Relationship of total fluoride intake to beneficial effects and enamel fluorosis

[Dental fluorosis in upper permanent incisors of public schoolchildren in Rio de Janeiro, Brazil]

OBJECTIVE

To assess the prevalence and severity of dental fluorosis in children aged 7 to 12.

METHODS

The study population comprised 266 children aged 7 to 12 years, enrolled in a public school in the city of Rio de Janeiro, Brazil, selected using a simple random sample method. All examinations were carried out between August and December 1999 by a single trained and calibrated examiner (Kappa = 0.92). After obtaining their parents' consent the children had their upper permanent incisors examined under natural light. Their teeth were previously cleaned and dried with cotton rolls. The differential diagnosis between milder forms of dental fluorosis and nonfluoride enamel opacities was made according to Russel's diagnostic criteria. The severity of fluorosis was assessed by the Thylstrup and Fejerskov Index (TF).

RESULTS

The prevalence of dental fluorosis was 7.9% (CI 95%, 5.0-11.8). The severity ranged from 1 to 3 and 77% of the affected teeth had a TF score of 1.

CONCLUSION

These results suggest that dental fluorosis does not represent a public health problem in this population.

Fluoride intake and prevalence of dental fluorosis: trends in fluoride intake with special attention to infants

BACKGROUND

Although the predominant beneficial effect of fluoride occurs locally in the mouth, the adverse effect, dental fluorosis, occurs by the systemic route. The caries attack rate in industrialized countries, including the United States and Canada, has decreased dramatically over the past 40 years. However, the prevalence of dental fluorosis in the United States has increased during the last 30 years both in communities with fluoridated water and in communities with nonfluoridated water. Dental fluorosis is closely associated with fluoride intake during the period of tooth development.

METHODS

We reviewed the major changes in infant feeding practices that have occurred since 1930 and the changes in fluoride intakes by infants and young children associated with changes in feeding practices.

RESULTS AND CONCLUSIONS

Based on this review, we conclude that fluoride intakes of infants and children have shown a rather steady increase since 1930, are likely to continue to increase, and will be associated with further increase in the prevalence of enamel fluorosis unless intervention measures are instituted.

RECOMMENDATIONS

We believe the most important measures that should be undertaken are (1) use, when feasible, of water low in fluoride for dilution of infant formulas; (2) adult supervision of toothbrushing by children younger than 5 years of age; and (3) changes in recommendations for administration of fluoride supplements so that such supplements are not given to infants and more stringent criteria are applied for administration to children.

Dental fluorosis in permanent incisor teeth in relation to water fluoridation, social deprivation and toothpaste use in infancy

OBJECTIVES

To determine the prevalence and severity of fluorosis in permanent incisor teeth in young children in a fluoridated and a fluoride-deficient community and to establish what relationship, if any, there was between the occurrence of dental fluorosis and the reported use of fluoride toothpaste in childhood.

DESIGN

A prevalence study of children aged 8-9 years who had been continuous residents in fluoridated Newcastle or fluoride-deficient Northumberland.

METHOD

The permanent maxillary central incisor teeth were examined clinically and photographically by one examiner using the Thylstrup-Fejerskov index; the photographs were read blind to child identity and clinical score. A closed-response questionnaire enquired into the child's early experiences of toothbrushing and use of fluoride toothpastes. Social deprivation was measured by a Jarman score. The study took place in 1998.

OUTCOME MEASURE

Prevalence of dental fluorosis measured by the Thylstrup-Fejerskov index.

RESULTS

Complete data were available for 78% (n = 409) and 79% (n = 403) of eligible sampled children in the two areas, respectively. Clinical and photographic results agreed closely and had high reproducibility. The prevalence of fluorosis was 54% in the fluoridated area and 23% in the fluoride-deficient area when all grades (> 0) of fluorosis were included; percentage prevalence of mild to moderate fluorosis (> or = 3) was 3% and 0.5% in the two areas, respectively. Multivariate analysis indicated that area of residence (odds ratio = 4.5), Jarman score (odds ratio = 0.99 per Jarman unit) and type of toothpaste (odds ratio = 1.6) were statistically significantly related to presence or absence of fluorosis: the risk factors were--fluoridated area, affluence, and use of adult toothpaste.

CONCLUSIONS AND RECOMMENDATIONS

The prevalence of aesthetically important dental fluorosis was low, although higher in the fluoridated area. Use of a child's toothpaste (with lower fluoride concentration) could decrease risk in a fluoridated area. Adherence to the guidelines published by the British Society of Paediatric Dentistry is recommended.

