Abstract
Introduction: Brackets bonded to enamel surface depend on the adhesion material and the quality of the bracket base. Objective: The aim of this study was to compare the shear bond strength of metallic brackets with Metal Injection Molding (MIM) technology base or welded base. Materials and Methods: Forty mandibular extracted premolars mounted in acrylic resin blocks were divided randomly into two groups, both bonded with Transbond XT. In Group 1, brackets with MIM technology bases (Masel) were used, and in group 2, brackets with a welded base (Morelli) were used. After 24 hours, all brackets were tested for shear bond strength in a universal testing machine. Intergroup comparison was performed with an independent t test. Results: MIM base brackets showed a mean maximum load registered of 107.55 N, a mean shear bond strength of 9.58 MPa with a standard deviation of 5.80 MPa and the welded base brackets showed a mean maximum load of 167.37 N, a mean shear bond strength of 13.28 MPa with a standard deviation of 2.58 MPa. The difference between the two groups was statistically significant, indicating a higher shear bond strength of the welded base brackets. Conclusion: It was concluded that the brackets with welded bases presented a significantly higher shear bond strength than the brackets with MIM bases.
Highlights
Brackets bonded to enamel surface depend on the adhesion material and the quality of the bracket base
metal injection molding (MIM) base brackets showed a mean maximum load registered of 107.55 N, a mean shear bond strength of 9.58 MPa with a standard deviation of 5.80 MPa and the welded base brackets showed a mean maximum load of 167.37 N, a mean shear bond strength of 13.28 MPa with a standard deviation of 2.58 MPa
It was concluded that the brackets with welded bases presented a significantly higher shear bond strength than the brackets with MIM bases
Summary
Brackets bonded to enamel surface depend on the adhesion material and the quality of the bracket base. Failure of bracket bonding during the course of orthodontic therapy is not an uncommon occurrence [9], the bracket bases have been modified to improve the anatomy and to achieve better mechanical retention by perforations, meshes, grooves, spherical designs, and different metal particles [7]. Several authors have suggested that the microscopic characteristics of the bracket base, the mesh designs, may increase or decrease the effectiveness of mechanical interlocking with the adhesive. These features include rough or smooth mesh wires, mesh size, wire diameter, weld points, the integrity of the enamel surface, the conditioning procedure, and the type of adhesive system used [10 - 12]
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