Diagnostic accuracy of tele-dentistry in screening children for dental caries by community health workers in a lower-middle-income country.

BACKGROUND: Tele-dentistry can be useful for dental caries screening of children, especially in lower-middle-income countries (LMICs). AIM: To evaluate the diagnostic accuracy of mobile phone photographs taken by a community health worker (CHW) for caries detection in Iran. DESIGN: Children aged 6-12 years were visually examined by a paediatric dentist. Following dental examinations, intraoral photographs were taken by a trained CHW. Two remote dentists assessed intraoral photographs for dental caries. Diagnostic accuracy of tele-dentistry for caries detection was evaluated. In addition, the questionnaire about oral health and parents' views towards tele-dentistry was prepared. RESULTS: One hundred thirty-one children aged 8.74 ± 1.62 years participated. The caries prevalence was 30% for the whole dentition. Tele-dentistry demonstrated high accuracy, with a sensitivity exceeding 80% and specificity exceeding 90%. The inter-rater reliability for remote dentists' assessments to the gold standard dental examination ranged from substantial to almost perfect (kappa: 75%-93%). Additionally, 80% of parents whose children participated in this study had positive views towards tele-dentistry. CONCLUSION: Tele-dentistry was shown to be an alternative approach to clinical examinations for caries detection among school children. Employing non-dental care professionals in tele-dentistry has been emerged as a reliable and cost-effective approach, especially in LMICs.

Parental acceptance of Silver Diamine Fluoride in two lower-middle-income countries: Iran and Tajikistan.

BACKGROUND: Using Silver Diamine Fluoride (SDF) may be an effective public health approach for managing dental caries in children. Parental acceptance of SDF has rarely been investigated in low-income and middle-income countries (LMICs). The aim of this study was to evaluate parental acceptance of SDF to manage dental caries in children aged 2-12 in Iran and Tajikistan. METHODS: This cross-sectional study was conducted in the Kurdistan province of Iran and Khatlon region of Tajikistan, 2022-2023. Parents watched a video about SDF and its weaknesses and strengths as compared to conventional approaches before completing the questionnaire. We also reported Prevalence Ratios with 95% confidence intervals for the relationship between parental acceptance and associated demographic factors as well as dental attitude and experience. RESULTS: Participants were 245 and 160 parents in Iran and Tajikistan, respectively. In both countries, a majority (Iran: 61.6%, Tajikistan: 77.9%) accepted SDF over conventional treatments for all primary teeth. The majority also accepted SDF only for posterior permanent teeth (Iran: 73.5%, Tajikistan: 78.7%). Black discoloration was the main reason for rejecting SDF. Overall, demographic factors and dental experience and attitude were not significantly associated with SDF acceptance. CONCLUSIONS: SDF was widely accepted by Iranian and Tajik parents. Establishing parental acceptance of SDF is an important step toward its application in LMICs where inexpensive solutions are needed.

Food insecurity and dental caries prevalence in children and adolescents: A systematic review and meta-analysis.

BACKGROUND: Food insecurity (FI) is associated with dietary practices, which can act as a risk factor for dental caries. AIM: This study aimed to investigate the relationship between FI and dental caries prevalence in children and adolescents. DESIGN: MEDLINE (via PubMed), EMBASE, SCOPUS, ISI web of knowledge, Cochrane, and ProQuest Dissertations & Theses Global database (up to April 19, 2022) as well as reference lists were searched. Eligible studies compared dental caries prevalence in food-secure and food-insecure individuals younger than 19 years. Two independent reviewers performed study selection, data extraction, and risk of bias assessment using a modified Newcastle-Ottawa Scale. Meta-analysis was performed, and the pooled odds ratio (OR) was calculated at 95% confidence interval (95% CI). RESULTS: Among the 1350 retrieved records, 10 cross-sectional reports were selected for systematic review. Six studies involving 8631 participants were included in the meta-analysis. More than half of the reports were published within the period 2019-2021. All studies except one were judged as low risk of bias. Overall, the prevalence of dental caries was greater among the food-insecure children and adolescents (OR: 2.01, 95% CI: 1.52-2.65, p < .001, I2 : 73.5%). Similarly, all three categories of FI were significantly associated with caries experience (marginal FI: OR: 1.88, 95% CI: 1.56-2.27, p < .001, I2 : 0.0%; low FI: OR: 2.42, 95% CI: 1.42-4.14, p = .001, I2 : 74.4%; very low FI: OR: 2.37, 95% CI: 1.88-3.00, p < .001, I2 : 0.0%). CONCLUSION: The results showed a significant association between FI status and dental caries in both childhood and adolescence; however, there was a lack of longitudinal studies for a better understanding of this association. Health policies leading to reduction in FI may also aim to reduce dental caries.

