The position of glenoid fossa in different skeletal patterns and its relation to the functional occlusal plane

Background : Glenoid fossa position plays an important role in the establishment of different craniofacial patterns. The purposes of this study were to verify the position of the glenoid fossa in subjects with different sagittal and vertical skeletal patterns, to assess the correlation between the position of glenoid Fossa and skeletal patterns (sagittal and vertical), and to assess the correlation between the position of the glenoid fossa and the functional occlusal plane. Materials and method : A lateral cephalometric study was carried out on 124 subjects aged 18-30 years who were classified according to skeletal sagittal relationships using ANB angle into three groups (Cl. І = 48, Cl. ІІ = 41, Cl. ІІІ = 35 subjects), and according to skeletal vertical relationships using MP-SN angle into three groups (normal angle = 67, high angle = 23, low angle = 34 subjects). Cephalometric analysis comprised both sagittal and vertical measurements for the assessment of the position of the glenoid fossa in relation to surrounding skeletal structures. The assessment was achieved by measuring three angular and seven linear variables using the AutoCAD computer program 2008. Results : The results revealed that in sagittal skeletal relation, the glenoid fossa position was more posterior in skeletal Class II when compared with skeletal Class III, while in the vertical plane; the position of the glenoid fossa relative to Basicranial structures was more caudal in low angle subjects when compared with subjects with normal or high angle vertical relationships. On the other hand, there was no correlation between the position of the glenoid fossa and the functional occlusal plane. Conclusions : Class II skeletal relation is associated with a more posterior position of the glenoid fossa when compared to Class III skeletal relation regarding the Anteroposterior plane. Subjects presenting with high angle vertical relationships show a more cranial position of the glenoid fossa in relation to the cranial base when compared to subjects with either normal or low angle vertical relationships regarding the vertical plane. This study did not reveal a strong relationship between the glenoid fossa position and the functional occlusal plane in anteroposterior and vertical relationships.