Low-level Laser-assisted Orthodontics in Enamel Etching: An In-vitro Evaluation

Introduction: The use of laser irradiation to etch enamel in preparation for the direct bonding of orthodontic appliances has been studied. This study compares shear bond strength, surface characteristics, and Adhesive Remnant Index (ARI) scores of teeth prepared for bonding with phosphoric acid etching, laser etching, SEP, and laser + acid etching. Materials and Methods: One hundred and twenty-six premolars were randomly divided into 6 groups and a different method was used to prepare the tooth enamel in each group for bonding: etching with 37% phosphoric acid for 15 s and 60 s; irradiation with a 0.8-W and 1.5-W Er: YAG laser for 10 s; application of a SEP, Er: YAG laser etching for 10 s followed by etching with 37% phosphoric acid for 15 s. After etching the tooth surface, standard edgewise premolar brackets were bonded; 1 tooth in each group was not bonded and was examined under a scanning electron microscopic. The brackets were debonded 24 h later; shear bond strengths were measured, and ARI scores were recorded. Results: The findings in this study showed that acceptable bond strength could be achieved with laser 1.5 W output. However mean shear bond strength of laser 1.5 W and 0.80 W is lower as compared to conventional acid etching 60 s and 15 s, laser + acid etching, and SEP. The evaluation of ARI scores demonstrated differences in bond failure site among the groups. Conclusions: Irradiation with the 0.80-W laser did not produce sufficient etching for orthodontic bonding. Enamel etching with a 1.5-W laser for 10 s could be a viable alternative to other methods.