The association between edentulism and progress of multimorbidity over 12 years among older American adults.

OBJECTIVES: To examine the relationship between edentulism and the progress of multimorbidity, and the role of nutritional intake and behaviours among older Americans. METHODS: We used 7 waves (2006-2018) of the Health and Retirement Study, a longitudinal survey of older Americans (number included in analysis 2,224). Edentulism was assessed in 2006 and 2012. Multimorbidity was indicated by 5 self-reported conditions: diabetes, heart conditions, lung diseases, cancer, and stroke. Behavioural factors were smoking, excessive alcohol consumption, physical activity, and body mass index. Nutritional intake was calculated by summing 10 nutrients (Protein, Vitamins C, D, B12, E, Calcium, Zinc, Polyunsaturated fatty acids, Folate and ß- carotene). Multilevel models for analysis of longitudinal data were used to assess the association between change in repeated measures of multimorbidity (between 2006 and 2018) and edentulism (2006) adjusting for nutritional intake, behavioural and socioeconomic factors. RESULTS: Participants who were edentate in 2006 and 2012 had higher rate-ratios (RR) for change in multimorbidity between 2006 to 2018 (RR: 1.29 and 1.28, respectively). After adjusting for socioeconomic factors, total nutrients and behavioural factors, these RR attenuated to 1.12 (95%CI: 1.06, 1.18) and 1.10 (95%CI: 1.05, 1.16), respectively. Total nutrition was negatively associated with progress of multimorbidity, but after adjusting for socioeconomic and behavioural factors the association became insignificant. Total nutrients rates in 2013 were significantly lower among those who were edentate in 2006 and 2012. CONCLUSION: There was a longitudinal association between edentulism and progress of multimorbidity. The relationship appeared to be mediated be behaviours and nutrition.

Mesenchymal Stem Cells Treatment Aggravates Tumor Growth Regardless Its Route of Administration: An In vivo Study.

OBJECTIVES: to clarify the effect of MSCs in cancer growth and to detect whether the rout of administration (either locally inside the tumor tissue or systemic )could affect the outcome of treatment or not. METHODS: Eighteen female mice were involved in the study. All mice were subcutaneously inoculated with Ehrlich tumor cells into the right flank. After three week of tumor growth; the mice were divided randomly in to three groups six mice for each ; group I: untreated Erlish tumor group; group II: Erlish tumor treated by local injection of 1 x106 MSCs/week inside the tumor tissue, group III: Erlish tumor treated by systemic injection of 1 x106 MSCs iv in tail vein/week. Tumor growth was recorded .After 4 weeks of stem cells injection, all rats were sacrificed by cervical dislocation and tumor tissues were collected for histopathological study. inflammatory cytokine TNF was assessed by ELISA, lncRNA MALAT ,NFKB and MMP2 genes expression were assessed by Quantitative RT-PCR. RESULTS: Erlish tumor was developed as a well-defined capsule composed by connective tissue infiltrated by inflammatory and neoplastic cells surrounded the tumors. The tumor growth regarding size and weight of tumor tissue was significantly aggravated after both local and systemic treatment MSCs (p value =0.007, 0.001) respectively. Inflammatory cytokines  TNF and NFKB were significantly elevated (p value <0.0001), lncRNA MALAT, MMP2 expressions were significantly induced (p value <0.0001), after MSCs treatment with more significant increase in those treated by local intratumor injection of MSCs compared to those treated by systemic MSCs(p value <0.0001). CONCLUSION: Ehrlich tumor model is feasible and easily monitored tumor model. Although MSCs have anti-inflammatory effect and the ability to regenerate the damaged tissue; it could aggravate tumor growth as it exploited by cancer cells for behave of tumor cells.

Is the inability to afford dental care associated with untreated dental caries in adults?

