| Objective:In order to provide a reference for the clinical treatment of orthodonti-orthognathic patients,the three-dimensional features of the hard tissues in the upper and lower jaw areas were studied by cone-beam computed tomography(CBCT)in adult patients with skeletal class Ⅲ malocclusions and mandibular deviation.Methods:60 adult patients with skeletal class Ⅲ malocclusions and mandibular deviation were selected as the experimental group of this study,and 30 normal volunteers were selected as the control group.CBCT scans were performed on all samples,and the same radiologist performed CBCT scans.All data are uniformly saved in DICOM(Digital Imaging and Communication in Medicine)format and imported into Mimics Research19.0 3D software to generate 3D virtual models of hard tissues.Then,the three Mimics views were combined to determine the required mark points,and the coordinates of the mark points were imported into UG(Unigraphics NX 12.0)software to establish the cranial reference plane,so as to measure the related indexes of upper and lower jaws.These include the position of the hard tissues of the upper jaw,the morphology of the maxilla,the inclination of the maxillary teeth,the position of the mandible and the morphology of the mandible.According to the central sagittal plane of the skull,in the experimental group,the cranioface was divided into two sides,the side located at the submental point was the deviation side,and the other side is the opposite side of the deviation side.The experimental group was divided into moderate and severe mandibular deviation groups according to the distance from the submental point to the median sagittal plane.Among them,29 patients with moderate mandibular deviation were group 1,and 31 patients with severe mandibular deviation were group 2.The experimental and control samples were measured in the same way,and the same indicators were measured.The measurements were made by the same experimenter with an interval of 10 days.SPSS(Statistical Product and Service Solutions 22.0)software was used in the statistical analysis of this study,and the reliability of the two measurements was verified by the correlation coefficient within the group.The paired ttest was used to test both sides of the samples,and the independent sample t-test was used to test the control group and the experimental group.At the same time,the correlation between different measurement indexes was discussed and analyzed through pearson correlation coefficient.Results:(1)Compared with the control group,there were significant differences in the lateral inclination and horizontal rotation of the maxillary occlusal plane and the horizontal rotation of the maxillary alveolar process in group 2(P < 0.05).(2)Compared with the control group,the maxillary canines in the experimental group had significant mesobuccal compensation(P < 0.01)on both sides,except the opposite side of the skew in group 1,and the deviated side was more serious(P < 0.01).The oblique maxillary first molars in the experimental group showed significant buccal tilt(P < 0.01).Bilateral maxillary first molars in group 1 were medial inclined(P < 0.05),while there was no difference in group 2(P>0.05).The maxillary incisor of the experimental group had labial inclination(P < 0.05),and the mesiodistal inclination of the maxillary central incisor of the experimental group 2 was statistically significant(P < 0.05).(3)Compared with the control group,the horizontal rotation of the mandible in group 2 was significantly different(P < 0.01).In group 1,the mandibular ramus and mandibular body length were larger on both sides(P < 0.05),and that on the deviated side was more obvious(P < 0.01).In group 2,only the mandibular body on the opposite side of the deviation was longer(P < 0.05).The sagittal inclination of the mandible on both sides of group 1 was significantly reduced(P < 0.01),and the transverse inclination and sagittal inclination of the mandibular ramus in group 2 were decreased only on the opposite side of the deviation,and the transverse inclination was more obvious(P < 0.01).(4)The position of maxillary teeth and alveolar process were positively correlated with the position of mandible(P < 0.05).For maxillary central incisor and maxillary first molar,their buccollingual and mesiodistal inclination and maxillary canines on the deviated side were correlated with the mandibular chin deviation(P < 0.05).The length of bilateral mandibular ramus and the length of mandibular body on the deviated side were negatively correlated with the mandibular position deviation(P < 0.05),and the sagittal inclination of bilateral mandibular ramus was positively correlated with the mandibular position deviation(P < 0.05).The offset of mandibular chin and the degree of horizontal rotation of mandible were negatively correlated with the lateral inclination of the mandibular ramus on the opposite side of the deviation.Conclusion:(1)Maxillary position asymmetry mainly exists in patients with severe maxillary deviation and mostly exists in teeth and alveolar process.(2)Lateral and sagittal compensations were found in the maxillary anterior teeth of patients with skeletal classⅢ malocclusions,especially in the deviated side.The posterior area showed buccal compensations in the deviated side,and bilateral medial compensations were present in patients moderate mandibular deviation.(3)The asymmetry of mandible is different in patients with moderate and severe maxillary deviations of patients with skeletal class Ⅲmalocclusions.Patients with moderate mandibular deviation have excessive growth of bilateral mandibular ramus and mandibular body,especially in the deviated side.The overgrowth of the mandible body on the opposite side of the deviation and the decrease of the transverse and sagittal inclination of the mandibular ramus than the other side,and with the rotation of the mandible.(4)The maxillary teeth and alveolar process will appear corresponding compensatory phenomenon due to the three-dimensional deviation of mandible,and there is a strong correlation between the positions of the two.The inclination of teeth in the deviated side and maxillary central incisor were correlated with the mandibular position deviation.The deviation of the mandible is correlated with the length of bilateral mandibular ramus,the development of the mandible body in the deviated side and the angle of the ramus on the both sides. |
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