Recommendation for a non-animal alternative to rat caries testing.

PURPOSE: As a requirement of the Food & Drug Administration's final monograph on "Anticaries drug products for over-the-counter human use", the toothpaste industry has been conducting animal caries tests on every fluoride-containing toothpaste introduced into the U.S. market since 1996. The practice of testing in animals, although required by law, is in stark conflict with the corporate policy of many U.S. and global toothpaste manufacturers, in which, if possible, alternatives to animal testing are utilized. A provision does exist within the regulation which allows the use of an alternative method to demonstrate efficacy. However, to take advantage of this provision, a petition must be submitted to the FDA and in this petition data demonstrating the alternative provides results of "equivalent accuracy" must be included. After many years of research, model development and model comparisons, we have identified one particular laboratory model that demonstrated excellent correlation with the currently accepted animal caries models. This model, known as the Featherstone pH cycling model, is discussed in this paper. METHODS: The Featherstone pH cycling model has been shown to produce results of equivalent accuracy to the animal caries model by: (1) demonstrating a clinically relevant fluoride dose response similar to that shown in the animal caries model (including 1100 ppm F, 250 ppm F and placebo); (2) demonstrating similar results to the animal caries model for clinically proven dentifrice formulations relative to positive and negative controls; (3) demonstrating discriminating ability in strong agreement with the animal caries model for differentiating between a dentifrice formulation with attenuated fluoride activity and a USP standard; and (4) providing a clinically relevant representation of the caries process, as demonstrated by orthodontic banding studies. In addition, the model sufficiently addresses both salivary and abrasive/anticalculus agent interference concerns. RESULTS: For more than 50 years, fluoride has been the first defense in the fight against dental caries. The clinical effectiveness of fluoride is well accepted and documented extensively in the literature. The mechanism through which fluoride provides its benefit is very straightforward and well understood. The proposed laboratory model effectively simulates the effect of the caries process and has been shown to demonstrate equivalent accuracy to animal caries. This indicates that there are strong scientific grounds for the use of this model as an alternative to the animal caries test. Based on the strength of the data and the correlations noted between the two models, we recommend that the scientific community and the toothpaste industry broadly accept the Featherstone laboratory pH cycling model as an appropriate alternative to animal testing, particularly for ionic fluoride based dentifrices.

The Featherstone laboratory pH cycling model: a prospective, multi-site validation exercise.

PURPOSE: To demonstrate the robustness of the Featherstone pH cycling model when tested in three independent laboratories and to evaluate the use of "non-inferiority" testing at those laboratories. METHODS: The fundamental principles for the Featherstone laboratory pH cycling model to be an appropriate alternative to animal testing is that it must demonstrate equivalent accuracy to the "Gold Standard" (rat caries model) by: (1) providing a meaningful representation of the caries process; (2) demonstrating a proportionate response to fluoride dose (or concentration); (3) being able to show that clinically proven formulations perform similarly relative to the controls; and (4) differentiating products that have attenuated fluoride activity. RESULTS: This cross-validation study confirmed the ability of the three independent laboratories to discriminate between various concentrations of fluoride-containing dentifrice formulations, demonstrated that clinically proven formulas perform as expected and identified an attenuated fluoride formulation (NaF/CaCO3 dentifrice - 1100 ppm NaF) as inferior compared to the 1100 ppm F (NaF/silica) positive control.

In vitro remineralization efficacy of NaF systems containing unique forms of calcium.

