Evaluation of the effect of aging on the shear bond strength between old composite resin restoration and the repair composite resin: an in-vitro study.

Background: The current study aimed to evaluate the effect of aging on the repair bond strength between old composite resin and repaired composite resin and to evaluate which type of repair composite material provides better bond strength in different time durations.

Methods: Eighty nano-hybrid composite specimens were randomly divided into four groups (N.=20) and exposed to accelerated aging from 0 to 2 years.