[Study on digital models of normal deciduous dentition in 189 children from Shanghai].

PURPOSE: To study the gender difference and the regulation of growth and development in normal deciduous dentition． METHODS: A total of 189 children with normal deciduous dentition aged 3 to 6 years in several kindergartens in Xuhui District in Shanghai were selected. The three-dimensional(3D) digital dental models were reconstructed by intraoral scanning. Geomagic Studio, a 3D reverse engineering software, was employed to extract the data, such as the dental arc perimeter of C(APC), the dental arc perimeter of E(APE), the dental arc length of C(LC), the dental arc length of E(LE), the dental arc width of C(C-C), the dental arc width of E(E-E), the mesiodistal width of the deciduous crown, the maxillary and mandibular space. SPSS 22.0 software package was used for data analysis. RESULTS: Parameters of deciduous dentition in boys were significantly elevated than in girls(P＜0.05). All the boys and girls were divided into 4 groups by age. In 3-year-old group, significant differences were observed in maxillary APC, C-C, E-E(P＜0.05) between boys and girls. In 4-year-old group, all boys' parameters were significantly greater than girls'(P＜0.05) except maxillary LC. In 5-year-old group, there were significant differences in all the parameters between boys and girl(P＜0.05) except maxillary APE and mandibular APC, LC, LE, C-C. No significant difference was observed in all the parameters except mandibular APE in 6-year old group. The significant difference between boys and girls were observed in the mesiodistal width of each deciduous crown except that of the maxillary lateral incisor and mandibular central incisor (P＜0.05). There were significant differences in maxillary LE and E-E among children of different ages(P＜0.05).The maxillary space was significantly greater than the mandibular space(P＜0.01). CONCLUSIONS: There was gender difference in children's normal deciduous dentition, especially when they were 4 years old.

[Oral health behavior and parental cognition of first-grade children in urban and suburban areas of Shanghai].

PURPOSE: To investigate oral health behaviors of first-grade school children and parents' cognition of oral health in urban and suburban areas of Shanghai, and to analyze and compare the differences between the two areas, so as to provide reference for formulating oral health intervention measures and oral health education. METHODS: A total of 3 312 first-grade school-aged children in Shanghai were included by cluster random sampling method. Relevant data were collected through questionnaire survey of parents' oral health and clinical oral examination of children. Chi-square test was used to compare the differences in oral health behaviors of children and parents' oral health cognition between urban and suburban area with SAS 9.4 software package. RESULTS: The proportion of children who brush their teeth more than twice a day in urban and suburban areas was 72.55% and 44.26%, and the proportion of children who brushed their teeth with fluoride toothpaste was 53.25% and 44.79%, respectively. Compared with the suburban area, the brushing habits of school-aged children in urban area were better, the difference was statistically significant(P＜0.05). In terms of medical habits, the proportion of children with no dental experience in urban and suburban areas was 26.99% and 44.08%, and the proportion of children with toothache in the past year was lower than that in the last dental visit, the difference was statistically significant (P＜0.05). In terms of parents' cognition and attitude towards oral health knowledge, parents in urban areas were more correct than those in suburban areas, with the average correct rate being 82.56% and 70.42%, and the difference was statistically significant (P＜0.05). CONCLUSIONS: There are regional differences in oral health behaviors of first-grade school children and parents' oral health knowledge between urban and suburban area in Shanghai. It is suggested that relevant government departments should strengthen oral health education and oral health behavior guidance for parents, and strengthen oral health investment in non-central urban areas.

[The effect of fluoride varnish Duraphat in preventing deciduous dental caries in preschool children].

PURPOSE: To evaluate the effect of fluoride varnish Duraphat on preventing caries of primary teeth caries, and provide scientific basis for the establishment of oral health care. METHODS: 1140 preschool children aged 3~4 years old were chosen from 25 public kindergartens in Xuhui district of Shanghai by cluster sampling method, they were divided into 2 groups on a voluntary basis with the informed consent of the child's parents. 762 preschool children in Fluoride Varnish group were taken oral examination and used fluoride varnishes every 6 months, 378 preschool children in the control group were without treatment. Oral health instruction was given to all the children. The data of caries prevalence, mean dmft, caries incidence and mean increments of dmft (decayed, missing and filled teeth) of 2 groups were compared. The results were analyzed using SAS 9.4 software package. RESULTS: After 2 years, caries prevalence, mean dmft, caries incidence and mean increments of dmft of fluoride varnish groups were lower than those of control group and the difference was statistically significant (P＜0.05). CONCLUSIONS: Fluoride varnish Duraphat is effective in decreasing caries incidence and mean dmft increments of primary teeth in preschool children and is worthy to be used widely in Xuhui district.

