The clinical effects of unilateral distalization of upper molars in Class II,malocclusion by micro-implant anchorage.

Objective:To study the clinical effects of unilateral distalization upper molars in class II malocclusion by micro-implant anchorage.Method:7 Class II,subdivision malocclusion patients withⅠ～Ⅱ° Crowding or midline shifting(5 females and 2 males) were selected as the subjects,aged from 15 to 30 years old(18.7 on average),All the patients were treated with non-extraction treatment by distalizing the unilateral upper molar with micro-implant anchorage.The micro-implant was embedded in buccal alveolar bone between maxillary second premolar and maxillary first molar,and then the Ni-Ti coil spring was set maxillary second premolar and maxillary first molar.The duration for distalization of upper molars was from 3 to 5 months(about 4 months on average).This study had measured the change in velocity,distance and position of the maxillary first molar,which evaluated molar moving form character to test anchorage intensity.Casting Model and Cephalometric analysis were used.All results were analyzed by statistics.Result:The upper molar was bodily distalized by 4.2 mm on the side with(1.25±0.25) mm/M.The horizontal circumvolving angle,the intrusion and buccally move of the first molar were of statistics significance.The upper incisor position remained stable throughout treatment.The lower incisor position remained unchanged as well as the mandible plane and the lower facial height.Conclusion:The results of this study have shown that the micro-implant placed in the maxillary interradicular bone provided absolute anchorage for unilateral or bilateral distalization of maxillary molar.It is an effective and reliable method for distalizing maxillary molars without the loss of anchorage.This treatment requires minimal patient compliance and also shortens the whole treatment period and is easy to insert and remove.However,it should be cautious for applying the micro-implant anchorage to distalize the maxillary molar because of its side effects.