Evaluation of Shear Bond Strength of Metallic Brackets with Different Acid Concentrations

Demjaha M. , Kjurchieva Chuchkova G. , Qilerxhiu G. , Kanurkova L. , Kiseri Kubati J.

Abstract: Summary: The study examines the impact of varying acid concentrations during enamel etching on the shear bond strength (SBS) of metallic orthodontic brackets. Aim of study: To evaluate the enamel damage caused by different acid concentrations during enamel etching; to determine the impact of acid concentration during enamel etching on the bond strength of orthodontic brackets; to determine the etch concentration which will achieve the optimal bond strength while minimizing enamel damage. Material and methods: Sixty extracted premolar teeth were categorized into three groups and etched with 3.7%, 18.5%, and 37% phosphoric acid. The SBS was evaluated using a universal testing machine, with results indicating a correlation between acid concentration and SBS. Lower concentrations provided satisfactory SBS while minimizing enamel damage, emphasizing the potential for safer orthodontic treatments. Subsequently shear bond strength of orthodontic brackets was tested in Universal Testing Machine. Results and discussion: The lowest mean bond strength (9.02 MPa) was recorded among the teeth etched with 3.7% phosphoric acid. While the highest mean SBS was found in the group of teeth etched with 37% phosphoric acid (11.81). The group of teeth etched with 18.5% phosphoric acid represented intermediate SBS values, which was 9.99 MPa. Teeth etched with 37% phosphoric acid showed higher adhesion at the enamel/resin interface, while the teeth etched with 3.7% phosphoric acid had higher adhesion at the resin/bracket interface. Findings for the group of teeth etched with 18.5% phosphoric acid were in between. Conclusions: Lower concentrations of acid can provide satisfactory shear bond strength of metallic brackets.

Keywords: Shear bond strength, metallic brackets, enamel etching, orthodontic bonding, acid concentration