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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., (© 2017 S. Karger AG, Basel.)

Background: Dental caries remains the most prevalent chronic condition in children and a major contributor to poor general health. There is ample evidence of a skewed distribution of oral health, with a small proportion of children in the population bearing the majority of the burden of the disease. This minority group is comprised disproportionately of socioeconomically disadvantaged children. An in-depth longitudinal study is needed to better understand the determinants of child oral health, in order to support effective evidence-based policies and interventions in improving child oral health. The aim of the Study of Mothers' and Infants' Life Events Affecting Oral Health (SMILE) project is to identify and evaluate the relative importance and timing of critical factors that shape the oral health of young children and then to seek to evaluate those factors in their inter-relationship with socioeconomic influences., Methods/design: This investigation will apply an observational prospective study design to a cohort of socioeconomically-diverse South Australian newborns and their mothers, intensively following these dyads as the children grow to toddler age. Mothers of newborn children will be invited to participate in the study in the early post-partum period. At enrolment, data will be collected on parental socioeconomic status, mothers' general and dental health conditions, details of the pregnancy, infant feeding practice and parental health behaviours and practices. Data on diet and feeding practices, oral health behaviours and practices, and dental visiting patterns will be collected at 3, 6, 12 and 24 months of age. When children turn 24-30 months, the children and their mothers/primary care givers will be invited to an oral examination to record oral health status. Anthropometric assessment will also be conducted., Discussion: This prospective cohort study will examine a wide range of determinants influencing child oral health and related general conditions such as overweight. It will lead to the evaluation of the inter-relationship among main influences and their relative effect on child oral health. The study findings will provide high level evidence of pathways through which socio-environmental factors impact child oral health. It will also provide an opportunity to examine the relationship between oral health and childhood overweight.

Over the past 5-10 years, zero-inflated (ZI) count regression models have been increasingly applied to the analysis of dental caries indices (e.g. DMFT, dfms). The main reason for that is linked to the broad decline in children's caries experience, such that dmf and DMF indices more frequently generate low or even zero counts. This article specifically reviews the application of ZI Poisson and ZI negative binomial regression models to dental caries, with emphasis on the description of the models and the interpretation of fitted model results given the study goals. The review finds that interpretations provided in the published caries research are often imprecise or inadvertently misleading, particularly with respect to failing to discriminate between inference for the class of susceptible persons defined by such models and inference for the sampled population in terms of overall exposure effects. Recommendations are provided to enhance the use as well as the interpretation and reporting of results of count regression models when applied to epidemiological studies of dental caries., (Copyright © 2012 S. Karger AG, Basel.)

Background: In this article, the authors present evidence-based clinical recommendations regarding the use of nonfluoride caries preventive agents. The recommendations were developed by an expert panel convened by the American Dental Association (ADA)Council on Scientific Affairs. The panel addressed several questions regarding the efficacy of nonfluoride agents in reducing the incidence of caries and arresting or reversing the progression of caries., Types of Studies Reviewed: A panel of experts convened by the ADA Council on Scientific Affairs, in collaboration with ADA Division of Science staff, conducted a MEDLINE search to identify all randomized and nonrandomized clinical studies regarding the use of non fluoride caries-preventive agents., Results: The panel reviewed evidence from 50 randomized controlled trials and 15 nonrandomized studies to assess the efficacy of various nonfluoride caries-preventive agents., Clinical Implications: The panel concluded that certain nonfluoride agents may provide some benefit as adjunctive therapies in children and adults at higher risk of developing caries. These recommendations are presented as a resource for dentists to consider in the clinical decision-making process. As part of the evidence based approach to care, these clinical recommendations should be integrated with the practitioner’s professional judgment and the patient’s needs and preferences.

