Aderonke A. Akinkugbe

Projections of U.S. Edentulism Prevalence Following 5 Decades of Decline

After decades of decline in prevalence of complete tooth loss (edentulism), the trend continues to be misinterpreted, producing flawed projections and misdirected health goals. We investigated population trends in edentulism among U.S. adults aged ≥15 yr by creating time-series data from 5 national cross-sectional health surveys: 1957-1958 (n ≈ 100,000 adults), 1971-1975 (n = 14,655 adults), 1988-1998 (n = 18,011 adults), 1999-2002 (n = 12,336 adults), and 2009-2012 (n = 10,522 adults). Birth cohort analysis was used to isolate age and cohort effects. Geographic and sociodemographic variation in prevalence was investigated with a sixth U.S. survey of 432,519 adults conducted in 2010. Prevalence through 2050 was projected with age-cohort regression models using Monte-Carlo simulation of prediction intervals. Across the 5-decade observation period, edentulism prevalence declined from 18.9% in 1957-1958 (95% confidence limits: 18.4%, 19.4%) to 4.9% in 2009-2012 (95% confidence limits: 4.0%, 5.8%). The most influential determinant of the decline was the passing of generations born before the 1940s, whose rate of edentulism incidence (5%-6% per decade of age) far exceeded later cohorts (1%-3% per decade of age). High-income households experienced a greater relative decline, although a smaller absolute decline, than low-income households. By 2010, edentulism was a rare condition in high-income households, and it had contracted geographically to states with disproportionately high poverty. With the passing of generations born in the mid-20th century, the rate of decline in edentulism is projected to slow, reaching 2.6% (95% prediction limits: 2.1%, 3.1%) by 2050. The continuing decline will be offset only partially by population growth and population aging such that the predicted number of edentulous people in 2050 (8.6 million; 95% prediction limits: 6.8 million, 10.3 million) will be 30% lower than the 12.2 million edentulous people in 2010.

Directed Acyclic Graphs for Oral Disease Research

Directed acyclic graphs (DAGs) are nonparametric graphical tools used to depict causal relations in the epidemiologic assessment of exposure-outcome associations. Although their use in dental research was first advocated in 2002, DAGs have yet to be widely adopted in this field. DAGs help identify threats to causal inference such as confounders, bias due to subject selection, and inappropriate handling of missing data. DAGs can also inform the data analysis strategy based on relations among variables depicted on it. This article uses the example of a study of temporomandibular disorders (TMDs), investigating causal effects of facial injury on subsequent risk of TMD. We illustrate how DAGs can be used to identify 1) potential confounders, 2) mediators and the consequences of attempt to estimate direct causal effects, 3) colliders and the consequences of conditioning on colliders, and 4) variables that are simultaneously mediators and confounders and the consequences of adjustment for such variables. For example, one DAG shows that statistical adjustment for the pressure pain threshold would necessarily bias the causal relation between facial injury and TMD. Finally, we discuss the usefulness of DAGs during study design, subject selection, and choosing variables to be measured in a study.

Systematic Review and Meta-analysis of the Association Between Exposure to Environmental Tobacco Smoke and Periodontitis Endpoints Among Nonsmokers

