Maxillo-mandibular Transverse Relationship of Primary Second Molar and Permanent First Molar of Children in Mixed Dentition: A Cone-Beam Computed Tomography Analysis

This study examined the transverse relationship between the maxilla and mandible in children with mixed dentition. The study focused on the primary second molar and the permanent first molar in relation to the anteroposterior skeletal patterns using cone-beam computed tomography (CBCT). A total of 102 patients from the Pediatric Dentistry Department at Pusan Dental Hospital were classified into three skeletal groups (Class I, Ⅱ, Ⅲ) based on the ANB angle (angle formed by A-point-nasion-B-point). CBCT scans were analyzed to assess the transverse dimensions of basal bone and dento-alveolar measurements. The results showed that Class Ⅲ patients exhibited a significantly narrower maxillary basal bone compared with Class I and Ⅱ patients. The mandibular basal width was not significantly different between the classes. For primary second molars, Class Ⅲ patients showed significantly narrower maxillary alveolar bone width at the root bifurcation level (51.7 ± 2.5 mm, <i>p</i> < 0.05) compared with Class I and II patients. For permanent first molars, the maxillary occlusal fossa distance was smallest in Class II (45.4 ± 2.4 mm, <i>p</i> < 0.05), and was significantly different from Class I and Class Ⅲ. Maxillary first molar inclination was more lingually inclined in Class Ⅱ patients (99.0 ± 4.2°, <i>p</i> < 0.05) compared with Class Ⅲ patients, whereas Class Ⅲ patients exhibited more buccal inclination. This study highlights the correlation between transverse discrepancies and anteroposterior skeletal classifications, with Class Ⅲ showing a narrower maxillary base and Class Ⅱ patients presenting greater lingual compensation. These findings may aid pediatric dentists in diagnosing transverse relationships in mixed dentition.