Providing dental insurance can positively impact oral health outcomes in Ontario.

BACKGROUND: Universal coverage for dental care is a topical policy debate across Canada, but the impact of dental insurance on improving oral health-related outcomes remains empirically unexplored in this population. METHODS: We used data on individuals 12 years of age and older from the Canadian Community Health Survey 2013-2014 to estimate the marginal effects (ME) of having dental insurance in Ontario, Canada's most populated province (n = 42,553 representing 11,682,112 Ontarians). ME were derived from multi-variable logistic regression models for dental visiting behaviour and oral health status outcomes. We also investigated the ME of insurance across income, education and age subgroups. RESULTS: Having dental insurance increased the proportion of participants who visited the dentist in the past year (56.6 to 79.4%, ME: 22.8, 95% confidence interval (CI): 20.9-24.7) and who reported very good or excellent oral health (48.3 to 57.9%, ME: 9.6, 95%CI: 7.6-11.5). Compared to the highest income group, having dental insurance had a greater ME for the lowest income groups for dental visiting behaviour: dental visit in the past 12 months (ME highest: 17.9; 95% CI: 15.9-19.8 vs. ME lowest: 27.2; 95% CI: 25.0-29.3) and visiting a dentist only for emergencies (ME highest: -11.5; 95% CI: - 13.2 to - 9.9 vs. ME lowest: -27.2; 95% CI: - 29.5 to - 24.8). CONCLUSIONS: Findings suggest that dental insurance is associated with improved dental visiting behaviours and oral health status outcomes. Policymakers could consider universal dental coverage as a means to support financially vulnerable populations and to reduce oral health disparities between the rich and the poor.

Childhood obesity and dental caries: an ecological investigation of the shape and moderators of the association.

BACKGROUND: Despite sharing a common risk factor in dietary sugars, the association between obesity and dental caries remains unclear. We investigated the association between obesity and dental caries in young children in England in an ecological study. METHODS: We analysed data from 326 lower tier English local authorities. Data on obesity and dental caries were retrieved from 2014/15 to 2016/17 National Child Measurement Programme and 2016/17 National Dental Epidemiology Programme. We used fractional polynomial models to explore the shape of the association between obesity and dental caries. We also examined the modifying effect of deprivation, lone parenthood, ethnicity, and fluoridation. RESULTS: Best fitting second order fractional polynomial models did not provide better fit than the linear models for the association between obesity and prevalence and severity of dental caries; therefore, the linear model was found suitable. Despite significant association, after adjusting for the effect of deprivation, obesity was neither associated with prevalence (coefficient = 0.2, 95% CI - 0.71, 0.75), nor with severity (coefficient = 0.001, 95% CI - 0.03, 0.03) of dental caries. In fully adjusted models, the proportion of white ethnicity and being in fluoridated areas were associated with a decrease in dental caries. The association between obesity and dental caries was moderated by the effect of deprivation, white ethnicity, and lone parenthood. CONCLUSIONS: The association between obesity and dental caries was linear and moderated by some demographic factors. Consequently, interventions that reduce obesity and dental caries may have a greater impact on specific groups of the population.

