Effect of Different Surface Pretreatment Methods on Shear Bond Strength of Orthodontic Brackets Bonded with a Self-Adhesive Composite

Patients undergoing fixed orthodontic treatments face a higher risk of white spot lesions (WSLs) due to difficulties in effective plaque control. Several preventive measures provide remineralization and antibacterial benefits that reduce WSLs. These measures, while protective, may adversely affect the shear bond strength (SBS) of orthodontic brackets, potentially leading to bracket debonding and impacting overall treatment effectiveness. This study comparatively evaluated the effects of pretreatments with fluoride varnish, chlorhexidine fluoride mouthwash (CHXF), and fluoridated casein phosphopeptide-amorphous calcium phosphate (CPP-ACPF) on the shear bond strength (SBS) of orthodontic brackets bonded with GC Ortho Connect composite resin.

Sixty extracted premolar teeth were randomly divided into four groups. The first group was the control without pretreatment, and the second to fourth groups were pretreated with 5% fluoride varnish for 4 minutes, with a CHXF for 7 days, and with CPP-ACPF for 3 minutes, respectively.  Specimens were subsequently tested for the SBS in a universal testing machine. Each tooth was visually examined and magnified (×10) using a Nikon SMZ800 to evaluate the adhesive remnant index (ARI).One-way ANOVA, followed by post hoc Tukey tests used for statistical analysis. The significance level was set at P<0.05.

Evaluation of SBS showed no significant differences between the control, chlorhexidine fluoride mouthwash, and CPP-ACPF groups (P>0.05). However, the SBS of the fluoride varnish group was significantly lower than in other groups (P<0.05). Adhesive remnant index (ARI) scores did not show significant differences between the four groups (P=0.057).

The results showed that the SBS of the brackets in the CPP-ACPF paste, CHXF, and fluoride varnish groups were higher than the appropriate range for orthodontic purposes.