The Clinical Study Of Distalizing Upper Molar By Implant Anchorage

In recent years , micro-implant has been used as anchorage in orthodontics .The method is simple , convenient and unreliable . Micro-implant also can provide absolute anchorage .The author use micro-implant in orthodontic clinic ,appraise anchorage action and its influence to cranio-facial hard and soft tissue during maxillary molar distalization .Objective To study clinical effect and action peculiarity of distalizing maxillary molar when micro-implant is used as anchorage for Angle class II malocclusion . Comparing micro-implant anchorage to intraoral anchorage (pendulum appliance), analyse action characteristic respectively . Then evaluating synthetically therapy effect of the method for applying this technique in orthodontics thoroughly . Method 27 micro-implants were embeded into maxillary alveolar bone of 14 patients between 13 to 30 years old to distalize maxillary molars as anchorages .We too clinical experiment and evaluated effects by implant anchorage. Then contrast the method to intraoral anchorage (pendulum appliance) method . Noting result through study cast and cephalometric roentgenogram , Taking statistic analysis using data . Then we analyzed differences in molar removing mode ,anchorage loss circumstances ,cranio- facial hard and soft tissue change of the two methods by study cast and cephalometric tracing measurement.Result 27 micro-implants were embedded into maxillary alveolar bone of 14 patients, 23 micro-implants were stable and occluding relation of maxillary andmandibular first molar became neutral .The position of maxillary first molar and maxillary central incisor have no change according to statistical ananlysis . Removal distance of maxillary molar is averagely 4.5mm , Removing velocity is 1.03mm, buccomove 1.55mm,distal linguorotation angle horizonta lly 4.9°, distal tipping angle 4.6°.Cranio-facial soft tissue change lightly . ANS-Me increase0.95mm, SN-OP decrease 0.9°, FH-MP increase 0.8°, A-PFP increase 0.4mm .Other measurement items have no change .Differences of implant anchorage and intraoral anchorage are as follows :1. Therapy time and removing velocity :Therapy time is spectively 4.4 months , 4.2 months in implant anchorage and intraoral anchorage group ; removing velocity is spectively 1.03mm/M , 0.92mm/M.2. Maxillary molar removing mode :Implant anchorage group : The distal tipping angle of molar is 4.6° , rotation angle is 4.9 °, buccomove is 1.55mm , intraoral anchorage group : the number is 12.6°, 2.8°and 0.50mm 3. Strongness or weakness of anchorage :strongness or weakness of anchorage is measured by position change of maxillary central incisor and maxillary first premolar . Implant group : maxillary first premolar labiomove 0.11 mm mesial tipping increase 0.4°. maxillary central incisor labiomove 0.15mm mesial tipping increase 0.5 intraoral anchorage group : the number is 0.56mm 1.8°. 0.51mm , 2.2°. Statistical analysis showed implant anchorage exceeded intraoral anchorage greatly.4. Cranio-facial hard and soft tissue change :nine items were measured . Micro-implant group : A-PFP ANS-Me FH-MP increase 0.20mm 0.95mm. 0.8°, SN-OP decrease 0.9°.In pendulum appliance...