Measurement of the craniofacial bone and dental arch between different malocclusions in the mixed dentition

Abstract:

Objective：To explore the three-dimensional differences in the morphological features of the craniofacial bone and dental arch between children with different sagittal skeletal malocclusions in the mixed dentition. Methods：This study included 180 children（aged 8-12 years） in the mixed dentition who consulted with the doctor for the first time in the Department of Pediatric Dentistry，Stomatological Hospital of Chongqing Medical University，and they were assigned to three groups：skeletal class Ⅰ malocclusion group （60 cases），skeletal class Ⅱ malocclusion group（60 cases），and skeletal class Ⅲ malocclusion group（60 cases）. Lateral cephalometric radiograph and the measurement data of 3D scanning model were compared between these groups. Results：Compared with the skele－tal class Ⅰ malocclusion group，the skeletal class Ⅱ malocclusion group showed significant reductions in SNB angle（74.60±3.13 vs. 77.33±3.74，P=0.00） and mandibular length（Cond-Pog）（90.20±4.72 vs. 92.90±5.44，P=0.00） and significant increases in SNA angle（81.42±3.13 vs. 79.77±5.39，P=0.03），Y-axis angle （67.45±3.99 vs. 64.72±6.82，P=0.00），and inclination of the lower anterior teeth（IMand-ML）（96.93±5.48 vs. 93.13±6.53，P=0.00）. The skeletal class Ⅱ malocclusion group had a smaller upper posterior maxillary width（UPMW） than the skeletal class Ⅲ malocclu－sion group（31.17±2.33 vs. 32.36±5.19，P=0.07）. Compared with the skeletal class Ⅰ malocclusion group，the skeletal class Ⅲ malocclusion group showed significant reductions in SNA angle（76.00±4.21 vs. 79.77±5.39，P=0.00），maxillary length（ANS-PNS）（38.53±3.63 vs. 42.60±2.90，P=0.00），upper total arch length（UTAL）（24.37±2.68 vs. 25.68±2.24，P=0.00），anterior cranial base length（N-S）（57.12±3.05 vs. 58.67±3.10，P=0.01），facial height（N-Me）（99.70±4.91 vs. 101.77±5.78，P=0.03），Y-axis angle（62.50±4.22 vs. 64.72±6.82，P=0.02），and IMand-ML（85.17±6.81 vs. 93.13±6.53，P=0.00），and had a forward mandibular position（S-Co）（13.92±2.57 vs. 15.15±2.79，P=0.01）. Conclusion：The morphological features of the craniofacial bone and dental arch vary between different sagittal skeletal malocclusions in the mixed dentition. The main manifestations of skeletal class Ⅱ malocclusion are smaller mandibular length，higher IMand-ML，and slightly smaller UPMW；the main manifestations of skeletal class Ⅲ malocclusion are smaller maxillary length，N-S，and N-Me，forward mandibular position，lower IMand-ML，and smaller UTAL. These results provide a reference for early identification and cor－rection of skeletal and dental developmental abnormalities in children with malocclusions.