Abstract:

BACKGROUND: Self-locking brackets straight wire appliance is a kind of low fraction and light force correction technique. The combination of self-locking brackets without ligation and high-performance elastic arch wire provide revolutionary change of the efficient correction and fixed orthodontic technique on the clinical treatment.  
OBJECTIVE: To investigate the changes of mandibular position and facial ratio of patients with angle class Ⅱ division 2 malocclusion by Damon-Ⅲ self-locking brackets technique.
METHODS: The sample was consisted of 13 patients with angle class Ⅱ division 2 malocclusion treated by traditional Roth straight wire appliance and 13 patients with angle class Ⅱ division 2 malocclusion treated by Damon-Ⅲ self-locking brackets technique. The pre-and after-treatment cephalometric films were measured to assess the treatment effect.
RESULTS AND CONCLUSION: After treatment, the sella-nasion-point A (SNA) angle was increased in Damon-Ⅲ self-locking brackets group and Roth straight wire appliance group, and the sella-nasion-point B (SNB) angle was decreased. It indicated that the mandible in two groups changed significantly in sagittal direction, and had the trend to increase in vertical. Compared with the self-locking brackets group after treatment, the lower mandible had the clockwise trend and the increasing of the mandibular posterior alveolar was not obvious (P < 0.05), the lower incisors inclined was obvious (P < 0.05). The study showed that the changes of the lower mandible and facial proportion caused by the Damon-Ⅲ self-locking brackets combined with occlusal guide plate+Class Ⅱ traction was more obvious than the changes caused by Roth straight wire appliance combined with occlusal guide plate+Class Ⅱ traction, and had the favorable regulation on the lower incisors inclination.