Three-dimensional Symmetry Analysis Of Craniofacial Hard Tissue Structure Of Skeletal Class ? Jaw Deflection Adult

Objective: We tried to study the craniofacial hard tissue structure of patients with skeletal Class III facial asymmetry using cone-beam computerized tomography(CBCT)technology,and to explore the site and degree of asymmetry.Methods: Thirty-four skeletal class III malocclusion in adult patients with mandibular deviation were included in the deviated group and thirty-one without deviation as the non-deviated group.The CBCT scan was used to analyze the asymmetry index of 22 landmarks in craniofacial hard tissues.Twenty-two landmarks were located in six subregions: the maxillary region,mandibular ramus region,mandibular body region,zygomatic bone and zygomatic arch region,temporal bone region,and nasal bone region.Results:1.There were statistically significant differences of the asymmetry index between the two groups and points focus on the menton,upper and lower molars and alveolar process,lower incisors and alveolar process,gonion,coracoid points,and the asymmetry index on the deviated group was larger than the non-deviated group.2.There is a moderate positive correlation between menton shift and asymmetry of lower incisors,alveolar process of lower incisors,lower molars alveolar process;There is a weak positive correlation between menton shift and asymmetry of upper molars,alveolar process of upper molars,lower molars,coracoid points,upper incisors.3.In 9 of 31 non-deviated patients,regional asymmetry of jaw occurred.Among them,3 cases(9.68%)showed only maxillary asymmetry,3 cases(9.68%)showed only mandibular body asymmetry,and 3 cases(9.68%)showed only mandibular ramus asymmetry.Among the 34 deviated patients,there were 10 cases(29.41%)of asymmetry of maxillary and mandibular,and the remaining 24 cases(70.59%)were asymmetry of the mandible only.Conclusion:1.Compared with skeletal class III non-deviated people,there is an asymmetry in the mandibular body,the mandibular ramus,and the maxillary alveolar area.2.In skeletal Class III deviated patients,the mandibular area is characterized by osseous asymmetry,and the maxillary site is represented by the compensation of teeth and alveolar ridges.Asymmetric growth of the mandible leads to secondary asymmetry in the maxillary.3.The asymmetry of the relevant landmarks of skull base,zygomatic bone,temporal bone,and nasal bone in skeletal class III deviants was not significantly different from that of skeletal class III non-deviated.