Comparative Study of Adhesion of Brackets with Metal Injection Molding (MIM) Technology and Welded bases: In vitro Study

Luis A. V. Izquierdo1, Francyle S. H. Sanches1, Francisco Molina1, Rafael P. Henriques2, Emerson F. Cruz2, Karina M. S. Freitas3, *
1 Department of Orthodontics, University of Hemispheres, Quito, Ecuador, FACOP, Bauru, Brazil
2 Department of Health Sciences, FACOP, Bauru, Brazil
3 Department of Orthodontics, Uninga University Center, Maringa, Brazil

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Creative Commons License
© 2020 V. Izquierdo et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: ( This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Correspondence: Address correspondence to this author at the Department of Orthodontics, Uninga University Center, Maringa, Brazil; Tel: 55 14 991026446; E-mail:



Brackets bonded to enamel surface depend on the adhesion material and the quality of the bracket base.


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.


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.


It was concluded that the brackets with welded bases presented a significantly higher shear bond strength than the brackets with MIM bases.

Keywords: Shear bond strength, Bracket base design, Bonding, Orthodontics, MIM technology, Dental enamel.