Modelling time-varying risk factors of tooth loss: Results from joint model compared with extended Cox regression model.

AIM: To illustrate the use of joint models (JMs) for longitudinal and survival data in estimating risk factors of tooth loss as a function of time-varying endogenous periodontal biomarkers (probing pocket depth [PPD], alveolar bone loss [ABL] and mobility [MOB]). MATERIALS AND METHODS: We used data from the Veterans Affairs Dental Longitudinal Study, a longitudinal cohort study of over 30 years of follow-up. We compared the results from the JM with those from the extended Cox regression model which assumes that the time-varying covariates are exogenous. RESULTS: Our results showed that PPD is an important risk factor of tooth loss, but each model produced different estimates of the hazard. In the tooth-level analysis, based on the JM, the hazard of tooth loss increased by 4.57 (95% confidence interval [CI]: 2.13-8.50) times for a 1-mm increase in maximum PPD, whereas based on the extended Cox model, the hazard of tooth loss increased by 1.60 (95% CI: 1.37-1.87) times. CONCLUSIONS: JMs can incorporate time-varying periodontal biomarkers to estimate the hazard of tooth loss. As JMs are not commonly used in oral health research, we provide a comprehensive set of R codes and an example dataset to implement the method.

Periodontitis is associated with an increased hazard of mortality in a longitudinal cohort study over 50 years.

AIM: To evaluate the association between periodontal disease and all-cause mortality in a longitudinal cohort study over 50 years. MATERIALS AND METHODS: Participants (N = 1156) in the Veterans Affairs Dental Longitudinal Study, aged 25-85 years at enrollment in 1968, received comprehensive medical and oral exams approximately every 3 years through 2007. Periodontal status was defined using person-level, mean whole-mouth radiographic alveolar bone loss (ABL) scores using a five-point Schei ruler, each unit representing 20% increments of ABL. Time-varying Cox regression models estimated hazard ratios (HRs) for the association between continuous and categorical ABL and mortality, adjusting for covariates. RESULTS: Each one-unit increase in mean ABL score was associated with a 14% increase in the hazard of mortality (adjusted HR = 1.14, 95% confidence interval [CI] 1.02, 1.27). When assessed categorically, HRs for average scores of 2 to <3 and 3 to ≤5 showed increasing associations with hazard of mortality, relative to 0 to <1 (adjusted HR = 1.17, 95% CI 0.94, 1.46; and HR = 1.65, 95% CI 0.94, 2.85, respectively). By contrast, we observed null associations for average scores of 1 to <2 relative to 0 to <1 (adjusted HR = 1.00, 95% CI 0.86, 1.17). CONCLUSIONS: Time-varying periodontal status assessed using radiographic ABL was positively associated with all-cause mortality even after confounder adjustment.

Association between Parity and Dental Caries Experience among US Women: Findings from the National Health and Nutrition Examination Survey.

AIM AND OBJECTIVE: This study aims to investigate the association between parity and dental caries among US women. MATERIALS AND METHODS: National Health and Nutrition Examination Survey (NHANES 2001-2004) data for parous women aged 20-45 years were used for our analysis (n = 1,914). The association between parity (number of pregnancies resulted in live births) and caries experience [the decayed, missing, and filling teeth (DMFT) index] was analyzed using bivariate and multivariate regression analyses. SAS software version 9.1 was used for the statistical analyses. We used survey procedures (e.g., SURVEYFREQ, SURVEYMEANS, and SURVEYREG) that incorporate information on the appropriate weights to account for NHANES's complex sampling design. RESULTS: The bivariate analysis showed a trend of increase in dental caries experience among parous women as the number of live births increased (p = 0.007). After adjusting for confounders, such as age, socioeconomic status (SES), dental care coverage, and utilization, a significant association was still observed between parity level and dental caries experience (p = 0.009). CONCLUSION: Our results suggest that higher parity can be associated with dental caries experience among US women of reproductive age. CLINICAL SIGNIFICANCE: Clinicians should be aware of this finding to promote better oral health care and education among women with increased parity.