MALOCCLUSION, PAST ORTHODONTIC TREATMENT, AND SATISFACTION WITH DENTAL APPEARANCE AMONG CANADIAN ADULTS.

OBJECTIVE: To examine whether malocclusion and past orthodontic treatment are associated with satisfaction with dental appearance among Canadian adults. METHODS: Using data from the 2007-09 Canadian Health Measures Survey, this cross-sectional study analyzed information from 2184 respondents (1005 men and 1179 women) aged 20-59 years. The outcome variable was satisfaction with dental appearance. Ordinal logistic regression was used to investigate the relation between satisfaction with dental appearance and 2 independent variables: malocclusion and past orthodontic treatment. RESULTS: Of the participants, 70% were "very satisfied" or "satisfied" with the appearance of their teeth. The prevalence of malocclusion and past orthodontic treatment was 25% and 20%, respectively. Controlling for the effect of covariates, malocclusion had a significant negative effect on satisfaction with dental appearance (p = 0.02), but past orthodontic treatment did not (p = 0.36). Satisfaction with dental appearance was greater among those in the higher-income group, never smokers, those with better self-rated health, those with no anterior decayed teeth, and those with no anterior filled teeth. CONCLUSION: Past orthodontic treatment was not linked to satisfaction with dental appearance in this sample of Canadian adults. Public health programs and clinicians should focus on addressing esthetic problems by restoring inadequate anterior teeth fillings, restoring anterior tooth decay, and implementing smoking cessation programs before considering orthodontic treatment.

The potential oral health impact of cost barriers to dental care: findings from a Canadian population-based study.

BACKGROUND: Prior to the 2007/09 Canadian Health Measures Survey, there was no nationally representative clinical data on the oral health of Canadians experiencing cost barriers to dental care. The aim of this study was to determine the oral health status and dental treatment needs of Canadians reporting cost barriers to dental care. METHODS: A secondary data analysis of the 2007/09 Canadian Health Measures Survey was undertaken using a sample of 5,586 Canadians aged 6 to 79. Chi square tests were conducted to test the association between reporting cost barriers to care and oral health outcomes. Logistic regressions were conducted to identify predictors of reporting cost barriers. RESULTS: Individuals who reported cost barriers to dental care had poorer oral health and more treatment needs compared to their counterparts. CONCLUSIONS: Avoiding dental care and/or foregoing recommended treatment because of cost may contribute to poor oral health. This study substantiates the potential likelihood of progressive dental problems caused by an inability to treat existing conditions due to financial barriers.

Oral pain and its covariates: findings of a Canadian population-based study.

OBJECTIVE: To describe the prevalence of oral pain in Canada and to identify its covariates. METHODS: Data were derived from the 2007-2009 Canadian Health Measures Survey. Data were analyzed for a total of 5284 respondents (2558 males, 2726 females) aged 6-79 years. The outcome variable was self-reported pain in the mouth in the past 12 months. Bivariate and multivariate analyses were used to investigate the relationship between oral pain and 4 sets of covariates: socio-demographic factors, dental service utilization, oral health behaviours and clinical oral health. RESULTS: Oral pain in the past 12 months was reported by 11.7% of respondents. Oral pain was slightly, but not significantly, more prevalent among females than males (13.6% vs. 10.0%). The lowest and highest prevalence of oral pain were reported by children and young adults, respectively. Multivariate analyses suggested that oral pain was significantly more prevalent among adolescents and adults, those in the lowest income groups, those who avoided a dental professional because of the cost and those with untreated decayed teeth. CONCLUSION: Canadians with financial barriers to accessing dental care and those with untreated dental decay were at risk of having dental pain. These findings have important implications for the provision of dental care in Canada.

Time loss due to dental problems and treatment in the Canadian population: analysis of a nationwide cross-sectional survey.

