Development of a device to measure bracket debonding force in vivo
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Development of a device to measure bracket debonding force in vivo
The European Journal of Orthodontics 2007 29(6):564-570; doi:10.1093/ejo/cjm069
Jos» Renato Prietsch*, Ana Maria Spohr*, Isaac Newton Lima da Silva**, JoÑo Carlos Pinheiro Beck** and Hugo Mitsuo Silva Oshima*
* School of Dentistry
** School of Engineering, Pontifical Catholic University of Rio Grande do Sul, Porte Alegre, Brazil
Abstract
The purposes of this study were to develop a device to measure bracket debonding force in vivo and to evaluate, in vitro, the bond strength obtained with the device and with tensile and shear bond strength (SBS) tests performed in a universal testing machine.
The device was developed using polypropylene pliers (3M Unitek). The basic principle consisted of measuring the applied force to debond, using two strain gauges (Kyowa) bonded to the region of major deformation of the plier handles. The crowns of 75 bovine incisors were embedded in acrylic resin and orthodontic brackets were bonded to the facial surface with Transbond XT (3M Unitek). In group A (n = 25) debonding was carried out with the device, while tensile bond strength testing was performed in group B (n = 25) and SBS testing in group C (n = 25). A universal testing machine (EMIC-DL-2000) was used for these last two groups.
According to analysis of variance and Tukey's test ( = 0.05), the mean bond strength for group C (7.71 MPa) was statistically higher than for groups A (2.98 MPa) and B (2.69 MPa). Groups A and B were not statistically different.
The device was shown to be feasible to obtain in vivo bond strength values for orthodontic brackets, and that the bond strength values were dependent on the method and direction of debonding.
Address for correspondence Ana Maria Spohr, Pontifical Catholic University of Rio Grande do Sul (PUCRS), School of Dentistry (Block 6), Laboratory of Dental Materials, Av. Ipiranga 6681, CEP: 90616-900 Porto AlegreÛRS, Brazil, E-mail: anaspohr@terra.com.br
Copyright © 2007 European Orthodontic Society
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