The Efficiency Of Maxillary Expansion By Clear Treatment:A Systematic Review

Objective:To assess the scientific evidence related to the efficiency of clear aligner treatment(CAT)in upper arch expansion through Meta-analysis,for providing a reference for clinical application and determination of treatment plan for patients.Methods:The clinical studies related to arch expansion in Chinese and English by clear treatment published before March 1,2020 were searched by computer.The database includes PubMed、Cochrane Library、EMBASE、Web of science、CNKI、CBM、Wanfang Database.Two researchers searched for the retrieved literature independently according to the predetermined inclusion and exclusion criteria.Then researchers use Methodological index for non-randomized studies,MINORS to evaluate the quality.The data was analyzed by Revman 5.3.software.Different effect models are selected according to the heterogeneity test results between different studies.The weighted mean difference(WMD)combined with 95%confidence interval(CI)in the effect size.Descriptive analysis is used for those cannot be Meta-analysis.Results:429 articles were retrieved in this study.Finally 7 articles were included,all of which are non-randomized control trial,NRCT.The literature quality evaluation results show that 1 article is of high quality,6 articles are of medium quality.The sample size of each independent study is 11-64,and the total sample size of the literature included in this study is 196.Meta-analysis results are as follows:1.Clear treatment used to elder adolescents and adults with upper dental arch expansion is effective.The width of crown of each tooth position after treatment was increased compared with data before treatment(P<0.05).The expansion of the dental arch is mainly reflected in the premolar area.The width between upper canines is increased about 1.60mm on average after expansion(WMD=].60,95%CI:1.07-2.12,P≤0.00001),The achieved expansion is about 0.60mm less than predicted(WMD=-0.60,95%CI:-0.93～-0.28,P=0.0003),The width between upper first premolars is increased about 1.83mm on average after expansion(WMD=1.83,95%CI:0.54-3.12,P=0.005),The achieved expansion is about 0.76mm less than predicted(WMD=-0.76,95%CI:-1.00～-0.52,P<0.00001),The width between upper second premolars is increased about 2.09mm on average after expansion(WMD=2.09,95%CI:0.87～3.31,P=0.0008),The achieved expansion is about 0.91mm less than predicted(WMD=～0.91,95%CI:-1.43～-0.39,P=0.0006),The width between upper first molars is increased about 1.34mm on average after expansion(WMD=1.34,95%CI:0.32～2.35,P=0.01),The achieved expansion is about 1.12mm less than predicted(WMD=-1.12,95%CI:-1.33～-0.92,P<0.00001),2.The efficiency of upper arch expansion varies with different tooth position.The efficiency of arch expansion decreases from canine to molar.The expansion efficiency of upper canine is 71%(WMD=0.71,95%CI:0.63～-0.79,P<0.00001),the expansion efficiency of upper first premolar is 69%(WMD=0.69,95%CI:0.63～0.75,P<0.00001),the expansion efficiency of upper second premolar is 65%(WMD=0.65,95%CI:0.54～0.76,P<0.00001),the expansion efficiency of upper molar is 56%(WMD=0.56,95%CI:0.44～0.67,P<0.00001).3.The expansion of clear treatment mainly comes from the bodily movement of the teeth as well as the tilting movement.The largest bodily movement efficiency is the canine and the smallest is the first molar.All teeth have a certain tilting movement.The largest tilting movement is the first molar.4.The designed expansion amount of molar have a significant negative correction with the efficiency of bodily movement.Conclusions:1.Clear treatment used to elder adolescents and adults with upper arch expansion is effective,while there is difference between planned expansion with ClinCheck Pro and actual clinical result.The actual arch expansion efficiency decreases from the canine to the first molar,2.It will cause extra buccal inclination of molars crown in addition to bodily buccal movement while Clear treatment used to upper arch expansion.3.Reducing the frequency of appliance replacement at the stage of arch expansion,taking appropriate overcorrections,or combining with other auxiliary measures in clinical practice can increase the effect of upper arch expansion,thus reducing additional refinements or restarts.