Objective: The objective of this study was to evaluate micro-shear bond strength of a self-etching primer adhesive system to fluorosed enamel. Materials and Methods: Extracted human molars were classified according to the severity of fluorosis using Thylstrup and Fejerskov index into four groups (TFI: 0, normal; 1-3, mild fluorosis; 3-6, moderate fluorosis; 6-7, severe fluorosis) and divided into following two sub-groups. For the first sub-group, a self-etching primer adhesive system (Clearfil SE Bond, Kuraray Japan) was applied to the ground enamel surfaces and the other sub-group was conditioned with 37% phosphoric acid for 30s prior to application of the adhesive system. Teeth were then restored with a resin composite (Clearfil ST, Kuraray Japan), stored for 24 hrs in water and micro-shear bond strengths were measured. The data were analyzed using two-way ANOVA and Sheffe's test (p=0.05).
Results: Micro-shear bond strengths to fluorosed enamel (MPa±SD)
|
Category of fluorosis |
SE Primer |
37% Phosphoric acid + SE Primer |
|
Normal |
28.8 ± 7.2 |
29.3 ±4.8 |
|
Mild |
25.7 ± 3.7 |
31.5 ± 7.0 |
|
Moderate |
29.6 ± 4.2* |
35.0 ± 4.8* |
|
Severe |
25.1 ± 3.5** |
30.2 ± 6.0** |
n=24 for each group
Same asterisk symbols show statistically significant differences. No statistically significant difference was there between the adhesive systems and different degree of fluorosis. However, significant difference in bond strength was found in moderate and severe groups with the previous phosphoric acid etching.
Conclusion: Severity of fluorosis does not affect the micro-shear bond strength of a self etching bonding system to fluorosed enamel.