[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.

[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.