The benefits of high-potency fluoride dentifrices.

National surveys show that the incidence of caries in children, adults, and seniors is still quite high, despite interpretations to the contrary. The dental profession and general public agree that the standard level of 1,000 ppm to 1,500 ppm fluoride (F) in most dentifrices reduces dental caries. Many studies using higher concentrations of fluoride in dentifrices and gels, 2,000 to 5,000 ppm F, have shown that caries prevention increases with fluoride concentration.

Dietary models for root caries.

A stepwise multiple logistic regression was computed to assess which of the nutritional variables differentiate the healthy and diseased group of participants in the Forsyth Specialized Caries Center (n = 275). Variables considered as candidates for the model included the consumption per week of sugars, starch, cheese, fruits and fruit juices, noncariogenic foods, and dairy products. Two variables--sugars and cheese--were statistically significant by the stepwise procedure. Increased intake of sugar was associated with being in the root caries group, whereas high intake of cheese was negatively associated with root caries. Thus, cheese seems to have a protective effect after sugar intake is controlled for. Odds ratios were computed to quantify the influence of the variables. An increase of two exposures of sugar per day corresponded with an odds ratio of 1.26. The odds ratio continues to increase with sugar intake so that an increase to five exposures per day gives an odds ratio of 1.79. This model is consistent with past in vitro studies suggesting that cheese protects against caries formation when sugar intake is controlled for and that increasing frequency of sugar intake increases the odds of root caries.

Using a fluoride-releasing resin to reduce cervical sensitivity.

Significant research indicates that dental hypersensitivity is caused by open dentinal tubules. A review of such research is presented as well as results of a study using fluoride resin in a composite restoration to reduce sensitivity.

Gingival recession: intra-oral distribution and associated factors.

This study assesses the role of poor oral hygiene and forceful toothbrushing as risk factors for recession. As part of a cross-sectional root surface caries study, 298 subjects, 42 to 67 years of age, with at least one exposed root surface, were examined. Since 66% of the root surface exposure and practically all the abrasion was on buccal surfaces, the analyses focused only on the buccal surface. Analysis of variance on subject means for buccal recession showed both calculus and presence of buccal root surfaces with abrasion to be significantly associated with recession after adjusting for age and gender. Root surface abrasion was considered a surrogate variable for forceful brushing. An additional analysis utilized means for each tooth, aggregating across subjects. For each of the 32 tooth types mean buccal recession, percent of exposed root surfaces with abrasion (%ra), and mean debris and calculus scores were calculated. Partial correlation coefficients across tooth types between recession and calculus, adjusting for abrasion, and for recession and abrasion adjusting for calculus, were 0.55. Interpretation of the %ra as a crude measure of forceful brushing is supported by its strong negative correlation across tooth types, with mean debris (r = -0.8) and mean calculus (r = -0.7). Separate analyses on premolars and on molars suggested that recession on premolars may be primarily due to brushing force and on the molars may be primarily due to debris and calculus. The findings suggest that recession is positively associated with percent abrasion (reflecting forceful brushing) and with poor oral hygiene.

The relative anticaries effectiveness of sodium monofluorophosphate and sodium fluoride as contained in currently available dentifrice formulations.

A 36-month double-blind clinical caries study was conducted to determine the comparative anticaries efficacy of sodium monofluorophosphate (MFP) and sodium fluoride (NaF) as incorporated in dentifrice formulations. The test dentifrices which were utilized are commercially available in the United States and all have been granted the American Dental Association Seal of Acceptance for anticaries efficacy. The study was conducted in accordance with the 1988 Guidelines of the American Dental Association Council on Dental Therapeutics. The two formulations used in the NaF versus MFP comparison were Colgate Winterfresh Gel with 0.76% sodium monofluorophosphate in a silica base and Crest Regular Flavor Toothpaste with 0.24% sodium fluoride in a silica base. A third commercially-available NaF dentifrice, Colgate Junior Toothpaste with 0.243% sodium fluoride in a silica base, was included in the study for further comparison. Schoolchildren residing in Maine, U.S.A. received a baseline caries clinical examination and then were randomly assigned to the twice-daily use of one of the three dentifrices which were purchased in the marketplace and repackaged in plain white tubes. Caries clinical examinations were subsequently conducted after 2 and 3 years' use of the dentifrices. A total of 2,222 children participated in both the 2 and 3-year caries clinical examinations. The 36-month DFS (decayed and filled surfaces) and the DFT (decayed and filled teeth) mean caries increments for the three dentifrice groups were virtually identical. The children using the MFP formulation experienced a DFS of 1.50 and a DFT of 1.08; those using the Crest NaF formulation experienced a DFS of 1.48 and a DFT of 1.07; subjects in the third group (Colgate Junior Toothpaste, 0.243% NaF) had a DFS of 1.49 and DFT of 1.06. The statistical evaluation of the data consisted of the calculation of 90% confidence bounds for the ratio of (true) mean increments, in accordance with the 1988 American Dental Association Guidelines. Expressed in the language of the Guidelines, the analyses indicated that, (1) the anticaries efficacy provided by the MFP formulation, (Colgate Winterfresh Gel with 0.76% MFP) is "as good as" that provided by the NaF formulation, (Crest Regular Flavor Toothpaste, with 0.243% NaF), and (2) the anticaries efficacy provided by the one NaF formulation (Colgate Junior Toothpaste, with 0.243% NaF) is "as good as" that provided by the other, (Crest Regular Flavor Toothpaste, with 0.243% NaF).

