Effect of Er: YAG Laser Pretreatment on Shear Bond Strength between Enamel White Spot Lesions and Glass Ceramics: An in Vitro Study

doi:10.13701/j.cnki.kqyxyj.2026.04.009

Abstract

Abstract: Objective: To compare the effects of different enamel surface pretreatments and bonding interface etching methods on the surface morphology and shear bond strength (SBS) of enamel white spot lesions (WSLs). Methods: Sixty teeth were randomly selected from 108 intact extracted premolars. A 4.0 mm×4.0 mm×2.0 mm enamel block was cut from the central buccal surface of each crown. After artificial demineralization, the enamel blocks were randomly divided into group D (demineralization only) and group R (resin penetration pretreatment). Based on different enamel etching methods, the samples in each group were further divided into three equal subgroups: P (37% phosphoric acid treatment), L (Er:YAG laser irradiation), and LP (Er:YAG laser irradiation + 37% phosphoric acid treatment). The surface morphology and roughness of the enamel were examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. After cutting off the roots and embedding the remaining 48 premolars (with only the buccal enamel surface exposed), corresponding treatments were applied based on the above grouping information. Cylindrical glass-ceramic columns were then bonded to the center of the buccal surfaces. The SBS was evaluated through shear bond strength test, and the fracture modes were recorded using SEM. Results: The etching methods significantly affected the enamel surface roughness and shear bond strength of the WSLs (P<0.05), while resin penetration pretreatment showed no statistically difference (P>0.05). The groups treated with the Er:YAG laser combined with 37% phosphoric acid etching exhibited the highest roughness and SBS, followed by the laser-only groups, with the 37% phosphoric acid groups showing the lowest values. Resin penetration pretreatment did not improve the SBS of the WSLs, but significantly affected the fracture patterns among groups (P<0.05). The adhesive failure mainly occurred in group D, whereas the mixed failure occurred in group R. Conclusion: Er:YAG laser pretreatment alone or combined with 37% phosphoric acid etching significantly improves the surface morphology of WSLs and increases the SBS between WSLs and glass ceramics.

Key words: white spot lesions, resin penetration, Er:YAG laser, shear bond strength, glass ceramics

YANG Yuanyuan, TIAN Jingyu, DING Yu, MENG Qingfei, MENG Jian. Effect of Er: YAG Laser Pretreatment on Shear Bond Strength between Enamel White Spot Lesions and Glass Ceramics: An in Vitro Study[J]. Journal of Oral Science Research, 2026, 42(4): 318-324.

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