PURPOSE: To determine the in vitro remineralization potential of a new calcium phosphate technology in a 1000 ppm F system. METHODS: 3 mm diameter bovine enamel specimens were mounted, ground and polished, and softened in a carbopol-lactic acid solution (pH = 5.0) for 36 hours at 37 degrees C. Specimens were then measured for baseline Vickers microhardness and stratified (N = 10, mean VHN = 35) into the following groups: Group A: distilled water (negative control); Group B: MI Paste Plus (900 ppm F); Group C: Theramed SOS (1450 ppm F); Group D: "control" dentifrice (1000 ppm F); and, Group E: "test" dentifrice (1000 ppm F) admixed with a new functionalized calcium phosphate system. The groups were then cycled for 10 days in a pH cycling model consisting of four 2-minute treatment periods (diluted 1:3 with distilled water) and one 4-hour acid challenge (carbopol-lactic acid, pH = 5.0) per day. Between these events, specimens were immersed in artificial saliva (pH = 7.0). After 10 days of cycling, the specimens were measured for Vickers surface microhardness and were subsequently microdrilled, with the powder measured for fluoride content using a calibrated fluoride-sensitive electrode. RESULTS: Significant differences resulted between the distilled water and fluoride-containing groups. Among the fluoride-containing groups, Group B demonstrated statistically low levels of enamel fluoride deposition and deltaVHN, while Group E statistically outperformed Group D. Among the groups with different calcium systems (Groups B, C, and E), Groups C and E were found to be statistically equivalent and superior to Group B with respect to both bioavailable fluoride and deltaVHN. Based on our results, these data demonstrated the combination of a new calcium phosphate technology plus 1000 ppm F, produced significantly greater remineralization relative to both the 1000 ppm F test dentifrice and MI Paste Plus, and was statistically equivalent to Theramed SOS.

In vitro assessments of experimental NaF dentifrices containing a prospective calcium phosphate technology.

PURPOSE: To determine the fluoride dose response of experimental NaF dentifrices containing a prospective calcium phosphate technology, along with the corresponding relative enamel and dentin abrasion values. METHODS: 3 mm diameter bovine enamel specimens were mounted, ground and polished, and softened in a carbopol-lactic acid solution (pH = 5.0) for 36 hours at 37 degrees C. Specimens were then measured for baseline Vickers microhardness and stratified (N = 18, mean VHN = 33) into eight groups. These groups consisted of a placebo paste, four test dentifrices (A, B, C, D) with three of the four (A, B, C) containing a promising calcium phosphate ingredient, Crest Cavity Protection, MI Paste Plus, and PreviDent Booster 5000. The groups were cycled in a lesion reversal pH cycling model consisting of four 2-minute treatment periods (diluted 1:3 with DI water) and one 4-hour acid challenge (carbopol-lactic acid, pH = 5.0) per day. Between these events, specimens were immersed in artificial saliva (pH = 7.0). After 20 days of cycling, the specimens were microdrilled and analyzed for fluoride content, and also measured for Vickers surface microhardness after 10 and 20 days of cycling and after a 2-hour and 16-hour post-cycle acid challenge (carbopol-lactic acid, pH = 5.0). Separately, relative dentin and enamel abrasion (RDA and REA) were performed using the ADA recommended radiotracer method. RESULTS: A fluoride dose response was observed for the test dentifrices after 10 and 20 days of pH cycling, with test dentifrice C promoting the highest remineralization among the groups while both the MI Paste Plus and PreviDent systems provide the least remineralization (one-way ANOVA, SNK, P < 0.05). With respect to enamel fluoride uptake, the group facilitating the highest incorporation of fluoride into the enamel lesion was test dentifrice C, while the least effective NaF system was the MI Paste Plus (one-way ANOVA, SNK, P < 0.05). In terms of formulation abrasion, the REA scores were similar among the test dentifrices, MI Paste Plus, and PreviDent and compared favorably to the ADA reference material score (one-way ANOVA, SNK, P < 0.05); relative to the ADA reference material RDA score, the data indicate that MI Paste Plus was essentially non-abrasive, while PreviDent was significantly more abrasive to dentin (one-way ANOVA, SNK, P < 0.05). Altogether, these data show the developmental test dentifrices demonstrate a fluoride dose response and show great promise in remineralizing white-spot enamel lesions relative to MI Paste Plus and PreviDent.

Soft rawhide reduces calculus formation in dogs.