The history of clinical trials would include events in 1747 on board the Salisbury, a British Navy vessel at sea with 12 seamen critically ill with scurvy. Involving these 12 sailors in a study, an officer on board by the name of Lind evaluated six potential treatments for scurvy, and rapidly reached the conclusion that daily consumption of citrus fruits returned the men fit for duty in approximately six days (Bull, 1959). The concept of experimental randomization was first developed by Sir R.A. Fisher (1925, 1926), and the method was introduced to medical research via a study of tuberculosis treatment by Amberson and co-workers (1931), who randomized 24 TB patients into two groups, one to receive the experimental therapy, the other serving as the control. Amberson et al. also incorporated the concept of blinding into their study. Sir Austin Bradford Hill codified and built on the principles of scientific experimentation developed by Fisher, and introduced the use of random numbers in the allocation of patients in the British Medical Research Council (1948) study of the effect of streptomycin in the treatment of tuberculosis (Daniels and Hill, 1952; Hill, 1952). The first applications of clinical trial methodology for testing interventions on dental, oral, and maxillofacial diseases and conditions are more difficult to determine. For dental caries prevention, however, Chilton and Fertig (1958) and Slack and Martin (1964) were certainly among the early caries clinical trial pioneers. As clinical trials have come into the mainstream of clinical research in medicine and dentistry, a great deal of developmental work has focused on their methodological enhancement. The most successful of these efforts have come from fruitful, ongoing collaborations among clinician investigators, biostatisticians, data management specialists, biomedical ethicists, and others with an academic interest in clinical trial design and utilization. During the past 25 years, the emergence of systematic reviews and the evidence-based medicine (EBM) movement have also contributed significantly to the increasing reliance on randomized clinical trial outcomes for the advancement of better clinical practice (Richards et al., 1997; Straus and Sackett, 1998; www.cochrane.org/cochrane/ccbroch.htm#BDL, 2002).

This paper reviews the current place of dentifrices, toothbrushes and rinses in the personal dental products market using data from the United States as an illustration. The clinical evolution of fluoride in dentifrices and rinses is briefly outlined, as is the changing view of the balance between the systemic and topical effects of the element on preventing dental caries. Issues involved in the current scientific arena are described as are issues related to caries trends and preventive technologies that deserve attention in the future.

The purpose of this analysis is to compare three different statistical models for predicting children likely to be at risk of developing dental caries over a 3-yr period. Data are based on 4117 children who participated in the University of North Carolina Caries Risk Assessment Study, a longitudinal study conducted in the Aiken, South Carolina, and Portland, Maine areas. The three models differed with respect to either the types of variables included or the definition of disease outcome. The two "Prediction" models included both risk factor variables thought to cause dental caries and indicator variables that are associated with dental caries, but are not thought to be causal for the disease. The "Etiologic" model included only etiologic factors as variables. A dichotomous outcome measure--none or any 3-yr increment, was used in the "Any Risk Etiologic model" and the "Any Risk Prediction Model". Another outcome, based on a gradient measure of disease, was used in the "High Risk Prediction Model". The variables that are significant in these models vary across grades and sites, but are more consistent among the Etiologic model than the Predictor models. However, among the three sets of models, the Any Risk Prediction Models have the highest sensitivity and positive predictive values, whereas the High Risk Prediction Models have the highest specificity and negative predictive values. Considerations in determining model preference are discussed.

The University of North Carolina caries risk assessment was conducted between 1986 and 1989 with 5000 children initially in grades 1 and 5 from low fluoride sites in South Carolina and Maine. Clinical, microbiologic, behavioral, and demographic factors served as independent variables used in logistic multiple regression models to determine the predicted caries risk classification of each child. The 3-yr DMFS increment of each child was the dependent variable, and the 20-25% of those in each cohort with the highest increment were considered the high risk group. Sensitivity and specificity values averaged 0.60 and 0.83 respectively, indicating the misclassification of substantial numbers of children. This paper reports analysis of the DMFS increments of the misclassified children. The majority of children had DMFS increments within one or two surfaces of the classification cut points. Many false negative children had increments composed entirely of filled surfaces, often of minimal extent and without evidence of previous decay. Many false positive children had increments composed of decayed surfaces and would have benefitted from being identified as high risk and assigned to a preventive program. Other false positive children had sealants placed after the baseline examination that undoubtedly reduced their true increment. It is concluded that the consequences of misclassification are not serious for most children in this study.

