Changes Of Camouflage Treatment In Skeletal Class ? Malocclusion Adults On 3 Dimensions: A Comparative Study

Objective:The aim of the study was to analyze the changes of occlusal planes,arches,skeletal mandibular-maxillary bases and the surrounding hard tissues bases in camouflage treated skeletal Class III malocclusion adults,by using cone-beam computed tomography?CBCT?and 3-dimensional digital models.Analyzing and summarizing three dimensional measurements to provide a clinical basis.Methods:The records of 28 adult skeletal Class III malocclusion patients?18 males and 10females,with an average age:24.47±2.03 years old?were included in this study.They were selected according to the inclusion criteria from Orthodontic department of stomatological hospital of Tianjin Medical University between 2016 August and 2019May.CBCT image data and plaster casts were obtained before and after camouflage treatment.Application of Invivo5 software for 3D reconstruction,constructing a three dimensional reference plane,measuring and analysing the cranial and maxillofacial hard tissues,occlusal plane and mandibular plane.Application of 3 shape R700scanner converted plaster casts into digital models,measuring arches and skeletal mandibular-maxillary bases by software OrthoAnalyzer 2013.For the statistical evaluation,the paired t-test was used and the Pearson correlation coef?cient was calculated to determine the relationship between the measurements.P<0.05 was considered statistically significant.Results:1.Changes in hard tissue and occlusal plane:After the treatment,the weighted PAR index of all patients decreased by34.50±8.97 points?P<0.01?,greater than 22 points,which was greatly improved.Sagittal arguments:SNA,ANB,Wits value were increased,SNB,APDI were decreased,and ANB increased by?0.78±0.20?°,Wits value increased by?4.00±0.62?mm,APDI reduced by?2.87±1.07?°,which was statistically significant?P<0.01?.Vertical arguments:MP-SN,FH-MP,ODI,ANS-Me,N-Me,ANS-Me/N-Me were increased,S-G₀ decreased.Occlusal arguments:OPA,OPP,OP-diff,OPC were increased,among them OPA,OPP were statistically significantly increased?P<0.05??2.Changes in tooth inclination and relative position:After treatment,only the sagittal tooth inclination of U1-FH increased,U5-FH,U6-FH,U7-FH,L1-MP,L5-MP,L6-MP,L7-MP were reduced,among them U6-FH,L5-MP were statistically significantly decreased?P<0.05?.U1-FH increased by?12.20±3.66?°,L6-MP decreased by?6.05±3.12?°,and the differences were greatly statistical significant?P<0.01?.After treatment,the coronal tooth inclination of U1C-FH,U5C-FH,U6C-FH,U7C-FH were decreased,L1C-MP,L5C-MP,L6C-MP,L7C-MP were increased.After treatment,the vertical distances of maxillary teeth to PP plane and PL plane were decreased,U5H-PL,U6H-PL were statistically significant?P<0.05?.U1H-PP were decreased by?1.39±0.69?mm,and U1H-PL were decreased by?4.33±1.86?mm,and the differences were greatly statistical significant?P<0.01?.L1H-MP,L7H-MP,L7H-G₀ were increased,L5H-MP,L6H-MP,L1H-G₀,L5H-G₀,L6H-G₀ were decreased,L1H-G₀,L5H-G₀ were statistically significantly decreased?P<0.05?,L6H-MP decreased by?1.28±0.75?mm,the difference were greatly statistically significant?P<0.01?.3.Model analysis before and after treatment:After treatment,curve of Spee,OB were decreased,OJ,PH,PL,PD were increased.OJ were increased by?4.14±0.61?mm,PH were increased by?0.97±0.44?mm,PL were increased by?2.42±1.13?mm,the difference were greatly statistically significant?P<0.01?.After treatment,anterior maxillary arch width were increased,middle and posterior maxillary arch width were decreased,mandibular arch width were increased.Length of dental arch were increased in the maxillary and decreased in mandibular.UAD increased by?1.47±0.94?mm,UD increased by?1.66±1.14?mm,LPP1 increased by?1.70±1.07?mm,LPP2 increased by?1.98±1.40?mm,and the differences were statistical significant?P<0.05?.After treatment,the anterior and posterior maxillary basal arch width increased,the middle maxillary basal arch width decreased.The anterior and middle mandibular basal arch increased,the posterior mandibular basal arch width decreased.UL were increased,and LL were decreased.UL increased by?1.40±0.53?mm,which was statistically significant?P<0.05?.After treatment,the maxillary WALA ridge width decreased in the premolar area,and increased in canine and molar area.The mandibular WALA ridge width decreased in molar area,and in other positions increased.LW4 decreased by?0.66±1.54?mm,which was statistically significant?P<0.05?.Conclusion:1.Skeletal Class?adults improved on sagittal after camouflage treatment.SNA,ANB,wits value were increased,SNB,APDI were decreased.2.Skeletal Class?adults could be well controlled on mandible plane and occlusal plane with correct vertical control.The upper incisor were moderately labial inclined and the lower incisor were moderately upright,OPP were increased.Occlulsal plane rotated clockwise.As a result,the mandible plane rotated clockwise,the Angle of the mandible plane increased,and the ratio between the anterior facial height and all anterior facial height increased,which is conducive to the backward movement of the mandible and the improvement of the facial shape.3.In addition to the sagittal and vertical directions,horizontal control is also indispensable.In orthodontic camouflage treatment,changes in teeth and dental arch are the main manifestations,and adaptive changes are also made in the basal bone arch and the WALA ridge.