OBJECTIVE A systematic review was conducted to summarize the epidemiological evidence on environmental tobacco smoke (ETS) exposure and prevalent periodontitis endpoints among nonsmokers. METHODS We searched PubMed, EMBASE, Web of Science, Pro-Quest dissertations, and conference proceedings of a dental research association. We included studies from which prevalence odds ratios (POR) could be extracted for periodontitis determined by examiner measurements of clinical attachment level (CAL) and/or probing pocket depth (PD) or self-report of missing teeth. Studies determined ETS exposure by self-report or biomarker (cotinine) levels. RESULTS For studies reporting CAL and/or PD (n = 6), associations were stronger with cotinine-measured exposure (n = 3; random effects POR [95% prediction interval] = 1.63 (0.90, 2.96)) than self-reported exposure (n = 3; random effects POR = 1.15 (0.68, 1.96)). There was no meaningful difference in summary estimate for studies reporting CAL and/or PD endpoint (n = 6; random effects POR = 1.34 (0.93, 1.94)) as opposed to tooth loss (n = 2; random effects POR = 1.33 (0.52, 3.40)). CONCLUSIONS There appears to be a positive association between exposure to ETS and prevalent periodontitis endpoints among nonsmokers, the magnitude of which depended mostly on the method of ETS assessment. IMPLICATIONS The notoriety of ETS is often discussed in terms of its associations with cancer, chronic conditions like cardiovascular diseases, and respiratory illnesses in children. However, very little attention is paid to its association with oral diseases, especially periodontitis. Periodontitis affects a large proportion of the population and is a major cause of tooth loss. This study summarized the epidemiologic association between exposure to ETS and periodontitis among nonsmokers. Although the findings are consistent with a positive association, methodological weaknesses relating to study design, assessment of ETS, periodontitis, and adjustment covariates were highlighted and recommendations for improvement in future studies provided.

Do Genetic Markers of Inflammation Modify the Relationship between Periodontitis and Nonalcoholic Fatty Liver Disease? Findings from the SHIP Study

An association between periodontitis and nonalcoholic fatty liver disease (NAFLD) has been reported by experimental animal and epidemiologic studies. This study investigated whether circulating levels of serum C-reactive protein (CRP) and a weighted genetic CRP score representing markers of inflammatory burden modify the association between periodontitis and NAFLD. Data came from 2,481 participants of the Study of Health in Pomerania who attended baseline examination that occurred between 1997 and 2001. Periodontitis was defined as the percentage of sites (0%, <30%, ≥30%) with probing pocket depth (PD) ≥4 mm, and NAFLD status was determined using liver ultrasound assessment. Serum CRP levels were assayed at a central laboratory, and single-nucleotide polymorphisms previously identified through genome-wide association studies as robustly associated with serum CRP were combined into a weighted genetic CRP score (wGSCRP). Logistic regression models estimated the association between periodontitis and NAFLD within strata of serum CRP and separately within strata of the wGSCRP. The prevalence of NAFLD was 26.4% (95% confidence interval [CI], 24.6, 28.1) while 17.8% (95% CI, 16.0–19.6) had ≥30% of sites with PD ≥4 mm. Whereas the wGSCRP was not a modifier (Pinteraction = 0.8) on the multiplicative scale, serum CRP modified the relationship between periodontitis and NAFLD (Pinteraction = 0.01). The covariate-adjusted prevalence odds ratio of NAFLD comparing participants with ≥30% of sites with PD ≥4 mm to those with no site affected was 2.39 (95% CI, 1.32–4.31) among participants with serum CRP <1 mg/L. The corresponding estimate was 0.97 (95% CI, 0.57–1.66) for participants with serum CRP levels of 1 to 3 mg/L and 1.12 (95% CI, 0.65–1.93) for participants with serum CRP >3 mg/L. Periodontitis was positively associated with higher prevalence odds of NAFLD, and this relationship was modified by serum CRP levels.

A New Way to Estimate Disease Prevalence from Random Partial-Mouth Samples

AIM Standard partial-mouth estimators of chronic periodontitis (CP) that define an individuals disease status solely in terms of selected sites underestimate prevalence. This study proposes an improved prevalence estimator based on randomly sampled sites and evaluates its accuracy in a well-characterized population cohort. METHODS Importantly, this method does not require determination of disease status at the individual level. Instead, it uses a statistical distributional approach to derive a prevalence formula from randomly selected periodontal sites. The approach applies the conditional linear family of distributions for correlated binary data (i.e. the presence or absence of disease at sites within a mouth) with two simple working assumptions: (i) the probability of having disease is the same across all sites; and (ii) the correlation of disease status is the same for all pairs of sites within the mouth. RESULTS Using oral examination data from 6793 participants in the Arteriolosclerosis Risk in Communities study, the new formula yields CP prevalence estimates that are much closer than standard partial mouth estimates to full mouth estimates. CONCLUSIONS Resampling of the cohort shows that the proposed estimators give good precision and accuracy for as few as six tooth sites sampled per individual.

