[Research Updates: Cariogenic Mechanism of Streptococcus mutans].

The prevalence of dental caries remains high, posing a major burden on the public health of the global society. Microorganisms are the main cause of dental caries, among which Streptococcus mutans ( S. mutans) is one of the most widely recognized cariogenic bacteria. In recent years, the progress in research technology enabled the academic circle to conduct more in-depth research into caries-inducing S. mutans at the DNA, RNA and protein levels, and to gain thereby a new understanding of the surface structure and extracellular matrix composition of S. mutans. In this paper, we summarized recent findings on the cariogenic mechanism of S. mutans in order to help reveal more targets and potential approaches for the future development of caries prevention agents that target S. mutans, and to promote the development of dental caries prevention campaign.

Trend on dental caries status and its risk indicators in children aged 12 years in China: a multilevel analysis based on the repeated national cross-sectional surveys in 2005 and 2015.

BACKGROUND: This study aimed to explore the trend and risk indicators for dental caries of children aged 12 years in China based on national oral health survey data in 2005 and 2015. METHODS: Research data were from the two latest national oral health surveys conducted in mainland China, including 30 and 31 provinces, autonomous regions, and municipalities in 2005 and 2015, respectively. Children aged 12 years were clinically examined for dental caries and dental fluorosis according to the World Health Organization criteria. Sociodemographic characteristics and oral health-related behaviours were collected using questionnaires. Multilevel zero-inflated negative binomial regression model was used to investigate the association between dental caries severity and dental fluorosis, sociodemographic characteristics, and oral health-related behaviours. RESULTS: The final analyses included 12,350 and 27,818 children surveyed in 2005 and 2015, respectively. The standardized prevalence of dental caries increased from 27.05% (95% confidence interval [CI], 24.25-28.85) in 2005 to 37.92% (95% CI, 34.94-40.90) in 2015, and the respective standardized mean decayed, missing, filled teeth (DMFT) index scores increased from 0.50 (standard deviation [SD], 1.04) to 0.83 (SD, 1.45) (P < 0.001). Fujian province had the highest increase in dental caries, followed by Liaoning, Heilongjiang, Hainan, and Yunnan. Results revealed that children who were girls, more frequently experienced dental pain, and had more recent dental visits, had significantly higher DMFT scores after adjusting for the survey year and other variables (all P < 0.05). CONCLUSIONS: Dental caries of 12-year-old children in China deteriorated from 2005 to 2015, particularly in the northeast and southwest regions. Dental caries was associated with sex, dental pain, and dental service utilization.

The relationship between different types of caries and periodontal disease severity in middle-aged and elderly people: findings from the 4th National Oral Health Survey of China.

BACKGROUND: The relationship between dental caries and periodontal disease is still controversial. The objective of this study was to explore the relationship between different types of caries and periodontal disease severity in middle-aged and elderly people in China. METHODS: The study population consisted of 4407 middle-aged and 4117 elderly subjects. Caries were divided into the following three types: type A, crown caries; type B, lesions involving both the crown and root, representing mixed-type caries; and type C, root caries. These three types together represent the overall caries situation, which we call type ABC. Caries were quantitated by decayed and filled teeth (DFT index). Periodontitis was evaluated by clinical attachment loss. RESULTS: Middle-aged people with periodontitis had a significant association with DFT type B (OR: 1.21, 95% CI 1.17-1.25) and type C (OR: 1.40, 95% CI 1.24-1.56). Elderly people with periodontitis had a significant association with DFT type C (OR: 1.28, 95% CI 1.21-1.35). CONCLUSIONS: In China, caries types B/C were positively correlated with periodontitis in the middle-aged group, and only caries type C was positively correlated with periodontitis in the elderly group.

A two-week single-group longitudinal test of a new sonic-powered toothbrush simulating the 'bass brushing technique' with tapered bristles on the brush head for reduction of dental plaque and gingivitis.

