The Study Of The Characteristics Of Horizontal And Vertical Development Of Maxilla In Skeletal Class ? Patients With Facial Asymmetry And Vertical Discrepancy Of Bilateral Gonion

Objective:Identifying symmetry and discrepancy of maxilla can be essential in the presurgical orthodontic procedure of skeletal class ? patients with facial asymmetry.The aims of this preliminary retrospective study were to evaluate the symmetry and discrepancy of maxilla in three directions based on the vertical discrepancy of bilateral gonion in skeletal class ? patients with facial asymmetry and to provide a theoretical basis for the establishment of treatment plan both in preoperative orthodontic and surgical programs.Materials and methods:69 skeletal Class ? patients who received orthodontic-orthognathic treatment from March 2016 to March 2018 in the 2^nd Department of Orthodontics at the affiliated stomatology hospital of China Medical University were divided into 3 groups.S:symmetry group,?n=24?;ASV:asymmetry group with vertical discrepancy of bilateral gonion,?n=17?;ASNV:asymmetry group without vertical discrepancy of bilateral gonion,?n=28?.The skeletal characteristics of the bone in sagittal and vertical direction were evaluated by the software Winceph.Bilateral difference of maxillary canine and first molar to horizontal plane?U3-HPD,U6-HPD?,maxillary midsagittal plane?U3-MSPD,U6-MSPD?,distance from intersection of maxillary central incisors to MSP,ANS,PNS to midsagittal plane?SP?,angle of MSP and SP were measured using ProPlan CMF 2.0?Materialise Belgium?through three dimensional mulitislice spiral CT images.SPSS was used for data analysis.Results:There was no statistic differences of age among three groups.S?11female13male?ASV?10female 7male?and ASNV?14female 14male?showed no skeletal differences in sagittal and vertical direction.U3-HPD,U6-HPD in ASV?-1.40±1.71mm;-2.32±3.11mm?showed greater maxillary vertical excess in nondeviated side.U6-MSPD in ASV?1.26±1.38mm?presented asymmetry of maxillary width and greater menton deviation?9.53±3.92mm?than ASNV?6.62±2.61mm?and S?0.84±0.60mm?.The maxillary width was symmetrical in S and ASNV and there was no vertical discrepancy of maxilla in deviated side and nondeviated side.Conclusions:The skeletal Class ? patients who exist vertical discrepancy of bilateral gonion with facial symmetry present greater menton deviation,asymmetry of maxillary width and greater maxillary vertical excess in the nondeviated side.