Glenoid Fossa Position In Subjects With Different Facial Types: A Cephalometric Study

As the relationship of the mandible to the cranial base influence both sagittal and vertical facial disharmonies,glenoid fossa determine the scope of mandibular movement and is closely correlated to mandibular movement, as one part of the craniofacial complex.Glenoid fossa position is likely to play an important role in the establishment of different craniofacial patterns.Many experimental and clinical contributions have demonstrated the effects of orthopaedic/orthodondic therapies on glenoid fossa position and morphology.Glenoid fossa displacement is partly due to concomitant physiological growth and remodelling of surrounding structures. All cephalograms were taken by means of the same X-ray device and by a single technician.The aim of the present study was to investigate the cephalometric relationships between the glenoid fossa and other craniofacial components in subjects presenting with different sagittal and vertical skeletal characteristics.This study would provide some valuable references for the orthodontical diagnosis, treatment and craniofacial growth and development. The study consists of two parts:1. Glenoid fossa Position in Subjects with Different sagittal Facial Types.A cephalometric study was carried out on a sample of 110 subjects(53 males and 57 females,aged 12-14 years) before any treatment. The sample divided into 3 groups:40 skeletal class I (20 males and 20 females),36 skeletal classâ…¡(17 males and 19 females)and 34 skeletal class III (16 males and 18 females). Each groups were homogenous as to age and sex distribution.All subjects were selected from the files of the Department of Orthodontics , Stomatological College of the Fourth Military Medical University. Criteria for case selection include (1) facial symmetry and normal angle vertical relationships, (2) no orthodontic treatment,injury, TMJ trauma,and surgical treatment history,and (3) lateral films with well detectable contours of the glenoid fossa. The comparisons among the three groups according to the sagittal relationships revealed significantly larger distances T-Fs', T-Ae'and T-Ar'in skeletal Class II when compared with skeletal Class III. Significant differences for sagittal measurements were found TMJ position (horizontal distances from point T to Ar',Ae'and Fs') is more posterior in skeletal Class II when compared with skeletal Class III.The Glenoid fossa position is one of the components of horizontal malocclusion. The location of glenoid fossa can be considered one of the indicators of certain of skeletal structures.This study would provide some references for the orthodontical diagnosis , treatment and craniofacial growth and development.2. Glenoid fossa Position in Subjects with Different vertical Facial Types.A cephalometric study was carried out on a sample of 117 subjects( 58 male and 59 female,aged 12-14 years) before any treatment.The sample divided into 3 groups: 42 normal angle vertical relationships (21 males and 21 females),36 low angle vertical relationships (18 males and18 females) and 39 high angle vertical relationships (19 males and 20 females). Each groups were homogenous as to age and sex distribution. All subjects were selected from the files of the Department of Orthodontics , Stomatological College of the Fourth Military Medical University. Criteria for case selection include (1) facial symmetry and skeletal class I, (2) no orthodontic treatment ,injury,TMJ trauma,and surgical treatment history,and (3) lateral films with well detectable contours of the glenoid fossa. Statistically significant differences among the three groups according to the vertical relationships were found between normal and low angle groups, and between low and high angle groups for Fs-Fs',Ae-Ae'. The comparisons among the three groups revealed significantly larger distances Fs-Fs',Ae-Ae'in low angle subjects when compared with subjects with nomal or high angle vertical relationships. The position of the glenoid fossa relative to the basicranial structures was more inferior in low angle subjects when compared with subjects with normal or high angle vertical relationships.Deep bite patients are mostly characterized by low angle; Open bite patients are mostly characterized by high angle. Glenoid fossa position is likely to play an important role in the establishment of different vertical craniofacial patterns. This study would provide some valuable references for the orthodontical diagnosis, treatment and craniofacial growth and development.