OBJECTIVE: To investigate the effect of a new powered toothbrush with tapered bristles on the brush head for the reduction of dental plaque and gingivitis. METHODS: This was a single-centre, single-group, longitudinal clinical trial. Thirty-two participants who were typical manual toothbrush users were recruited and assigned the sonic-powered brush. Interviews were arranged on the 1st , 4th , and 15th days which represented the baseline (T1 ), middle (T2 ) and final (T3 ) time points, respectively. At each visit, the plaque index (PlI), gingival index (GI), bleeding on probing (BOP) and probing depth (PD) were recorded for the Ramfjord index teeth, gingival crevicular fluid(GCF) samples were collected and the proportions of eight periodontal pathogenic bacteria were analysed. Repeated-measures analysis of variance (ANOVA) was used for comparisons at different time points. RESULTS: PlI was significantly reduced by 41.67% from T1 to T2 (p<0.001) and decreased by 18.57% from T2 to T3 (p=0.003). GI also varied significantly from T1 to T2 (p=0.018) and T1 to T3 (p=0.037). A 35.86% reduction in the BOP percentage occurred after using the sonic-powered toothbrush for 3 days (p=0.001). However, no significant difference was observed in the mean values of PD at different examination intervals (p=0.529). There was no significant difference in the proportions of bacteria between T1 and T3 (p>0.05). CONCLUSION: This research demonstrated the efficacy of the sonic-powered brush handle together with tapered bristles on the brush in reducing plaque and gingivitis within a short time period.

Dental expenditure, progressivity and horizontal inequality in Chinese adults: based on the 4th National Oral Health Epidemiology Survey.

BACKGROUND: The financial burden of oral diseases is a growing concern as the medical expenses rise worldwide. The aim of this study was to investigate the dental expenditure, analyze its progressivity and horizontal inequality under the general health finance and insurance system, and identify the key social determinants of the inequality for Chinese adults. METHODS: A secondary analysis used the data of 13,464 adults from the 4th National Oral Health Epidemiological Survey (NOHES) in China was undertaken. The dental expenditure was collected and divided into out-of-pocket and health insurance payments. Horizontal inequality index and Kakwani index were used to analyze the horizontal inequality and progressivity, respectively. The decomposition model of the concentration index was set up to explore the associated socioeconomic determinants. RESULTS: The results showed that a mean dental expenditure per capita of Chinese adults was $20.55 (95% Confidence Interval-CI: 18.83,22.26). Among those who actually used dental service, the cost was $100.95 (95%CI: 93.22,108.68). Over 90% of dental spending was due to out-of-pocket expenses. For self-reported oral health, the horizontal inequality index was - 0.1391 and for the decayed tooth (DT), it was - 0.2252. For out-of-pocket payment, the Kakwani index was - 0.3154 and for health insurance payment it was - 0.1598. Income, residential location, educational attainment, oral hygiene practice, self-reported oral health, age difference were the main contributors to the inequality of dental expenditure. CONCLUSION: Dental expenditure for Chinese adults was at a lower level due to underutilization. The ratio of payments of dental expenditure and utilization was disproportional, whether it was out-of-pocket or insurance payment. Individuals who were more in need of oral care showed less demand for service or not required service in time. For future policy making on oral health, it is worth the effort to further promote the awareness of the importance of oral health and utilization of dental service.

Relationship between the genetic polymorphisms of vicR and vicK Streptococcus mutans genes and early childhood caries in two-year-old children.

BACKGROUND: The VicRK two-component signalling system regulates virulence and cariogenicity in Streptococcus mutans (S. mutans). The purpose of this study was to explore the genetic polymorphisms of the vicR and vicK genes, which are associated with dental caries in children with S. mutans. METHODS: In this study, 121 (from each group) clinical S. mutans strains were isolated from caries-free children and children with high-severity caries to sequence the vicR and vicK genes. Genomic DNA was extracted from S. mutans strains and amplified using PCR. The PCR products were purified and sequenced. A chi-squared test and ABI Variant Reporter software were used to analyse the sequencing results. RESULTS: The 242 clinically isolated S. mutans strains contained the full-length vicR and vicK genes. No nucleotide sequence insertions or deletions were observed in the two genes. Four silent point mutations were identified in the vicR genes, and no missense mutations could be detected. Forty-one mutations were identified in the vicK genes. In addition to 32 silent mutations, 9 missense mutations at the 173, 337, 470, 1051, 1132, 1258, 1260, 1277, and 1348 bp positions were found. The distribution frequencies of the missense mutations were not significantly different between the groups, except for the C470T mutation. The frequency of the C470T missense mutation was higher in the high-severity caries group than in the caries-free group. CONCLUSIONS: vicR sequences are highly conserved in S. mutans clinical isolates. The locus 470 missense mutation of the vicK gene may be related to caries in children with S. mutans.