[Analysis of caries and its risk factors of the first permanent molar among primary school students in Pudong, Shanghai and Lichuan, Jiangxi Province].

PURPOSE: To Investigate the current situation of caries of primary school students in Shanghai Pudong and Lichuan, Jiangxi province, and analyze the risk factors of dental caries, in order to provide scientific evidence for prevention and treatment of dental caries. METHODS: A stratified cluster sampling method was applied to choose 10 primary schools from Lichuan and 2 primary schools from Pudong area, respectively. A total of 1922 pupils aging from 6 to 12 were selected. Oral health examination was applied to each student and questionaire survey was conducted among their parents. The results were analyzed with SPASS 21.0 software package. RESULTS： Two hundred and sixty-one caries was found in Lichuan pupils, with the caries rate of 23.6% and DMFT being 0.37±0.766. 96 caries was found in Pudong pupils, with the caries rate of 11.8% and DMFT being 0.19±0.582. There was significant difference between two areas. Analysis of risk factors showed a significant correlation between children's pre-bedtime sweets and other bad habits, as well as low level of education of children's parents and dental caries. CONCLUSIONS: The caries of primary school students in rural areas are significantly worse than those in urban areas; bad living habits are risk factors of caries and the knowledge of caries prevention should be popularized in school students to enhance the awareness of oral health among pupils.

[Evaluation of the effect of one-step self etching adhesives applied in pit and fissure sealing].

PURPOSE: To observe the effect of three one-step self etching adhesive systems used in fit and fissure sealant and explore the feasibility of application in caries prevention in school. METHODS: Seven hundred and twenty completely erupted mandibular first molars in 360 children aged 7 to 9 years old were chosen. The split-mouth design was used to select one side as the experimental group, divided into A1(Easy One Adper), B1(Adper Easy One), and C1(iBond SE).The contra lateral teeth served as A2,B2 and C2 groups (phosphoric acid). The retention and caries status were regularly reviewed .The clinical effect of the two groups was compared using SPSS19.0 software package for Chi - square test. RESULTS: At 3 and 6 months, pit and fissure sealant retention rate in A1 and A2, B1 and B2,C1 and C2 group had no significant difference. At 12 months, sealant retention in A1 and B1 group was significantly lower than A2 and B2 group (P<0.05). No significant difference was found between C1 and C2 groups (P>0.05). At 24 months, sealant retention rate in A1, B1 and C1 group was significantly lower than A2, B2 and C2 group (P<0.05). The caries rate in A1and A2, B1 and B2, C1 and C2 group had no significant difference during different follow-up time (P>0.05). CONCLUSIONS: The clinical anticariogenic effect of three kinds of one-step etching adhesives and phosphoric acid etching sealant was similar .One-step self etching adhesive system was recommended for pit and fissure sealant to improve the students' oral health. The long-term retention rate of one-step self etching adhesive system was lower than the phosphoric acid method to long term observation is needed.

[Investigation of the first permanent molar caries in primary school students in Xuhui District of Shanghai Municipality].

PURPOSE: To investigate the prevalence and current status of caries about the first permanent molars of students in elementary schools in Xuhui District of Shanghai Municipality in order to provide evidence for prevention and treatment strategies of caries. METHODS: Random cluster samples of 5698 students aged from 7 to 12 years old were examined with regard to caries epidemic status of the first permanent molars. The results were analyzed by SPASS13.0 software package. RESULTS: The caries prevalent rate of the first permanent molars was 16.18%.The mean DMFT of the caries patients was 1.80. The females' mean caries prevalent rate and DMFT of the first permanent molars were both significantly higher than males'. The caries rate increased rapidly with aging from 7 to 12(P<0.01).The overall filling rate of the first permanent molars was 56.04%.The prevalence of the first permanent molars in the mandible was significantly higher than that in the maxilla (P<0.01).The caries rate of students, who brushed teeth twice a day or more, was significantly lower than those who brushed teeth once a day or less. CONCLUSIONS: The caries prevalence of the first permanent molars in students of 7 to 12 years old in elementary schools in Xuhui District of Shanghai municipality was less optimistic. Some concrete measures should be taken to prevent and treat caries.