Laser Etched vs Conventional Etched Enamel: Effect on Shear Bond Strength of Orthodontic Brackets

Abstract

Aim: The purpose of this study was to assess the shear bond strength of the teeth prepared for bonding with different power outputs of Erbium, Chromium doped: Yttrium-Scandium-Gallium-Garnet (Er,Cr:YSGG) laser etching and to compare different power outputs of laser etching with 37% phosphoric acid. Materials and methods: A total of 105 premolars, extracted for orthodontic purposes were randomly divided into five groups. Different methods were used in each group to prepare the tooth enamel for bonding. The methods are as follows: Etching for 15 seconds with 37% phosphoric acid; irradiation with 1.5 W/10 Hz Er,Cr:YSGG laser, 1.5 W/20 Hz, 2 W/10 Hz and 2 W/20 Hz Er,Cr:YSGG laser. After surface preparation standard edgewise stainless steel premolar brackets were bonded and was examined under scanning electron microscope. The brackets were debonded 24 hours later and shear bond strengths were measured. Results: Enamel etching with 37% phosphoric acid for 15 seconds provides a higher shearbond strength for orthodontic bonding but laser etching with 2 W/20 Hz produced a comparable level of shearbond strength to phosphoric acid etched group. While 1.5 W/20 Hz and 2 W/10 Hz produced clinically acceptable shear bond strength for orthodontic bonding and 1.5 W/10 Hz produced the least shearbond strength and not acceptable for orthodontic bonding. Statistical significance was found between the groups (p  0.01). Group 1 is the highest followed by group 5. Conclusion: Irradiation with 1.5 W/20 Hz and 2 W/10 Hz were irregular and superficial, in contrast to phosphoric acid. But etching with laser 2 W/20 Hz produced adequate bond strength and could be a viable alternative to other methods.