OBJECTIVE To investigate the epidemiology of dental caries and its correlated factors of 12-year-old children in Dongxiang, Baoan and Yugu races. METHODS According to the method of third national oral health epidemiologic investigation, 448 12-year-old children in Dongxiang, Baoan and Yugu races were randomly collected and the epidemiological investigation of dental caries, oral bacteriological detection and oral hygiene behavior were carried out. RESULTS 1) The caries prevalence rate of Dongxiang, Baoan and Yugu races were 40.52%, 44.29%, 46.45%, respectively. The average caries of Dongxiang, Baoan and Yugu races were 0.92, 0.90, 1.13, respectively. 2) The main ranks of Streptococcus mutans in saliva were class 2 and class 3 in Dongxiang and Baoan races. However, it was class 0 or class 1 in Yugu race. The level of Streptococcus mutans in dental plaque was higher in Dongxiang and Baoan races than in Yugu race. 3) The children's everyday brushing rate was higher in Yugu race than in Dongxiang and Baoan races (P<0.01). But there were no difference between Dongxiang and Baoan races. CONCLUSION The caries prevalence rates of 12-year-old children in Dongxiang, Baoan and Yugu races are high. The main factors of high caries prevalence rate were low brushing rate and dental plaque couldn't be removed effectively. Oral health education should be strengthened in the three race areas.
AIM:To explore the oral health status of middle aged people in Gansu Province and get scientific information for the oral health prevention.METHODS:An equal-sized stratified multi-stage random sampling design was applied in the investigation.According to the standard and method used in the third national oral health epidemiologic investigation,the oral health investigation was made to 791 people aged from 35-44 in Gansu.RESULTS:The caries prevalence rate was 62.58%.There was no difference between urban and rural samples(P0.05).But the caries prevalence rate of femal was higher than male(P0.05).The mean dental crown caries was 1.89 and root caries was 1.01 respectively.The detection rates of gingival bleeding,dental calculus,periodontal pocket and periodontal attachment loss were 93.55%,99.37%,60.93% and 38.18% respectively.All the detection rates were higher than the results of the third national oral health epidemiologic investigation.The detection rate of diseases of oral macosa was 6.70%.The dentition defection rate was 36.41% and the repaired rate was 35.42%.The main denture-prosthesis was removable partial dentures and irregular fixed bridge.The rate of removable partial dentures was higher in female and rural than in male and urban.CONCLUSION: In general,the oral healthy status of middle aged people in Gansu province is not ideal.The prevalence of caries and periodontal disease is serious.It is essential to strengthen the oral health education and guide them to have good oral healthy habit and correct medical treatment behavior,so as to prevent oral diseases and improve their life quality.
With the development of human genomics, the genetic factors associated with dental caries have receiving increasing attention. This study was performed to evaluate the relationship between lactoferrin (LTF) and mannose-binding lectin 2 (MBL2) gene single nucleotide polymorphisms (SNPs) and dental caries susceptibility in Chinese children.This prospective case-control study included 360 unrelated children (aged 12-15 years) who received oral health examinations and questionnaire surveys. The children were divided into two groups by counting the numbers of decayed, missing, and filled teeth (DMFT/dmft): case group (n = 162, DMFT/dmft ≥ 1) and control group (n = 198, DMFT/dmft = 0); non-invasive saliva samples were collected to extract genomic DNA. Six SNPs (rs2073495C/G, rs1042073C/T, rs10865941C/T, and rs1126477A/G in LTF; rs7096206C/G and rs7095891G/A in MBL2) were tested by mass spectrometry.The study included 360 individuals with (85 boys and 77 girls) and without a history of caries (96 boys and 102 girls). There were no statistically significant differences in alleles and genotypes among the six SNPs between the two groups.There is no evidence that polymorphisms of LTF and MBL2 genes are associated with dental caries susceptibility in populations from northwest China; further confirmation is needed with larger sample sizes.
