Abstract: Objective：To evaluate the clinical effect of distalizing mandibular dentition with micro-implant in patients with skeletal classⅢmalocclusion. Methods: In the study, 20 patients with skeletal class Ⅲmalocclusion were selected. They are consist of 8 males and 12 female with an age range from 16 to 38 years old and an average age of (21.5±5.6) years.They were treated with straight wire technique and the implant were inserted into the mandibular external oblique line to distlize the lower dentition to a class Ⅰmolar relationships.Cephalometrics films were taken before and after treatment. The changes of hard tissue and soft tissue were analyzed by evaluating 26 measurement measurements. Results: ClassⅠmolar relationships were achieved, and the profile were improved after treatment. ANB increased by（0.80±1.02）°，Wits increased by （1.67±1.74） mm，after treatment（P<0.05）.The lower dentition were significantly retracted after treatment with L1-NB distance decreased by（2.64±1.50） mm, P<0.05; the mesial buccal cusp and mesial root of the lower first molars were retracted by （3.26±1.95） mm and （0.79±1.27） mm respectively （P<0.05）; the mesial buccal cusp of the lower second molars were retracted by （3.06±1.80） mm （P<0.05）. After treatment, mandibular teeth got uprighted distally. From incisors to molar, L1/MP, L5/MP, L6/MP, L7/MP angle decreased by(6.37±8.53)°, (10.59±8.50)°, (11.48±7.22)°, (15.72±7.16)°on average respectively （P<0.05）, all of those changes had the statically significant effects. Soft tissue change after treatment, the distance from lower lip to esthetic plane were decreased by (1.70±1.59) mm on average （P<0.05）. Conclusion: Distalizing mandibular dentition with micro-implant can get an satisfying result in patients with skeletal class Ⅲmalocclusion, the lower teeth were retracted by controlled tipping movement.

Key words: Malocclusion, Skeletal class Ⅲ malocclusion, Implant anchorage, Cephalometry