BACKGROUND: The purpose of this study was to quantify time loss due to dental problems and treatment in the Canadian population, to identify factors associated with this time loss, and to provide information regarding the economic impacts of these issues. METHODS: Data from the 2007/09 Canadian Health Measures Survey were used. Descriptive analysis determined the proportion of those surveyed who reported time loss and the mean hours lost. Linear and logistic regressions were employed to determine what factors predicted hours lost and reporting time loss respectively. Productivity losses were estimated using the lost wages approach. RESULTS: Over 40 million hours per year were lost due to dental problems and treatment, with a mean of 3.5 hours being lost per person. Time loss was more likely among privately insured and higher income earners. The amount of time loss was greater for higher income earners, and those who reported experiencing oral pain. Experiencing oral pain was the strongest predictor of reporting time loss and the amount of time lost. CONCLUSIONS: This study has shown that, potentially, over 40 million hours are lost annually due to dental problems and treatment in Canada, with subsequent potential productivity losses of over $1 billion dollars. These losses are comparable to those experienced for other illnesses (e.g., musculoskeletal sprains). Further investigation into the underlying reasons for time loss, and which aspects of daily living are impacted by this time loss, are necessary for a fuller understanding of the policy implications associated with the economic impacts of dental problems and treatment in Canadian society.

Trends in self-reported cost barriers to dental care in Ontario.

BACKGROUND: The affordability of dental care continues to receive attention in Canada. Since most dental care is privately financed, the use of dental care is largely influenced by insurance coverage and the ability to pay-out-of pocket. OBJECTIVES: i) to explore trends in self-reported cost barriers to dental care in Ontario; ii) to assess trends in the socio-demographic characteristics of Ontarians reporting cost barriers to dental care; and iii) to identify the trend in what attributes predicts reporting cost barriers to dental care in Ontario. METHODS: A secondary data analysis of five cycles (2003, 2005, 2009-10, 2013-14 and 2017-18) of the Canadian Community Health Survey (CCHS) was undertaken. The CCHS is a cross-sectional survey that collects information related to health status, health care utilization, and health determinants for the Canadian population. Univariate and bivariate analyses were conducted to determine the characteristics of Ontarians who reported cost barriers to dental care. Poisson regression was used to calculate unadjusted and adjusted prevalence ratios to determine the predictors of reporting a cost barrier to dental care. RESULTS: In 2014, 34% of Ontarians avoided visiting a dental professional in the past three years due to cost, up from 22% in 2003. Having no insurance was the strongest predictor for reporting cost barriers to dental care, followed by being 20-39 years of age and having a lower income. CONCLUSION: Self-reported cost barriers to dental care have generally increased in Ontario but more so for those with no insurance, low income, and aged 20-39 years.

Area-level inequalities in the provision of NHS orthodontic care in England from 2016 to 2019.

Objective To investigate geographic inequalities in the provision of NHS orthodontic care in England at the area level.Methods NHS dental activity data were analysed for the three financial years April 2016 to March 2019. The measures used were units of dental activity (UDA), units of orthodontic activity (UOA) and commencement of orthodontic treatment. Two orthodontic activity indices were created to assess relative volumes of care. Deprivation was measured using the index of multiple deprivations. Slope and relative inequality indices were used to assess inequality.Results Nearly 12.4 million UOA and 572,987 courses of treatment in England were reported under NHS arrangements in the three years studied. There were significant variations in the rates of UOA (0-716) and UDA (148-918) provided per 100 children (0-17 years) at the local authority level. The variation was not associated with deprivation at the local authority level.Conclusions There were significant disparities in the provision of NHS orthodontic treatment at the local authority level, but this was not associated with area-level measures of deprivation. Inequality in the uptake of orthodontic care may not be due to area-level disparities in service provision.

Dental treatment needs in the Canadian population: analysis of a nationwide cross-sectional survey.