Analysis of sucrose-induced small RNAs in Streptococcus mutans in the presence of different sucrose concentrations.

Streptococcus mutans (S. mutans) is the major pathogen contributing to dental caries. Sucrose is an important carbohydrate source for S. mutans and is crucial for dental caries. Small RNAs (sRNAs) are key post-transcriptional regulators of stress adaptation and virulence in bacteria. Here, for the first time, we created three replicate RNA libraries exposed to either 1 or 5% sucrose. The expression levels of sRNAs and target genes (gtfB, gtfC, and spaP) related to virulence were assessed. In addition, some phenotypic traits were evaluated. We obtained 2125 sRNA candidates with at least 100 average reads in 1% sucrose or 5% sucrose. Of these candidates, 2 were upregulated and 20 were downregulated in 1% sucrose. Six of these 22 differentially expressed sRNAs were validated by qRT-PCR. The expression level of target gene gtfB was higher in 1% sucrose. The adherence ratio of S. mutans was higher in 1% sucrose than in 5% sucrose. The synthesis of water-insoluble glucans (WIGs) was significantly higher in 5% sucrose than in 1% sucrose. These data suggest that a series of sRNAs can be induced in response to sucrose, and that some sRNAs might be involved in the regulation of phenotypes, providing new insight into the prevention of caries.

The relationship between children's oral health-related behaviors and their caregiver's social support.

BACKGROUND: Social support might play a role in helping people adopt healthy behaviors and improve their health. Stronger social support from mothers has been found to be positively related to higher tooth brushing frequency in 1- to 3-year-old children. However, little is known regarding the relationship between the caregiver's social support and the oral health-related behaviors of 5-year-old children in China. This study aimed to investigate this relationship. METHODS: A cross-sectional study was conducted among 1332 5-year-old children and their caregivers in Guangzhou, southern China. Data were collected using questionnaires that were completed by the caregivers and the children's caries status were examined. The caregivers' social support was measured using the Social Support Rating Scale. The measurements of the children's oral health-related behaviors included the frequencies of sugary snack intake and tooth brushing, utilization of dental services, and patterns of dental visits. Univariate and multiple logistic regression analyses were used to analyze the relationships between the variables. RESULTS: No association was found between the caregiver's social support and the child's oral health-related behaviors in a multiple logistic regression analysis. However, other factors, particularly the oral health-related behaviors of the caregiver, were found to be significantly linked to the child's oral health-related behaviors. CONCLUSIONS: The oral health-related behaviors of 5-year-old children in Guangzhou are unrelated to the caregiver's social support but are related to other specific factors, particularly the caregiver's oral health-related behaviors.

Genetic polymorphisms of the sortase A gene and social-behavioural factors associated with caries in children: a case-control study.

BACKGROUND: Streptococcus mutans (S. mutans) is the primary etiological agent of dental caries. Sortase is a transpeptidase that anchors several surface proteins to the S. mutans cell wall and has been shown to play a major role in cariogenicity. The purpose of this study was to explore the genetic polymorphisms of the sortase gene (srtA) and the social-behavioural factors associated with dental caries in children with S. mutans. METHODS: In this case-control study, 121 S. mutans strains were separately selected from caries-free children and high-severity caries children for sequencing of the srtA gene. Social and behavioural data were collected by self-administered questionnaires. Genomic DNA was extracted from S. mutans strains and amplified by PCR to obtain the srtA gene. The purified PCR products were sequenced and analysed for mutations with ABI Variant Reporter software. The distribution of missense mutations and the mean of social-behavioural factors were compared between the groups. A multiple logistic regression model was used to control for confounding factors. RESULTS: The mutation frequencies at loci 168 (P = 0.023) and 470 (P = 0.032) were significantly different between the groups. The best-fitting model showed that greater age, high frequencies of solid sugar consumption, prolonged breastfeeding, a high proportion of visible plaque, and S. mutans with a T at locus 168 of the srtA gene were associated with high-severity caries in children (P < 0.05). Children carrying a G at locus 168 of S. mutans had a decreased risk for high-severity caries (OR = 0.32, 95% CI = 0.12-0.86) compared with those carrying a T. CONCLUSIONS: The present study suggested that the locus 168 missense mutation of the srtA gene may correlate with caries susceptibility in children with S. mutans. In addition, age, duration of breastfeeding, solid sugar consumption, and poor oral hygiene contributed to this complex disease.