Risk of enamel fluorosis in nonfluoridated and optimally fluoridated populations: considerations for the dental professional

BACKGROUND

Few studies have evaluated the impact of specific fluoride sources on the prevalence of enamel fluorosis in the population. The author conducted research to determine attributable risk percent estimates for mild-to-moderate enamel fluorosis in two populations of middle-school-aged children.

METHODS

The author recruited two groups of children 10 to 14 years of age. One group of 429 had grown up in nonfluoridated communities; the other group of 234 had grown up in optimally fluoridated communities. Trained examiners measured enamel fluorosis using the Fluorosis Risk Index and measured early childhood fluoride exposure using a questionnaire completed by the parent. The author then calculated attributable risk percent estimates, or the proportion of cases of mild-to-moderate enamel fluorosis associated with exposure to specific early fluoride sources, based on logistic regression models.

RESULTS

In the nonfluoridated study sample, sixty-five percent of the enamel fluorosis cases were attributed to fluoride supplementation under the pre-1994 protocol. An additional 34 percent were explained by the children having brushed more than once per day during the first two years of life. In the optimally fluoridated study sample, 68 percent of the enamel fluorosis cases were explained by the children using more than a pea-sized amount of toothpaste during the first year of life, 13 percent by having been inappropriately given a fluoride supplement, and 9 percent by the use of infant formula in the form of a powdered concentrate.

CONCLUSIONS

Enamel fluorosis in the nonfluoridated study sample was attributed to fluoride supplementation under the pre-1994 protocol and early toothbrushing behaviors. Enamel fluorosis in the optimally fluoridated study sample was attributed to early toothbrushing behaviors, inappropriate fluoride supplementation and the use of infant formula in the form of a powdered concentrate.

CLINICAL IMPLICATIONS

By advising parents about the best early use of fluoride agents, health professionals play an important role in reducing the prevalence of clinically noticeable enamel fluorosis.

Total fluoride intake and implications for dietary fluoride supplementation

This paper reviews the history and validity of recommended "optimal" levels of systemic fluoride intake and the available information on levels of fluoride intake in young children from foods and beverages (including water), dentifrices, dietary fluoride supplements, mouthrinses, and gels. Most of the studies emphasize the substantial variation in ingestion among individuals. Often, a substantial proportion of individuals received fluoride well beyond the mean exposure reported in the study. Limitations in the existing data make it difficult to determine the total distribution of fluoride intake from all sources. Therefore, hypothetical combinations of possible daily fluoride intake from the three main sources (diet, dentifrices, and supplements) are presented for those aged 6, 12, 24, and 36 months, with associated mean intake per kg body weight. Findings suggest that some children exceed the "optimal" level of fluoride intake from single sources alone, while others can from a combination of sources. Moreover, if current recommended "optimal" levels, which have been derived on an empirical basis, are actually lower than what has been quoted in the literature, then more children could be ingesting excessive amounts of fluoride, which could increase their risk of developing objectionable dental fluorosis. The variation and complexity of fluoride ingestion from all sources should be considered in the evaluation of recommendations for use of dietary fluoride supplements.

The prevalence and severity of enamel fluorosis in North American children

The question considered in this review is the extent to which changes in the prevalence or severity of enamel fluorosis have occurred over the last half-century. Emphasis is given to a review of those studies in which subjects are drinking water that is fluoride deficient and those in which subjects are drinking optimally fluoridated water, either adjusted or natural. Trends in fluorosis were examined using two definitions of fluorosis (definite and any signs) and three types of comparisons--comparisons of pooled estimates from all available studies that include data from different communities and time periods, comparisons of estimates from the same communities at different times, and comparisons of estimates from selected studies in the early years of fluorosis research with results of the US National Fluorosis Survey done by the National Institute of Dental Research. A clear increase in fluorosis among populations drinking community water that contains less than 0.3 ppm fluoride was found. Results of the comparisons using studies with Dean's Index pooled at different time points, comparisons in the same communities over time, and comparisons of prevalence found in selected communities before fluoride was widely available with the National Fluorosis Survey all support this conclusion. An increase in the prevalence of fluorosis in those drinking optimally fluoridated water likely has occurred as well; however, evidence for such a trend is not as clear as for fluoride deficient communities because of mixed results depending on the type of comparison. The majority of fluorosis cases continue to be mild and seem of little esthetic consequence for most of the public or dental profession. But a few cases of more severe fluorosis can be found now in some communities. Because the prevalence of fluorosis is now higher than 50 years ago, we can conclude that fluoride availability to the developing enamel during critical periods when enamel is at risk of fluorosis has increased in North American children.

