Comparison of Er:YAG laser and acid etching methods prior to lingual retainer application in vitro

Abstract

The aim of this study is to compare the bond strength, fracture type, and the amount of microleakage related to lingual retainers bonded on enamel surface etched with either Erbium:Yttrium-Aluminum-Garnet (Er:YAG) laser or acid etching methods. The enamel of extracted 132 upper incisor teeth was etched using either 37% phosphoric acid or Er:YAG laser (Fotona Light Walker H02-N 2940 nm, 120 mJ, 10 Hz, 1.2 W in MSP mode). Teeth were embedded in acrylic as two teeth in each sample with 135° angulation and retainer wires were bonded on the lingual surface of the samples. Two-year aging protocol was applied using a chewing simulator and a thermal cycler. Shear bond strength (SBS), adhesive remnant index (ARI), and microleakage were measured. SBS and microleakage data were analyzed using the Mann–Whitney U test and ARI scores using the Pearson chi-square test. The SBS was found significantly higher in the acid-etched group. There was no statistically significant difference in the total microleakage means between groups. There was no statistically significant difference in the microleakage between the enamel-adhesive and adhesive-retainer interfaces for the mesial and distal sides. Higher microleakage values were measured between the enamel and the adhesive surfaces compared to adhesive-retainer interface for both groups. Within the limitations of our study, acid etching promises better bond strength for lingual retainers compared to Er:YAG laser etching. There was no significant difference between the groups in terms of microleakage.