Marginal analysis of ordinal clustered longitudinal data with informative cluster size.

The issue of informative cluster size (ICS) often arises in the analysis of dental data. ICS describes a situation where the outcome of interest is related to cluster size. Much of the work on modeling marginal inference in longitudinal studies with potential ICS has focused on continuous outcomes. However, periodontal disease outcomes, including clinical attachment loss, are often assessed using ordinal scoring systems. In addition, participants may lose teeth over the course of the study due to advancing disease status. Here we develop longitudinal cluster-weighted generalized estimating equations (CWGEE) to model the association of ordinal clustered longitudinal outcomes with participant-level health-related covariates, including metabolic syndrome and smoking status, and potentially decreasing cluster size due to tooth-loss, by fitting a proportional odds logistic regression model. The within-teeth correlation coefficient over time is estimated using the two-stage quasi-least squares method. The motivation for our work stems from the Department of Veterans Affairs Dental Longitudinal Study in which participants regularly received general and oral health examinations. In an extensive simulation study, we compare results obtained from CWGEE with various working correlation structures to those obtained from conventional GEE which does not account for ICS. Our proposed method yields results with very low bias and excellent coverage probability in contrast to a conventional generalized estimating equations approach.

Depression and Differential Oral Health Status Among U.S. Adults With and Without Prior Active Duty Service in the U.S. Military, National Health and Nutrition Examination Survey 2011-2018.

INTRODUCTION: Veterans suffer from lower overall well-being than non-veterans because of their unique life course. This study aims to compare the impact of depression on oral health for veteran and non-veteran populations. MATERIALS AND METHODS: Data from 11,693 adults (18+) participating in the National Health and Nutrition Examination Survey (2011-2018) were analyzed. The outcome variables were dichotomous (at/above mean) decayed, missing, and filled teeth due to caries (DMFT), as well as the components, namely, missing teeth, filled teeth (FT), and decayed teeth (DT). The primary predictor variable combined depression screening outcome and veteran status (veteran/depressed, veteran/not depressed, non-veteran/depressed, and non-veteran/not depressed). Covariates included socioeconomic factors, demographics, wellness factors, and oral health-related habits. Associations between outcome and predictor variables were assessed with a fully adjusted logistic regression analysis. RESULTS: Veterans, regardless of depression status, had more DMFT, FT, missing teeth, and DT compared to non-veterans. After controlling for covariates, veterans suffering from depression had higher odds of DT (1.5, 95% CI, 1.0-2.4) compared to non-veterans without depression. In general, veterans who screened negative for depression had better oral health compared to all groups, with lower odds of DT (0.7, 95% CI, 0.6-0.9) and higher odds of FT (1.4, 95% CI, 1.1-1.7) compared to non-veterans with and without depression. CONCLUSIONS: This study found that not only veterans have higher odds of overall caries experience, but also veterans suffering from depression have higher odds of active caries compared to non-depressed veterans. Most veterans lack Veterans Health Administration dental benefits and face challenges maintaining oral health on top of medical and mental health burdens. Our results add further urgency to increasing dental care access for this vulnerable population because of the exacerbation of unmet oral health care needs attributable to the additional mental health challenges veterans face.

Influence of Obesity on Periodontitis Progression Is Conditional on Interleukin-1 Inflammatory Genetic Variation.