This clinical investigation was conducted to evaluate the impact of a unique soft rawhide product on the formation of dental calculus in a housed colony of beagle dogs. The study was designed as a 2-way crossover test with 4-week test periods and a 1-week wash-out period between the test periods. All dogs were provided a dry commercial diet and tap water ad libitum. The dogs were stratified into two groups of matched pairs on the basis of their calculus and plaque formation rates. Each test period was initiated immediately following a complete supragingival scaling and crown polishing and the dogs in the test group received a soft rawhide treat about 4-hours after their normal feeding. Examinations were performed about 20 to 24-hours after the last feeding by an experienced clinical examiner using conventional indices. The data indicated that once daily feeding of the soft rawhide chew product resulted in statistically significant reductions in the formation of dental calculus (28.0%), dental plaque (19.0%), and gingivitis (46.0%).

Epidemiologic survey of erosive tooth wear in San Antonio, Texas.

OBJECTIVES: To estimate the prevalence of erosive tooth wear in children aged 12-17 years in the southwest region of San Antonio, Texas, within Bexar County. METHODS: A convenience sample of 307 children aged 12-17 years was selected from two junior high schools. The population consisted predominantly of Hispanic Mexican Americans. The true prevalence of erosive tooth wear within the US is known from only one study, and then only for limited sectors of the population. The Tooth Wear Index, Screening for Oral Health using the Association of State and Territorial Dental Directors (ASTDD) criteria and oral health and dietary assessment questionnaires were used as survey parameters. The questionnaire included data on detailed dietary habits relating primarily to the consumption of acidic beverages and foods. RESULTS: The overall prevalence of erosion within our convenience sample was 5.5 percent. All affected children showed erosive tooth wear low in severity and confined to the enamel with no exposed dentin. A chi-square test was performed to test for associations between the presence of erosion and consumption level of certain acidic foods at a significance level of 5 percent. Few significant and consistent associations were found between erosive tooth wear and consumption frequency categories of groups of acidic foods and beverages using a non-validated food intake questionnaire on purported risk foods. Soda drinks were associated. Mexican acidic foods were not. CONCLUSION: This study indicated a low prevalence and low severity of dental erosion in a convenience sample of children aged 12-17 years in southwest San Antonio, Texas. Issues of sampling and response bias preclude these findings being generalized to other populations and regions.The results should be viewed with caution. Because the local consumption of some purported risk foods appears to be increasing, this study provides a base-line for future assessments of erosive tooth wear in this population.

The effect of saliva on dental caries.

BACKGROUND: The multiple functions of saliva play a significant role in the prevention of dental caries. METHODS: Chewing gum is known to stimulate salivary flow, and the results of studies of the role of stimulated saliva in the oral clearance of food particles, neutralization of dental plaque acids and reduction of the incidence of dental caries have been reported. The author reviews the results of these clinical caries trials. RESULTS: Seven clinical trials have evaluated the impact of chewing gum on caries incidence. These studies have shown that chewing sugar-free gum after meals results in a significant decrease in the incidence of dental caries and that the benefit is due to stimulating salivary flow rather than any chewing gum ingredient. CONCLUSIONS: Stimulating salivary flow through the chewing of sugar-free gum after meals has been shown to reduce the incidence of dental caries. CLINICAL IMPLICATIONS: Practical measures for stimulating salivary flow after meals or snacks should be considered in caries prevention programs.

Development of a standardisation device for photographic assessment of dental fluorosis in field studies.

