Comparison of Lithium Disilicate–Reinforced Glass Ceramic Surface Treatment With Hydrofluoric Acid, Nd:Yag, and Co2 Lasers on Shear Bond Strength of Metal Brackets Publisher Pubmed



Alavi S¹ ; Samie S¹ ; Raji SAH² Show Affiliations
Source: Clinical Oral Investigations Published:2021

Abstract

Objectives: To evaluate and compare the effects of different surface conditioning methods of lithium disilicate–reinforced ceramic on shear bond strength (SBS) of metallic brackets. Materials and methods: Thirty-six lithium disilicate ceramic blocks mounted in acrylic resin blocks were assigned to 3 groups (n = 12): 9.6% hydrofluoric acid (HF); neodymium-doped yttrium aluminium garnet (Nd:YAG) laser; and carbon dioxide (CO2) laser. The glass ceramic surfaces were primed with a silane, and the brackets were bonded using a light-cured composite resin. SBS test was carried out in a universal testing machine at 0.5 mm/min crosshead speed until the brackets were debonded. The remaining adhesive was evaluated under a stereomicroscope in terms of the adhesive remnant index (ARI). The surface hardness was determined with a 100-gr force using a microhardness tester. Glass ceramic surface changes were evaluated using the scanning electron microscope. One-way ANOVA and post hoc Tamhane tests were used to compare microhardness values, and Kruskal-Wallis and Mann-Whitney U tests were used to analyze SBS values and ARI. Results: The median and interquartile range of SBS values in 3 groups were 6.48 (1.56–15.18), 1.26 (0.83–1.67), and 0.99 MPa (0.70–2.10), respectively. Microhardness analysis revealed significant differences between the CO2 laser and intact porcelain groups (P = 0.003), without significant differences between the other groups. Group 1 exhibited the highest ARI. Conclusion: Neither CO2 nor Nd:YAG lasers resulted in adequate surface changes for bonding of brackets on ceramics compared with the samples conditioned with HF. CO2 laser decreased the microhardness of ceramics. Clinical relevance: Surface conditioning with HF resulted in clinically acceptable SBS values. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.