ABSTRACT
Objective:To evaluate the therapeutic effects of orthodontic therapy with mandibular first molar extraction.Methods:77 cases of malocclusion were divided into 3 groups:Bilateral mandibular first premolar extraction group(A,30 cases),unilateral man-dibular first molar extraction group(B,27cases)and bilateral mandibular first molar extraction group(C,20 cases).The OGS indexes were measured before and after orthodontic treatment and statistically analysed.Results:Remarkable occlusal improvement was seen in all three groups after treatment(P0.05).OGS indexes among the three groups after treatment were significantly different(P<0.05).The improvement in group A was more significant than that in group C(P<0.01)and the improvement in group C was more significant than that in group B(P<0.01). Conclusion:Orthodontic therapy with bilateral mandibular first molar extraction is effective in orthodontic treatment of malocclusion, but is not as effective as that with bilateral mandibular first premolar extraction.
ABSTRACT
Objective To assess the relationship between position of incisor and soft tissues changes in class Ⅲ malocclusion cases after orthodontic treatment.Methods All 26 patients in this study were diagnosed as skeletal class Ⅲ malocclusion.The lateral X-ray cephalometric films taken at the beginning and the end of the treatment were analyzed for position of incisor and soft tissues changes.Statistical analysis Waft performed using SAS v8.0 software.Resuits There was correlation between the labial inelination of upper and lower incisors and the soft tissue profile.Conclusion Soft tissue will be harmonious by the labial inclination increase of the upper incisor teeth and reduction of the lower incisor teeth.
ABSTRACT
Objective: To determine the relation between root resorption and different types of malocclusion. Methods: 108 Chinese patients with orthodonctic treatment by fixed Edgewise appliance were divided into three groups according to Angle's types of malocclusion. Paired measurements of root degrees of all visual root shape on panoramic radiographs were taken before and after orthodonctic treatment. Then root resorption and its distribution were analized. Results: Root resorption occurred during orthodontic treatment in each group(P