Background. Few researchers have investigated the relationship between supernumerary teeth (ST) and impacted incisors. The authors investigated the relationship between ST and impacted incisors in the maxillary anterior area in the mixed dentition.Methods. Using cone-beam computed tomography, the authors diagnosed 417 ST among 294 patients (age range, 6-12 years; 220 boys and 74 girls). The number, morphology, growth orientation, and position of ST were recorded along with the presence of impacted incisors.Results. The authors reported that 23.1% of patients having ST (n = 68; mean [standard deviation] age 8.5 [1.6] years) also had impacted incisors. Morphology (molariform and odontomelike), growth orientation (normal and no orientation), and position (coronal) of the ST were significantly associated with impacted incisors (P < .05 for all). An increase of 1 year in age was associated with a decreased risk of having ST accompanied by impacted incisors (odds ratio, 0.76; 95% confidence interval, 0.63 to 0.92). An increase of 1 ST more than doubled the risk of having an impacted incisor (odds ratio, 2.39; 95% confidence interval, 1.44 to 3.96).Conclusions. In this population, the number, morphology, growth orientation, and position of ST as well as the patient's age were associated with impacted incisors in the maxillary anterior area during the mixed dentition.

Objectives: To compare cranial base morphology in different vertical facial types and explore their regularity. Methods: Sixty-nine Class I patients, aged 10-15 years, were selected from the Department of Orthodontics, School of Stomatology, China Medical University. They were divided into three groups: high angle group (12 males and 10 females), average angle group (11 males and 13 females) and low angle group (14 males and 9 females). Single factor analysis of variance, as well as paired t-test, was used to analyze the differences of the measurements among the three groups. Results: Significant differences could be found in cranial base angle, sella angle, Ba-SE-FMS angle, posterior cranial base angle and the length of SO-Ar. The gradual decrease of cranial base angle, sella angle and Ba-SE-FMS angle from low angle to high angle showed significant differences; moreover, the posterior cranial base angle and the length of SO-Ar gradually decreased and also showed significant differences. The length of posterior cranial base in the high angle group was shortest; however, there was no statistically significant difference between the average angle and low angle groups. The anterior cranial base angle of high angle patients increased; there was no statistically significant difference between the low angle and the average angle patients. Conclusions: The structure of the cranial base in different vertical facial types presents certain regularity and it could be considered that the growth of the cranial base is involved in the development of different vertical facial types. The posterior cranial base seems to have a significant influence on the formation of vertical facial types.

Objective To investigate the effect of orthodontic therapy on disorder syndrome of temporomandibular joint.Method Perform orthodontic therapy on 37 patients with disorder syndrome of temporomandibular joints.Result 26 patients healed,9 became better,in whom the healing rate of adults was lower.Conclusion Comprehensive therapy is needed in patients with disorder syndrome of temporomandibular joint and the balance and stability should be emphasized after orthodontic therapy.