OBJECTIVE: To assess whether inability to afford dental care is associated with the number of teeth with untreated dental caries and whether this association is independent of socioeconomic factors and ethnicity. BASIC RESEARCH DESIGN: Data were from the National Health and Nutrition Examination Survey (NHANES) (2015-2018), a cross-sectional national survey of non-institutionalised Americans. CLINICAL SETTING: The survey included clinical assessment of tooth condition, data on sociodemographic factors, use of dental services, health insurance, number of teeth and affordability of dental care when needed. PARTICIPANTS: The analysis included 9,440 participants aged 18 years and over. MAIN OUTCOME MEASURES: The association between number of teeth with untreated caries and affordability of dental care was assessed adjusting for age, gender, ethnicity, income, education, dental visits, and health insurance. RESULTS: The mean number of teeth with untreated caries was 0.51, and 13% reported inability to afford care. Mean numbers of teeth with untreated caries among those unable and able to afford dental care were 1.46 and 0.36, respectively. In the fully adjusted model, the rate ratio for teeth with caries among those who could not afford dental care was 2.45 (95% Confidence Intervals 'CI': 2.04, 2.95). Income and education inequalities were slightly attenuated after accounting for inability to afford care. Other statistically significant predictors included education, and irregular dental visits. CONCLUSION: Inability to afford dental care may exacerbate inequalities in dental caries. The findings highlight the need for affordable access to dental services.

Is the inability to afford dental care associated with untreated dental caries in adults?

OBJECTIVE: To assess whether inability to afford dental care is associated with the number of teeth with untreated dental caries and whether this association is independent of socioeconomic factors and ethnicity. BASIC RESEARCH DESIGN: Data were from the National Health and Nutrition Examination Survey (NHANES) (2015-2018), a cross-sectional national survey of non-institutionalised Americans. CLINICAL SETTING: The survey included clinical assessment of tooth condition, data on sociodemographic factors, use of dental services, health insurance, number of teeth and affordability of dental care when needed. PARTICIPANTS: The analysis included 9,440 participants aged 18 years and over. MAIN OUTCOME MEASURES: The association between number of teeth with untreated caries and affordability of dental care was assessed adjusting for age, gender, ethnicity, income, education, dental visits, and health insurance. RESULTS: The mean number of teeth with untreated caries was 0.51, and 13% reported inability to afford care. Mean numbers of teeth with untreated caries among those unable and able to afford dental care were 1.46 and 0.36, respectively. In the fully adjusted model, the rate ratio for teeth with caries among those who could not afford dental care was 2.45 (95% Confidence Intervals 'CI': 2.04, 2.95). Income and education inequalities were slightly attenuated after accounting for inability to afford care. Other statistically significant predictors included education, and irregular dental visits. CONCLUSION: Inability to afford dental care may exacerbate inequalities in dental caries. The findings highlight the need for affordable access to dental services.

Mesenchymal stem cells enhance AQP1 expression in the sublingual salivary gland of ovariectomized menopausal rat model.

BACKGROUND: Ovariectomized menopausal rat model was used to investigate the effects of menopause on the sublingual salivary gland (SSG) and the potential therapeutic effect of human umbilical cord blood mesenchymal stem cells (hUCB-MSCs). METHODS: Thirty rats were equally divided into three groups: sham-operated (SHAM), ovariectomized (OVX), and ovariectomized stem cells injected (OVX+ hUCB-MSCs). Expressions of α-SMA, AQP1, Sca-1, PCNA, ssDNA, and caspase-3 were determined. Homing of hUCB-MSCs was detected by fluorescence microscopy and examination of immunostained sections for human CD105 and CD34 was performed. Morphometric data were statistically analyzed using the Kruskal-Wallis test followed by Scheffé's method. Correlation of AQP1 with Sca-1-positive sublingual stem cells was also analyzed. RESULTS: In the SSGs of the OVX group, ballooned mucus acinar cells, atrophied serous cells, and a decreased number and height of duct lining cells were observed. The interstitial spaces were edematous, and the blood vessels were congested. The significant decrease in the positive area % of α-SMA and AQP1, the number of Sca-1-positive sublingual stem cells, and proliferating cells was associated with a significant increase in apoptotic cells. The OVX+hUCB-MSCs group showed significant structural improvement, manifested by the normal appearance of mucus and serous acini, as well as the number and height of striated duct cells. A significant increase in the positive area % of α-SMA and AQP1 and the number of proliferating and Sca-1-positive sublingual stem cells was observed. Interestingly, a significantly positive Pearson's correlation between the area % of AQP1 and the number of Sca-1-positive sublingual stem cells was also recorded. CONCLUSION: Our results indicated a positive effect of hUCB-MSCs therapy for SSG pathology in a post ovariectomy rat model as evidenced by an improvement in the histologic architecture, upregulation of the immunostained area % of α-SMA and AQP1, increase in the number of Sca-1-positive sublingual stem cells and proliferating cells, and downregulation of apoptotic cells.

