Background: 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.
Methods: 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).
Results: A repeated measures ANOVA on rank-transformed data was used and differences in time between G1 and G2 were revealed (P<0.001). 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).
Conclusions: 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.