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Survival analyses have been used to overcome some of the limitations encountered with other statistical analyses. Although extended Cox hazard modeling with time-dependent variables has been utilized in several medical studies, it has never been utilized in assessing the complex relationship between mutans streptococci (MS) acquisition (time-dependent covariate) and time to having dental caries (outcome). This study involved secondary analyses of data from a prospective study conducted at the University of Alabama at Birmingham. Low socioeconomic status, African-American preschool children from Perry County, AL, USA (n = 95) had dental examinations at age 1 year and annually thereafter until age 6 years by three calibrated dentists. Salivary MS tests were done at ages 1, 1.5, 2, 2.5, 3, and 4 years. The patterns of and relationship between initial MS detection (time-dependent covariate) and dental caries experience occurrence were assessed, using extended Cox hazard modeling. The median time without MS acquisition (50% of the children not having positive MS test) was 2 years. Approximately 79% of the children had positive salivary MS tests by the age of 4 years. The median caries experience survival (50% of the children not having dental caries) was 4 years. During the follow-up period, 65 of the children (68.4%) had their initial primary caries experience. Results of the extended Cox hazard modeling showed a significant overall/global relationship between initial caries experience event at any given time during the follow-up period and having a positive salivary MS test at any time during the follow-up period (hazard ratio = 2.25, 95% CI 1.06-4.75). In conclusion, the extended Cox modeling was used for the first time and its results showed a significant global/overall relationship between MS acquisition and dental caries. Further research using causal mediation analysis with survival data is necessary, where the mediator "presence of MS" is treated as a time-dependent variable. [ABSTRACT FROM AUTHOR]

Marginalized zero-inflated count regression models have recently been introduced for the statistical analysis of dental caries indices and other zero-inflated count data as alternatives to traditional zero-inflated and hurdle models. Unlike the standard approaches, the marginalized models directly estimate overall exposure or treatment effects by relating covariates to the marginal mean count. This article discusses model interpretation and model class choice according to the research question being addressed in caries research. Two data sets, one consisting of fictional dmft counts in 2 groups and the other on DMFS among schoolchildren from a randomized clinical trial comparing 3 toothpaste formulations to prevent incident dental caries, are analyzed with negative binomial hurdle, zero-inflated negative binomial, and marginalized zero-inflated negative binomial models. In the first example, estimates of treatment effects vary according to the type of incidence rate ratio (IRR) estimated by the model. Estimates of IRRs in the analysis of the randomized clinical trial were similar despite their distinctive interpretations. The choice of statistical model class should match the study's purpose, while accounting for the broad decline in children's caries experience, such that dmft and DMFS indices more frequently generate zero counts. Marginalized (marginal mean) models for zero-inflated count data should be considered for direct assessment of exposure effects on the marginal mean dental caries count in the presence of high frequencies of zero counts. [ABSTRACT FROM AUTHOR]

This study explored the potential association between childhood asthma and caries using oral examination and health interview data from the Third National Health and Nutrition Examination Survey 1988-1994 (NHANES III). We fitted GEE Poisson regression models with adjustment for parents' income, gender, race, exposure to potentially xerostomic drugs, and the presence of pit and fissure sealants. There was no association between the use of drugs commonly used by asthmatics (antihistamines, corticosteroids, and antiasthmatic inhalers) and df/DMF scores. Asthmatic children 4-10 years of age at all severity levels had similar dfs scores to the controls, however, severely asthmatic children 4-10 years of age had significantly lower DMFS (p = 0.010) and DMFT (0.049) scores than controls. Similarly, severely asthmatic children 11-16 years of age had significantly lower DMFT scores than controls (p = 0.024) and DMFS scores approaching statistical significance (p = 0.053). While our analysis adjusted for covariates, potential confounders such as fluoride intake from water, diet, use of topical fluorides, and dose of antiasthmatic medication could not be addressed. Our results indicate that any association between asthma and dental caries may occur primarily in younger children with no evidence of an association between asthma and dental caries as children mature. [ABSTRACT FROM AUTHOR]