Studying the prevalence and etiology of Class II subdivision malocclusion using cone-beam computed tomography

Background: The purpose of this study was to investigate the prevalence of subdivision malocclusions in Class II/1 and Class II/2 patients and to see if the II/2 group had greater skeletal asymmetry. Methods: From a sample of more than 1500 records, 256 Class II malocclusions met inclusion criteria. Of these, 214 were Class II/1 and 42 were Class II/2. Seven landmarks identified on cone-beam computed tomography scans were used to make eight bilateral linear measurements. Right and left side differences were calculated for each subject, and median values were compared. Linear measurements from the Class I side of the subdivision malocclusion to the Class II side were compared. Results: Of II/1 subjects, 22.9% had a subdivision malocclusion versus 50% of the II/2. There were no significant side-to-side differences between Class II/1 and II/2 subjects. There were greater differences in the II/2 group between the Class I side of subjects to the Class II side than in the II/1 group. Conclusion: All mandibular variables indicated greater degrees of mandibular asymmetry in the II/2 group; only condylion to pogonion proved statistically significant. (C) 2017 Published by Elsevier Inc. on behalf of World Federation of Orthodontists.