Cone-beam Computed Tomographic Evaluation Of The Dental And Skeletal Asymmetry Characteristics And The Relationship Of Patients With Class ? Subdivision Malocclusion

ObjectiveTreating Class ? subdivision malocclusion has been a challenge for orthodontists,and there must be many treatments for class ? subdivision malocclusion because of the complicated asymmetry of dental and skeletal.This study aimed to explore the characteristics of dental and skeletal asymmetry in Class ? subdivision malocclusion,and to assess the relationship between the condyle-glenoid fossa and first molar.MethodsThe study group comprised 32 consecutive patients(22 boys and 10 young women;average age,18.6 years)who sought orthodontic treatment at the Department of Orthodontics,Stomatological Hospital of Chongqing Medical University.Intraoral photographs and dental casts of the patients were reviewed to determine the study sample,accorded to the district inclusion and exclusion criteria.And cone-beam computed tomographic images of the 32 patients with Class ? subdivision malocclusion were three-dimensionally reconstructed using the Mimics software.Forty-five anatomic landmarks on the reconstructed structures were selected and 27 linear and angular measurements were performed.Paired-samples t –tests were used to compare the average differences between the Class I and Class ? sides;Pearson correlation coefficient(r)was used for analyzing the linear association.ResultsThe faciolingual crown angulation of the mandibular first molar(p < 0.05),sagittal position of the maxillary and mandibular first molars(p < 0.01),condylar head height(p < 0.01),condylar process height(p < 0.05),and angle of the posterior wall of the articular tubercle and coronal position of the glenoid fossa(p < 0.01)were significantly different between the two sides.The morphology and position of the condyle-glenoid fossa significantly correlated with the three-dimensional changes in the first molar.ConclusionsThe distal position of the mandibular first molar and the mesial posistion of maxillary first molar on class ? side,as well as significant lingual inclination of the mandibular first molar on the Class ? side were the dental characteristics of Class ? subdivision malocclusion.Condylar morphology and glenoid fossa position asymmetries between two sides were the major components of skeletal asymmetry and the skeletal asymmetry were well correlated with the three-dimensional position of the first molar.