Mechanism and timing of fluoride effects on developing enamel

Fluoride appears to specifically interact with mineralizing tissues, causing an alteration of the mineralization process. In enamel, fluorosis results in a subsurface hypomineralization. This hypomineralized enamel appears to be directly related to a delay in the removal of amelogenins at the early-maturation stage of enamel formation. The specific cause for this delay is not known, although existing evidence points to reduced proteolytic activity of proteinases that hydrolyze amelogenin. This delay in hydrolysis of amelogenins could be due to a direct effect of fluoride on proteinase secretion or proteolytic activity, or to a reduced effectiveness of the proteinase due to other changes in the protein or mineral of the fluorosed enamel matrix. The formation of dental fluorosis is highly dependent on the dose, duration, and timing of fluoride exposure. The early-maturation stage of enamel formation appears to be particularly sensitive to the effects of fluoride on enamel formation. Although the risk of enamel fluorosis is minimal with exposure only during the secretory stage, this risk is greatest when exposure occurs in both secretory and maturation stages of enamel formation. The risk of fluorosis appears to be best related to the total cumulative fluoride exposure to the developing dentition.

The effects of a break in water fluoridation on the development of dental caries and fluorosis

Durham, NC, fluoridated since 1962, had an 11-month cessation of fluoridation between September, 1990, and August, 1991. The purpose of this study was to assess the effects of this break on the development of caries and fluorosis in children. Study participants were continuously-resident children in Kindergarten through Grade 5 in Durham's elementary schools. There were 1696 children, 81.4% of those eligible, for whom a questionnaire was completed and clinical data recorded. Age cohorts were defined by a child's age at the time that fluoridation ceased. Caries was recorded in children in the Birth Cohort through Cohort 3, and fluorosis for children in Cohorts 1 through 5. Caries was assessed in the primary first and second molars according to the decayed-filled index; fluorosis on the labial surfaces of the upper permanent central and lateral incisors was assessed by the Thylstrup-Fejerskov (TF) index. Mother's education was associated with caries; higher education of the mother had an odds ratio of 0.53 (95% CI 0.40, 0.76) for caries in the child. No cohort effects could be discerned for caries. Overall prevalence of fluorosis was 44%. Prevalence in Cohorts 1, 2, 3, 4, and 5 was 39.8%, 32.3%, 33.0%, 62.3%, and 57.1%, respectively. These cohort differences remained statistically significant in regression analysis. It was concluded that while the break had little effect on caries, dental fluorosis is sensitive to even small changes in fluoride exposure from drinking water, and this sensitivity is greater at 1 to 3 years of age than at 4 or 5 years.

Dental fluorosis among persons exposed to high- and low-fluoride drinking water in western Norway

The aim of this project was to study the prevalence and severity of dental fluorosis among persons exposed to moderate- to high- or low-fluoride drinking water in western Norway, and to assess the risk factors involved. Subjects aged 5 to 18 years who had been lifelong consumers of moderate- to high-fluoride groundwater (> or = 0.50 mg F/L) were selected for the study (n = 113). A comparison group (n = 105) was chosen among consumers of low-fluoride surface water (approximately 0.10 mg F/L) in the same district. The Thylstrup-Fejerskov (TF) Index was used to score dental fluorosis. A questionnaire was used to obtain information on fluoride exposure and other relevant factors. Among the consumers of low-fluoride water 14.3% showed dental fluorosis (TF score 1-2) as compared to 78.8% in the group consuming moderate- to high-fluoride water (TF scores 1-7). Premolars were most frequently affected, but severe cases (TF scores 3-7) were equally prevalent in maxillary central incisors and first molars. In logistic regression analysis with TF score 0 or TF score > or = 1 as the dependent variable, only fluoride concentration in the drinking water was associated with a statistically increased risk of dental fluorosis (odds ratio: 18.9; 95% CI: 8.85-40.44). In the study area, which was characterised by multiple fluoride sources, uncontrolled groundwater with moderate to high fluoride content was the most important factor in the development of dental fluorosis. In order to prevent dental fluorosis, groundwater wells should routinely be analysed for fluoride.

Fluoride exposure and dental fluorosis in Newburgh and Kingston, New York: policy implications

OBJECTIVES

This analysis was conducted to determine the changes in the effect of exposure to fluoridation and other sources of fluoride on dental fluorosis in children attending Newburgh and Kingston school districts in New York State.

