Influence of enamel sandblasting prior to etching on shear bond strength of indirectly bonded lingual appliances.

OBJECTIVE: To test the null hypothesis was that there is no difference in the mean shear bond strength of indirectly bonded lingual brackets prepared with or without sandblasting prior to acid etching. MATERIALS AND METHODS: Forty extracted human premolars were obtained and randomly divided into two groups of 20 each: group I (control), phosphoric acid and indirect bonding with Maximum Cure and Phase II (Reliance, Itasca, Ill); and group II, sandblasting with 50 µm aluminum oxide (Microetcher, Danville Engineering, Danville, Calif) prior to etching and indirect bonding. All products were used according to the manufacturer's instructions. Instron universal testing machine was used to apply an occlusogingival shear force directly onto the enamel-bracket interface at a speed of 0.5 mm/min. The groups were compared using unpaired Student's t-test. Kaplan-Meir survival plots and log-rank test were done to compare the survival distribution between the two groups. RESULTS: Mean (SD) shear bond strength for group I was 13.17 (4.33) MPa and for the group II was 16.42 (5.41) MPa. Significant difference was observed in the bond strengths of the two groups evaluated (P = .048). However, the log-rank test demonstrated that clinical performance of the groups evaluated was not significantly different (P = .091). The adhesive remnant index (ARI) was significantly higher when using sandblasting prior to acid etching than in the control group (P = .011). CONCLUSIONS: Intraoral sandblasting prior to enamel etching increased the bond strength of lingual brackets, but the clinical performance of the groups was not significantly different.