PURPOSE: This study evaluated the agreement between clinical and photographic assessment of dental fluorosis (DF) in 73 children during a field study, using portable equipment and a standardising device. MATERIALS AND METHODS: A dental exam was performed using the Tooth Surface Index of Fluorosis (TSIF). Photographs of the facial aspects of front teeth and from the occlusal aspect of the mandibular posterior teeth were taken. All photographs were taken following a standard operating procedure. Photographs of anterior and posterior teeth were coded and assigned a random study number. Examiners scored photographs as fluorosis cases or non-cases. RESULTS: Agreement among the clinical examiners ranged from good to excellent. Agreement was also good for the repeated photographic evaluations. In total, 22% of the children were diagnosed with DF during a clinical exam, and 19% were diagnosed with DF using the photographs. CONCLUSIONS: Development of this method aided in the photographic assessment of DF. The photographs obtained were a useful tool for documenting DF, to re-train examiners, and to determine intra- and inter-examiner agreement.

Pilot clinical study to assess caries lesion activity using quantitative light-induced fluorescence during dehydration.

This study aimed to evaluate the ability of quantitative light-induced fluorescence (QLF) to assess caries lesion activity using visual examination (VE) as the gold standard. Twenty-four visible white spot lesions on buccal surfaces were examined from 23 children, ages 9 to 14 years. At baseline, the surface was hydrated with water, and thereafter, it was dehydrated with continuous compressed air during image acquisition. QLF images were acquired at 0 (baseline), 5, and 15 s. QLF variables [ QLF V : fluorescence loss ( ? F ), lesion size (S), ? Q : ? F × S ] was recorded. Changes-in- QLF V per second ( ? QLF V ) were determined: ? QLF V = ( QLF VN ? QLF V Baseline ) / N , where N indicates dehydration time. One experienced dentist conducted VE independently using a dental unit's light, compressed air, and explorer.

Ability of quantitative light-induced fluorescence (QLF) to assess the activity of white spot lesions during dehydration.

PURPOSE: To determine the ability of QLF to assess the activity of white spots using visual examination (VE) as the gold standard. METHODS: Thirty-four specimens were prepared from extracted human permanent posterior teeth presenting natural white spots on the approximal surface. Fluorescence images were acquired at 1-second intervals for the first 10 seconds and every 5 seconds thereafter to 45 seconds. During image acquisition, specimens were dehydrated with compressed air. QLF variables of fluorescence loss (deltaF [%]), lesion size (S [mm2]), and deltaQ (deltaFxS [% x mm2]), were determined. Change in QLF variables per second (deltaQLF(D): deltaF(D), deltaS(D), deltaQ(D)) was determined using the following equation: (subsequent QLF-variables--baseline QLF-variables)/dehydration time. Five experienced dentists independently conducted VE under standardized conditions using a dental unit's light, compressed air, with an explorer, used only to check surface structure. Prior to VE, examiners had participated in a half-day training seminar on VE. After drying the specimens, examiners graded the lesions according to dullness of surface, roughness and presence of microcavitation. Agreement by at least three of them determined the activity status of lesions. RESULTS: deltaQLF(D) values of Active white spot group (n = 7) were compared with those of Inactive white spot group (n = 27) using a two-sample t-test. In general, the active group presented larger values of deltaQLF(D) than the inactive group; however, there were no differences in deltaF(D) and deltaS(D). There were significant differences in deltaQ(D) up to 6 seconds of dehydration (P < 0.05), and no differences after 7 seconds. The results suggest that deltaQ(D) can differentiate between active and inactive white spot lesions using QLF during the first few seconds of dehydration.

Accuracy of ultrasound measurement of progressive change in occlusal enamel thickness.

OBJECTIVE: To evaluate the effectiveness of ultrasound on measuring the thickness of enamel in abrasion. STUDY DESIGN: Flat areas on occlusal surfaces of 20 premolar teeth were marked. Two initial ultrasonic measurements on marked areas were obtained by the first researcher. Then the tooth was measured in the axial direction with a compass. The cusp tips were abraded by an abrasive paper, then the second and third ultrasonic measurements were taken. The second researcher repeated the third ultrasonic measurement to evaluate the interobserver variation. All specimens were sectioned and the remaining enamel thickness was measured under polarized light microscope. RESULTS: Pearson's correlation analysis showed a high level of intraobserver agreement for the ultrasonic measurements of the first researcher (r = .891, P < .000 initial; r = .690, P < .001 first abrasion; r = .885, P < .000 second abrasion). Third ultrasonic measurements of the first and second researchers were positively and significantly correlated with histological readings (r = .966, P < .000; r = .466, P = .039). CONCLUSIONS: The ultrasonic system used in this study was reliable in measuring enamel thickness.

