Objectives: The aim of this study was to assess the effect of treatment with sodium perborate on the shear bond strength of two resin-based composite systems to pulpal dentine.  

Materials and Methods: Sixty extracted maxillary anterior teeth were divided into six groups (n=10) according to the type of restorative system: etch and rinse adhesive (Adper Single bond 2) with Filtek Z250 or self-etch adhesive (Silorane system Adhesive) with Filtek P90 and bonding protocol (bonding with no sodium perborate, immediate and late bonding). Bond strength was tested in a universal testing machine, and data were analyzed using two-way analysis of variance with independent samples t-test and one-way analysis of variance with Tukey’s HSD post-hoc (p≤0.05).

Results: Treatment with sodium perborate significantly lowered the shear bond strength between both composite systems and pulpal dentine, (p<0.001). The mean shear bond strength values were significantly higher in the late bonding compared to the immediate bonding groups for both composites, (p<0.001).

Conclusions: Treatment of the pulpal dentine with sodium perborate significantly reduced the immediate shear bond strength between the dentine and composites. The shear bond strength can be returned to nearly normal values if the final bonded restoration is delayed for two weeks after treatment.