Factors related to children's caries: a structural equation modeling approach.

BACKGROUND: Dental caries among preschool children is highly prevalent in many less-developed countries. METHODS: A model which explored the factors related to children's dental caries was tested in this study using structural equation modeling. Caregivers of children aged 5 years were surveyed on their socioeconomic status, and their oral health knowledge, attitudes and practices. In addition, information on their children's oral health practices, dental insurance and dental service utilization were collected. Examination of caries was conducted on all children who returned fully completed questionnaires. RESULTS: The results showed that socioeconomic factors influenced children's oral health practices through the impact of caregivers' oral health knowledge and practices; that caregivers' oral health knowledge affected children's oral health practices through the influence of caregivers' oral health attitudes and practices; and finally, that children's oral health practices were linked directly to their caries. CONCLUSION: The findings have important applications for promoting policies aimed at advancing children's oral health.

Relationship between children's oral health-related behaviors and their caregiver's sense of coherence.

BACKGROUND: Sense of coherence (SOC) is hypothesized to be an important psychological factor that enables people to cope with stressors and successfully maintain and improve health. Mother's SOC has been shown to be an important psychological factor associated with oral health and oral health-related behaviors of adolescents and 11- to 12-year-old children. However, little is known about the relationship between the caregiver's SOC and oral health-related behaviors of the preschool children. The objective of this study was to investigate the relationship between oral health-related behaviors of 5-year-old children in Southern China and SOC of their caregiver. METHODS: A cross-sectional study was conducted in a randomized sample of 1332 children aged 5 years and their caregivers in Guangzhou, Southern China. Data were collected through questionnaires completed by the caregivers. The Chinese short version of Antonovsky's SOC scale (13 items) was employed to assess the caregiver's SOC. The outcome variables were the child's oral health-related behaviors, including frequency of sugary snack intake, toothbrushing frequency, utilization of dental service, and pattern of dental visits. Multiple logistic regression was used to analyze the relationship between the variables. RESULTS: No association was found between the children's sugary snack intake and the mother's or the father's SOC. After adjustment for other significant factors related to the child's oral health-related behaviors, 8.9% of the children whose grandparents (as caregivers) had higher SOC scores had a lower frequency of sugary snack intake, compared with the children whose grandparents had lower SOC scores (OR = 0.61, 95% CI = 0.50-0.73, p = 0.008). The other measures of oral health-related behaviors of the child were not significantly associated with the caregiver's SOC. CONCLUSION: Sugary snack intake behavior of the 5-year-old children was not associated with the mother's or the father's SOC. It was associated with the SOC of their grandparents, who are a small group of the caregivers in China.

Association between periodontitis and hypertension: cross-sectional survey from the Fourth National Oral Health Survey of China (2015-2016).

OBJECTIVES: To evaluate the association between periodontitis severity and hypertension based on Chinese epidemiological data. DESIGN: This cross-sectional survey enrolled adults from the Fourth National Oral Health Survey of China (2015-2016). SETTING: The data were obtained from the Fourth National Oral Health Survey of China (2015-2016). PARTICIPANTS: The study included individuals aged 35-44 years (n=4409), 55-64 years (n=4568) and 65-74 years (n=4218). PRIMARY AND SECONDARY OUTCOME MEASURES: Periodontal status, defined on the basis of the 2017 classification scheme, and periodontal parameters (eg, bleeding on probing (BOP)) were compared between individuals with hypertension and individuals with normotension. Smoothed scatterplots were constructed to demonstrate the associations of periodontal parameters and periodontal status with hypertension. RESULTS: Severe periodontitis (stages III and IV) was present in 41.4% of individuals with hypertension and 28.0% of individuals with normotension, respectively (p<0.001). The prevalence of severe periodontitis was higher in individuals with hypertension than that in individuals with normotension among participants aged 35-44 years (18.0% vs 10.1%, p<0.001) and 55-64 years (40.2% vs 36.7%, p=0.035), but not in participants aged 65-74 years (46.4% vs 45.1%, p=0.429). Therefore, the difference in periodontal status between individuals with hypertension and individuals with normotension decreased with age. There were higher prevalences of BOP, probing depth (PD) ≥4 mm and PD ≥6 mm in individuals with hypertension than in individuals with normotension (52.1% vs 49.2%, 19.6% vs 14.7% and 1.8% vs 1.1%, respectively). Periodontitis severity and the proportion of teeth with PD ≥4 or ≥6 mm were positively associated with hypertension. CONCLUSION: Periodontitis is associated with hypertension in Chinese adults. Hypertension prevalence increased with periodontitis severity, particularly among young participants. Accordingly, it is necessary to improve the education, awareness of periodontal treatment and preventive management among individuals at risk of hypertension, particularly in the younger population.