Quantitative light fluorescence: a technology for early monitoring of the caries process.

Quantitative light fluorescence (QLF) can detect about twice as many demineralized precavitated enamel areas a conventional visual examination or any other caries detection instrument. This technology has been used in several controlled clinical trials with the consistent observation that it is capable of monitoring and quantifying changes in the mineral content and size of clinically visible noncavitated white spot lesions; therefore, it can be used to assess the impact of preventive measures on the remineralization and reversal of the caries process. The anticipated future use of QLF with dehydration to identify active areas of demineralization will markedly enhance the utility of this technology in clinical dental research and dental practice.

A 6-month clinical study assessing the safety and efficacy of two cetylpyridinium chloride mouthrinses.

PURPOSE: To evaluate the effects of two experimental cetylpyridinium chloride (CPC) mouthrinses containing 0.075% and 0.10% CPC on the development of gingivitis and plaque versus a placebo control over a period of 6 months. METHODS: This was a randomized, single center, parallel group, double blind, positive and placebo controlled clinical trial. A 0.12% chlorhexidine rinse served as the positive control for validation of the methodology. At the beginning of the trial, 366 subjects were balanced and randomly assigned to treatment groups. Subjects received a dental prophylaxis and began rinsing twice a day with 15 ml of their assigned mouthwash for 30 seconds after brushing their teeth. Subjects were assessed for gingivitis and gingival bleeding by the Löe-Silness Gingival Index method and plaque by the Turesky modification of Quigley Hein Plaque Index at baseline and after 3 and 6 months of product use. Oral soft tissue health was also assessed. RESULTS: After 3 and 6 months, subjects rinsing with either 0.075% or 0.10% CPC had significantly (P< 0.0001) less gingivitis, gingival bleeding, and plaque, on average, than those on placebo. The 6-month mean reductions in gingivitis, gingival bleeding, and plaque for the 0.075% and 0.10% CPC rinses versus placebo were 23%, 30% and 17%, and 20%, 27% and 19%, respectively. There was no statistically significant difference in efficacy between the two CPC mouthrinses. Reductions at 3 months were similar to those seen at 6 months. Significant benefits were observed with chlorhexidine, thereby validating the study. CLINICAL SIGNIFICANCE: This study clearly demonstrates that CPC mouthrinses formulated to deliver therapeutic benefits when used twice daily can significantly prevent the development of gingivitis, gingival bleeding, and plaque over a 6-month period.

Fluoride intake from foods, beverages and dentifrice by children in Mexico.

OBJECTIVES: This investigation monitored fluoride ingestion in Mexican children who were susceptible to developing dental fluorosis. METHODS: Total fluoride intake, from dietary and toothpaste samples, was determined in 15-36-month-old children from Mexico City and Veracruz, Mexico. A duplicate plate technique was used. Plasma fluoride levels were also determined in this group of children. RESULTS: The children ingested a mean (+/-SD) of 0.20 +/- 0.08 and 0.18 +/- 0.07 mg fluoride/kg/day, in Mexico City and Veracruz, respectively. There was no statistically significant difference between the fluoride ingested by children in the two cities (P > 0.9). Plasma from children in Mexico City and Veracruz contained a mean of 1.30 +/- 0.81 and 0.87 +/- 0.72 micro mol fluoride/l, respectively, and these values were not significantly different. CONCLUSIONS: Our results lead to the conclusion that mean fluoride ingested from the combination of foods and beverages was within the proposed safe threshold for fluoride intake of 0.05-0.07 mg F/kg/day. Most of the fluoride intake by these children was derived from the ingestion of fluoridated toothpaste. When all sources of ingested fluoride were added and total fluoride intake was calculated, the children, both in Mexico City and Veracruz, were ingesting amounts of fluoride well above the upper limits of the proposed safe threshold for fluoride intake.

