ABSTRACT
Objective: To evaluate the change of tooth root volume and length after rapid maxillary expansion by CBCT three dimensional reconstruction method. Methods: 33 patients underwent rapid maxillary expansion were examined by CBCT before and after treatment. The CBCT images of the first,second premolars and the first molars were segmented and reconstructed by Mimics image processing software for the analysis of the changes of root volume and length. All data were analyzed by SPSS software statistically. Results: After maxillary expansion,all root volumes were reduced(P ＜ 0. 05),more reduction was observed in anchorage teeth than in non-anchorage teeth(P ＜ 0. 05). The length of most teeth roots was not decreased(P＞ 0. 05) except the buccal and distal roots of the first molars(P ＜ 0. 05). Conclusion: Rapid maxillary expansion may result in root resorption and this resorption is mainly based on the volume decrease.
ABSTRACT
Objective:To evaluate the effects of maxillary protraction with or without rapid maxillary expansion in the treatment of Class Ⅲ malocclusion by Meta-Analysis.Methods:The randomized controlled trail,quasi-randomized controlled trail and the clinical controlled trail about the treatment of Class Ⅲ malocclusion by protraction with or without expansion were searched in the database of Cochrane Library,Embase,PubMed,Medline,CBM,Wan Fang,CNKI,VIP.2 authors qualified and extracted the data independently.Then the Meta-analysis was performed by using the RevMan 5.3 software.Results:7 studies with 228 cases were included,114 cases were treated by maxillary protraction with expansion and the other 114 cases by maxillary protraction without expansion.The Meta-analysis showed that:there was no significant difference in SNA,SNB,ANB and SN-PP except ANS-Me,U1-NA,SN-MP.A favorable improvement of the sagittal relationship between maxillary and mandibular was observed by using protraction whether with expansion or not.The expansion did not shorten the course of treatment,but it lowered the inclination of upper incisors,resulting in more clockwise rotation of mandibular plane and increase of the facial vertical dimension.Conclusion:Maxillary protraction with rapid maxillary expansion can be used in the treatment of class Ⅲ malocclusion with incisor labioclination.