| Purpose:The incidence of skeletal Class Ⅱ malocclusion was high in adolescents and the mandibular retraction was a common feature,which affected the function,growth and development.Orthopedic treatment was often used to intervene it in clinic.It has been confirmed that the reconstruction of condyle was helpful to promote mandibular growth and corrected the sagittal relationship.However,the prognosis and long-term stability of treatment were still in doubt.Some studies have pointed out that different condylar morphology would affect the curative effect and long-term stability of orthopedic treatment.Based on this,our study explored the morphological characteristics of condyle and mandible in adolescent patients via CBCT(cone beam computed tomography),and to clarify the symmetry and morphological differences in different vertical growth patterns,in order to provide reference for clinical accurate diagnosis and correction.Methods:LCRs(lateral cephalograms)and CBCT images of 60 Class Ⅱ adolescent subjects were selected from the Department of Orthodontics,School and Hospital of Stomatology,Shandong University from February 2019 to June 2022.According to SN-MP angle measured on LCRs,they were divided into three vertical skeletal groups.In Mimics(materialise’s interactive medical image control system)21.0,CBCT images were calibrated for orientation and the mandibles were measured after three-dimensional reconstruction.Upper and lower boundaries of condyles were determined by cross-sectional view,and then condyles were segmented,measured and analyzed.Statistical analyses were performed by SPSS 26.0.Paired t-test and Wilcoxon signed rank test were used to analyze the morphological symmetry of condyles and mandibles;The differences of condylar and mandibular morphology among three groups was performed by One-way analysis of variance(ANOVA)and Kruskal-Wallis test;Pearson and Spearman correlation analysis was used to analyzed the correlation between ages and condyle,mandible measurement indexes and the correlation between condyle,mandible and cephalometric values.The significance difference level is set to α=0.05.Results:1.There were symmetrical differences in condylar surface area and morphological index in patients with skeletal Class Ⅱ(P<0.05),but there was no obvious vertical preference.The difference had nothing to do with vertical growth patterns.2.There were significant differences in the length of mandibular body and ramus among different vertical growth patterns(P<0.05).Low-angle group had the longest mandibular body,while high-angle group had the shortest mandibular ramus.FMA and S-Go/N-Me values were negatively correlated with the length of the mandibular body and ramus.3.Condylar volume,morphological index,condylar head volume,and long axis diameter of the condyle in different vertical growth patterns were statistically different(P<0.05),and low-angle group was the largest.While the normal-angle and high-angle groups had no statistical difference in the measurement items of condylar morphology,and their mean distributions were similar.4.FMA and S-Go/N-Me values were negatively correlated with volume,surface area,MI and long axis diameter of condyle,and volume,surface area and of condylar head.Moreover,MI had the strongest correlation.Conclusion:1.There were symmetrical differences in the condylar surface area and morphological index in adolescent patients with skeletal Class Ⅱ,but it was not significantly related to the vertical growth patterns.It is necessary to analyze the symmetry before orthopedic treatment in patients with skeletal Class Ⅱ.2.Different vertical growth patterns were affected by the mandibular body and ramus and high-angle subjects had shorter mandibular body and ramus.3.There were significant differences in condylar size and long axial diameter in three vertical growth patterns.The condylar shapes were smaller in patients with higher vertical angle. |
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