The effect of topical fluoride varnish on the shear bond strength of orthodontic brackets

Abstract

AIM: The present study examined the effect of topical fluoride treatment on the shear bond strength (SBS) of orthodontic brackets using single-dose fluoride varnishes and assessed according to different post-application times and the pattern of debond. METHODS: Of the 105 extracted human mandibular premolars used in the study, 70 were subjected to the SBS test and the remaining 35 to the Adhesive Remnant Index (ARI) test. The teeth were divided into a control group and six test groups: Kolorz ClearShield 5% NaFl varnish Day 1, 8, and 15; and Vanish 5% NaFl varnish Day 1, 8, and 15. The samples were coated with their respective varnish, following which, brackets were bonded. Each specimen was subjected to a shear force in a universal testing machine until failure. Data were analysed using the analysis of variance (ANOVA). RESULTS: At all time intervals, the mean SBS of the Vanish groups was not significantly different from the control group, and the shear strength in the ClearShield groups was significantly higher than the control and Vanish groups, except at Day 8 (no difference). For the same bonding material, there was no significant difference in mean SBS over different time intervals. ARI scores showed no significant difference between the groups. CONCLUSION: The application of single-dose fluoride varnish, irrespective of the length of time between the fluoride treatment and bonding procedure, does not negatively affect the shear bond strength of orthodontic brackets.