RESUMO
OBJECTIVE: To evaluate the rate of lower canine retraction, anchorage loss, and changes on lower canines and first molars axial inclination using self-ligating and conventional brackets. MATERIALS AND METHODS: Twenty-five adult patients with a treatment plan involving extractions of four first premolars were selected for this split-mouth trial and had either conventional or self-ligating brackets bonded to lower canines in a block randomization. Retraction was accomplished using 100-g nickel titanium closed-coil springs, which were reactivated each 4 weeks. Oblique radiographs were taken before and after total canine retraction and the cephalograms were superimposed on stable structures of the mandible. Cephalometric points were digitized twice by a single-blinded operator for error control and the average of the points were used to determine the following variables: canine cusp horizontal changes, molar cusp horizontal changes, and angulation changes in canines and molars. Paired t tests were used to analyze the blinded data for group differences. RESULTS: All patients reached final phase without bracket debonds. No differences were found between the two groups for all variables tested. No serious harm was observed. CONCLUSION: Both brackets showed the same rate of canine retraction and loss of anteroposterior anchorage of the molars. No changes were found between brackets regarding the inclination of canines and first molars. CLINICAL RELEVANCE: Using self-ligating brackets to retract lower canines will not increase the velocity of tooth movement, does not increase anchorage, and does not decrease tipping.
Assuntos
Dente Canino , Procedimentos de Ancoragem Ortodôntica , Braquetes Ortodônticos , Fios Ortodônticos , Técnicas de Movimentação Dentária/instrumentação , Adulto , Cefalometria , Feminino , Humanos , MasculinoRESUMO
OBJECTIVE: To evaluate the velocity of canine retraction, anchorage loss and changes on canine and first molar inclinations using self-ligating and conventional brackets. MATERIALS AND METHODS: Twenty-five adults with Class I malocclusion and a treatment plan involving extractions of four first premolars were selected for this randomized split-mouth control trial. Patients had either conventional or self-ligating brackets bonded to maxillary canines randomly. Retraction was accomplished using 100-g nickel-titanium closed coil springs, which were reactivated every 4 weeks. Oblique radiographs were taken before and after canine retraction was completed, and the cephalograms were superimposed on stable structures of the maxilla. Cephalometric points were digitized twice by a blinded operator for error control, and the following landmarks were collected: canine cusp and apex horizontal changes, molar cusp and apex horizontal changes, and angulation changes in canines and molars. The blinded data, which were normally distributed, were analyzed through paired t-tests for group differences. RESULTS: No differences were found between the two groups for all variables tested. CONCLUSIONS: Both brackets showed the same velocity of canine retraction and loss of anteroposterior anchorage of the molars. No changes were found between brackets regarding the inclination of canines and first molars.
Assuntos
Dente Canino/patologia , Procedimentos de Ancoragem Ortodôntica/instrumentação , Desenho de Aparelho Ortodôntico , Braquetes Ortodônticos , Técnicas de Movimentação Dentária/instrumentação , Adolescente , Adulto , Pontos de Referência Anatômicos/patologia , Dente Pré-Molar/cirurgia , Cefalometria/métodos , Ligas Dentárias/química , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Masculino , Má Oclusão Classe I de Angle/terapia , Maxila/patologia , Dente Molar/patologia , Níquel/química , Procedimentos de Ancoragem Ortodôntica/métodos , Fios Ortodônticos , Titânio/química , Ápice Dentário/patologia , Coroa do Dente/patologia , Extração Dentária/métodos , Adulto JovemRESUMO
INTRODUCTION: The purpose of this study was to use photoelastic analysis to compare the system of forces generated by retraction T-loop springs made with stainless steel and titanium-molybdenum alloy (TMA) (Ormco, Glendora, Calif) with photoelastic analysis. METHODS: Three photoelastic models were used to evaluate retraction T-loop springs with the same preactivations in 2 groups. In group 1, the loop was constructed with a stainless steel wire, and 2 helicoids were incorporated on top of the T-loop; in group 2, it was made with TMA and no helicoids. RESULTS: Upon using the qualitative analysis of the fringe order in the photoelastic model, it was observed that the magnitude of force generated by the springs in group 1 was significantly higher than that in group 2. However, both had symmetry for the active and reactive units related to the system of force. CONCLUSIONS: Both springs had the same mechanical characteristics. TMA springs showed lower force levels.