In vitro assessment of toothbrushing effects on orthodontic bracket debonding: comparing stainless steel and ceramic brackets with two adhesive systems

Background: This study aimed to compare the bracket failure of metal and ceramic orthodontic brackets bonded with two different adhesives using the conventional shear bond test and a custom-made toothbrush simulator. Methods: Forty-eight bovine teeth were extracted, bracketed, pH-cycled (14 days), randomly divided into four groups: metallic brackets bonded with B&E bonding agent (MB) and OrthoVita (MO), and ceramic brackets bonded with the B&E (CB) and the OrthoVita (CO). The bracket failure was evaluated with a universal testing machine (UTM) and a custom-made toothbrush simulator (TBS) (n = 6). Similarly, the amount of adhesive remaining on the bracket following debonding was evaluated using the Adhesive Remnant Index (ARI). Statistical Package for Social Sciences (SPSS) version 22 was used for statistical analysis. A two-way ANOVA was used for shear bond testing, while Fishers Exact test was used for the comparison of toothbrush simulator results. Results: The mean values of shear bond strengths (± SE) were MB 58.32 ± 4.48 MPa, MO 22.57 ± 5.64 MPa, CB 27.36 ± 2.66 MPa, and lastly, CO 12.54 ± 3.64 MPa (p < 0.001). In the case of toothbrush simulation, all the samples remained intact in the group MB following 75,000 cycles. In group MO: two samples debonded < 10,000 cycles, four remained intact. In CB, three samples debonded < 10,000 cycles, one debonded < 20,000–30,000 cycles, and only two samples remained intact. In the CO group four samples debonded < 10,000 cycles, while two samples remained intact. Conclusion: Metallic brackets and B&E Universal adhesive showed superior results. MB proved to have the strongest bonding comparatively.