[Analysis of distalization of lower canine by light-segmented archwire].

OBJECTIVE: To analyze the practical effect of distalization of lower cuspiud by light-segmented archwire. METHODS: 17 cases were selected. In all cases, two lower first bicuspids were extracted and lower molars were designed as reinforced anchorage. In the first half year, lower cuspids were distalized with light-segmented archwire, and lower incisors were in the physiologic drift stage. Before the treatment, three months and six months after the treatment, cephalograms and study models were recorded respectively. The data were analyzed with SPSS 10.0. RESULTS: The distance of mesiolization of the first lower molar was 1.14 mm in half a year. The distance of distalization of the lower cuspid was 5.02 mm in half a year. No significant difference was found in LM-MP and SN-MP angle. LI-NB angle was decreased by 9.57 degrees. Crowding of lower incisors was transferred from -2.55 mm to 1.08 mm. CONCLUSION: During distalization of lower cuspid by light-segmented archwire, anchorage tooth was stable, lower cuspids were distalized effectively, and lower incisors drifted towards the ideal position automatically.

[Changes of cranio-facial hard tissue after orthodontic treatment in bimaxillary protrusive patients].

OBJECTIVE: The aim of this study is to investigate the changes of hard tissue profile in anterior-posterior and vertical direction in bimaxillary protrusion patients after orthodontic treatment. METHODS: A total of 24 bimaxillary protrusion patients (male 8, female 16), aged from 11.2 to 29.0 (average 16.9 years old), were selected to be treated with standard edgewise technique consisted of 4 first premolars extraction. Cephalometrics were taken before and after treatment. The changes of hard tissue profile were studied using the computer-aid X-ray cephalometric analysis. RESULTS: 1. The length of the maxillary and the mandible increased significantly, but the anterior-posterior relationship of the maxillary and the mandible did not change significantly. 2. The anterior and posterior facial height increased significantly, but the ratio of anterior and posterior facial height and the angle of MP-FH which reflected the inclination of the mandible plane did not change significantly. 3. The height of the upper and lower first molar increased significantly along with the increase of the anterior and posterior facial height. 4. The height of the upper incisors increased significantly, but the height of the lower incisors decreased significantly. CONCLUSION: The anchorage in anterior-posterior and vertical direction were controlled preferably, the patients did not manifest disadvantageous vertical growth trend.