The European Journal of Orthodontics Advance Access published online on November 5, 2009
The European Journal of Orthodontics, doi:10.1093/ejo/cjp077
A novel bracket base design: biomechanical stability
* Department of Oral and Maxillo-Facial Science, University of Naples "Federico II"
** Institute of Composite and Biomedical Materials, National Research Council, Naples, Italy
Address for correspondence Dr Rosa Valletta, Dipartimento di Scienze Odontostomatologiche e, Maxillo-Facciali, Università degli studi di Napoli "Federico II", Via S. Pansini 5, 80131 Napoli, Italy, E-mail: valletta{at}unina.it
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Abstract |
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The aim of this research was to investigate the retention of a bracket equipped with a novel base, the R-system®. The design of the bracket base is characterized by concentric grooves. The behaviour of this bracket was compared with a bracket with a conventional mesh base from the same manufacturer.
Thirty lower adult bovine incisors were selected and metallic brackets were bonded using the Concise adhesive system. Each bracket–adhesive–enamel interface was investigated according to torsion debonding. One-way analysis of variance was used for statistical evaluation. Finite element analysis was also undertaken. In order to assess if the technique was detrimental to the enamel, the mode of failure was determined using the Adhesive Remnant Index (ARI). The debonded surfaces were analysed using scanning electron microscopy (SEM) and electron dispersion spectrometry (EDS).
The R-system® provided a bond strength greater than that of the mesh-base bracket. EDS showed that the amount of calcium on the novel base was higher than that on the conventional base, which allowed transfer of torsional stress more uniformly to the substrate, resulting in higher bond values for the R-system®. On the other hand, as debonding of the R-system® occurred at the enamel–composite interface, lesions to the enamel substrate are possible.