Does the Seating Force Affect the Shear Bond Strength of Brackets? An InVitro Study

The purpose of this study was to observe two different seating forces on conventional and self-ligating brackets using shear bond strength (SBS).

The study material consisted of 48 recently extracted human premolars divided into four groups: Group I, conventional bracket (Master series, AO) 100 g seating force applied; Group II, conventional bracket (Master series, AO) 200 g seating force applied; Group III, self-ligating bracket (Empower, AO) 100 g seating force applied; and Group IV, self-ligating bracket (Empower, AO) 200 g seating force applied. All teeth were bonded with Transbond XT by the same operator. Following the bonding procedure, all teeth were stored in deionized water at 37°C for 30 days, and they were thermal cycled. A universal testing machine was used to obtain the SBS records. The Kruskal-Wallis statistical test was used to determine the significant differences in SBS between the four groups, and the Mann-Whitney U test with Bonferroni correction was used to compare the subgroups.

The mean shear bond strength was 15.70 MPa for Group I, 13.97 MPa for Group II, 8.38 MPa for Group III, and 8.31 MPa for Group IV. Significant differences in the SBS values were recorded between the self-ligating groups and conventional bracket groups. Seating forces on the brackets did not show any differences among the groups.

Within the limitations in this study, 100 g and 200 g forces can be applied because both seating forces showed acceptable SBS results.