METHODS

Data for this analysis were obtained from two surveys conducted in the 1986 and 1995 school years. Analyses were limited to 3500, 7-14-year-old lifelong residents of a fluoridated or a nonfluoridated community. Dean's classification and DMFS index were used for recording dental fluorosis and caries, respectively. A questionnaire was used to collect fluoride exposure data. Regression procedures were used to estimate the effect of fluoridation, fluoride supplements, and brushing before the age of 2 years on dental fluorosis.

RESULTS

Children examined in 1996 were at higher risk for both questionable and very mild to severe dental fluorosis if they received fluoride from water or daily tablet use, or started brushing before the age of 2 years. The increase in risk from 1986 to 1995 was greater for African-American children.

CONCLUSION

This analysis showed that the risk of developing dental fluorosis did not decline over time in these communities. Continuous exposure to water fluoridation had an observable effect on dental fluorosis. However, implementation of fluoridation in Newburgh Town did not result in an increase in dental fluorosis prevalence.

Biological mechanisms of dental fluorosis relevant to the use of fluoride supplements

Fluorosis occurs when fluoride interacts with mineralizing tissues, causing alterations in the mineralization process. In dental enamel, fluorosis causes subsurface hypomineralizations or porosity, which extend toward the dentinal-enamel junction as severity increases. This subsurface porosity is most likely caused by a delay in the hydrolysis and removal of enamel proteins, particularly amelogenins, as the enamel matures. This delay could be due to the direct effect of fluoride on the ameloblasts or to an interaction of fluoride with the proteins or proteinases in the mineralizing matrix. The specific mechanisms by which fluoride causes the changes leading to enamel fluorosis are not well defined; though the early-maturation stage of enamel formation appears to be particularly sensitive to fluoride exposure. The development of fluorosis is highly dependent on the dose, duration, and timing of fluoride exposure. The risk of enamel fluorosis is lowest when exposure takes place only during the secretory stage, but highest when exposure occurs in both secretory and maturation stages. The incidence of dental fluorosis is best correlated with the total cumulative fluoride exposure to the developing dentition. Fluoride supplements can contribute to the total fluoride exposure of children, and if the total fluoride exposure to the developing teeth is excessive, fluorosis will result.

Changes in dental fluorosis and dental caries in Newburgh and Kingston, New York

OBJECTIVES

This study sought to determine whether the prevalence of dental fluorosis and dental caries had changed in a fluoridated community and a nonfluoridated community since an earlier study conducted in 1986.

METHODS

Dental fluorosis and dental caries data were collected on 7- to 14-year-old lifelong residents (n = 1493) of Newburgh and Kingston, NY.

RESULTS

Estimated dental fluorosis prevalence rates were 19.6% in Newburgh and 11.7% in Kingston. The greatest disparity in caries scores was observed between poor and nonpoor children in nonfluoridated Kingston.

CONCLUSIONS

The prevalence of dental fluorosis has not declined in Newburgh and Kingston, whereas the prevalence of dental caries has continued to decline.

Fluorosis risk from early exposure to fluoride toothpaste

Swallowed fluoride toothpaste in the early years of life has been postulated to be a risk factor for fluorosis, but the epidemiological evidence is weakened by the fact that most of the relevant studies were done in developed countries where an individual is exposed to multiple sources of fluoride.

OBJECTIVES

To quantify the risk of fluorosis from fluoride toothpaste in a population whose only potential source of fluoride was fluoride toothpaste.

METHODS

Case-control analyses were conducted to test the hypothesis that fluoride toothpaste use before the age of 6 years increased an individual's risk of fluorosis. Data came from a cross-sectional clinical dental examination of schoolchildren and a self-administered questionnaire to their parents. The study was conducted in Goa, India. The study group consisted of 1189 seventh grade children with a mean age of 12.2 years.

RESULTS

The prevalence of fluorosis was 12.9% using the TF index. Results of the crude, stratified, and logistic regression analyses showed that use of fluoride toothpaste before the age of 6 years was a risk indicator for fluorosis (OR 1.83, 95% CI 1.05-3.15). Among children with fluorosis, beginning brushing before the age of 2 years increased the severity of fluorosis significantly (P<0.001). Other factors associated with the use of fluoride toothpaste, such as eating or swallowing fluoride toothpaste and higher frequency of use, did not show a statistically significant increased risk for prevalence or severity of fluorosis.

CONCLUSIONS

Fluoride toothpaste use before the age of 6 years is a risk indicator for fluorosis in this study population.

