[Evaluation of condylar asymmetry in different skeletal patterns with cone-beam CT].

PURPOSE: The aim of this study was to evaluate condylar asymmetry in different skeletal patterns with cone-beam CT (CBCT). METHODS: A total of 110 subjects aged from 18 to 30 years were selected from patients who had undergone CBCT examinations retrospectively. All the subjects were divided into three groups according to their skeletal patterns: Class Ⅰ (Cl Ⅰ: 0°≤ANB≤5°), Class Ⅱ (Cl Ⅱ: ANB>5°) and Class Ⅲ (Cl Ⅲ: ANB<0°). In addition, each group was further divided into two subgroups according to genders. Condylar (Co-Sig), ramus (Go-Sig) and condyle-plus-ramus (Co-Go) asymmetry were assessed by identifying landmarks on the reconstructed images with a 3-dimentional (3D) reference plane. The coordinates of the landmarks were calculated statistically. The data were analyzed statistically with SPSS17.0 software package. RESULTS: The condyle-plus-ramus and ramus asymmetry (Co-Go R-L and Go-Sig R-L) were affected by the ANB angle (P<0.05) respectively, and the differences mainly came from the y coordinate (P<0.05). When comparing the two sides of the three groups respectively, the Co-Go, Go-Sig and Co-Sig of some patients had gender difference and left-right difference. The z coordinate of point Menton (Me) had significant difference (P<0.05) caused by different skeletal patterns, while the coordinates of x and y were similar (P>0.05). CONCLUSIONS: Condyle-plus-ramus and the ramus asymmetry were affected by different skeletal patterns and the differences were caused by the height primarily. Patients of Class Ⅲ usually manifest mandibular protrusion while Class Ⅱ with mandibular retrognathism. Whether the degree of chin deviation differs according to the condylar asymmetry needs further investigation.

[Clinical aesthetic effectiveness of restoring the subgingival residual crowns of anterior teeth with crown lengthening surgery].

PURPOSE: To evaluate the clinical effects of restoring the subgingival residual crowns of anterior teeth with periodontal and prosthodontics treatment. METHODS: Twenty-five patients with 28 subgingival residual crowns were treated by root canal therapy, crown lengthening surgery, and restored with post- core crown after 8 weeks. Changes in tooth mobility, gingival health were examined and clinical effect of crown restoration were evaluated at regular intervals of 1 month, 6 months and 12 months after restoration respectively. RESULTS: One year after restoration，the gingival health was improved and the overall effective rate was 89.28%. Three teeth were failed, one was due to mild tooth loose，and the other two were due to exposure of crown margin. CONCLUSIONS: For subgingival residual crowns of anterior teeth, crown lengthening surgery can conserve the biological width, and produce enough height of ferrule. Restoration can obtain satisfactory effects, but the indication must be selected properly.

[Clinical efficacy of Nd:YAG laser combined with Vitapex paste in the treatment of periapical cysts around single root].

PURPOSE: To explore the clinical efficacy of Nd:YAG laser combined with Vitapex paste in the treatment of periapical cysts around single root. METHODS: Thirty-four teeth with periapical cysts in 34 patients were treated from August 2014 to August 2016 in Taizhou People's Hospital using Nd: YAG laser, Vitapex paste was injected into the small periapical cysts, followed by conventional root canal filling. The clinical efficacy was observed every 3 months after surgery, the follow period was from 10 months to 2 years. RESULTS: Thirty four patients with 34 teeth were treated, and 32 teeth were followed up, 29 were cured, the failure rate was 6.3%. CONCLUSIONS: Nd:YAG laser combined with Vitapex paste is satisfactory in the treatment of periapical cysts around single root, which is worthy of wide clinical application.

[An epidemiological investigation of caries status of the first permanent molars of children aged 7-9 year in Taizhou City].

PURPOSE: To investigate caries prevalence of the first permanent molars of children aged 7-9 years in Taizhou city. METHODS: According to caries diagnostic criteria of WHO, 3653 primary school students in downtown areas of Taizhou city were surveyed; the data were statistically analyzed with SPSS 20.0 software package. RESULTS: The total caries prevalence rate of the first permanent molars was 24.99%. The average decayed-missing-filled (DMFT) teeth were 0.49.The total filling rate was 3.62%. The caries prevalence of the first permanent molars in 7-，8- and 9 year-old children was 15.37%,20.38% and 39.67%， respectively. The caries prevalence of girls was 27.61%, which was significantly higher than boys (21.84%).The caries prevalence (%) rate of the first permanent molars in the mandible was significantly higher than that in the maxilla. CONCLUSIONS: Caries prevalence of the first permanent molars is high in children aged 7-9 years in Taizhou city. Caries prevention and treatment measures should be strengthened for children in order to reduce the incidence of dental caries.

[Investigation of malocclusion and orthodontic treatment proportion of middle school students in Hailing district, Taizhou city].

PURPOSE: To investigate the prevalence of malocclusion and orthodontic treatment proportion of middle school students in Hailing district, Taizhou city. METHODS: Standard investigation form was made based on the individual normal occlusion and Angle's classification of malocclusion. 9018 middle school students were investigated. SPSS 19.0 software package was used for Chi-square test. RESULTS: The prevalence of malocclusion was 69.38%. ClassⅠ, ClassII and Class III malocclusions were observed in 52.48%, 30.62% and 16.90% of the sample, respectively. The correction rate was lower than those reported for other cities. CONCLUSIONS: The findings of the investigation reveal the need to improve public health plans for orthodontic treatment and to increase the rate of correction in Hailing district, Taizhou city.