Clinical studies on MFP/calcium containing abrasive.

Monofluorophosphate (MFP) is unique in that its calcium salt is relatively soluble. Because of this property MFP can be combined with a dicalcium dihydrate (dical) abrasive in a dentifrice formulation without loss of efficacy. It has been reported that fluoride uptake by artificial lesions in enamel and dentine is significantly greater from an MFP formulation containing dical than from an equivalent calcium-free formulation. Additionally, it has been shown in an in situ remineralisation study that brushing with MFP dical significantly increases the levels of fluoride and calcium in plaque, and produces a concomitant increase in remineralisation of artificial caries lesions, as compared to brushing with MFP silica. All of the foregoing suggests that dical may enhance the benefit of MFP in a dentifrice formulation. MFP dentifrices have been tested more exhaustively in human clinical trials than any other form of fluoride dentifrice. In some trials the test formulation contained dical while in others a non-calcium abrasive system was employed. Collectively, studies of F/dical formulations have not produced more impressive results than studies of calcium-free MFP agents. However, there has never been a direct comparison of the conventional 0.76 per cent sodium monofluorophosphate dentifrice in a dicalcium phosphate abrasive system with a dentifrice containing a similar level of MFP combined with a non-calcium containing abrasive. In the closest approximation to such a study, an MFP/NaF dentifrice with a dical abrasive was compared to an MFP/NaF dentifrice with a silica abrasive system.(ABSTRACT TRUNCATED AT 250 WORDS)

A critical review of the relative anticaries efficacy of sodium fluoride and sodium monofluorophosphate dentifrices.

While there is broad consensus in the research community that fluoride dentifrices provide important anticaries benefits, debate still remains as to the most efficient form of fluoride used in toothpastes. Recently, the authors of this paper collaborated as part of a scientific advisory group whose objective was to comprehensively review all clinical information available comparing the anticaries efficacy of the two agents most widely used in fluoridated toothpastes, sodium fluoride (NaF) and sodium monofluorophosphate (SMFP). This review included a detailed analysis of each published study pertinent to the question, a comprehensive meta-analysis of all available clinical findings, and an epidemiological assessment of how anticaries benefits of dentifrices may be anticipated to propagate with time. Overall, the use of meta-analysis of head-to-head clinical comparisons between the two fluoride-active systems was found to be the most valid means for comparing the relative efficacy of NaF and SMFP dentifrices. Results of this analysis demonstrated that NaF was significantly more effective than SMFP in preventing caries (p < 0.01). While the numerical difference in efficacy between NaF and SMFP measured between 5 and 10% (total DMFS) over a 2- to 3-year clinical period, this could be expected, on theoretical grounds, to propagate to substantially larger differences (e.g. 10-20%) over 10-20 years. Hence, the difference in efficacy between these two actives was judged to be clinically important as well as statistically significant. Based upon these findings the authors recommend that NaF be used as the active system in fluoridated dentifrices whenever practically feasible. However, the authors caution that this recommendation pertains to the formulation of NaF in highly compatible abrasive systems, which must be demonstrated by critical evaluation of ionic fluoride within formulations for stability, availability and bioavailability. One additional recommendation emanating from this review is that important improvements must be made in the design, execution and reporting of future caries clinical trials in order to bring these important methods up to scientifically acceptable standards.

CaF2 in enamel biopsies 6 weeks and 18 months after fluoride treatment.