Miniature electron cyclotron resonance (ECR) ion sources are widely used in compact ion implanters, miniature neutron tubes, and miniature ion thrusters. To understand the mechanism of miniature ECR ion source, a miniature deuterium ion source developed by Peking University is taken as the research object. In this work, a global model based on particle balance equations is developed for studying the hydrogen plasma and the deuterium plasma inside the miniature ECR source. The research results show that both the hydrogen discharge process and the deuterium discharge process of the ion source are strongly dependent on the gas pressure and microwave power. The calculated results show that high power is beneficial to increasing the proportion of H<sup>+</sup>(D<sup>+</sup>) ions, low pressure is helpful in augmenting the ratio of <inline-formula><tex-math id="M3">\begin{document}$ {\text{H}}_2^ + $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20212250_M3.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20212250_M3.png"/></alternatives></inline-formula>(<inline-formula><tex-math id="M4">\begin{document}$ {\text{D}}_2^ + $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20212250_M4.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20212250_M4.png"/></alternatives></inline-formula>) ions, high pressure and low power are beneficial to enhancing the proportion of <inline-formula><tex-math id="M5">\begin{document}$ {\text{H}}_3^ + $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20212250_M5.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20212250_M5.png"/></alternatives></inline-formula>(<inline-formula><tex-math id="M6">\begin{document}$ {\text{D}}_3^ + $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20212250_M6.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20212250_M6.png"/></alternatives></inline-formula>) ions. In addition, there is a large difference in ion proportion between hydrogen discharge and deuterium discharge. Under the same operating parameters, the proportion of D<sup>+</sup> ions is 10%–25% higher than the proportion of H<sup>+</sup> ions since the plasma density of deuterium discharge is higher than that of hydrogen plasma. Therefore, during the operation of miniature source, H<sub>2</sub> gas, instead of D<sub>2</sub> gas, can be used in experiment, and the proportion of D<sup>+</sup> ions under the corresponding operating parameters can be estimated based on the proportion of H<sup>+</sup> ions. Finally, the calculated results show that high microwave power is a prerequisite for achieving the high proportion of H<sup>+</sup> (D<sup>+</sup>) ions. However, owing to the limitation of microwave coupling efficiency, the miniature ECR ion source cannot work when the microwave power is greater than 150 W, so that the H<sup>+</sup> (D<sup>+</sup>) proportion cannot be further increased, thereby limiting its further applications in neutron sources, implanters, etc. Therefore, how to improve the microwave coupling efficiency has become one of the key research contents of the miniature ECR ion source. The global model proposed in this paper is helpful in understanding the physical process of the miniature ECR ion source, but there are also some shortcomings. Firstly, the effect of the secondary electron emission coefficient is not considered in the model, so it is impossible to study the influence of wall materials on ion proportion in detail. Secondly, the dissociation degree depends on the plasma measurements, and the error of plasma measurements in turn affect the accuracy of the model to a certain extent. In addition, only the hydrogen plasma model and deuterium plasma model are established in this work, based on which it is impossible to study the processes of other gas discharge plasmas. In the future, the above factors will be considered and the model will be further improved to establish a complete and self-consistent global model of the miniature ECR ion source.
[Objective]To know knowledge and behavior on oral health of freshmen, to provide proof for the freshmen's oral health education as well as protect the university students' oral health. [Methods] According to the Third National Oral Health Epidemiologic Questionnaire, made a research about oral health knowledge and behavior among 1 065 freshmen in Northwest University for Nationalities. [Results] More than 60% freshmen had correct realization about common oral problems; 87.32% freshmen never used dental floss before; more than 90% freshmen concerned about their oral health; however, nearly 40% freshmen sought medical advice inactively. [Conclusion] We should promote the freshmen's education about oral health, raise their awareness of oral medical care, standardize their oral health behavior, update their out-date views of medic-seeking, and improve their oral health condition.
To investigate the oral health status of undergraduate university students and to guide their oral hygiene behaviors.3516 college students in Northwest University for Nationalities were investigated in this study according to the criterion issued by World Health Organization (WHO) on the basic methods of oral health investigation in 1997.The caries prevalence rate among the students investigated was 47.87%. The average decayed teeth were 1.29. The obturation rate of caries was 20.42%. The students came from city showed significant higher caries rate than those from countryside, and so did the female students compared with the male students. Dental calculus rate was 79.78%. The dental segments related were 3.75. The worst situation was among male students and students from countryside. The examined rates were 53.30% of crowded incisor, 42.58% of maximum upper-incisor anomaly, 50.60% of the maximum lower-incisor anomaly and 31.09% of molar malposition, respectively. More rates of dentofacial anomalies showed no differences of significance between different area and gender.In general, the oral health status of the college students are not ideal. It is necessary to advocate early examination, early prevention and early treatment among the students in university.
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