Comparison of bracket bond strength to etched and unetched enamel under dry and wet conditions using Fuji Ortho LC glass-ionomer

Background. Acid etching prior to orthodontic bracket bonding may result in enamel wear or cracks following bracket removal. The manufacturer of Fuji Ortho LC glass-ionomer (GI) claims that it can bond brackets to wet unetched enamel. This study aimed to compare the bracket bond strength to etched and unetched enamel under dry and wet conditions. Methods. In this in vitro study, 60 intact premolar teeth were randomly assigned to 6 groups (etched and dried, etched and moistened with distilled water, etched and moistened with saliva, unetched and dried, unetched and moistened with water, unetched and moistened with saliva). In all the groups, Leon 4 brackets were bonded to the enamel using Fuji Ortho LC GI. The teeth were immersed in distilled water at 37°C for 24 hours and subjected to shear loads at a crosshead speed of 5 mm/min in a Zwick machine for bond strength testing. Data were analyzed with ANOVA, Tukey test and independent t-test. Results. The mean bond strength values in groups 1 (etched, dry), 2 (etched, moistened with water), 3 (etched, moistened with saliva), 4 (unetched, dry), 5 (unetched, moistened with water) and 6 (unetched, moistened with saliva) were 21.86, 16.46, 10.49, 8.12, 9.15 and 9.52 MPa, respectively. Significant differences in bond strength were detected between groups 1 and 2 and all the other groups (P < 0.05), with no significant difference between groups 1 and 2 (P > 0.05). Conclusion. Fuji Ortho LC GI provided adequate bond strength between brackets and enamel. To acquire higher bond strength, brackets must be bonded to etched and dried enamel.