Fluoride concentrations were studied in enamel biopsies from maxillary central incisors 6 weeks and 18 months after fluoride treatment. In the short-term study biopsies were obtained prior to and after treatment with acidic sodium or ammonium fluoride. The findings showed that large amounts of fluoride were deposited in enamel from NH4F treatment (mean concentration 84,723 ppm), indicating substantial CaF2 formation. NaF treatment resulted in mean fluoride concentrations of 7,818 ppm. In the 18-month study, biopsies from 58 placebo-treated teeth were analyzed for total fluoride (mean 1,733 ppm). Twenty-five additional biopsies from placebo-treated and 58 from NH4F-treated teeth were analyzed for KOH-soluble (CaF2) and KOH-nonsoluble (apatitic) fluoride. The mean values for total fluoride were 1,669 and 2,085 ppm in the placebo-treated and in the NH4F-treated groups, respectively. The corresponding mean values for KOH-nonsoluble fluoride were 1,467 and 1,731 ppm and for KOH-soluble fluoride 202 and 354 ppm, respectively. The increase in enamel fluoride after fluoride treatment was only marginally significant. Biopsies from the ammonium fluoride treated group were significantly more likely to have high (30 vs. 8%) and moderate (28 vs. 16%) CaF2 levels and less likely to have low levels than biopsies of placebo-treated teeth (chi-square = 8.0 with 2 d.f.; p = 0.018). It is concluded that very substantial amounts of CaF2 are present in enamel 6 weeks after treatment, and small amounts may persist in the surface enamel for as long as 18 months.

Reaction paper: the use of topical and systemic fluorides in the present era.

Systemic fluoride may enhance the resistance of the tooth by way of (1) an alteration in tooth morphology, and (2) a conversion of the hydroxyapatitic mineral to a fluoridated state with an attendant reduction in solubility and an enhancement of the remineralization phase of the caries process. It has been reported by a number of investigators, although it is not universally accepted, that the posterior teeth from fluoridated areas have a distinct morphology that is less susceptible to caries attack. Fluorapatite and hydroxyapatite do not differ appreciably with respect to the amount of mineral that dissolves at a specified concentration of acid. However, if solubility is considered as a function of pH at equilibrium, i.e., the final pH after the dissolution products have entered the solvent--a model more akin to the in vivo situation--hydroxyapatite is the conspicuously more soluble of the two minerals. In this connection, epidemiologic data suggest that children with unusually high levels of surface enamel fluoride have little or no caries. This observation is consistent with the finding that the solubility of solid apatite solutions with varying degrees of fluoride substitution was inversely related to fluoride content, with minimal solubility at 0.5 substitution, a value observed in natural teeth at the very outermost surface of the enamel. Evidence of a preeruptive effect of fluoride has also been shown in field studies in which subjects had reduced levels of caries with fluoride exposure in childhood only.

The efficacy of a novel toothbrush design.

The single-blind study compared a novel toothbrush design (Aquafresh Flex soft, medium, and firm bristle versions) to a widely-available, standard brush with soft bristles. Subjects (n = 32-35/group, mean age = 46 yrs) were randomly assigned to the four groups and instructed to maintain their normal oral hygiene routine. Safety, as well as plaque (Turesky et al. index as modified by Soparkar) and gingivitis (Loe-Silness index as modified by Lobene) were evaluated for the Ramfjord teeth at baseline, two weeks, and six weeks. At termination, all brands were considered to be safe. After two weeks, the mean plaque scores for each of the four groups were reduced significantly, although a difference between the control group and the test groups could not be demonstrated. Between two and six weeks, the mean plaque scores for the test brushes leveled off while the corresponding score for the control brush increased significantly (p = 0.02). The gingivitis scores showed a similar pattern. This pattern suggests more favorable user acceptance for the test brushes, which is consistent with information provided by the subjects on a post-study questionnaire. Presumably, this phenomenon is associated with the unique design of the test brushes.

Association of the microbial flora of dental plaque and saliva with human root-surface caries.

