Can enamel etching with the Er:YAG laser be an alternative to the conventional phosphoric acid for bracket bonding? A systematic review and meta-analysis

Abstract

This systematic review and meta-analysis aimed to evaluate the effect of Er:YAG laser etching on shear bond strength (SBS) of brackets bonded to the enamel and compare to the phosphoric acid (control). Electronic databases (PubMed, Scopus, and Web of Science) and a manual search were conducted up to January 2021. In vitro studies comparing Er:YAG laser and phosphoric acid etching for metal bracket bonding to human teeth, that performed aging of samples submitted to SBS tests were included. The risk of bias was assessed considering specific parameters. Statistical analysis was conducted using the RStudio statistical program for meta-analysis. Among 1456 potentially eligible studies, 19 were selected for full-text analysis, and 12 were included for qualitative and quantitative analysis. In the general meta-analysis, phosphoric acid etching showed higher SBS (n = 516; p = 0.02; I 2 = 95.4%). The 100 mJ (p = 0.05; I 2 = 76.2%) and <100 mJ subgroup (p < 0.01; I 2 = 89.5%) showed a significant difference, favoring phosphoric acid etching, however, there was no significant difference in the >100 mJ subgroup (p < 0.32; I 2 = 93.3%). In the 500-thermocycle subgroup, phosphoric acid etching had a significantly higher SBS (p < 0.01; I 2 = 96.2%), however, there was no significant difference in etching techniques for the 5000-cycle subgroup (p = 0.10; I 2 = 69.1%). Although Er:YAG laser provides lower SBS than phosphoric acid etching, it provides an adequate bracket bonding. Further investigations to establish a laser protocol and clinical evidence are important for the consolidation of Er:YAG laser as a viable alternative to phosphoric acid.