Chlorhexidine application for bond strength preservation in artificially-created caries-affected primary dentin

This study evaluated the effect of 2% chlorhexidine digluconate (CHX) on immediate and six-month bond strength (μTBS) and nanoleakage (NL) of an etch-and-rinse adhesive system to sound and caries-affected primary dentin. Flat dentin surfaces from 20 primary molars were assigned to according to substrate (sound dentin and caries-affected dentin — pH-cycling for 14 days) and treatment (control — C and CHX – 2% CHX for 60 s after acid etching). After adhesive (Adper Single Bond) application, composite buildups were constructed and sectioned to obtain bonded sticks (0.8 mm2) to be subjected to microtensile testing immediately or after six-month of water aging. Two sticks from each tooth at each time were immersed in silver nitrate solution to assess nanoleakage (NL) qualitatively. The μTBS means were analyzed by three-way repeated measures ANOVA and Tukey׳s tests (α=0.05). After six-month of water aging, significant reductions in μTBS values were observed only in C groups, irrespective of substrate. The values obtained to caries-affected dentin were lower compared with sound dentin. NL was more evident in C groups, mainly after six-month and was not influenced by substrate. Chlorhexidine prevents the bond degradation and reduces the nanoleakage of an etch-and-rinse adhesive system to sound and caries-affected primary dentin after six-month of water aging.