Determining the factors associated with oral health-related quality of life in Chinese elders: Findings from the fourth national survey.

OBJECTIVE: The purpose of this study was to assess the associations between the self-reported oral health-related quality of life (OHRQoL) of older Chinese people and their socio-economic status and oral health using data collected in the 4th National Oral Health Survey. METHODS: After multistage stratified cluster sampling, 4332 adults aged 65-74 years participated in the study. After a clinical examination, the participants completed a structured questionnaire. A Mandarin version of the General Oral Health Assessment Index (GOHAI) was included in the questionnaire. Clinical examinations were carried out using the criteria recommended by the World Health Organization. Multivariate analysis was used to evaluate the associations of the clinical and socio-demographic variables with the GOHAI scores of the participants. RESULTS: The weighted mean (SE) GOHAI score was 51.6 (0.0). Female sex and having more than 10 missing teeth, unrestored tooth spaces, more than 10 decayed teeth and a periodontal pocket ≥6 mm were negatively associated with the GOHAI score, while having a higher education level and living in the Eastern region of China were positively associated with the GOHAI score. CONCLUSION: After adjustment for confounders, the OHRQoL of older Chinese individuals was mainly affected by untreated dental caries and the loss of teeth. Older Chinese individuals who were male, had a higher education level, were from the Eastern region, had no unrestored tooth spaces or deep periodontal pockets and had fewer decayed or missing teeth had higher GOHAI scores, indicating better OHRQoL.

Oral health status of rural-urban migrant children in South China.

BACKGROUND: In China, there is a massive rural-urban migration and the children of migrants are often unregistered residents (a 'floating population'). AIM: This pilot study aimed to profile the oral health of migrant children in South China's principal city of migration and identify its socio-demographic/behavioural determinants. DESIGN: An epidemiological survey was conducted in an area of Guangzhou among 5-year-old migrant children (n = 138) who received oral examinations according to the World Health Organization criteria. Parents' oral health knowledge/attitude, child practices, and impact of children's oral health on their quality-of-life (QoL) were assessed. RESULTS: The caries rate and mean (SD) dmft were 86% and 5.17 (4.16), respectively, higher than those national statistics for both rural and urban areas (P < 0.05). Oral hygiene was satisfactory (DI-S < 1.0) in 3% of children. Oral health impacts on QoL were considerable; 60% reported one or more impacts. 58% variance in 'dmft' was explained by 'non-local-born', 'low-educated parents', 'bedtime feeding', 'parental unawareness of fluoride's effect and importance of teeth', and 'poor oral hygiene' (all P < 0.05). 'Non-local-born' and 'dmft' indicated poor oral health-related QoL (both P < 0.05), accounting for 32% of variance. CONCLUSION: Oral health is poor among rural-urban migrant children and requires effective interventions in targeted sub-groups.

Effect of poly (γ-glutamic acid)/tricalcium phosphate (γ-PGA/TCP) composite for dentin remineralization in vitro.

