Cone-beam computed tomographic evaluation of the temporomandibular joint and dental characteristics of patients with Class II subdivision malocclusion and asymmetry / 대한치과교정학회지

OBJECTIVE: Treating Class II subdivision malocclusion with asymmetry has been a challenge for orthodontists because of the complicated characteristics of asymmetry. This study aimed to explore the characteristics of dental and skeletal asymmetry in Class II subdivision malocclusion, and to assess the relationship between the condyle-glenoid fossa and first molar. METHODS: Cone-beam computed tomographic images of 32 patients with Class II 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 II sides; Pearson correlation coefficient (r) was used for analyzing the linear association. RESULTS: The 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. CONCLUSIONS: Asymmetry in the sagittal position of the maxillary and mandibular first molars between the two sides and significant lingual inclination of the mandibular first molar on the Class II side were the dental characteristics of Class II subdivision malocclusion. Condylar morphology and glenoid fossa position asymmetries were the major components of skeletal asymmetry and were well correlated with the three-dimensional position of the first molar.

Role of Static Posturography in Fatigue Assessment due to Flight TasksLoad / 现代生物医学进展

Objective:To explore the role of static posturography in the assessment of fatigue due to flight tasks.Methods:Thirtymale college students were asked to perform simulated flight tasks consecutively forfour hours.Meanwhile their statie posturography and tasks performance would be repeatedly measured during the task-load at end of every hour.Based on the changed significantly parameters,the static balance index would be built by principle component analysis.Then its correlation with task-load level would be further analyzed by curve estimation.Results:Static postural control declined significantly under effect of simulated flight tasks.With task load sustaining,static balance index increased significantly and correlated linearly with duration of task load (R2=0.949).Besides,there was quadratic relationship between the change of multi-tasks performance and duration of task load (R2=0.968).And correlation of multi-tasks performance with static standing balance level also had been proved to be quadratic (R2=0.976).Conclusions:Static posturography correlated linearly with flight task-load level,which could reflect fatigue level caused by task load.