Evaluation of mandibular volume classified by vertical skeletal dimensions with cone-beam computed tomography

Objective: To investigate the relationship between anteroposterior and vertical differences in maxillofacial morphology and mandibular volume. Materials and Methods: Subjects comprised 213 Japanese adults (84 males and 129 females) who were divided into three groups based on mandibular basal arch (ANB) and Wits, measured in a cephalometric analysis: Class I (-1 degrees <= ANB < 4 degrees, -1 mm <= Wits < 0 mm), Class II (ANB >= 4 degrees, Wits >= 0), and Class III (ANB < -1 degrees, Wits < -1 mm). Subjects were also divided into three groups based on the mandibular plane angle (Mp), as follows: hypodivergent (Mp < 23 degrees), normodivergent (Mp = 23-30 degrees), and hyperdivergent (Mp > 30 degrees) groups. Mandibular volume was measured from cone-beam computed tomographic images that were analyzed using Analyze (TM) image processing software and compared among the three groups in each classification. Results: No significant differences were noted in mandibular volume among Classes I, II, and III. An inverse relationship was found between mandibular volume and Mp, and a significant difference was noted in mandibular volume between the hypodivergent and hyperdivergent groups. Conclusions: In addition to two-dimensional analysis, such as lateral cephalometry, three-dimensional information such as volume, provided by cone-beam computed tomography, contributes to a more detailed assessment of maxillofacial morphology.