A study about time of correction of maxillary protraction induced by Angle III malocclusion

Objective:To study the most effective initiating time of correction of maxillary protraction induced by Angle Ⅲ malocclusion in the children by protraction appliance.Methods:45 cases with skeletal class Ⅲ Malocclusion were divided into 3 groups:3～6 years old group, 7～10 years old group and 11～13 years old group(15 cases each group) and they were treated with maxillary protraction. Before and after treatment, the cephalometry were used and the results of three groups were compared.Results:The correction was effective to all of three groups. The corrective time of 3 to 6 years old group(3.8±0.4 months) was the shortest and the side effects were the least among the three groups, meanwhile, they had more skeletal changes(69.5%) and less dental changes(31.5%) than the other two groups. The corrective results of 11 to 13 years old group were the worst among the three groups with a longer corrective time(9±0.5 months), less skeletal changes(59.5%) and more dental changes(41.0%) than the other two groups(P0.05).Conclusion:The optimal time of correction of maxillary protraction induced by Angle Ⅲ malocclusion in the children by protraction appliance is from 3 to 6 years old, and the younger, the better.