Comparative Study Of Condyle-fossa Spatial Relationships And Morphologies Of Skeletal Class Ⅱ Malocclusion Patients Among Different Vertical Skeletal Pattern

Objective: The aim of this study was to compare the mandibular condyle-fossa spatial relationships and morphologies in skeletal class Ⅱ patients among different vertical skeletal pattern and in normal sagittal and vertical skeletal morphology to clarifying the interrelation between the vertical and sagittal skeletal pattern on affecting the temporomandibular joints(TMJ).Method and material: Cone-beam computed tomography(CBCT)images of68 adult patients(136 TMJ)aged 18-30 years old who visited the Department of Orthodontics for orthodontic treatment and required CBCT as a part of diagnostic record-taking were recruited.The subjects were divided Based on a proper sample calculation,four groups of 17 CBCT images each were made according to their ANB and mandibular plane(SN-MP)angles: class Ⅱ low SN-MP angle(CⅡ-LA),class Ⅱ normal SN-MP angle(CⅡ-NA),class Ⅱ high SN-MP angle(CⅡ-HA)and class I normal SN-MP angle(CI-NA).Morphology of the condyle,mandibular fossa and condylar position were compared among the groups.Results: The low,normal,and high angle groups in skeletal class Ⅱ patients were dominantly positioned concentrically,posteriorly and anteriorly,respectively.While the condyles of subjects with normal sagittal class I and normal vertical facial pattern tended to concentrically and anteriorly positioning.The condylar position varied in groups according to the differences in anterior joint space(AJS),Since no significant differences in posterior joint space(PJS).The CI-NA group was only significantly differenced in condylar position compared to CⅡ-NA using chi-square test.The high and low angle groups showed significant differences in superior joint spaces,mediolateral condyle width,and condyle head angle.Abnormal condylar morphology was typical in the high and low angle groups.In particular,high angle facial morphology.No significant differences were found in the condylar position and TMJ morphology between right and left sides,only in CⅡ-NA,the DMF was higher in the right side.the factor of gender has been proven to have a certain influence on the morphology and position of the condyle and which have changed through each different group.According to the anteroposterior condylar position,the AEA was significantly lower in anterior-positioned condyles respect to concentric and posterior ones.Conclusions: Both skeletal class Ⅱ malocclusion and vertical craniofacial pattern showed a significant correlation with the form and position of the condyle,the vertical skeletal morphology have more influence on TMJ morphology than sagittal skeletal one.This relationship should be considered for predicting and establishing a proper treatment plan for temporomandibular diseases during orthodontic treatment.