Over 4000 first and fifth grade children from the areas surrounding Aiken, South Carolina, and Portland, Maine, participated in a 4-yr study to develop caries risk assessment models. The predictors used at baseline included detailed clinical examinations, salivary microbiological tests, and sociodemographic and dental behavior data. Mean 3-yr caries increments in South Carolina were twice those in Maine. For the four risk assessment models (two grade cohorts at two sites) specificity values averaged 0.83 and sensitivity values averaged 0.60. Clinical predictors such as prior DMFS, pit and fissure morphology, and predicted caries risk status were the major contributors to the models.

This paper seeks to achieve four goals, each of which forms the basis for a section in the presentation. First, the rationale of risk assessment is fully described. In this section, some of the necessary conditions are identified that make disease prediction worth pursuing. The second section discusses some essential background to the understanding of risk assessment in dentistry. In this segment, attention is focused on population-based and individual-based perspectives, alternative approaches to expressing health risk, and methods for comparing the predictive accuracy of alternative risk assessment models. The third section of the paper develops a conceptual framework for risk assessment in dentistry. Particular emphasis is devoted to the identification of risk factors and their incorporation into alternative statistical models. In the fourth section, empirical data are offered by which certain comparisons of the alternative risk models can be drawn. The paper concludes with a discussion that emphasizes data and technical limitations, speculates on future applications, and suggests new avenues for research.

Caries prediction by Classification And Regression Tree (CART) analysis is an appropriate and powerful alternative or complement to the commonly used classification methods of logistic regression and discriminant analysis, both parametric and nonparametric. The binary classification tree method discussed in this article is designed for complex data and does not require assumptions about the predictor variables or about the presence or absence of interactions among the predictor variables. Furthermore, the results give insight into the structures and interactions in the data and are easy to interpret and apply. In preliminary applications of the CART algorithms to data from The University of North Carolina Caries Risk Assessment Study, the method produced prediction rules having sensitivities and specificities that were similar to or slightly better than those associated with logistic and discriminant analyses. The classification trees constructed tended to involve far fewer predictor variables than required for adequate logistic and discriminant models. For example, for first-grade children in Aiken, South Carolina, nine variables were used to define a prediction rule having 64% sensitivity and 86% specificity. Ten-fold cross-validation estimates for future data were 58% and 79%, respectively. For first-grade children in Portland, Maine, two variables were used to define a prediction rule having 62% sensitivity and 77% specificity. The cross-validation estimates for future data were 58% and 78%, respectively. A brief, and previously unavailable, explanation of the CART method is given for the special case of a dichotomous outcome variable.

The baseline caries experienced of approximately 5,000 children in South Carolina and Maine was used as the dependent variable in caries risk assessment analyses. Clinical, microbiologic, and demographic factors served as independent variables in a multivariate relationship to caries through regression and discriminant function analyses. Four factors--number of dental visits by the child in the past year, presence of white spot lesions, and both the urgency of need for restorative care and the future caries increment predicted by the examiner--associated significantly and consistently with caries prevalence in primary and permanent teeth of first and fifth graders at both study sites. Several factors associated significantly with caries prevalence at only one site or grade within a site, suggesting that wide applicability of a specific caries risk assessment model may be limited. In these analyses, sensitivity ranged from .60 to .72 and specificity varied from .86 to .91 in the four grade-site groups. The ultimate goal of this longitudinal study is to identify highly caries-prone children in time to prevent the occurrence of a future caries increment. Although the lack of consistent association of many variables, including microbiologic factors, with baseline caries prevalence was unexpected, it is expected that some of these variables will contribute predictive power in the prospective study.