BACKGROUND: Nationally representative clinical data on the oral health needs of Canadians has not been available since the 1970s. The purpose of this study was to determine the normative treatment needs of a nationally representative sample of Canadians and describe how these needs were distributed. METHODS: A secondary analysis of data collected through the Canadian Health Measures Survey (CHMS) was undertaken. Sampling and bootstrap weights were applied to make the data nationally representative. Descriptive frequencies were used to examine the sample characteristics and to examine the treatment type(s) needed by the population. Bivariate logistic regressions were used to see if any characteristics were predictive of having an unmet dental treatment need, and of having specific treatment needs. Lastly, multivariate logistic regression was used to identify the strongest predictors of having an unmet dental treatment need. RESULTS: Most of the population had no treatment needs and of the 34.2% who did, most needed restorative (20.4%) and preventive (13.7%) care. The strongest predictors of need were having poor oral health, reporting a self-perceived need for treatment and visiting the dentist infrequently. CONCLUSIONS: It is estimated that roughly 12 million Canadians have at least one unmet dental treatment need. Policymakers now have information by which to assess if programs match the dental treatment needs of Canadians and of particular subgroups experiencing excess risk.

Oral health inequality in Canada, the United States and United Kingdom.

The objective of this study was to quantify the magnitude of absolute and relative oral health inequality in countries with similar socio-political environments, but differing oral health care systems such as Canada, the United States (US), and the United Kingdom (UK), in the first decade of the new millennium. Clinical oral health data were obtained from the Canadian Health Measures Survey 2007-2009, the National Health and Nutrition Examination Survey 2007-2008, and the Adult Dental Health Survey 2009, for Canada, the US and UK, respectively. The slope index of inequality (SII) and relative index of inequality (RII) were used to quantify absolute and relative inequality, respectively. There was significant oral health inequality in all three countries. Among dentate individuals, inequality in untreated decay was highest among Americans (SII:28.2; RII:4.7), followed by Canada (SII:21.0; RII:3.09) and lowest in the UK (SII:15.8; RII:1.75). Inequality for filled teeth was negligible in all three countries. For edentulism, inequality was highest in Canada (SII: 30.3; RII: 13.2), followed by the UK (SII: 10.2; RII: 11.5) and lowest in the US (SII: 10.3; and RII: 9.26). Lower oral health inequality in the UK speaks to the more equitable nature of its oral health care system, while a highly privatized dental care environment in Canada and the US may explain the higher inequality in these countries. However, despite an almost equal utilization of restorative dental care, there remained a higher concentration of unmet needs among the poor in all three countries.

Comparing the magnitude of oral health inequality over time in Canada and the United States.

OBJECTIVES: To assess the magnitude of, and changes in, absolute and relative oral health inequality in Canada and the United States, from the 1970s till the first decade of the new millennium. METHODS: Data were obtained from four national surveys; two Canadian (NCNS 1970-1972 and CHMS 2007-2009) and two American (HANES 1971-1974 and NHANES 2007-2008). The slope and relative index of inequality were used to measure absolute and relative inequality, respectively. Percentage change in inequality was also calculated. RESULTS: Relative inequality for untreated decay increased by 91% in Canada and 189% in the United States, while for filled teeth it declined by 63% in Canada and 16% in the United States. Relative inequality in edentulism rose by 200% and 78% in Canada and United States, respectively. Absolute inequality declined in both countries. CONCLUSIONS: There was persistent absolute and relative inequality in Canada and the United States. An increase in relative inequality for adverse outcomes suggests that improvements in oral health were occurring primarily among the rich, while reductions in relative inequality for filled teeth indicate higher utilization of restorative services among the poor. These results point to the necessity of tackling the sociopolitical determinants of health to mitigate oral health inequality in Canada and the United States.

Validation of the Persian short version of the Oral Health Impact Profile (OHIP-14).