The poly (γ-glutamic acid)/tricalcium phosphate (γ-PGA/TCP) composite was fabricated as a novel biomineralization material function in preventing caries. Demineralized bovine dentin specimens were prepared and randomly divided into 5 groups (i. α-TCP, ⅱ. γ-PGA, ⅲ. γ-PGA/TCP, ⅳ. CPP-ACP, and ⅴ. deionized water) and subjected to 14 days of pH cycling. Remineralization ability was evaluated by lesion depth, mineral loss and microhardness. The morphology of dentin depositions was observed with scanning electron microscope (SEM), the crystal structure was determined by X-ray diffraction (XRD), and the wettability was tested by contact angle measurements. ANOVA revealed specimens treated by γ-PGA/TCP presented the statistically least lesion depth (p<0.01) and mineral loss (p<0.001), and the highest hardness (p<0.001). SEM revealed prominent intra- and inter-tubular precipitates in both γ-PGA and γ-PGA/TCP groups. The XRD patterns of the deposition structures in all groups were similar to those of sound dentin, and the contact angle of water decreased after γ-PGA/TCP treatment.

Associated Factors of Oral Health-related Quality of Life in Chinese Adolescents Aged 12-15 Years.

adolescents aged 12 to 15 years based on the 4th National Oral Health Survey and to explore its associated factors. METHODS: Students aged 12 to 15 years were recruited using to a multistage stratified random sampling method. All the subjects received oral examination and completed a questionnaire. Information relating to OHRQoL was collected through a Mandarin version of the child oral impacts on daily performances (Child-OIDP) questionnaire. The relationship between the Child-OIDP scores and independent variables was assessed using a Mann-Whitney U-test, Kruskal-Wallis test and a multivariate Poisson regression. RESULTS: A total of 89,582 subjects were included in the analysis, of whom 76.6% reported oral impacts in the last 6 months. Eating was the most affected daily performance. The results of the regression analysis showed that factors associated with adolescents' OHRQoL included sex, location of residence, region, only child status, parents' level of education, frequency of sugar consumption, self-perception of general/oral health, dental appointments in the past 12 months, oral health knowledge status, age, decayed, missing and filled teeth (DMFT) index and number of teeth with gingival bleeding. CONCLUSION: Oral impacts were common among Chinese adolescents, although most were not so severe. Eating was the most commonly affected performance. Sex, location of residence, region, only child status, parents' level of education, frequency of sugar consumption, selfperception of general/oral health status, dental appointments in the previous 12 months, oral health knowledge status, age, DMFT index and number of teeth with gingival bleeding were found to be associated with OHRQoL.

The prevalence of dental erosion and associated risk factors in 12-13-year-old school children in Southern China.

BACKGROUND: Dental erosion has been investigated in developed and developing countries and the prevalence varies considerably in different countries, geographic locations, and age groups. With the lifestyle of the Chinese people changing significantly over the decades, dental erosion has begun to receive more attention. However, the information about dental erosion in China is scarce. The purpose of this study was to explore the prevalence of dental erosion and associated risk factors in 12-13-year-old school children in Guangzhou, Southern China. METHODS: This cross-sectional survey was performed by two trained, calibrated examiners. A stratified random sample of 12-13-year-old children (774 boys and 725 girls) from 10 schools was examined for dental erosion using the diagnostic criteria of Eccles and the index of O'Sullivan was applied to record the distribution, severity, and amount of the lesions. Data on the socio-economic status, health behaviours, and general health involved in the etiology of dental erosion were obtained from a self-completed questionnaire. The analyses were performed using SPSS software. RESULTS: At least one tooth surface with signs of erosion was found in 416 children (27.3%). The most frequently affected teeth were the central incisors (upper central incisors, 16.3% and 15.9%; lower central incisors, 17.4% and 14.8%). The most frequently affected surface was the incisal or occlusal edge (43.2%). The loss of enamel contour was present in 54.6% of the tooth surfaces with erosion. Of the affected tooth surfaces, 69.3% had greater than one-half of the tooth surface was affected. The results from logistic regression analysis demonstrated that the children who were female, consumed carbonated drinks once a week or more, and those whose mothers were educated to the primary level tended to have more dental erosion. CONCLUSIONS: Dental erosion in 12-13-year-old Chinese school children is becoming a significant problem. A strategy of offering preventive care, including more campaigns promoting a healthier lifestyle for those at risk of dental erosion should be conducted in Chinese children and their parents.

Effect of histone demethylase KDM5A on the odontogenic differentiation of human dental pulp cells.

