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The purpose of this investigation was to study the genotoxic potential of fluoride (in the form of sodium fluoride, NaF) using in vitro and in vivo sister-chromatid exchange (SCE) assays with Chinese hamster cells. The NaF concentrations used in cultures of Chinese hamster ovary (CHO) cells ranged from 0 to 6.3 mM, both with and without S9 activation. Fluoride analysis of the culture medium demonstrated that it contained little indigenous fluoride, and the concentration of added fluoride was not affected by the components of the medium or the S9 mix. The CHO cells cultured in 6.3 mM NaF almost vanished, and at the concentration of 5.3 mM NaF in cultures without S9 microsome, only M1 cells were observed. In in vivo studies, Chinese hamsters were intubated with NaF dosages of 0, 0.1, 1.0, 10, 60 and 130 mg/kg, and the bone marrow (CHBM) cells were examined for SCE frequencies. Bone fluoride data showed that the intubated NaF was effectively absorbed. Death occurred in 3 of the 8 animals given 130 mg NaF/kg. The results indicated that NaF, in dosages up to 5.3 mM in CHO cell cultures and 130 mg/kg in in vivo CHBM cells, did not significantly increase the SCE frequencies over those observed in the negative (distilled water) controls. However, examination of the cell cycle revealed an inhibitory effect of NaF on cell proliferation with doses of NaF at or greater than 1.0 mM in cultured CHO cells and at or greater than 60 mg NaF/kg in in vivo CHMB cells. The results of the present study indicated an inhibition of the cell cycle and death of the cells with increasing concentrations of fluoride but not effect of fluoride on SCE frequency in CHO and CHBM cells.

A series of studies was conducted to investigate the use of the rat as an in vivo model for studies of dental stain and to identify dietary factors which influence stain formation in this model. It was determined that appreciable amounts of stain formed on the molar teeth of rats provided a synthetic diet containing lactalbumin, and the amount of stain increased throughout a four-week test period. Stain formation was also observed when rats were provided their diet by gastric intubation. Topical applications of chlorhexidine generally resulted in an increase in stain formation, as did the presence of tea in the drinking water. These studies support the use of the rat for investigations of dental stain.

This study was designed to evaluate the use of salivary cotinine, salivary thiocyanate, and expired-air carbon monoxide as biochemical validation measures for assessing the smoking status of adults. The participants were 20 known non-smokers plus 216 admitted smokers and 102 proclaimed quitters participating in a clinical trial of approaches to facilitate smoking cessation. Conventional analytical procedures were utilized. By use of data from known non-smokers and admitted smokers, the sensitivity and specificity of the validation measures were as follows: salivary cotinine, 99% and 100%; expired-air carbon monoxide, 96% and 100%; and salivary thiocyanate, 67% and 95%, respectively. The salivary cotinine and expired-air carbon monoxide tests confirmed smoking cessation for 55% and 74%, respectively, of the proclaimed quitters. The length of time since quitting was significantly related to the results observed with the latter measures. Consideration of these observations along with various practical factors suggests that expired-air carbon monoxide assays may be the validation measure of choice for most clinical trials.

Two rat caries studies were conducted in which oat hulls, sodium trimetaphosphate, and combinations thereof were incorporated into two different caries-producing diets. The type of diet used was found to influence the anti-caries effects of oat hulls. In many instances, the cariostatic effect of the two agents was additive or even synergistic.

A clinical trial was conducted to evaluate the effects of a sanguinaria-zinc chloride dentifrice on the prevention of plaque formation and gingivitis. A total of 59 young adults, 18 to 30 years of age, either performed supervised brushing with a 0.075% sanguinaria-0.05% zinc chloride dentifrice, a 0.24% sodium fluoride dentifrice, or rinsed daily with a 0.05% NaF solution. Clinical evaluations for plaque and gingivitis were performed after 7, 14, and 21 days of the test regimen. After 21 days, all subjects resumed twice daily supervised brushing and flossing and post-test evaluations were conducted after two weeks. The results showed that after 7, 14, and 21 days both groups using dentifrices had significantly less plaque and gingivitis than the group using the rinse, and there were no significant differences between the two groups using either the sanguinaria-ZnCl2 or the NaF dentifrices.

This study was designed to compare various salivary parameters between smokers and non-smokers and to determine the influence of a nicotine-containing chewing gum (used to aid in quit-smoking efforts) upon these same parameters. At the baseline examination, subjects were assigned to one of three groups: non-smokers who did not utilize any gum, smokers provided a nicotine-containing gum, and smokers provided a placebo gum. Saliva was collected from all subjects and analyzed for acidogenicity and buffer pH as well as for levels of thiocyanate, lactoperoxidase, lysozyme, lactoferrin, and secretory IgA. After 15 weeks of gum usage, saliva was again collected from each subject and the identical analyses performed. Significant differences were observed between smokers and non-smokers with regard to three parameters: The saliva of smokers contained greater concentrations of thiocyanate and lower concentrations of lactoferrin, at the baseline examination and after the 15-week test period. In addition, the CO content of alveolar air was higher in smokers at both examination periods. In contrast, the use of the nicotine gum per se had no effect on any of the test parameters.

