Application of life table methodology in determining dental caries rates.

Probabilities of caries risk over time measured from eruption of first and second molars are illustrated using life table methodology. Life table rates based on 4,365 children in the National Preventive Dentistry Demonstration Program indicate that both fluoridation and sealants are effective in preventing caries on occlusal and buccal/lingual surfaces of molars. Effectiveness would probably have been greater on occlusal surfaces if sealants had been applied closer to the time of eruption. Similarities and differences between conventional DMFS indices and life table probabilities are discussed.

A case study in contesting the conventional wisdom: school-based fluoride mouthrinse programs in the USA.

This paper presents the events surrounding the dissemination of the results of a major preventive dentistry demonstration program designed and conducted to provide evidence of the effectiveness and actual costs of a combination of commonly used preventive procedures. It then reviews the controversy provoked when the results of that program were counter to the conventional wisdom of the day, prevailing national policy, and public health practice. An analysis of possible reasons for this reaction follows. The paper concludes with some observations about how such a situation might be approached to minimize similar controversy in the future.

Comparative effects of a 4-year fluoride mouthrinse program on high and low caries forming grade 1 children.

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.

University of North Carolina Caries Risk Assessment Study: comparisons of high risk prediction, any risk prediction, and any risk etiologic models.

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.

Comparative effectiveness of visual/tactile and simplified screening examinations in caries risk assessment.

Central to the development of a model for identifying children at high risk to caries is a clinical evaluation to assess dental status and other conditions potentially useful in caries prediction. Traditionally, this evaluation has been based on a relatively lengthy visual/tactile examination conducted by a dentist. Replacing the dentist examination with a dental auxiliary conducted screening evaluation could lead to reduced time and costs. The 4-yr University of North Carolina Caries Risk Assessment Study involved approximately 5000 schoolchildren initially in Grades 1 and 5 living near Aiken, South Carolina, and Portland, Maine. The effectiveness of caries prediction models using visual/tactile examination data were compared with the same models using simplified screening evaluation data. Results showed sensitivity ranged from 0.57 to 0.61 for the visual/tactile and screening models by site and grade cohort. Specificity for the models ranged from 0.80 to 0.83. None of these differences in sensitivity and specificity between visual/tactile (dentist) and screening (hygienist) models was statistically significant. Findings show that for the prediction of children at high risk to dental caries the clinical evaluation may be conducted with no reduction of precision by using dental hygienist performed screening evaluations rather than dentist conducted visual/tactile examinations. While no cost data were collected, these results imply that costs to future prediction programs could be reduced by using screening evaluations.

Identifying children who will experience high caries increments.

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.

Development and application of a prediction model for dental caries.

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.

The University of North Carolina caries risk assessment study: caries increments of misclassified children.

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.

The University of North Carolina Caries Risk Assessment study: further developments in caries risk prediction.

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.

Comparison of two screening tests for Streptococcus mutans and evaluation of their suitability for mass screenings and private practice.

Two simple microbiological tests for quantitating salivary Streptococcus mutans levels were compared with each other and evaluated for suitability for mass screenings and private practice. Both tests use mitis salivarius medium with bacitracin (MSB) and are selective for S. mutans. One test estimates colonies grown on agar (MSBA) and the other estimates colonies grown in broth that adhere to glass (MSBB). Both are scored from 1 (lowest) to 5 (highest). Children (293) in grades 5 and 6 in Tallahassee, Florida (nonfluoridated) were tested for S. mutans levels. Scores of children by both tests were significantly similar (chi 2, regression and Kappa statistical analysis). Correlation coefficients (regression) between scores and DMFS increments of the previous 4 yr were 0.35 (MSBA) and 0.26 (MSBB). Both tests were very good in identifying children with low caries increments, but positive scores did not correlate well with high caries increments. Sampling and interpreting took 2 min (MSBA) and 1 min (MSBB). Cost of MSBA/child was $1.15, and MSBB/child $1.25. These tests are economical and suitable for mass screenings to identify low risk populations who do not require preventive treatment.

University of North Carolina caries risk assessment study. III. Multiple factors in caries prevalence.

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.

The University of North Carolina Caries Risk Assessment Study. I: Rationale and content.

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.

The University of North Carolina Caries Risk Assessment Study. II. Baseline caries prevalence.

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.

Operation of the National Preventive Dentistry Demonstration Program.

Operation of large-scale, multiple-site demonstration programs is an infrequent activity, one for which most investigators have had little previous experience. The success of a demonstration program, however, often rests on operational aspects. Following the completion of a major demonstration, the writers discuss the design of their program, the problems they encountered in its operation, and the aspects they would change in future demonstrations.

Recent dental caries and treatment patterns in US children.

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.

Effect of secular decline in caries on the evaluation of preventive dentistry demonstrations.

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.

Assessment of private dental practice: implications for dental education.

The development and testing methods for assessing the quality of private general dental practice are described. The assessment instrument, evolved through the contributions of a panel of private practitioners, provides for the evaluation of the structure, process, and outcome of practice. General practitioners, trained as evaluators, tested the instrument in 300 urban group, urban nongroup, and rural practices in 14 states. The distribution of assessment scores for the entire project sample is compared with those of the sample dentists who graduated before and after 1974. The implications of the project and its results to dental education are discussed.

Resolved: that a fifth year of dental education be a requirement. Remarks for the negative.

Those representing the affirmative side of the issue have failed to provide convincing evidence supporting the necessity of a required fifth year of dental education. The mechanism is already in place for additional education and experience through expanding general practice residency programs for students desiring additional experience. A required fifth year would increase the cost of dental education for all students at a time of diminishing resources and would undoubtedly result in greater health care costs for the public. The overcrowded curriculum can be addressed successfully and far more economically by restructuring the present predental/dental curriculum continuum instead of adding a required fifth year. In conclusion, the negative side asserts that there are more practical, less expensive, and more feasible ways to address the issues confronting dental education today than by adding a mandatory year to the education process.

Indications for sealant use in a community-based preventive dentistry program.

Dental caries is a disease that recently has undergone, and may still be undergoing, dramatic changes in distribution of incidence and prevalence. The most recent epidemiologic data available have been reviewed in this paper to illustrate that caries is becoming a disease primarily of pits and fissures, with less differentiation than previously acknowledged between fluoridated and fluoride-deficient areas. The present distribution of caries suggests that prevention may be accomplished more effectively through targeted sealant programs than through currently popular mass preventive programs. Existing information can be used to identify logical target groups for sealant programs, and age specific tooth eruption and caries attack information can be used to design delivery methods. Although the adoption of targeted sealant programs represents a departure from the traditional mass approach to prevention in dental programs, the present-day caries distribution requires that the initiation of such programs be given serious consideration. At the very least program administrators are encouraged to invoke the planning-implementation-evaluation process. Current programs should be evaluated carefully in view of today's disease patterns and the clinical significance of the results achieved. The content, design, and timing of future community-based programs should reflect individualized community diagnosis and the application of new epidemiologic data as well as a careful evaluation of the results achieved by current preventive procedures.