Effect of chlorhexidine application on shear bond strength of brackets bonded with a resin-modified glass ionomer.

Introduction: The purpose of study was to assess the effect of chlorhexidine application on the shear bond strength and bond failure site of a resin-modified glass ionomer (Fuji Ortho LC, GC Europe, Leuven, Belgium). Methods: Forty-five bovine permanent mandibular incisors were randomly divided into 3 groups of 15. Group 1 had no chlorhexidine treatment and served as the control; groups 2 and 3 had chlorhexidine application immediately before and 1 week before bonding, respectively. Stainless steel brackets (DB, Leone, Sesto Fiorentino, Italy) were bonded with the resin-modified glass ionomer. After bonding, all samples were stored in distilled water for 24 hours and subsequently tested in a shear mode on a testing machine. Analysis of variance (ANOVA) and the Scheffé test were applied to determine significant differences in the shear bond strength values, and the chi-square test was used to determine significant differences in the adhesive remnant index scores among the groups. Significance for all statistical tests was predetermined at P <0.05. Results: Group 1 (no chlorhexidine application) showed significantly higher shear bond strength values than group 2 (chlorhexidine applied immediately before bonding). No significant differences were found between groups 1 and 3 (chlorhexidine applied 1 week before bonding). Moreover, significant differences in debond locations were found among the 3 groups. Conclusions: Chlorhexidine application immediately before bonding significantly lowered the bond strength values of Fuji Ortho LC but did not affect its bond strength when applied 1 week before bonding.