Association between Oral Health and Frailty among Older Adults in Madinah, Saudi Arabia: A Cross-Sectional Study.

OBJECTIVES: This study aimed to examine the association between normative and subjective oral health indicators and frailty assessed by Frailty Phenotype (FP) and frailty index (FI) among older Saudi adults. DESIGN: cross-sectional study. SETTING: community and hospital-based. PARTICIPANTS: participants were 356 community-dwelling older adults attending dental clinics and social centres at Madinah, Saudi Arabia. METHODS: Frailty was measured with the frailty phenotype and a 34-item FI. Oral health included the following measures: self-rated oral health, number of teeth, and functional dentition. Covariates included sociodemographic factors and nutritional status. Logistic regression and negative binomial regression models were constructed to test the association between oral health indicators, FP, and FI, respectively. The first model was adjusted for demographic and socioeconomic factors, the second model was additionally adjusted for nutritional status. RESULTS: The number of teeth, functional dentition and self-rated oral health showed significant associations with frailty after adjusting for demographic and socioeconomic variables for both FP and FI. Adjusting for nutritional status attenuated the associations. CONCLUSION: This study has shown significant associations between oral health indicators namely number of teeth, functional dentition and self-rated oral health, and both FP and FI among Saudi older adults. Nutritional status appeared to mediate the association between oral health and frailty implicating inability to eat in this relationship.

Biochemical and histological study on the effect of levetiracetam on the liver and kidney of pregnant albino rats.

BACKGROUND: Levetiracetam is a broad-spectrum antiseizure agent and one of the most commonly prescribed drugs for epilepsy. The aim of this work was to assess the effect of levetiracetam at its therapeutic range on the liver and kidney of pregnant albino rats. MATERIALS AND METHODS: Forty pregnant rats were divided equally into two groups (I-II), Rats in the group I were gavaged 1.5 mL/day distilled water in two divided doses throughout pregnancy. Rats in the group II were gavaged 1.5 mL/day distilled water (containing 36 mg levetiracetam) in two divided doses throughout pregnancy. At the end of the experiment, blood samples were taken and the sera were separated and used for biochemical analysis. The kidneys and livers of both groups were excised and used for light and electron microscopic examination. RESULTS: Treatment with levetiracetam induced undesirable histopathological changes in the liver and kidney of pregnant albino rats. These changes were in the form of distortion of the hepatic architecture, dilatation of the central and the portal veins, widening of the Bowman's spaces, thickening and disruption of the glomerular basement membrane, fusion and effacement of secondary foot processes, cytoplasmic vacuolation, and swollen mitochondria with loss of their cristae. Such changes were confirmed by alteration of certain biochemical parameters related to the liver and kidney functions. CONCLUSIONS: Levetiracetam induced deleterious effects on the liver and kidney of pregnant albino rats. Further investigations are recommended to clarify the mechanism of levetiracetam toxicity.

The relationships among consumption of fruits, tooth loss and obesity.