Dental plaque was obtained from one or two sound root surfaces of subjects with different degrees of root-surface caries experience. From subjects with root-surface caries, plaque samples were also obtained from either one incipient or one more advanced lesion. Proportions of the total flora were determined for total streptococci and different streptococcal species, total and different Actinomyces species, and lactobacilli. A sample of saliva was obtained from about one-third of the subjects for determination of the concentrations of mutans streptococci and lactobacilli. The main observations were: (1) Subjects without root-surface caries or restorations (group I), as compared with subjects with root-surface caries with or without restorations (group II), were characterized by having a lower prevalence and proportion of mutans streptococci and a higher prevalence and proportion of A. naeslundii in plaque on sound root surfaces; (2) subjects in group I also tended to have a lower salivary concentration of mutans streptococci and lactobacilli than subjects in group II; (3) dental plaque on sound surfaces in group II subjects contained a lower proportion of mutans streptococci than plaque associated with incipient or advanced lesions; and (4) the prevalence and proportion of lactobacilli in plaque associated with sound as well as carious root surfaces were very low. The data reinforce findings from other studies and indicate that, as for coronal caries, the plaque and saliva populations of mutans streptococci specifically are correlated positively with the presence of root-surface caries.

In vivo study of slow-release fluoride resin and enamel uptake.

The purpose of this study was to investigate in vivo enamel fluoride uptake of a slow-release boron trifluoride BIS-GMA resin material. Study subjects were orthodontic patients with at least one pair of permanent bicuspid teeth indicated for extraction. The material was applied to the buccal surface of the test tooth 1 month prior to extraction; the contralateral tooth served as the control tooth. Following extraction, the resin was removed by soaking in acetone for 36 h and polishing with a sodium bicarbonate slurry. Prior scanning electron microscopic studies have shown that this cleaning procedure effectively removes all residual resin. Enamel fluoride analyses were completed for 12 pairs of teeth from 9 subjects. The mean differences in enamel fluoride concentrations between the treated and control teeth were significantly different from zero at the 0.01 level. At each successive depth, the absolute mean amount of fluoride uptake by the test teeth was fairly constant; however, the proportional mean amount or percent increase in fluoride concentration resulting from treatment became greater in the deeper enamel layers. The data suggest that this material has the potential to provide an effective means of introducing substantial amounts of permanently bound fluoride into surface enamel, even into the deeper layers.

Methodological issues relative to the quantification of root surface caries.

The purpose of this study was to assess the effect upon the quantification of root surface caries (RSC) of (1) the separation of the disease into its discrete clinical phases, (2) the confounding caused by the presence of restored abraded surfaces, and (3) the decision rule formulated for dealing with lesions and restorations which involve both crown and root. It was found that the apparent prevalence of RSC varied widely depending upon arbitrary decisions as to what stages of the disease were included in the measurement scheme. The addition of restorations (confined to the root) greatly enlarged the various disease measures, but probably also introduced some degree of error since there are several indications from the data and the clinical patterns of affected surfaces which suggest that some of the restored surfaces were formerly abraded rather than carious. The inclusion of lesions and restorations involving both root and crown produced another conspicuous increment in all disease measures, which is a cause for concern given that these components are included in some studies and ignored in others. These findings serve as the basis for several recommendations for future prevalence and incidence studies of RSC.

Clinical profiles of individuals with and without root surface caries.

As part of a collaborative multidisciplinary investigation of root surface caries (RSC), 273 subjects (median age = 57) were clinically evaluated for coronal caries, debris, calculus, gingivitis, periodontal pocketing, recession, abrasion, as well as RSC. The entire study group was divided into three subgroups: (1) subjects whose exposed root surface were without lesions or restorations (non-diseased individuals, n = 43); (2) subjects whose exposed root surfaces had one or more lesions and may or may not have had restorations (diseased individuals, n = 110); (3) subjects with one or more restorations but no lesions, since it was not known whether these restorations were preceded by RSC or abrasion the disease status of these individuals was unclear (n = 120). A comparison of Subgroup 1 (unequivocally non-diseased) and Subgroup 2 (unequivocally diseased) revealed that subjects without RSC had more teeth, less coronal caries, less recession, less debris, less calculus, less gingivitis, and more abrasion. We infer that the common factor underlying most if not all of the subgroup differences is oral hygiene which must therefore be a major disease determinant.

The reliability of the iodide permeability test applied to the natural dentition.

The purpose of this study was to assess the reliability of the iodide permeability test when applied to the human dentition. Twenty-two subjects were seen once a week for three weeks. At each visit, consecutive iodide permeability measurements were obtained: four from the right central incisor and four from the left. Results of these trials were examined for the degree of variability from one replication to another within the same day, as well as for the variability from one week to the next. Within-day and between-week reliability of the test results was assessed by two indices: the Hoyt Index, which estimates the reliability of the average of the four replicate measurements per tooth, and the Intraclass correlation, which estimates the reliability of a single measurement. The results indicate that the iodide permeability test produces sufficiently replicable measurements for use in future clinical studies.