Dental, skeletal asymmetries and functional characteristics in Class II subdivision malocclusions

Abstract

Treatment outcomes of Angle Class II subdivision malocclusions may be compromised because of the uncertainty of the aetiology. Previous studies have reported controversial ideas about the origins, but the existence of a primary contributor still remains unknown. Functional factors have been mentioned as a probable cause, but until now, there have been no supporting data. This study was a cross-sectional investigation of the characteristics of Angle Class II subdivision malocclusion, including dental, skeletal and functional factors, by comparison of the subdivision group and the normal occlusion group. The evaluations of dental and skeletal asymmetries of both groups were carried out by cone-beam computed tomography (CBCT) and analysis of dental casts. The functional deviations were evaluated by cast mounting and measuring. In the subdivision group, the asymmetric position of the glenoid fossa was found to be the most significant skeletal asymmetry. No dentoalveolar asymmetry was found in this group. The most important finding was that, in subdivision malocclusions, functional deviation resulting in pseudoasymmetry occurred in 32.86% of the study participants. This deviation is probably related to the disharmonious arch width between maxillary and mandibular dental arches in the premolar section. The origin of Angle Class II subdivision malocclusion is multifactorial, with dental, skeletal and functional factors included. Functional deviation occurs, probably due to dental arch width disharmony. Asymmetric position of the glenoid fossa may account for most of the skeletal asymmetry.

Three-dimensional positional assessment of glenoid fossae and mandibular condyles in patients with Class II subdivision malocclusion

“…9,10,11 The current study corroborated the recent findings of Li et al, 11 who reported right-and left-side differences in spatial positioning of glenoid fossae of patients with Class II subdivision malocclusion. Although they assessed the position of glenoid fossae in Class II subdivision in comparison with Class I patients, the present study is the first to have compared Class II subdivision with skeletal Class II patients.…”

“…Based on the standard deviation of 2.149 mm reported by Li et al 11 for the primary outcome of the current research (ie, sagittal position of the glenoid fossa), an alpha significance level of 0.05 and a power of 0.80 to detect differences between groups greater than 1.3 mm, a sample size of 41 patients per group was adopted. The sample consisted of 82 orthodontic patients (49 male and 33 female), all aged 12 to 17 years.…”

“…[9][10][11][12] Minich et al 10 compared Class II subdivision patients with Class I controls, and although they found significant skeletal and occlusal differences between the groups, dental components contributed to twothirds of all asymmetry. Li et al, 11 who also compared Class II subdivision and Class I malocclusions, showed that asymmetric patterns contributed majorly to the distal positioning of glenoid fossae.…”

“…Recent 3D evidence has shown that a Class II subdivision malocclusion might be associated not only with asymmetric occlusal pattern but also with skeletal components, [9][10][11] and 3D studies show great potential to aid in the visualization of the skull and TMJ structures. [9][10][11][12] Minich et al 10 compared Class II subdivision patients with Class I controls, and although they found significant skeletal and occlusal differences between the groups, dental components contributed to twothirds of all asymmetry. Li et al, 11 who also compared Class II subdivision and Class I malocclusions, showed that asymmetric patterns contributed majorly to the distal positioning of glenoid fossae.…”

Association between dental anomalies and malocclusion in Brazilian orthodontic patients

“…Agenesis has also been correlated with Class II malocclusions (15); despite hypodontia being one of the most common anomalies in our sample, it was not associated with any malocclusion. The cause of Class II subdivision malocclusion is multifactorial, comprising skeletal, dental and functional features (41). In that way, anomalies could contribute to develop these malocclusions.…”