BACKGROUND: This study evaluates whether specific patterns of interleukin (IL)-1 gene variants, known to affect periodontitis severity, influence the previously reported association between obesity and subsequent periodontitis progression in a longitudinal database. The study population included 292 men (aged 29 to 64 years at entry) from the Veterans Affairs Dental Longitudinal Study from whom DNA and dental and anthropometric endpoints were collected during multiple examinations (approximately every 3 years for up to 27 years). METHODS: Key variables assessed included: 1) periodontitis; 2) body mass index; 3) waist circumference to height (WHTR) ratio for central adiposity; 4) age; 5) smoking; 6) glucose tolerance; and 7) two previously reported versions of IL-1 genetic patterns associated with periodontitis severity and progression. Disease progression was determined using predefined criteria that used a combination of change in classification of disease severity based on alveolar bone loss and tooth loss during follow-up. Extended Cox regression analyses were used to estimate hazards of experiencing periodontal disease progression with or without adjustments for appropriate covariates. RESULTS: In hazard ratio analyses, men with WHTR >50% at baseline and positive for either IL-1 genotype version were at significantly higher risk (two-fold) for disease progression (P for interaction = 0.04). Participants positive for IL-1 genotype version 2 exhibited earlier progression (fewer years from baseline to first incidence of progression) than those who were negative (P = 0.02, adjusted for age and smoking). CONCLUSION: In this longitudinally monitored male population, observed effect of baseline central adiposity on future periodontitis progression is conditional on proinflammatory IL-1 genetic variations.

The Dietary Approaches to Stop Hypertension Diet and New and Recurrent Root Caries Events in Men.

OBJECTIVES: To examine the effect of overall dietary quality on number of teeth with new or recurrent root caries events during follow-up (root caries increment). DESIGN: Prospective study with dental examinations approximately every 3 years over 20 years. SETTING: Veterans Affairs Dental Longitudinal Study in greater Boston, Massachusetts, area. PARTICIPANTS: Men aged 47 to 90 (N = 533). MEASUREMENTS: A single calibrated examiner assessed root caries and restorations, calculus, probing pocket depth, and attachment loss on each tooth at each examination. The adjusted root caries increment (root-ADJCI) was computed from new and recurrent root caries events on teeth with recession of 2 mm or more. Dietary information was obtained from food frequency questionnaires. An adherence score was computed by comparing consumption frequency of 10 food groups (fruits, vegetables, total dairy, low-fat dairy, meat, total grains, high-fiber grains, legumes, fats, sweets) from the Dietary Approaches to Stop Hypertension (DASH) diet guidelines. Mean root-ADJCIs were compared according to DASH adherence score quartile using generalized linear negative binomial regression models, controlling for age, number of teeth at risk of root caries, time at risk of root caries, calculus, presence of removable denture, history of dental prophylaxis, body mass index, and smoking status. RESULTS: Men with DASH adherence scores in the highest quartile had a 30% lower mean root-ADJCI (1.86 teeth) than those in the lowest quartile (2.68 teeth) (P = .03). Root-ADJCI was lower with greater adherence to recommendations for vegetables and total grains and greater with greater sugar-sweetened carbonated beverage consumption. Root caries incidence rate did not vary significantly between quartiles. CONCLUSION: A higher-quality diet may reduce root caries risk in older men.

Association of endodontic involvement with tooth loss in the Veterans Affairs Dental Longitudinal Study.

INTRODUCTION: The effect of endodontic involvement on tooth loss has not been quantified, so the present study aimed to assess this relationship after controlling for other relevant risk factors for tooth loss. METHODS: We analyzed data from 791 participants (18,798 teeth) in the Veterans Affairs Dental Longitudinal Study. Potential tooth-level and person-level covariates were fitted into marginal proportional hazards models, including both apical radiolucencies (AR) and root canal therapy (RCT) status as time-dependent variables. Survival curves were plotted for teeth according to their AR and RCT status. RESULTS: Both current AR and RCT status were associated with increased risk of tooth loss (P < .01), after controlling for baseline levels of periodontal disease, caries, tooth type, number of proximal contacts, number of teeth, age, education, and smoking history. Root canal filled (RCF) teeth seemed to have better survival than non-RCF teeth among teeth with AR but worse survival than non-RCF teeth among teeth without AR. CONCLUSIONS: Endodontic involvement was associated with tooth loss, controlling for other potential risk factors. Additional prospective studies are needed to provide better evidence as to the impact of endodontic involvement on tooth loss.