Human dental pulp cells (hDPCs) possess the capacity to differentiate into odontoblast-like cells in response to exogenous stimuli. Histone methylation is one of the most robust epigenetic marks and is essential for the regulation of multiple cellular processes. Previous studies have shown that histone methyltransferases (HMTs) and histone demethylases (HDMs) are crucial for the osteogenic differentiation of human bone marrow, adipose tissue, and tooth tissue. However, little is known about the role of histone methylation in hDPC differentiation. Here, the expression levels of HMTs and HDMs were profiled in hDPCs undergoing odontogenic induction. Among several differentially expressed enzymes, HDM KDM5A demonstrated significantly enhanced expression during cytodifferentiation. Furthermore, KDM5A expression increased during early passages and in a time-dependent manner during odontogenic induction. Using a shRNA-expressing lentivirus, KDM5A was knocked down in hDPCs. KDM5A depletion resulted in greater alkaline phosphatase activity and more mineral deposition formation. Meanwhile, the expression levels of the odontogenic markers DMP1, DSPP, OSX, and OCN were increased by KDM5A knockdown. As a histone demethylase specific for tri- and dimethylated histone H3 at lysine 4 (H3K4me3/me2), KDM5A deficiency led to a significant increment in total H3K4me3 levels, whereas no significant difference was found for H3K4 me2. H3K4me3 levels on the promoters of the odontogenic markers increased after KDM5A knockdown in hDPCs. These results demonstrated that KDM5A is present in hDPCs and inhibits the odontogenic differentiation potentiality of hDPCs by removing H3K4me3 from specific gene promoters, suggesting that KDM5A-dependent histone demethylation may play an important role in reparative dentinogenesis.

The 4th National Oral Health Survey in the Mainland of China: Background and Methodology.

Oral disease patterns change over time and it is important to conduct epidemiological surveillance population surveys regularly to monitor the situation. The overall objectives of the present survey were: (1) to describe the oral health status of Chinese children and adults in the 2015-2016 4th National Oral Health Survey; (2) to investigate the oral health knowledge, attitudes, and behaviours among children and adults; (3) to explore the association among sociodemographic characteristics, oral health behaviours, and the oral health status of Chinese children and adults. A national oral health survey was conducted among a representative sample of Chinese children and adults. Local residents from the five age groups - 3 to 5 years, 12 to 15 years, 35 to 44 years, 55 to 64 years, and 65 to 74 years - were selected. A multi-stage cluster sampling method was adopted for the identification of participants. All 31 provinces, autonomous regions and municipalities of the mainland of China were included. All participants were clinically examined and information on their oral health status, including oral mucosal lesions, dental caries experience, periodontal health status, dental fluorosis, and dental prosthesis status, was collected according to the procedures and criteria recommended by the World Health Organization (WHO). A calibration training programme and quality control procedures were conducted to ensure the reliability of the findings. Information on sociodemographic background, oral health behaviours, knowledge and attitude was also collected from all five age groups through a questionnaire survey.

Dental Caries Status and its Associated Factors among 3- to 5-year-old Children in China: A National Survey.

OBJECTIVE: To investigate the prevalence and severity of dental caries among pre-school children in China as part of the 4th National Oral Health Survey. METHODS: The sampling process was conducted with a multistage stratified cluster method. A total of 40,360 children aged between 3 and 5 years were recruited for this study. Each participant was clinically assessed according to the 5th edition of the oral health survey's basic methods recommended by the World Health Organization (WHO) and their parents or grandparents completed a questionnaire at a face-to-face interview. The status of dental caries was shown in the form of the mean dmft and the prevalence of dental caries. The logistic regression analysis was performed to study the relationships between the prevalence of dental caries and the selected variables. RESULTS: The prevalence of dental caries was 50.8%, 63.6% and 71.9% for 3-, 4- and 5-year-olds, respectively. The mean dmft was 2.28, 3.40 and 4.24, respectively. Logistic regression analysis showed that children who were mixed-fed had a higher chance of staying free of dental caries; children who had dessert before going to bed were associated with a higher probability of caries. CONCLUSION: The status of dental caries among preschool children in China is on the increase. The preschoolers' dental caries status related to their breastfeeding conditions within the first 6 months of life and their snacking habits.