PURPOSE: The Oral Health Impact Profile (OHIP) questionnaire measures oral health-related quality of life and is widely used for assessing subjective oral health status. The objective of the present study was to describe the translation and validation of the shortened 14-item OHIP for native Persian (Farsi) speakers living in Iran. MATERIALS AND METHODS: The authors translated the OHIP-14 into Persian (OHIP-14-P), followed by back-translation into English, after which the Persian version was revised and modified. They administered the questionnaire to native Persian-speaking clients at a university-based dental clinic in Tehran, Iran (n = 240, 123 females and 117 males, mean age 39, range 18 to 76). They examined the convergent validity and discriminative validity of OHIP by analysing their association with various self-reported health outcomes. They evaluated the test­retest reliability by administering the instrument to 37 patients a second time. They analysed the internal consistency and reliability using a intraclass correlation coefficients (ICC) and Cronbach's reliability coefficient, respectively. RESULTS: The associations between scores of OHIP-14-P and its subscales with self-reported general (r(s) [Spearman's rank correlation coefficient] range 0.38 to 0.52) and oral health (r(s) range 0.25 to 0.45) confirmed convergent validity. Discriminative validity was confirmed through the significant relationship between OHIP-14-P scores with both the experience of pain and satisfaction with oral health (P < 0.001). The instrument's test­retest reliability (ICCs: 0.75 to 0.88) and internal consistency (Cronbach's α: 0.45 to 0.73 and Cronbach's α if subscale deleted: 0.88 to 0.85) were satisfactory. CONCLUSIONS: The Persian version of OHIP-14 was found to be a valid and reliable measure, and appropriate to be used among native Persian speakers visiting a dental clinic.

Persistent but narrowing oral health care inequalities in Canada from 2001 through 2016.

BACKGROUND: Similar to the United States, inequality in oral health care use is longstanding in Canada. It remains unclear whether this inequality is improving or worsening. In this study, the authors report on income-related inequality in dental visits in Canada and across its provinces over time and interprovincial inequality in dental visits among Canadian provinces. METHODS: The authors used 7 nationally representative health surveys of the Canadian population and collected data from 2001 through 2016. The magnitude of income-related inequality was measured using the slope index of inequality and relative index of inequality. Interprovincial inequality was examined using a number of indexes including the Theil index. RESULTS: Income-related inequality in dental visits was present in all survey years, with people in higher income groups reporting higher dental visit prevalence rates. However, results from the slope index of inequality and relative index of inequality showed a steady decline, meaning there was a decrease in the magnitude of inequality over time. Absolute and relative inequality decreased by 7.2% and 22.9% from 2000 through 2016, respectively. A similar decline was observed across most Canadian provinces. Interprovincial differences in dental visits also decreased over time. CONCLUSIONS: There appears to be persistent but narrowing income-related inequality in dental visits in Canada and across its provinces over time. In addition, it appears that Canadian provinces are becoming more equal in terms of dental services use. PRACTICAL IMPLICATIONS: Narrowing income-related inequality in dental visits in Canada is promising, suggesting a more equal distribution of dental visits. However, unequal use of dental services remains an issue affecting the Canadian population.

Current trends in endodontic irrigation amongst general dental practitioners and dental schools within the United Kingdom and Ireland: a cross-sectional survey.

Aims To investigate current trends in endodontic irrigation amongst general dental practitioners (GDPs) and dental schools within UK and Ireland. Secondly, to evaluate if significant differences exist between the irrigant practices of National Health Service (NHS) and private GDPs.Methodology In 2019, an online questionnaire was distributed to the 18 dental schools within the UK and Ireland and 8,568 GDPs. These surveys explored current trends in teaching and usage of endodontic irrigants. Chi-squared tests were performed to make comparisons between NHS and private GDPs (α <0.01).Results All 18 dental schools (100%) and 495 GDPs (6%) returned valid questionnaires. Three hundred and thirty (66.7%) practitioners were NHS and 165 (33.3%) were private. There was strong consensus on irrigation teaching amongst dental schools. These results aligned with GDP responses in terms of irrigant selection (sodium hypochlorite [NaOCl]); NaOCl concentration (≤3%); ethylenediaminetetraacetic acid (EDTA) contact time (>0-5 minutes); final rinse protocols (penultimate EDTA rinse); irrigant temperature (room); and agitation techniques (manual dynamic activation; >0-60 seconds). There was, however, considerable variation in NaOCl contact time and GDPs infrequently used chelating agents or agitation techniques. Compared with private practitioners, NHS GDPs used significantly lower NaOCl contact times and concentrations, less EDTA and activation techniques, and more chlorhexidine (P <0.01).Conclusions Overall, irrigation teaching within the UK and Ireland is consistent and evidence-based. Furthermore, trends in irrigant usage amongst UK GDPs are now more aligned with these teaching practices. Significant differences were, however, observed between NHS and private practitioners.

