Dennis H. Leverett

Caries Risk Assessment in a Longitudinal Discrimination Study

Our objective was to develop and perfect a model for the assessment of risk of dental caries onset in children. Even though dental caries prevalence in children is continuing to decline, there is still a significant minority for whom it is a problem. In this study, we sought to ascertain whether a set of variables selected in a previous cross-sectional study could be used to differentiate between caries-free six-year-olds who would or would not subsequently present with clinically-detectable caries. A total of 472 caries-free six-year-olds—286 from a fluoridated community and 186 from a fluoride-deficient community-was selected. Clinical examinations for DMFS, dental fluorosis, and plaque were conducted. Stimulated whole saliva was collected for analysis of mutans streptococci, lactobacilli, total viable flora, and fluoride, calcium, and phosphate concentrations. A questionnaire was used for collection of demographic data as well as information on prior fluoride exposure, dietary habits, and oral hygiene practices. By means of linear discriminant analyses, it was possible to predict correctly which children would develop caries within six to 12 months (sensitivity) in 82.8% of cases and which children would not develop caries during that period (specificity) in 82.4% of cases.

Randomized Clinical Trial of the Effect of Prenatal Fluoride Supplements in Preventing Dental Caries

This randomized, double-blind study tested the caries-preventive efficacy of prenatal fluoride supplementation in 798 children followed until age 5. Initially, 1,400 women in the first trimester of pregnancy residing in communities served by fluoride-deficient drinking water were randomly assigned to one of two groups. During the last 6 months of pregnancy the treatment group received 1 mg fluoride daily in the form of a tablet and the control group received a placebo. Both treatment and control subjects were encouraged to use postnatal dietary fluoride supplements. Caries was measured in children at age 3 and 5 while fluorosis was assessed at age 5. Caries activity was very low in both study groups: 92% of children remained caries-free in the treatment group and 91% remained caries-free in the placebo group. Fluorosis was observed in 26 subjects, all classified as very mild. Overall, there were no statistically significant differences in the study groups with respect to caries and fluorosis in deciduous teeth. The study had sufficient power to detect an absolute risk reduction of 5.1% while only a 1.5% reduction was observed. These findings do not support the hypothesis that prenatal fluoride has a strong caries-preventive effect.

Caries Risk Assessment by a Cross-sectional Discrimination Model

Although the prevalence of dental caries is continuing to decline, it still affects a majority of the US population and can be a serious problem for those afflicted. The objective of this project was to develop and perfect a model for assessment of risk of dental caries onset in children. In the first study, reported herein, a set of clinical, microbiological, biochemical, and socio-demographic variables was identified that distinguished, with an acceptable level of sensitivity and specificity, between children who had no previous caries experience and children who had high caries levels. A total of 313 children-age 12-15 years, 140 from a fluoridated community and 173 from a fluoride-deficient community-was selected on the basis of previous caries experience, either zero DMFS or high DMFS (> 6 in the fluoridated or ≥ 8 in the fluoride-deficient community). Clinical exams for DMFS, dental fluorosis, and plaque were conducted. Stimulated whole saliva was collected for analysis of mutans streptococci, lactobacilli, total viable flora, and fluoride concentration. A questionnaire was used for collection of demographic data as well as information on prior fluoride exposure, dietary habits, and oral hygiene practices. By means of discriminant analyses, with use of seven key clinical and laboratory variables, it was possible for zero-DMFS subjects to e classified correctly (specificity) in 77.6% of cases in the fluoridated community and in 86.1% of cases in the fluoride-deficient community. High-caries subjects were classified as such (sensitivity) in 79.3% and 88.1% of cases, respectively.

Correlations between Numbers of Microf lora in Plaque and Saliva

An epidemiologic investigation to reliably identify caries-susceptible subjects by microbiological and chemical assessment of plaque and saliva is currently in progress. As part of that study, the numerical relationships of mutans streptococci, lactobacilli and total viable microflora in plaque and saliva among 12- to 15-year-old children in a fluoridated community were determined. Paraffin-stimulated whole saliva and pooled dental plaque were collected. Each sample was suspended in reduced transport fluid, chilled on ice, and assayed. The bivariate normal distribution was found to be a suitable model for the distribution of the pairs [numbers of bacteria in plaque (log10), numbers of bacteria in saliva (log10)]. Statistically significant positive correlations were found between numbers of mutans streptococci in plaque and saliva, and between lactobacilli in plaque and saliva.

Effect of Daily Rinsing with Stannous Fluoride on Plaque and Gingivitis: Final Report

Two groups of children, ages 12 to 15, rinsed daily for 28 mo with aqueous fluoride solutions, one group using 0.05% sodium fluoride (NaF) and the other group using 0.1% stannous fluoride (SnF2). The SnF2 group had less plaque accumulation after four mo, but no difference was apparent at 16 and 28 mo. Gingivitis was less severe in the SnF2 group throughout the study, although the difference did not reach statistical significance. The 0.1% SnF2 solution, used daily as a mouthrinse, inhibits plaque formation, although this inhibitory effect is not apparent after 16 mo of rinsing.

The Effect of Daily Mouthrinsing with Stannous Fluoride on Dental Plaque and Gingivitis — Four-month Results

This clinical trial of a daily 0.1% SnF2 mouthrinse involved over 400 children, from 12 to 15 years of age. With 0.05% NaF as the active control, rinsing was conducted daily for four mo after baseline examinations. Four-month examinations showed significantly lower Plaque Index scores for the SnF2 group. Gingival Index scores for the SnF2 group were lower, but the difference did not reach statistical significance.

Dental Caries and Staining after Twenty-eight Months of Rinsing with Stannous Fluoride or Sodium Fluoride

The aim of this study was to compare the effects of daily mouthrinsing with aqueous solutions of 0.05% NaF or 0.1% SnF2 on dental caries and tooth staining. The study population consisted of 437 children, aged from 12 to 15 years at baseline, residing in a non-fluoridated community. By stratified random sampling, the subjects were divided into two groups, one group rinsing daily under supervision for 28 months with the NaF solution and the other with the SnF2 solution. The SnF2 group exhibited four to five times as much extrinsic stain as did the NaF group, although the stains were quite mild and not explicitly distinguishable between groups. There were no statistically significant differences between the two groups in terms of total DMFS. However, the increment of pit and fissure caries was 0.9 surfaces fewer for the SnF2 group (p = 0.04), while the increment of smooth surface caries was 0.6 surfaces fewer for the NaF group (p = 0.04). These data suggest that there may be a difference in mechanism of action between SnF2 and NaF rinses.

Interexaminer Agreement for Readings of Dip Slide Tests for Salivary Mutans Streptococci and Lactobacilli

This study reports the interexaminer agreement of three pairs of evaluators of salivary dip slide tests for mutans streptococci and lactobacilli. 717 Cariescreen SM and Bactotest LB dip slides were available for assessment by 2 dentists and 1 dental hygienist. A single calibration session was held prior to the onset of the study. Each dip slide was read once by each examiner independently. Among the three pairs of examiners, Pearson R values ranged from 0.84 to 0.90 for Cariescreen and from 0.78 to 0.87 for Bactotest. Kappa statistic values ranged from 0.56 to 0.61 for Cariescreen and from 0.70 to 0.74 for Bactotest. The range of agreement was from 72.2 to 76.9% for Cariescreen and from 86.4 to 88.3% for Bactotest. The majority of disagreements were of one category in magnitude, though there were a few disagreements of greater magnitude. This study found moderately strong agreement among the three examiners; it suggests that multiple examiners of dip slide tests carefully calibrated initially and periodically to ensure a high level of agreement.