Environmental tobacco smoke exposure and periodontitis prevalence among nonsmokers in the hispanic community Health Study/Study of Latinos.

OBJECTIVE To describe self-reported exposure to environmental tobacco smoke (ETS) and its association with periodontitis prevalence in a diverse group of Hispanics/Latinos. METHODS Data came from 8675 lifetime nonsmokers in the 2008-2011 Hispanic Community Health Study/Study of Latinos. Exposure to ETS was self-reported, while periodontitis was defined using the Centers for Disease Control and Prevention-American Academy of Periodontology criteria and the proportion of sites affected by clinical attachment level of ≥3 mm or pocket depth of ≥4 mm. Survey logistic regression estimated prevalence odds ratios (POR) and 95% confidence intervals (CI). In addition, we assessed whether greater hours of exposure to ETS in the past year was associated with greater periodontitis prevalence, and lastly, we conducted a simple sensitivity analysis of ETS misclassification. RESULTS Age-standardized prevalence estimates (95% CI) for ETS exposure and periodontitis were 57.6% (55.9, 59.4) and 39.8% (38.1, 41.4), respectively. After adjusting for confounders and periodontitis risk factors, we estimated an overall adjusted POR (95% CI) for the ETS-periodontitis association as 1.09 (0.95-1.26) with a confidence limit ratio (CLR) of 1.34. This association varied in magnitude by Hispanic/Latino background, ranging from 1.04 (0.75, 1.43 with a CLR = 1.91) among Central Americans to 1.76 (1.16, 2.66 with a CLR = 2.29) in Puerto Ricans. CONCLUSIONS Previously reported associations between ETS and periodontitis appear weak in this study. However, the magnitude of the association differs according to Hispanic/Latino background.

The role of partial recording protocols in reporting prevalence and severity of dental fluorosis

OBJECTIVES To evaluate the role of partial recording protocols (PRPs) in reporting prevalence and severity of dental fluorosis and assess whether prevalence/severity estimates derived from PRPs differ by race/ethnicity. METHODS Data from the National Health and Nutrition Examination Survey (NHANES) for the years 1999-2004 were analyzed with Stata(®) v.11. Prevalence of dental fluorosis obtained from a full-mouth examination (28 teeth gold standard) was compared with estimates derived from four subsets of teeth (maxillary canine-to-canine; maxillary first-premolar-to-first-premolar; all-premolars; all-molars). Sensitivity, negative predictive value (NPV), absolute bias, and correction factors were calculated against gold standard estimate. Analysis was stratified according to race/ethnicity to assess differences in estimates derived from PRPs. RESULTS All subsets underestimated prevalence albeit to varying degrees. Two subsets (all-premolars and all-molars) had prevalence and severity estimates closest to gold standard estimates. The all-molars subset (eight teeth) recorded the highest sensitivity (84.5%) and the lowest absolute bias (3.5%) of all subsets relative to gold standard. Subsets derived from esthetically relevant teeth produced the lowest fluorosis prevalence. For instance, the maxillary canine-to-canine subset underestimated prevalence by 9.5%; incorporating the maxillary first premolars in the span improved prevalence estimate by 31%. Among non-Hispanic Whites, the all-premolars subset produced estimates closest to gold standard while the all-molars subset produced estimates closest to the gold standard among non-Hispanic Blacks and Hispanics. CONCLUSION While the majority of dental fluorosis in the United States is very mild, concerns regarding its growing prevalence underscore the need for careful monitoring. The use of PRPs offers an alternative method of assessment, with validity of reported prevalence and severity dependent on choice of subset.