The study of temporomandibular joint in dentofacial abnormalities using cone beam computed tomography

Abstract

The article deals with the symmetry of dentofacial abnormality of temporomandibular joint, the position of mandible and rotation edges of temporomandibular joint heads in dentofacial abnormalities. The aim of the investigation is to compare the analysis of temporomandibular joint symmetry, the position of mandible and rotation edges of temporomandibular joint heads in dentofacial abnormalities based on the first and the second type of classification by Angle. The investigation was carried out among 27 patients with dentofacial abnormalities using cone beam computed tomography. The patients were divided into two groups based on types of malocclusion - the first type of occlusion by Angle and the second one by Angle’s classification. While studying the distance from the middle of articular heads on the right and on the left to midline, passing through pterygoid processes of sphenoid bone it was determined that in the second class of Angle’s classification of dentofacial abnormalities, articular heads are situated posteriorly to cranial basis on 2.45-3.47 mm (р<0.005). The difference between the rotation edges of temporomandibular joint heads is more than 5° of the 1st class according to classification and it occurred in 23.08% of patients; the second class occurred in 64.29%. The range of maximal difference of the rotation edge of the 1st class contains 5.2°, and the 2nd class of Angle’s classification includes 15.2°, that determines the severity of dentofacial abnormality of the second classification by Angle. In the second type of Angle’s classification articular heads of temporomandibular joint are situated posteriorly that confirms the pathogenesis of distal bite. Proposed methods of measurement can be used for differential diagnosis of skeletal forms of second type dentofacial abnormalities according to Angle’s classification. With increase of dentofacial abnormality severity, rotation of temporomandibular joint heads also increases. In the second type of Angle’s classification asymmetry of articular heads occurs on the right and left, three times more often in comparison with the first class.