Study of the effects of active and passive lacebacks in the biomechanics of the leveling phase using the MBT technique / "Estudo dos efeitos dos lacebacks ativos e passivos na biomecânica da fase de nivelamento utilizando-se a técnica MBT"
AUTOR(ES)
Ricardo Cesar Moresca
DATA DE PUBLICAÇÃO
2006
RESUMO
The purpose of this study was to evaluate the effects of active and passive lacebacks in the biomechanics of the leveling phase, using the MBT technique. The sample was composed of 29 Brazilian subjects (22 female and 7 male), Caucasian, with Class I malocclusion and mean age of 15 years and 5 months. The orthodontic treatment was planned with the extraction of the first premolars, and the leveling phase was performed with stainless steel wire only (0.014, 0.016, 0.018, 0.020 e 0.019 x 0.025). The anchorage control devices used in the upper and lower arches were, respectively, the IHG extraoral appliance and the fixed lingual arch. According to the type of laceback prescription, the sample was divided into four groups: group I 14 subjects in which active lacebacks were used in the upper arch; group II 9 subjects in which passive lacebacks were used in the upper arch; group III 19 subjects in which active lacebacks were used in the lower arch; group IV 10 subjects in which passive lacebacks were used in the lower arch. For each subject of the sample two lateral cephalometric radiographs were taken: one at the beginning and another at the end of the leveling phase, with a mean interval of 21 months. The data were collected using the resources of computerized cephalometry. To perform the analysis of errors, the cephalometric method was repeated in all subjects of the sample, by the same operator, with a minimum interval of 15 days between the measurements. The results revealed that the observed variations were compatible with the estimates of operational errors in cephalometric studies. After statistical analysis and interpretation of the results, it was observed that in group I, only the crown of the upper first molar presented a mesial movement. As to the upper central incisor, both the crown and the root presented a lingual movement. However, the inclination of these teeth was not affected. In group II, the upper first molar remained stable and only the crown of the upper central incisor moved lingually, leading to a clockwise rotation of this tooth. In group III, a mesial movement of both the crown and the root of the lower first molar was observed, along with its extrusion, whereas the position of the lower central incisor remained unchanged. The inclination of these teeth was not affected either. In group IV, it was observed that neither the lower first molar nor the lower central incisor experienced variations in the anteroposterior sense. Vertically, there only was extrusion of the lower first molar.
ASSUNTO(S)
orthodontics fios ortodônticos orthodontic appliances bráquetes ortodônticos orthodontic brackets orthodontic space closure tooth movement corrective movimentação dentária aparelhos ortodônticos ortodontia corretiva orthodontic wires fechamento de espaço ortodôntico
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