The fluoride content of foods and beverages from negligibly and optimally fluoridated communities.

In the spring of 1996, foods and beverages most commonly consumed by adolescents were analyzed for fluoride as part of a larger investigation. These foods were selected by interviewing 711 adolescents, 12-14 years of age, who were long-time residents of either an optimally or negligibly fluoridated community. The brand names of the identified foods and beverages most commonly purchased were determined by interviews with the parents. A total of 441 brand-name food and beverage items were purchased from both communities and were individually analyzed for fluoride. These analyses were done in order to estimate the fluoride content of various kinds of foods and beverages and to determine whether or not there was a significant difference between the two communities in the amount of fluoride ingested from these dietary sources. The food and beverage items were classified into dietary groups based on US Department of Agriculture (USDA) guidelines. Overall, the fluoride content of the sampled foods and beverages was low. In addition, there was no significant difference in the fluoride content of the same pre-packaged or ready-to-eat food or beverage items purchased in the two communities. However, a significant difference was found between the two communities in the fluoride content of fountain beverages and in cooked or reconstituted foods prepared using local water from the respective communities. Based on these results, we have estimated the mean daily, dietary fluoride intake for 3-5-year-old children who are more susceptible to developing dental fluorosis.

Development of a questionnaire to measure perceptions of, and concerns derived from, dental fluorosis.

OBJECTIVE: To develop a questionnaire in English and Spanish to measure concerns caused by children's (and their parents') perceptions of dental appearance. MATERIALS AND METHODS: The questionnaire addressed concerns in the physical, mental, and social domains, perceptions about discolourations and other oral conditions including tooth colour. Test-retest and internal reliability, and construct and criterion validity, were assessed as part of the development process. Children in Mexico City, Mexico and Indianapolis, Indiana answered the questionnaire and were examined for fluorosis using the TSIF index. Data were analysed using Cronbach's alpha, Pearson's, Spearman's and intraclass correlations, and percentage agreement tests. RESULTS: Ninety-five children and 28 parents participated in Mexico City; fluorosis was diagnosed in 66% of children. Seventy-one children and 65 parents participated in Indianapolis; fluorosis was diagnosed in 63% of children. English and Spanish questionnaires had acceptable test-retest performance, and moderate internal reliability. Criterion validity was acceptable, and the translated versions retained acceptable construct validity. Perceptions of discolourations were associated with concerns of the participants. Level of concern was higher in Indianapolis than in Mexico City, generally. Many participants reported that they were at least occasionally distressed or worried over the appearance of the children's teeth, that it hindered children from smiling freely, and that it was an unsatisfactory appearance. CONCLUSION: The developed questionnaire allowed children and parents to report perceived dental appearance problems and concerns.

Early detection of secondary caries using quantitative, light-induced fluorescence.

The authors hypothesize that the arrestment and remineralization of these lesions could be improved if secondary caries could be detected and monitored at earlier stages. Traditional diagnostic techniques detect secondary caries when it is relatively advanced and when significant tissue has been lost. This in vitro study evaluated the Quantitative Light-induced Fluorescence (QLF) system for detecting and monitoring demineralization surrounding tooth-colored restorations. This investigation was divided into three studies. The first study evaluated QLF for the detection and measurement of chemically induced lesions surrounding resin composite restorations. The second study evaluated QLF for the detection of demineralization around different tooth-colored restorations (glass ionomer, resin composite, compomer and smart material) created in a microbial caries model. Finally, the third study tested whether QLF was effective at detecting early wall lesions adjacent to resin composite restorations. Data from Study 1 demonstrated the potential for QLF to detect very early secondary caries and to distinguish between the different stages of early demineralization. Study 2 confirmed the potential for QLF to detect early secondary caries created by cariogenic bacteria and concluded that the four types of materials differed in their ability to prevent secondary caries in this model, with the glass ionomer being the most effective and the non-fluoride releasing composite performing the worst, which allowed for the development of larger lesions. The results of Study 3 suggest a potential application of the QLF system to detect early wall lesions. Data from this investigation strongly suggest that QLF is a potentially viable technology to detect and monitor early secondary caries.

