Analysis The Effect Of Distalizing Of Whole Maxillary Dentition With Miniscrew Anchorage In Re-treatment Cases

Objective:The purpose of this study is to evaluate the clinical effect of distalizing whole dentition when micro-implant is used as anchorage in re-treatment patients with anchorage losing.Method:12 adults of extraction orthodontic treatment previous history were selected to be retreated by distalizing the whole dentition with mini-screws anchorage.Two mini-screws were implanted in buccal alveolar intraseptal area between maxillary first molars and second molars.Lateral cephalograms and panoramic of each patient were taken before and after treatment,and the changes of hard-tissue and soft-tissue and dental arch width were studied.Results1.Changes of incisors:The incisors were significantly retracted after treatment with2.84°decreased in Ul-SN and 5.75°in Ul-Ll(p<0.05);Significant changes were observed in the distalization of the upper incisor 2.39mm at crown level and 0.55 mm at root level(p<0.05);The distalization of incisors was presented as a distal tipping movement.2.Changes of molars:The average amount of distalization of maxillary first molar was 2.65mm at the crown level and 2.03mm at the root level(p<0.05).3.Changes of hard tissues:The skeletal changes during treatment showed that the SN-MP angle decreased by 1.31°with statistical significance(p<0.05).The other measurements were not statistically different.4.Changes of Soft tissues:The mean distal repositionings of the upper lips relative to the E-line were 1.36mm(p<0.01).There was no significance of lower lip moved distally with 0.17 mm(p>0.05).5.Changes of dental arch width:There were significant differences in maxillary widths before and after distalization.Significant differences were seen interms of coronal arch width of canines,premolars and molars.The differences in expansion between the canine coronal arch width.premolar coronal arch width and molar coronal arch width of maxillary were increased by approximately 1.01?1.92and 1.22 mm(P<0.05).Conclusions:1.For being recreated patients,the method of distalizing whole dentition with miniscrew anchorage can achieve satisfactory treatment results.2.molars moves was similar to bodily movement with whole dentition distalizing by miniscrew anchorage;3.The soft tissue changes greatly based on tooth movement effect when distal whole dentition with miniscrew anchorage.