OBJECTIVE: to explore whether consumption of fruits attenuates the relationship between tooth loss and obesity among adult Americans. BASIC RESEARCH DESIGN: data from the Behavioral Risk Factor Surveillance System 2012, a cross-sectional survey. PARTICIPANTS: 20,103 adults aged 18 and over who participated in the Behavioral Risk Factor Surveillance System 2012, a nationally representative survey of non-institutionalized adult American. MAIN OUTCOME MEASURES: Obesity (Body Mass Index ≥ 30 kg/m²). Logistic regression analysis was used to assess the association between obesity and number of missing teeth adjusting for consumption of fruits socio-demographic factors, physical activity, diabetes and self-rated general health. RESULTS: The prevalence of obesity was higher among adults with ⟩ 6 missing teeth and among those with fruit intakes less than once a day. Individuals with ⟩ 6 missing teeth were at higher risk of obesity with odds ratios 1.25 (95% CI: 1.04, 1.50), the relationship attenuated after adjusting for fruit consumption. CONCLUSIONS: Frequent consumption of fruits was inversely associated with each of obesity and number of missing teeth. The findings imply a mediating role of fruit consumption in the relationship between tooth loss and obesity.

Professional Aspirations and Cultural Expectations: A Qualitative Study of Saudi Females in Dentistry.

The aim of this study was to explore the perceptions of Saudi female dentists and dental students on their motivation for and expectations of a career in dentistry. Twenty-one semistructured interviews were conducted with a purposive sample of Saudi female dentists (postgraduate students, generalists, specialists, academics, and unemployed), along with final-year female dental students from public and private dental schools. A topic guide, informed by the literature and piloted on a representative group of Saudi dentists, was used to guide the discourse. Interviews were recorded, transcribed verbatim, and then analyzed using framework analysis. We found that highly academic achieving females are interested in a prestigious, financially rewarding career in health care that fulfills their family and community expectations of balancing family life with work. Features of the job that facilitate this balance such as regular hours and no on-call were commonly important. A range of professional interests, most importantly specialization and holding academic positions, often involving studying abroad, emerged. Females' movement between sectors, location of work, and practice patterns in this study were shaped by their domestic circumstances. The findings suggest that Saudi females in dentistry aspire to fulfill their interest in a successful, professional, highly prestigious, progressive career while recognizing cultural expectations and maintaining a family-work balance and perceive this is possible through a career in dentistry. Knowledge Transfer Statement: This study makes an important contribution to the knowledge on this topic. The findings can inform decisions made by policy makers on dental education and workforce planning, as well as future dentists who plan to join the dental workforce. It gives insight into the motivation and career expectations of Saudi females in dentistry in light of the current economic and cultural changes, as well as their implication for the dental workforce.

Socioeconomic inequality in the provision of specific preventive dental interventions among children in the UK: Children's Dental Health Survey 2003.

Aim To assess socioeconomic inequality regarding specific preventive interventions (fissure sealants or any treatment to prevent caries) and dental visits among UK children.Method Data were from the Children's Dental Health Survey 2003, which included participants from England, Wales, Scotland, and Northern Ireland. The number of children in the analysis was 2,286. Variables were sex, age, area of residency (for example, England), mother's education, family social class, and deprivation level. Descriptive and regression analyses were performed.Results There were no significant socioeconomic differences in the use of preventive services. Deprivation and family social class (for example, intermediate and manual) were significantly associated with less regular dental visits (odd ratio 0.41, 95% CI [0.28, 0.63]; odd ratio 0.53, 95% CI [0.31, 0.89]; odd ratio 0.37, 95% CI [0.24, 0.58], respectively). Regular dental visits were associated with reporting preventive care for caries (odds ratio 2.25, 95% CI [1.45, 3.49]) and with the number of sealed tooth surfaces (rate ratio 1.73, 95% CI [1.16, 2.60]).Conclusion Despite apparent socioeconomic inequalities in regular dental visits, there was no significant inequality in using specific preventive interventions by children in the UK. This finding should be interpreted with caution considering the relatively small subsample included in this analysis.

Birth Weight, Breastfeeding, Maternal Smoking and Caries Trajectories.

