title: Development of a device to measure bracket debonding force in vivo.
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-2,000) was used for these last two groups. According to analysis of variance and Tukey's test (alpha = 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.
authors.affiliation: School of Dentistry, Pontifical Catholic University of Rio Grande do Sul, Porte Alegre, Brazil.
authors.forename: José Renato
authors.initials: JR
authors.lastname: Prietsch
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Spohr
authors.forename: Isaac Newton
authors.initials: IN
authors.lastname: Lima da Silva
authors.forename: João Carlos
authors.initials: JC
authors.lastname: Pinheiro Beck
authors.forename: Hugo Mitsuo
authors.initials: HM
authors.lastname: Silva Oshima
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D000818:Animals; D002417:Cattle; D001840:Dental Bonding; D017005:Dental Debonding / Q000295:instrumentation*; D003799:Dental Stress Analysis / Q000295:instrumentation; D004867:Equipment Design; D005240:Feasibility Studies; D007180:Incisor; D008422:Materials Testing / Q000295:instrumentation*; D016910:Orthodontic Brackets; D011126:Polypropylenes; D019279:Resin Cements / Q000737:chemistry; D033081:Shear Strength; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D014159:Transducers