Soft and hard tissue changes of hyperdivergent class Ⅱ patients before and after orthodontic extraction treatment / 北京大学学报(医学版)

ABSTRACT

Objective:To investigate the hard and soft tissue changing trend and contributing factors of skeletal class Ⅱ hyperdivergent patients before and after orthodontic camouflage treatment by analyzing the cephalogram and the three dimensional(3D)facial scan data.Methods:Eighteen skeletal class Ⅱhyperdivergent adult female patients who finished camouflage orthodontic treatment were selected.Skele-tal and dental measurements were carried out with the cephalometric analysis before and after the treat-ment.3D facial data before and after orthodontic treatment were acquired and the anatomical landmarks were set after the repositioning and superimposition process.Hard tissue measurement included 17 mea-surement indicators(sella-nasion-subspinale angle,sella-nasion-supramental angle,subspinale-nasion-supramental angle,facial angle,angle of convexity,Frankfort horizontal plane-mandibular plane angle(FH-MP),Y axis angle,sella-nasion plane-mandibular plane angle(MP-SN),pogonion-nasion-supra-mental distance,upper incisor-nasion-subspinale distance,upper incisor to sella-nasion,lower incisor-nasion-supramental distance,lower incisor-nasion-supramental angle,upper incisor to lower incisor,up-per incisor to sella-nasion,lower incisor-mandibular plane angle,and Z angle),and the changes before and after treatment were measured for 11 of them.Twenty soft tissue landmarks(left/right cheekbone,left/right chelion,left/right crista philtra,soft tissue gnathion,left/right gonion,glabella,labrale infe-rius,labrale superius,soft tissue menton,left/right mid-mandibular border,soft tissue pogonion,stomi-on superius,sublabial,subnasale,and supralabial)and 9 soft tissue indicators(lower lip height,facial convexity,lower vermilion height,mandibular contour,nasolabial angle,philtral length,philtral width,upper lip height,and upper vermilion height)were measured and recorded for treatment changes.Linear-regression analysis and correlation analysis were carried out for analyzing the relationship between hard and soft tissue changes before and after the treatment.Results:Significant differences were noticed for 18 out of the 20 cephalometric measurements and facial measurements before and after the treatment(P＜0.05),which mainly represented the sagittal retraction of lip area after the treatment.Significant vertical displacements were revealed for soft tissue menton after treatment[(1.88±2.61)mm,P＜0.05].Significant sagittal displacements were revealed for left/right cheilion[(-2.95±1.9)mm,(-2.90±1.92)mm],labrale inferius[(-4.94±1.95)mm],labrale superius[(-3.25±1.44)mm],sublabial[(-3.10±3.5)mm],and subnasale[(-1.23±1.06)mm]after treatment(P＜0.05).An average of 4.10°±2.57° increasement was noticed for Z angle after treatment.High correla-tion(r＞0.7)was noticed for the displacement of menton after treatment with FH-MP,with the rate of-0.183:1,and MP-SN,with the rate of-0.157:1.Moderate correlations(0.7≥r＞0.4)were no-ticed for the other measurements with correlations(P＜0.05).Conclusion:A certain extent of facial improvements could be achieved with orthodontic camouflage treatment for skeletal class Ⅱ hyperdiver-gent patients,which were mostly represented by the improvement of sagittal relationship of nose,lips,and chin.Certain correlations were noticed for the hard and soft tissue changes.