Baseline clinical dental examinations were conducted on 5,233 children in grades 1 or 5 from the areas surrounding Aiken, SC, and Portland, ME, as part of a longitudinal study being conducted to predict children at high risk to dental caries. Mean caries levels in the Aiken area were nearly twice those of the Portland area. Black children experienced slightly more disease than whites. In addition to lower levels of caries experience, Portland children also had more treatment needs met, as indicated by higher filled ratio scores.

For a comparative study of root caries, 502 adult lifelong residents of a naturally fluoridated community (1.6 ppm F) and 465 such residents of a nearby, comparable nonfluoridated community (0.2 ppm F) were examined. Substantially fewer carious lesions were found among adults in the fluoridated community relative to the nonfluoridated community. This was observed in virtually all age- and gender-specific groups. Given a cross-sectional design and considering only exposed root surfaces, root caries was related to age. In addition, the data from this study show that the number of root caries lesions is underestimated but that root caries prevalence is overestimated by the standard Root Caries Index (RCI). A less restrictive form of the RCI may lead to more valid estimation of root caries prevalence.

This has been a necessarily cursory overview of three types of clinical dental caries studies: the dental survey, the randomized clinical trial, and the non-randomized comparative study. Each of these studies may be used in its appropriate place, although only the survey and the randomized clinical trial are well-grounded in scientific theory. In general, the dental survey is well-suited to gathering basic cross-sectional data on dental caries, data that serve a variety of important practical and scientific interests in the dental care system. Clinical trials and non-randomized studies are applied in evaluating a variety of therapies for dental caries. Of the two, the randomized clinical trial is by far the more powerful. As a result, the clinical trial has found a central place in dentistry. The contributions that past and present clinical caries trials have made to dental health are quite evident to most observers. It is virtually inescapable that well-conducted clinical caries trials will make even more significant contributions to dental practice in the future, thereby further improving the oral health of all.

The purpose of this study was to demonstrate the effectiveness of two fluoride varnishes (Duraphat and Fluor Protector) in the prevention of dental caries in children residing in a non-fluoridated community. At baseline, 787 grade one children (6-7-yr old) were examined and randomly allocated into a control and two treatment groups. At 20 months, 703 children remained in the study. The mean baseline caries experience and the mean number of permanent teeth present at 20 months were not significantly different among the treatment and control groups. The mean DMFS increments after 20 months were 1.70, 1.73 and 2.02 for Fluor-Protector, Duraphat and control groups respectively (% reductions of 15.8 and 14.4 for Fluor-Protector and Duraphat groups). The mean dfs increments for primary molars after 20 months were 1.56, 1.62 and 1.74 for Fluor-Protector, Duraphat and control groups respectively (% reductions of 10 for Fluor-Protector and 7 for Duraphat).

Studies of dental preventive interventions often do not incorporate a concurrent, longitudinal control group in their study design. The existence of a secular decline in dental caries during the conduct of these studies may result in an overstatement of the effectiveness of the preventive intervention. Results of a recent large caries preventive study are analyzed using both a concurrent, longitudinal control group and an historical comparison group to demonstrate this effect. Differences in effectiveness of preventive procedures determined using the two types of control groups are sufficient to suggest a probable misinterpretation of results of studies using only historical comparisons.

This paper presents the comparative effectiveness of fluoride mouthrinse (FMR) on high and low caries forming children after a 4-yr exposure to weekly rinse beginning in the first grade. Over 1200 grade 1 children drawn from both fluoride deficient and fluoridated sites were divided into treatment and concurrent, longitudinal control groups. After 4 yr these children were stratified according to caries increment; those above the 75th percentile were considered high caries formers, all others were designated low caries formers. After adjustment of the mean increments for differences in SES, age, race, and sex in rinse and control groups, high caries formers (approximately 25% of the children) in the rinse and control groups in fluoride deficient areas showed increments of 7.00 and 7.79 surfaces, respectively, indicating a savings of 0.79 surfaces. Low caries formers (approximately 75% of the children) demonstrated increments of 1.11 DMFS in the rinse group and 1.40 in the control group (savings 0.29 DMFS). The pattern was quite similar for children in fluoridated areas except that the increments, as well as the savings realized, were lower. The results raise questions as to the practical effectiveness of school based FMR programs even for high caries forming children.

