Skeletal and dental asymmetries in Class II subdivision malocclusions using cone-beam computed tomography.
BACKGROUND
The objective of this study was to compare the degrees of skeletal and dental asymmetry between subjects with Class II subdivision malocclusions and subjects with normal occlusions by using cone-beam computed tomography.


METHODS
Thirty subjects with Angle Class II subdivision malocclusions (mean age, 13.99 years) and 30 subjects with normal occlusions (mean age, 14.32 years) were assessed with 3-dimensional cone-beam computed tomography scans. Independent t tests were used to compare orthogonal, linear, and angular measurements between sides and between groups.


RESULTS
Total mandibular length and ramus height were shorter on the Class II side. Pogonion, menton, and the mandibular dental midline were deviated toward the Class II side. Gonion and the anterior condyle landmark were positioned more posteriorly on the Class II side. The mandibular dental landmarks were located more latero-postero-superiorly, and the maxillary dental landmarks more latero-antero-superiorly on the Class II side. There was loss of maxillary arch length, and the mandibular molar was closer to the ramus on the Class II side.


CONCLUSIONS
The etiology of Class II subdivision malocclusions is primarily due to an asymmetric mandible that is shorter and positioned posteriorly on the Class II side. A mesially positioned maxillary molar and a distally positioned mandibular molar on the Class II side are also minor contributing factors.
School of Dental Medicine, University of Connecticut, Farmington, CT 06030, USA.
Derek A
DA
Sanders
Paul H
PH
Rigali
William P
WP
Neace
Flavio
F
Uribe
Ravindra
R
Nanda
D000293:Adolescent; D002508:Cephalometry / Q000379:methods; D002648:Child; D002680:Chin / Q000000981:diagnostic imaging / Q000473:pathology; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D003481:Cuspid / Q000000981:diagnostic imaging / Q000473:pathology; D003724:Dental Arch / Q000000981:diagnostic imaging / Q000473:pathology; D003766:Dental Occlusion; D005146:Facial Asymmetry / Q000000981:diagnostic imaging* / Q000473:pathology; D005147:Facial Bones / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D008312:Malocclusion, Angle Class II / Q000000981:diagnostic imaging* / Q000473:pathology; D008334:Mandible / Q000000981:diagnostic imaging / Q000473:pathology; D008335:Mandibular Condyle / Q000000981:diagnostic imaging / Q000473:pathology; D008437:Maxilla / Q000000981:diagnostic imaging / Q000473:pathology; D008963:Molar / Q000000981:diagnostic imaging / Q000473:pathology; D057887:Overbite / Q000000981:diagnostic imaging / Q000473:pathology; D010159:Palate / Q000000981:diagnostic imaging / Q000473:pathology