Effect of dentin surface pretreatment with four conditioning agents on micro-shear bond strength of a self-adhesive cement

BACKGROUND: To evaluate the effect of dentin surface pretreatment with four conditioning agents on the micro-shear strength of a self-adhesive cement. MATERIAL AND METHODS: 32 specimens of 6 mm high x 4 mm wide with dentin exposure were obtained and divided into four groups of NaOCI, CHX, EDTA and AgNPs (n = 8). 2 mL of each treatment agent was applied to the dentin for 60 seconds. Composite resin cylinders measuring 3 mm x 2 mm were cemented with RelyX U200 self-adhesive cement. Micro-shear testing was performed after 24 hours and one week (n = 4) with a 1 mm/min; failure values were recorded in MPa. The failure pattern was evaluated with a stereomicroscope at 20x. The Kruskal-Wallis test was used to evaluate differences between groups. The Mann-Whitney U test was used to evaluate between evaluation times. The significance level used was p<0.05. RESULTS: At 24 hours after cementation, the highest value of micro-shear bond strength was observed for chlorhexidine (15.951 MPa), this value were similar for NaOCl 4% and EDTA, however significant differences were observed when compared with AgNPs (p<0.05). When compared the values at 24 hours and after one week, no differences were observed (p>0.05). The most frequent failure pattern was mixed, followed by adhesive failure. CONCLUSIONS: Pretreatment of dentin with sodium hypochlorite, CHX and EDTA positively affected the 24-hour bonding capacity of RelyX U200 self-adhesive resin cement, although it decreased after one week. Key words:Dental cements, disinfectants, calcium chelators, nanoparticles.