| Objective: To explore the morphological characteristics of dental arch among different Vertical facial types and their relationships in adult females with skeletal class II by CBCT,so as to provide clinical guidance.Methods: A total of 78 adult female patients with skeletal Class II malocclusion were selected from the orthodontics Department of the Affiliated Stomatological Hospital of Guizhou Medical University and the Department of Orthodontics,Guiyang Stomatological Hospital.with an average age of 24.26 ± 4.23 years.Based on mandibular plane angle(SN-MP,FH-MP),the facial type was divided into three types in the vertical direction: low angle,average angle and high angle.Among them,Go-Gn plane was used as the mandibular plane(MP plane).The image data of cone beam computed tomography(CBCT)were collected.Save the imaging data in DICOM(Digital Imaging and Communications in Medicine)format,import the Mimics20.0 software to reconstruct the 3D model of the upper and lower jaw,determine the crown mark points of each research object,and then import the 3-Matic 12.0 software to establish the horizontal reference plane(occlusal plane OP)and generate the 3D coordinates,The measurement and analysis of line distance and angle were carried out.Among them,there were 28 measurement indexes reflecting the shape of skeletal Class II malocclusion and malformed dental arch.All date was analyzed by SPSS22.0.Results:1.Statistical differences were found in the shape of dental arch between different vertical facial types in adult female skeletal class II patients.The width of the upper anterior dental arch was wider in the low-angle facial type group than that in the average-angle facial type group and the high-angle facial type group.The width of the lower anterior dental arch was narrower in the high-angle facial typegroup than that in the average-angle facial type group and the low-angle facial type group.The width of the upper posterior dental arch was wider in the low-angle facial type group than that in the average-angle facial type group and the high-angle facial type group.The width of the lower posterior dental arch was the widest in the low-angle facial type group,followed by the average-angle facial type group and then the high-angle facial type group.Therefore,all the width of the upper(lower)anterior(posterior)dental arch were the widest in the low-angle facial type group.The length of the upper anterior dental arch was shorter in the low-angle facial type group than that in the average-angle facial type group and the high-angle facial type group,with statistically significant differences(P < 0.05).2.The index of anterior and posterior segment of the upper arch was lower than that of the average-angle facial type group and the high angle group,the index of posterior segment of the lower arch was lower than that of the average-angle facial type group and the high-angle facial type group,the angle of upper canine was lower than that of the average-angle facial type group and the low-angle facial type group,the angle of upper posterior arch was higher than that of the low-angle facial type group,the difference between the average-angle facial type group and the high-angle facial type group was not statistically significant,and the angle of lower posterior arch was higher than that of the average-angle facial type group and the low-angle facial type group Statistical significance(P <0.05).3.The difference in the width of the maxillary anterior dental arch to the width of the mandibular anterior dental arch was larger in the low-angle facial type group compared with the high-angle facial type group.The difference in the width of the maxillary posterior dental arch to the width of the mandibular posterior dental arch was larger in the low-angle facial type group compared with the average-angle facial type group and the high-angle facial type group.The difference in the length of the maxillary anterior dental arch to the length of the mandibular anterior dental arch was smaller in the low-angle facial type group compared with the average-angle facial type group and the high-angle facial type group,with statistically significant differences(P < 0.05).4.Pearson correlation analysis showed a correlation between the measured indexes of the shape of dental arch and the plane angle of the mandible.The width of the upper anterior dental arch,the upper posterior dental arch and lower posterior dental arch and the angle of the maxillary canine were negatively correlated with the plane angle of the mandible.The angle of the maxillary and mandibular posterior dental arch were positively correlated with the plane angle of the mandible,There was no significant correlation between other measurement indexes and SN-MP(P > 0.05).Conclusion:1.The dental arch presents different narrow degrees in the adult female skeletal class II patients with high-angle facial type.It is necessary for the patients with high-angle facial type to expand the width of dental arch and adjust its sagittal maladjustment in the early stage,so as to provide space for the adduction of the anterior teeth with labial inclination and improve the protrusive face.The early treatment is more urgent in the high-angle facial type group compared with the average-angle facial type group and the low-angle facial type group.2.The shape of dental arch is partial to a squared circle in the patients with low-angle facial type,In clinical treatment,the arch shape of the arch wire should be adjusted according to different vertical bone face types to make the arch and the muscles around the mouth and more harmonious.3.There is a negative correlation among the width of the anterior segment of the upper dental arch,the widths of the upper and lower dental arches,the angle of the maxillary canine,and the vertical bone surface type in adult females of class II.As the angle of the mandibular plane increases,it decreases gradually.There is a positive correlation among the anterior dental arch angles of the upper and lower mandibles,and the vertical bone surface type in the adult females of class II,which gradually increases with the increase of the angle of the mandibular plane. |
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