Evidence for the effects of low birth weight, breastfeeding and maternal smoking on childhood caries is mainly cross-sectional. We examined the association of these 3 putative early life factors with caries increment over a 4-y period among young children. We used data from a 4-y longitudinal caries-risk assessment study carried out among Scottish children. Early life factors were measured when children were aged 1 y (baseline). Caries assessment was repeated annually from ages 1 to 4, and the number of decayed, missing and filled primary tooth surfaces (dmfs) were used as a repeated outcome measure. The associations of low birth weight, breastfeeding and maternal smoking with dmfs at baseline and over time (trajectories) were assessed in linear mixed models. A total of 1,102 children were included in this analysis. Birth weight, breastfeeding and maternal smoking were not associated with dmfs at baseline. However, low birth weight and maternal smoking were associated with the rate of change in dmfs. By wave 4, the predicted mean difference in dmfs was 1.86 between children with low and normal birth weight, and 1.66 between children of smoking and non-smoking mothers. Children with low birth weight and smoking mothers had greater caries increments than those with normal weight and non-smoking mothers, respectively. There was no association between breastfeeding duration and childhood caries, either at baseline or over time.

Inequalities in preventive and restorative dental services in England, Wales and Northern Ireland.

Aims The objective of this study is to assess socioeconomic inequalities in the use of selected dental procedures.Methods Data is from the Adult Dental Health Survey 2009, a nationally representative cross-sectional survey of England, Northern Ireland and Wales. Overall, 6,279 participants were included in the analysis. Occupational classification and education were used to assess variations in the use of preventive, restorative services and tooth extraction using a series of logistic regression models, adjusting for age, sex, ethnicity, DMFT, self-reported oral health, dental visits and country.Results There were clear socioeconomic variations in the utilisation of preventive and restorative services. In the fully adjusted model those with no educational qualification were less likely to report ever having preventive services than those with a degree (OR 0.48, 95%CI: 0.36,0.65). Similarly, individuals in routine/manual occupation were significantly less likely to report ever having preventive services than those in managerial/professional occupation (OR 0.58, 95%CI: 0.46,0.74) in the fully adjusted model.Conclusion The findings imply that despite relatively equitable access and higher use of dental services in UK, the least educated and those at the bottom of social hierarchy are less likely to have preventive and restorative dental services.

Review of never and serious events related to dentistry 2005-2014.

Aims To review never and serious events related to dentistry between 2005-2014 in England.Methods Data from the National Reporting and Learning System (NRLS), with agreed data protection and intelligence governance, was used - snapshot view using the timeframe January 2005 to May 2014. The Strategic Executive Information System (STEIS) database was reported separately for 2012-2013 and 2013-2014. The free text elements from the database were analysed thematically and reclassified according to the nature of the patient safety incident (PSI).Results From the NRLS dataset, 32,263 patient safety events were reported between 1 January 2005 and 30 May 2014. Never events (NEs) from STEIS files were all wrong site extractions (WSS), reported separately for 2012-2013 and 2013-2014. The total number was 43.36 of the 43 PSIs were WSS involving: multiple extractions and bimodal age distribution (very young or over 60 years). Forty-seven percent of never events resulted in no harm, 20% low harm, 7% moderate harm, less than 1% severe harm and 23 deaths over this period (five of which were not related to dentistry). Serious harm and death risk factors included: care in an acute trust ward, peri oncological, reconstructive surgery (OMFS), patient age over 67 years with concurrent medical complexity (Ischaemic heart disease). Sixty percent of PSIs occurred in OS/OMFS in acute trust inpatients and 20% in primary care. From STEIS 2012-2013, 21 WSS were reported of which 50% occurred in oral surgery (OS) or oral and maxillofacial surgery (OMFS). The reported sites were 45% in operating theatre and 42% in dental surgery.Conclusion Incidences of iatrogenic harm to dental patients do occur but their reporting is not widely carried out. Improved awareness and training, simplifying the reporting systems improved non-punitive support by regulators would allow the improvement of patient safety in dental practise.

Association between child caries and maternal health-related behaviours.