The Food provision, cUlture and Environment in secondary schooLs (FUEL) study: protocol of a mixed methods evaluation of national School Food Standards implementation in secondary schools and their impact on pupils' dietary intake and dental health.

INTRODUCTION: Excess free sugar intake is associated with obesity and poor dental health. Adolescents consume substantially more free sugar than is recommended. National (UK) School Food Standards (SFS) are in place but are not mandatory in all schools, and their impact on the diets of secondary school pupils is unknown. We aim to evaluate how SFS and wider healthy eating recommendations (from the national School Food Plan (SFP)) are implemented in secondary schools and how they influence pupils' diets and dental health. METHODS AND ANALYSIS: Secondary-level academies/free schools in the West Midlands, UK were divided into two groups: SFS mandated and SFS non-mandated. Using propensity scores to guide sampling, we aim to recruit 22 schools in each group. We will compare data on school food provision and sales, school food culture and environment, and the food curriculum from each group, collected through: school staff, governor, pupil, parent surveys; school documents; and observation. We will explore the implementation level for the SFS requirements and SFP recommendations and develop a school food typology. We aim to recruit 1980 pupils aged 11-15 years across the 44 schools and collect dietary intake (24-hour recall) and dental health data through self-completion surveys. We will compare free sugar/other dietary intake and dental health across the two SFS groups and across the identified school types. School type will be further characterised in 4-8 case study schools through school staff interviews and pupil focus groups. Evaluation of economic impact will be through a cost-consequence analysis and an exploratory cost-utility analysis. ETHICS AND DISSEMINATION: Ethical approval was obtained from the University of Birmingham Ethical Review Committee (ERN_18-1738). Findings will be disseminated to key national and local agencies, schools and the public through reports, presentations, the media and open access publications. TRIAL REGISTRATION NUMBER: ISRCTN 68757496 (registered 17 October 2019).

Towards an understanding of the structural determinants of oral health inequalities: A comparative analysis between Canada and the United States.

OBJECTIVE: To compare the magnitude of, and contributors to, income-related inequalities in oral health outcomes within and between Canada and the United States over time. METHODS: The concentration index was used to estimate income-related inequalities in three oral health outcomes from the Nutrition Canada National Survey 1970-1972, Canadian Health Measures Survey 2007-2009, Health and Nutrition Examination Survey I 1971-1974, and National Health and Nutrition Examination Survey 2007-2008. Concentration indices were decomposed to determine the contribution of demographic and socioeconomic factors to oral health inequalities. RESULTS: Our estimates show that over time in both countries, inequalities in decayed teeth and edentulism were concentrated among the poor and inequalities in filled teeth were concentrated among the rich. Over time, inequalities in decayed teeth increased and decreased for measures of filled teeth and edentulism in both countries. Inequalities were higher in the United States compared to Canada for filled and decayed teeth outcomes. Socioeconomic characteristics (education, income) contributed greater to inequalities than demographic characteristics (age, sex). As well, income contributed more to inequalities in recent surveys in both Canada and the United States. CONCLUSIONS: Inequalities in oral health have persisted over the past 35 years in Canada and the United States, and are associated with age, sex, education, and income and have varied over time.