An 18-month longitudinal study of 197 5 to 18-yr-old children was conducted to assess the performance of multiple baseline variables in predicting which children would experience high increments of caries. Nine predictors were assessed; DMFS and defs scores, number of permanent teeth, indices of fissure retentiveness and occlusal morphology, S. mutans and lactobacilli levels, and sex and race. Discriminant analyses were applied to data for children in five age groups to identify the 30% who would have the largest 18-month DMFS increments. Prediction performance was assessed by comparisons with the actual high increment group, defined as those children with increments in the upper quartiles of the DMFS distributions within age groups. The analyses predicted between 56% and 91% of actual high increment children depending on age group. The children identified in the analyses experienced between 59% and 91% of the disease experienced by the actual high increment groups.

This paper has attempted to review dental caries epidemiology as it may relate to the subject of dental sealants. As such, the major emphasis has been on the epidemiology of permanent tooth caries among children and adolescents. The review touched four major areas. First, the current distribution of dental caries and its relationship to various epidemiological factors was discussed as it pertains to North America. Second, the evidence for declining caries experience was reviewed from a North American, European, and Australia/New Zealand perspective. Third, a superficial discussion of dental caries epidemiology in selected developing countries was offered and certain contrasts to caries patterns in developed countries were illustrated. Fourth, a brief attempt was made to evaluate the relative significance of pit and fissure caries in children.

This article presents the rationale and content of a current study that seeks to improve methods to identify children at high risk to dental caries. It summarizes the results of the development of a 12-factor, preliminary caries prediction model based on data derived from the National Preventive Demonstration Program. Despite data limitations, the model produced a sensitivity of .5 and specificity of .8 for four-year caries increment prediction in first- and fifth-grade children. Data on a number of additional potential predictors are being collected in two sites to expand and improve the existing model. These factors are identified.

This report presents dental caries and treatment patterns found in a longitudinal study of US children between 1978 and 1982 who were geographically dispersed across several fluoridated and nonfluoridated sites. The analyses include first- and fifth-grade children examined annually for four years in the National Preventive Dentistry Demonstration Program and who did not receive effective preventive procedures. The results indicate that in association with the caries decline in US children, treatment ratios increased by over 20 percent during the study period. FS/DFS ratios averaged 79 percent for the four grade/fluoridation status cohorts analyzed and were significantly higher in fluoridated than in nonfluoridated sites. The single-fissured surface was the dominant treatment or disease area observed and these surfaces tended to be restored early. In assessing tooth-surface status changes annually, tooth surfaces were more than twice as likely to change from sound to filled than from sound to decayed between yearly examinations at fluoridated sites. The lower levels of decay and higher degree of restorative care observed were not observed in lower SES and black children nearly to the extent as those for higher SES and white children in the population. The dental profession should shift its emphasis from the early restoration of fissured-surface defects to an expanded use of sealants for those with reduced decay and focus resources on a minority of the population with high caries levels who receive limited care.

The development and validation of a caries prediction model comprising 13 sociodemographic and dental examination variables on Grade 1 and Grade 5 children in the National Preventive Dentistry Demonstration Program are described. The objective was to derive a method of predicting children at high risk to caries early in order that preventive measures might be undertaken. True high risk children were defined in two ways: highest 25% of children based on their 4-yr DMFS increment, and their total DMFS score at the end of the study. In both cases, children predicted to be at high risk were defined as the 25% with the highest discriminant score. Discriminant function and logistic regression analyses were used to determine the extent to which the 13 variables collectively discriminated between true high risk and non-high risk children so defined. Sensitivity was approximately 0.50 and specificity around 0.82, using the 4-yr increment as the criterion for defining true high risk, and approximately 0.64 and 0.88, respectively, using the final DMFS score for defining true high risk.