Clinical exploration of correcting severe patho-occlusion by extracting mandibular second molar

Objective To evaluate the therapeutic effects of correcting severe patho-occlusion by extracting mandibular second molar.Methods Forteen cases with severe skelet al class Ⅲ malocclusion(male 4,female 10,age range12.0-17.1 years old,mean age(13.3±0.8)years who were diagnosed as requiring orthognathic operation,but had rejected surgical therapy were included.Pancherz analysis and traditional cephalometric analysis were performed before and after orthodontics.Results After the treatment,inclination of lower incisors was decreased 11.7 compared with prior treatment(P0.001).The negative value of the distance between upper and lower lip position to supg' changed to a positive value after the treatment(P0.001).Conclusions The results of the current preliminary study suggest that success in the treatment of some severe class Ⅲdeformity in the permanent dentition can be achieved with fixed appliances and the concave facial profiles can be changed to straight profiles.