OBJECTIVE: To examine the association between 2-6 year-olds' caries experience and selected maternal oral and general health-related behaviours in an American sample. METHODS: Data pertaining to 917 child/mother pairs was from the Third National Health and Nutrition Examination Survey 1988-1994. Child caries experience was indicated by the presence of one or more decayed or filled tooth. Data on maternal smoking, frequency of dental visits, consumption of unhealthy food and oral hygiene was linked to children data using the natality file. An aggregate behavioural variable was created. Logistic Regression models were used to assess the association between child caries experience and maternal behaviours adjusting for child's age, gender, ethnicity, dental visits and mother's age, education and poverty-income ratio. RESULTS: All four maternal behaviours were significantly associated with child caries in fully adjusted models with odds ratios 1.42 (95% CI: 1.01,2.01) for current smokers versus non-smokers, 1.01 (95% CI: 1.01,1.02) for frequent consumption of unhealthy food, 1.63 (95% CI: 1.15,2.31) for infrequent dental visits, and 2.49 (95% CI: 1.44,4.29) for poor oral hygiene. CONCLUSIONS: The results indicate that children's caries experience is related to a number of maternal behaviours including behaviours not directly related to caries such as smoking. Maternal oral and general health-related behaviours should be incorporated in children's caries risk assessment and in behaviour changing interventions provided in dental practice to improve children's oral health.

Relationship between family characteristics and children's regular toothbrushing with fluoride toothpaste.

OBJECTIVE: To examine the association between toothbrushing habits of 8-9 year-olds and maternal behaviours and attitudes towards oral health in a sample of Japanese population. METHODS: Cross-sectional data on mothers' behaviours and attitudes towards oral health and children's toothbrushing habits were collected from 378 mother-child pairs by self-administered questionnaires. Logistic regression examined the association of children's daily brushing with fluoride toothpaste with family characteristics, mother's behaviour (toothbrushing frequency, use of interdental aids and supervision of children's toothbrushing), and mother's attitudes towards oral health (priority for toothbrushing and dental fear). RESULTS: Children's favourable brushing habits were positively associated with child's gender (female) (OR 1.29; 95%CI:1.09,1.53), child's order of birth (first) (OR 1.53; 95%CI:1.05,2.23), maternal brushing habits (OR 2.42; 95%CI:1.73,3.40), and maternal dental fear (OR 1.45; 95%CI:1.10,1.90). None of the other examined factors were significantly associated with child toothbrushing behaviour. CONCLUSIONS: Matemal oral hygiene practice and attitude towards dentists appear to be important predictors of children's toothbrushing habits in this Japanese community sample.

Relationship between periodontal status and levels of glycated hemoglobin.

The objective of this study was to assess whether there is a bi-directional relationship between periodontal status and diabetes. Study 1 included 5,856 people without periodontal pockets of ≥ 4 mm at baseline. Relative risk was estimated for the 5-year incidence of periodontal pockets of ≥ 4 mm (CPI scores 3 and 4, with the CPI probe), in individuals with glycated hemoglobin (HbA1c) levels of ≥ 6.5% at baseline. Study 2 included 6,125 people with HbA1c < 6.5% at baseline. The relative risk was assessed for elevation of HbA1c levels in 5 years, with baseline periodontal status, assessed by CPI. Relative risk of developing a periodontal pocket was 1.17 (p = 0.038) times greater in those with HbA1c of ≥ 6.5% at baseline, adjusted for body mass index (BMI), smoking status, sex, and age. Relative risks for having HbA1c ≥ 6.5% at 5-year follow-up in groups with periodontal pockets of 4 to 5 mm and ≥ 6 mm at baseline were 2.47 (p = 0.122) and 3.45 (p = 0.037), respectively, adjusted for BMI, alcohol consumption, smoking status, sex, and age. The risk of developing periodontal disease was associated with levels of HbA1c, and the risk of elevations of HbA1c was associated with developing periodontal pockets of more than 4 mm.

Five-year incidence of periodontal disease is related to body mass index.

