RESUMO
OBJECTIVES: This study evaluated the effect of dentin pretreatment with silver nanoparticles (SNPs) and chlorhexidine (CHX) on the microshear bond strength (µSBS) durability of different adhesives to dentin. MATERIALS AND METHODS: Occlusal surfaces of 120 human molars were ground to expose flat dentin surfaces. The specimens were randomly assigned to six groups (n = 20). Three groups (A, B, and C) were bonded with Adper Single Bond 2 (SB) and the other groups (D, E, and F) were bonded with Clearfil SE Bond (SEB). Dentin was pretreated with CHX in groups B and E, and with SNPs in groups C and F. The specimens were restored with Z250 composite. Half of the bonded surfaces in each group underwent µSBS testing after 24 hours and the other half was tested after 6 months of water storage. RESULTS: SNP application was associated with a higher µSBS than was observed in the CHX and control groups for SEB after 24 hours (p < 0.05). A significantly lower µSBS was observed when no dentin pretreatment was applied compared to dentin pretreatment with CHX and SNPs for SB after 24 hours (p < 0.05). The µSBS values of the 6-month specimens were significantly lower than those obtained from the 24-hour specimens for all groups (p < 0.05). This decrease was much more pronounced when both adhesives were used without any dentin pretreatment (p < 0.05). CONCLUSIONS: SNPs and CHX reduced the degradation of resin-dentin bonds over a 6-month period for both adhesive systems.