two increments onto the treated substrate specimens (each was cured for 10s). Specimens were sliced into sticks (0.6±0.01 mm2) for microtensile bond strength testing (µTBS). Modes of failure were determined also using stereomicroscope.
Result: Results: Two-way ANOVA with repeated measure revealed a non significant effect for pre-aging period, repair material as well as for their interaction on repair bond strength of silorane-based resin composite.
Conclusion: Conclusions: Pre-aging of the repaired silorane-based resin composite, up to three months, have no negative effect on its repair µTBS even when single-step self-etch adhesive was used.