Effects of sandblasting before orthophosphoric acid etching on lingual enamel: in-vitro roughness assessment.

INTRODUCTION: In this study, we evaluated changes in lingual enamel roughness due to sandblasting with 27-, 50-, and 90-µm aluminum oxide particles followed by 37% orthophosphoric acid etching. METHODS: Twenty-four maxillary premolars were included in the study. The lingual enamel roughness of 20 teeth was evaluated using a laser confocal microscope before and after enamel conditioning. Group 1 (control) was etched with 37% orthophosphoric acid; groups 2, 3, and 4 were sandblasted with 27-, 50-, and 90-µm aluminum oxide particles, respectively, before acid etching. The lingual surfaces of the other 4 teeth were evaluated using scanning electron microscopy after they had received one of the conditioning methods under study. Paired t tests were used to compare the roughness parameters obtained before and after conditioning in each group, and 1-way analysis of variance was used to compare the surface roughness between groups. The significance level was set at 5% for all statistical analyses. RESULTS: The 4 conditioning methods significantly increased the roughness of the lingual enamel. However, the roughness increases in the groups that were sandblasted with 27-, 50-, and 90-µm aluminum oxide particles before orthophosphoric acid etching were statistically greater than was the increase in the group conditioned only with orthophosphoric acid. Scanning electron microscopy showed different conditioning patterns among specimens that were conditioned only with orthophosphoric acid and those sandblasted with aluminum oxide before acid etching. CONCLUSIONS: Lingual enamel conditioning with aluminum oxide sandblasting before acid etching results in greater roughness and produces a conditioning pattern different from that of acid etching alone.