Introduction: Recent innovations in bonding propose laser ablation as an alternative method to acid etching. Objectives: The objective of this study is to compare the effect of laser irradiation at medium-short pulse (MSP) mode, quantum-square pulse (QSP) mode, and acid etching on the shear bond strength (SBS) of orthodontic brackets to enamel.
Materials and methods: Forty-two premolars were allocated to three groups (14 each): (1) 37% phosphoric acid etching; (2) erbium-doped yttrium aluminum garnet (Er:YAG) laser etching with MSP mode; (3) Er:YAG laser etching with quantum- square pulse mode. Metallic brackets were bonded with Transbond XT. After photo polymerization, the SBS values were recorded with universal testing machine. Surface morphology was evaluated with scanning electron microscopy (SEM). The remaining adhesive was assessed using adhesive remnant index (ARI).
Results: Nonparametric test was used to analyze the statistical significance. A mean rank of 18.29 and 10.71 was obtained for QSP mode and acid etching with p = 0.015, 18.14; and 10.86 for MSP mode and acid etching with p = 0.019; and 14 and 15 for QSP mode and MSP mode with p = 0.748. Statistically significant difference was found between laser and acid-etched group. The SEM scan showed MSP mode with regular and uniform surface, like acid-etched sample, whereas QSP samples had irregular and severely rough surface. The ARI indicates that failure sites are mainly at the enamel/adhesive interface in the acid-etched and MSP mode group and at the bracket base/adhesive interface in QSP mode group.
Conclusion: Laser etching in MSP mode is a successful alternative to acid etching, and provides a safer debonding of the brackets from the enamel surface without causing fractures.
Keywords: Acid etching, Bonding, Laser, Shear bond strength.
How to cite this article: Sobha VV, Varma NKS, Ajith VV. Comparative Evaluation of Laser Etching and Acid Etching: An in vitro Study. Int J Laser Dent 2016;6(1):6-11.
Source of support: Nil
Conflict of interest: None