Distribution of cariogenic bacteria in carious lesions around tooth-colored restorations.

PURPOSE: To compare the distribution of the three most suspected cariogenic groups of bacteria, mutans streptococci, Actinomyces naeslundii genospecies 2, and lactobacilli in carious lesions around tooth-colored restorations. MATERIALS AND METHODS: Samples from extracted teeth with clinical secondary caries around tooth-colored restorations were immuno-labeled with antibodies to the referred groups of bacteria and subsequently analyzed three dimensionally using confocal microscopy. RESULTS: The three different bacterial groups were usually present in secondary caries around tooth-colored restorations suggesting that they are involved in its formation and development.

Tooth whitening through the removal of extrinsic stain with a power toothbrush: results of four randomized, examiner blind, positive controlled clinical studies.

PURPOSE: To assess the "whitening" through stain removal benefit delivered by a prototype power toothbrush and a positive control power toothbrush over a 2-week period. METHODS: Four independent studies with identical protocols were conducted to examine tooth whitening through the removal of extrinsic stain with power toothbrushes. These were randomized, positive-controlled, two treatment, parallel group, examiner-blind, 2-week studies involving approximately 20 healthy adults with longstanding visible extrinsic stain on the facial surfaces of the 12 anterior teeth. Approximately 10 subjects per group were enrolled into the study for each of the two treatment groups; a prototype-powered toothbrush group (Crest SpinBrush Pro Whitening) and a positive control powered toothbrush group (Sonicare Personal 4100). RESULTS: In these four studies, the positive control sonic power toothbrush statistically significantly (P < 0.05) reduced stain scores by 84%, 77%, 44% and 49% following 2 weeks of brushing. Importantly, the prototype whitening power toothbrush statistically significantly (P < 0.05) reduced stain scores by 88%, 65%, 59% and 57% following 2 weeks of brushing. In both the individual studies and a combined analysis involving all four studies, the adjusted mean changes between treatment groups did not differ significantly between the two treatment groups. In the combined analysis, a one-sided upper 95% confidence bound on the difference in stain reduction scores between the two toothbrushes (positive control minus prototype) was found to be 8.3% of the prototype toothbrush adjusted mean change. This supports that the prototype power toothbrush removed extrinsic stain at least as well as the positive control toothbrush across these four studies.

Dental fluorosis and altitude: a preliminary study.

PURPOSE: Previous studies have reported higher dental fluorosis prevalence in high-altitude communities than in low-altitude communities. This investigation determined and compared dental fluorosis prevalence in populations of children living at high and low altitudes in Mexico. MATERIALS AND METHODS: Fluorosis prevalence was determined in 7 to 10-year-old children: 67 in Mexico City (2,240 m) and 71 in Veracruz (sea level). Previous fluoride exposure of those children was surveyed by retrospective, questionnaire data. The fluoride content of water and salt from those communities was also documented. RESULTS: Fluorosis prevalence in Mexico City (53.0%) was significantly higher than in Veracruz (24.3%) (p < 0.0001). While there were statistical differences in one of the fluorosis risk factors between the two communities, the observed difference in fluorosis prevalence was still significant when data were analyzed after adjusting for the reported differences in that factor. CONCLUSION: Our results led to the conclusion that the difference in fluorosis prevalence in Mexico City and Veracruz could not be explained by differences in fluoride content of the salt or water samples, self-reported exposure to fluorosis risk factors or estimated fluoride intake.