BACKGROUND:It needs strong anchorage for shifting mandibular molar in orthodontics,which is a difficult problem to clinical orthodontic doctors.OBJECTIVE:To evaluate clinical effects and the characters by micro-implant anchorage during mandibular molars mesialization in Class Ⅰ malocclusal patients.METHODS:A total of 24 micro-implants were embedded mandibular bones between mandibular second premolar and mandibular first premolar of 15 Angle Ⅰ malocclusal patients as clinical anchorages for mesializing mandibular molars.The position changes of mandibular molars were measured from mesiodistal direction and vertical direction,and the implant anchorage loss was evaluated by maxillary central incisor.RESULTS AND CONCLUSION:The course of treatment was 10.4 months,and the velocity of mandibular second molar mesializing was 0.8 mm per month,with 8.5 mm in mesiodistal direction,there was no changes in the vertical direction.The distal tipping angle of molar was 2.5°,and the mandibular central incisor did not move.The method successfully mesialized mandibular molars to appropriate positions.No anchorage loss was found,The implant plays absolute anchorage during mandibular molar mesialization.