In vitro evaluation of microleakage under orthodontic brackets using two different laser etching, self etching and acid etching methods

This study evaluated the microleakage of brackets bonded by four different enamel etching techniques. Forty freshly extracted human premolars were divided randomly into four equal groups and received the following treatment: group 1, acid etching; group 2, self-etching primer (SEP); group 3, erbium:yttrium–aluminum–garnet (Er:YAG) laser etching; and group 4, erbium, chromium:yttrium–scandium–gallium–garnet (Er,Cr:YSGG) laser etching. After photopolymerization, the teeth were kept in distilled water for 1 month and then subjected to 500 thermal cycles. Then, the specimens were sealed with nail varnish, stained with 0.5% basic fuchsin for 24 h, sectioned, and examined under a stereomicroscope. In addition, they were scored for marginal microleakage at the adhesive–enamel and bracket–adhesive interfaces from the incisal and gingival margins. Statistical analyses consisted of the Kruskal–Wallis test and the Mann–Whitney U test with Bonferroni correction. Microleakage occurred between the adhesive–enamel and bracket–adhesive interfaces in all groups. For the adhesive–enamel surface, a significant difference was observed between group 1 and groups 2 (P = 0.011), 3 (P = 0.002), and 4 (P = 0.000) on the gingival side. Overall, significant differences were observed between group 1 and groups 3 (P = 0.003) and 4 (P = 0.000). In dental bonding procedures, acid etching was found to result in the least microleakage. Since etching with a laser decreases the risk of caries and is time-saving, it may serve as an alternative to acid etching.