Cone-beam computed tomography transverse analysis. Part I: Normative data

IntroductionThe application of cone-beam computed tomography (CBCT) in orthodontics ushered in a new era in 3-dimensional analysis that promises to provide more comprehensive understanding of craniofacial skeletal anatomy. That promise is now being realized in multiple studies. The purposes of this study were to investigate a portion of transverse dimension relationships by using CBCT and to propose a transverse analysis to assist practitioners with treatment decisions.MethodsThe CBCT scans of 241 patients with and without crossbite were analyzed to assess the width of the jaws and the inclination of the first molars. The dental and skeletal measurements were compared between the noncrossbite and the crossbite groups.ResultsThe noncrossbite group included patients who had apparently normal transverse relationships, but also a surprising number of patients with an obvious skeletal transverse discrepancy masked by dental compensation. The noncrossbite patients with molar inclinations within 1 SD of the mean were defined as the control group, and those with dental compensations were identified as either superior convergent or inferior convergent. The obvious unilateral crossbite patients demonstrated dental compensation in the maxillary first molar on the noncrossbite side, whereas the obvious bilateral crossbite patients had normal dental inclinations.ConclusionsSkeletally, both the bilateral and unilateral crossbite groups had narrower maxillary widths than did the controls, but also wider mandibles, with more severe bilateral crossbites. Dentally, the unilateral crossbite group had more upright teeth on the noncrossbite side. In the noncrossbite groups with dental compensations, the superior convergent and inferior convergent differences in both dental and skeletal characteristics were marked. Patients without crossbites can have significant discrepancies that might warrant treatment.