Numerous cross-sectional epidemiological studies suggest that obesity is associated with periodontal disease. This longitudinal study tested whether body mass index (BMI) was related to the development of periodontal disease in a sample of employed Japanese participants. Data are from the statutory medical checkups routinely collected for employees in and around Nagoya, Japan. The authors tested the relationship between BMI at baseline and the 5-year incidence of periodontal disease in a sample of 2787 males and 803 females. The hazard ratios for developing periodontal disease after 5 years were 1.30 (P < .001) and 1.44 (P = .072) in men and 1.70 (P < .01) and 3.24 (P < .05) in women for those with BMIs of 25-30 and ≥ 30, respectively, compared to those with BMI < 22, after adjusting for age, smoking status, and clinical history of diabetes mellitus. These findings demonstrate a dose-response relationship between BMI and the development of periodontal disease in a population of Japanese individuals.

Using universal patterns of caries for planning and evaluating dental care.

There are universal patterns of caries, in terms of prevalence, incidence, frequency distribution and rates of progression, in permanent teeth that can be considered working rules that can be applied when planning dental care. The universal patterns are: (1) caries levels follow trend lines; therefore, knowing the caries level at one age can be used to predict the levels at later ages in that cohort by looking at the trend line for that cohort; (2) the distribution of dental caries of a population exhibits the following characteristics: as the mean DMFT increases, the percentage of caries-free individuals falls and the caries distribution widens; this changing relationship between the mean DMFT and prevalence is not limited to a subgroup of the population who already have had some caries experience; (3) there is a specific mathematical relationship between the mean DMFT and mean DMFS; (4) there is a hierarchy of caries susceptibility by tooth type and sites on teeth; for a given DMFT or DMFS, there is a specific intra-oral pattern of caries by tooth type; (5) changes in mean DMFT scores for individuals and groups are not linear, but 'stepped'; there are groupings of teeth and tooth sites that may have similar 'resistance' to caries; (6) as the mean DMFT declines, the posteruptive time for initiation of caries increases and the progression rate of caries through enamel decreases. This is true regardless of the presence of fluoride. Any improvement in dental health will cause this effect.

Income, income inequality, dental caries and dental care levels: an ecological study in rich countries.

Research has shown that beyond a certain level of absolute income, there is a weak relationship between income and population health. On the other hand, relative income or income inequality is more strongly related to health than absolute income in rich countries. The objective of this study was to assess the relationships of income and income inequality with dental caries and dental care levels in 35- to 44-year-old adults among rich countries. Income was assessed by gross domestic product and gross national income, income inequality by Gini coefficient and the ratio between the income of the richest and poorest 20% of the population, dental caries by DMFT and dental care levels by the care, restorative and treatment indices. Pearson and partial correlation were used to examine the relationships between income, income inequality, caries experience and dental care. Income measures were not related to either dental caries or dental care levels. However, income inequality measures were inversely and significantly related to number of filled teeth, DMFT, care index and restorative index, but not to number of decayed or missing teeth. It is concluded that DMFT scores were higher in more equal countries and may be explained by greater levels of restorative care in those countries.

The role of cognitive ability in socio-economic inequalities in oral health.

Studies have postulated a role for cognitive ability in socio-economic inequalities in general health. This role has not been examined for oral health inequalities. We examined whether cognitive ability was associated with oral health, and whether it influenced the relationship between oral health and socio-economic position. Data were from the Third National Health and Nutrition Examination Survey (1988-1994), for participants aged 20-59 years. Oral health was indicated by extent of gingival bleeding, extent of loss of periodontal attachment, and tooth loss. Simple reaction time test, symbol digit substitution test, and serial digit learning test indicated cognitive ability. Education and poverty-income ratio were used as markers of socio-economic position. Participants with poorer cognitive ability had poorer oral health for all indicators. The association between oral health and socio-economic position attenuated after adjustment for cognitive ability. Cognitive ability explained part, but not all, of the socio-economic inequalities in oral health.