The mutagenicity of fluoride (as sodium fluoride, NaF) was investigated with Ames Salmonella/microsome assays in strains of TA97a, TA98, TA100, TA102 and TA1535. The concentrations of NaF tested ranged from 0.44 to 4421 micrograms/plate (0.1 to 1000 ppm F), both with and without microsome activation. In addition, the suggested antimutagenic effect of fluoride was evaluated with known mutagens at various concentrations of NaF (0.44-442.2 micrograms/plate, 0.1-100 ppm F). The data showed that NaF, in amounts from 0.44 to 442.2 micrograms/plate (0.1-100 ppm F), failed to significantly increase the number of the revertants over the number observed in the solvent (distilled deionized water) controls. Increases of NaF to, and beyond, 1100 micrograms/plate (250 ppm F) resulted in a toxic effect and a reduction of the revertants to various degrees among the strains. NaF in the presence of known mutagens did not significantly decrease the number of the revertants. The results of this study indicate that NaF does not have mutagenic or antimutagenic effects in the strains tested with Ames Salmonella assays.

Schoolchildren residing in a fluoride-deficient area were provided either a sodium fluoride (0.1% F) or a nonfluoride dentifrice for home use. About half the children provided each type of dentifrice were also given an initial prophylaxis. Combining the data with regard to the type of dentifrice indicated that the sodium fluoride dentifrice resulted in dental caries reductions of 24 and 26% as noted by the two examiners, respectively.

Fifty private practitioners and their office staff members were randomly assigned to one of four groups: participants received a protocol for smoking management and a lecture on the consequences and management of smoking, or in addition, had nicotine gum freely available to patients, had stickers attached to their charts, or had gum and reminders. The percentage of patients in each group who had quit smoking a year later was 7.7, 16.3, 8.6, and 16.9, respectively, indicating a significant main effect for the gum conditions. The availability of nicotine gum also significantly increased the amount of time that patients reported they received smoking cessation counseling from the dentists and office staff.

An International Collaborative Study was conducted in which one surface profile and two radiotracer methods for assessing abrasivity of dentifrices on human dentin were compared. The study consisted of two phases: an open phase in which participating laboratories used the method they routinely practiced; and a controlled phase in which an expert team for each method performed the abrasion tests using all three methods. Four test pastes of known abrasivity were evaluated by each method. Similar abrasivity values for the test pastes were obtained with the radiotracer methods, whereas the surface profile method produced significantly different values. The precision levels of the radiotracer methods were similar, and both were superior to those obtained by the surface profile method. The time needed to perform the tests by the ADA radiotracer method was significantly less than that needed by the other methods. These findings suggest that the ADA radiotracer method will be useful in assessing abrasivity of dentifrices.

Fluoride is an element which is widely distributed in our environment. Its cariostatic efficacy has been well documented, and numerous studies indicate that at a concentration of 1 ppm in water, fluoride is beneficial for caries prevention and does not appear to exacerbate any diseases. Currently, more than half the American population is consuming naturally or artificially fluoridated water and efforts are being made to increase this proportion significantly. In addition, the multiple use of fluoride for dental caries prevention is clearly increasing. It is a common practice to use fluoride in a variety of delivery systems, including dentifrices, mouthrinses, pediatric supplements, and professional or self-applied topical solutions or gels as well as dental restorative materials. These dental products may contain fluoride in concentrations as high as 12,300 ppm. Increasing exposure of the population to fluoride has raised questions about the safety of this measure and has established the need for objective reappraisal. In particular, interest has developed regarding the genotoxic effects of fluoride. Unfortunately, there is, at present, only a limited amount of information available concerning the potential genotoxic effects of fluoride, and the results that have been published are contradictory and often very confusing. A review of the literature clearly indicates the importance of, and necessity for, clarifying the conflicts and controversies regarding this important issue.

Two studies were performed on rats to determine the post-eruptive cariostatic effects of lithium alone and in combination with fluoride. The results failed to demonstrate any cariostatic effects of lithium when evaluated in this manner, nor any enhancement by lithium of the cariostatic activity of fluoride.

The addition of high concentrations of molybdenum to a topically applied sodium fluoride solution did not result in a statistically significant increase in fluoride uptake into subsurface lesions in human enamel when compared to that after treatment with fluoride alone in vitro. The addition of 3000 parts/10(6) molybdenum to a 1000 parts/10(6) fluoride topical solution had no impact in vivo on the cariostatic activity of topically applied fluoride in rats.