ABSTRACT
Statement of the Problem: Self-etch adhesives can activate matrix metalloproteinase [MMP] which hydrolyzes organic matrix of demineralized dentin. Epigallocatechin gallate [EGCG], especially found in green tea, could inhibit the activation of MMP.
Purpose: The aim of this study was to evaluate the effect of adding Epigallocatechin gallate [EGCG] into two types of adhesives on dentin bond strength.
Materials and Method: In this experimental study, 64 extracted third molars were randomly divided into 16 groups. Clearfil SE Bond and Filtek Silorane System with 0 micro M, 25micro M, 50micro M, and 100micro M concentration of 95% EGCG were used for bonding. Following the bonding and fabrication of beams [1 +/- 0.1 mm[2]] and storage in distilled water, the specimens were subjected to thermal cycles. Microtensile bond strengths of 8 groups were examined after 24 hours and others were tested after 6 months. The fracture modes of specimens were evaluated by stereomicroscope and SEM. Data were analyzed by three-way ANOVA and t-test [alpha = 0.05]
Results: The results of the three- way ANOVA test showed that types of bonding, storage time and interactive effect of EGCG concentration and bonding influenced the bond strength of specimens significantly [p<0.05]. The results of the t-test indicated that storage time only had significant effect on bond strength of Clearfil SE Bond with no EGCG [p= 0.017]. The most common failure modes in Filtek Silorane System groups and Clearfil SE Bond groups were adhesive and mixed/cohesive, respectively. The results of SEM at different magnifications showed that most fractures have occurred in the hybrid layer
Conclusion: Although adding 100 micro M volume of EGCG to Clearfil SE Bond can preserve the dentin bond, incorporation of EGCG in the silorane system, especially in high concentrations, decreases the bond strength after 6 months