Long-term evaluation of orthodontic brackets shear bond strength with or without fluoride-releasing adhesive

The aim of this study was the evaluation of the long-term effect on shear bond strength (SBS) of orthodontic brackets treated with or without a fluoride-releasing system.A total of 80 bovine teeth were randomly divided into 2 groups (G1, G2): in G1 teeth were treated with a fluoride-releasing system (Fluor Protector, Ivoclar Vivadent, Schaan, Liechtenstein) and with spectrum (Micerium, Genoa, Italy); in G2 only spectrum was used. Shear bond strength (SBS) was measured in MPa 24 hours after bonding (T0) and after 30 (T1), 60 (T2), 90 (T3) and 180 days (T4).A repeated measures ANOVA on rank-transformed data was used and differences in time between G1 and G2 were revealed (P0.001). From 3 months mean measurement of G1 was higher than G2 (P=0.015). No difference was revealed between T3 and T4 in either group (P=0.48 for G1 and P=0.46 for G2).After 3 months, G1 showed a significantly higher value than G2. Both groups did not show changes in shear bond strength between month 3 and month 6.