Dental caries and dental fluorosis among schoolchildren who were lifelong residents of communities having either low or optimal levels of fluoride in drinking water

OBJECTIVE

This paper reports findings for dental caries and dental fluorosis in 8-10- and 13-16-year-old schoolchildren who were lifelong residents of communities having either naturally occurring low (Broken Bow and Holdrege, NE; < 0.3 ppm) or optimal (Kewanee, IL; 1 ppm) levels of fluoride in drinking water.

METHODS

Findings are reported for participants who received both dental caries and dental fluorosis examinations (n = 495). The DMFS and TSIF indices, respectively, were used to assess dental caries and dental fluorosis.

RESULTS

The mean DMFS score adjusted for age, sealant presence, and fluoride use was significantly lower in Kewanee (1.8) than was the adjusted mean caries score in either Holdrege (2.9) or Broken Bow (3.6). Adjusted mean DMFS scores in Broken Bow and Holdrege were not statistically different. The mean percent of fluorosed tooth surfaces per person, adjusted for age and use of dietary fluoride supplements, was similar in the three communities (approximately 15%); more than 80 percent of tooth surfaces in all participants were fluorosis-free.

CONCLUSIONS

Findings from the present study suggest that water fluoridation still is beneficial and that dental sealants can play a significant role in preventing dental caries. In addition, findings from this survey appear to support the premise that the difference in dental fluorosis prevalence between fluoridated and nonfluoridated communities has narrowed considerably in recent years.

Fluoride supplement prescribing and dental referral patterns among academic pediatricians

OBJECTIVE

To determine how well the current fluoride supplementation schedule was known by academic pediatricians and to examine the fluoride supplement prescribing and dental referral practices among primary care faculty pediatricians at four medical centers.

SETTING

Four university medical centers in North Carolina.

SUBJECTS

Primary care faculty pediatricians.

METHOD

A questionnaire pretested for clarity was distributed to all identified full-time primary care pediatric faculty (42 members).

RESULTS

A total of 40 completed questionnaires were returned. Thirty-seven (93%) primary care faculty pediatricians reported that they routinely addressed the need for fluoride supplements for their patients, but only 28 (70%) determined the fluoride content of the drinking water before prescribing supplements. Thirty-five (87.5%) began supplements at the correct age, but fewer knew the correct doses for children of various ages. Only 23 (58%) referred their patients for oral examination and preventive care before the age of 36 months, contrary to American Academy of Pediatrics recommendations.

CONCLUSIONS

Pediatricians in an academic setting would be expected to be more knowledgeable of current recommendations than those in private practice. Failure to know and teach correct fluoride supplement recommendations and failure to recommend early professional dental involvement can result in less than optimum oral health.

Determinants and mechanisms of enamel fluorosis

Enamel fluorosis occurs when fluoride concentrations in or in the vicinity of the forming enamel are excessive during its pre-eruptive development. Fluoride concentrations in plasma, enamel and other tissues reflect the difference between intake and excretion, i.e. fluoride balance. In addition to the diet, modern sources of ingested fluoride include a variety of dental products, some of which have been identified as risk factors for fluorosis. Fluoride absorption is inversely related to dietary calcium which, at high concentrations, may cause net fluoride secretion into the gastrointestinal tract. The excretion of absorbed fluoride occurs almost exclusively via the kidneys, a process which is directly related to urinary pH. Thus, fluoride balance and tissue concentrations and the risk of fluorosis are increased by factors such as high protein diets, residence at high altitude, and certain metabolic and respiratory disorders that decrease pH. Factors that increase urinary pH and decrease the balance of fluoride include vegetarian diets, certain drugs and some other medical conditions. Although several other fluoride-induced effects might be involved in the aetiology of fluorosis, it now appears that inhibition of enzymatic degradation of amelogenins, which may delay their removal from the developing enamel and impair crystal growth, may be of critical importance. In addition to the effects of fluoride, disturbances in enamel formation that can be confused with fluorosis are caused by chronic acidosis and hypoxia independently of the level of fluoride exposure.

Lack of effect of long-term fluoride ingestion on blood chemistry and frequency of sister chromatid exchange in human lymphocytes

Two studies were conducted to assess the potential for adverse physiologic and genotoxic effects of long-term fluoride ingestion in adults residing in three communities with varying water fluoride levels (0.2 ppm, 1.0 ppm, and 4.0 ppm). All were long-time (> or = 30 years) residents of their respective communities. Plasma and urine samples were collected for fluoride analyses. Additional plasma was collected to determine blood chemistry, and plasma lymphocytes were examined to determine the frequency of sister chromatid exchange. Significant differences in urine (P = 0.001) and plasma (P = 0.0001) fluoride levels were found in the three communities. Seven of the blood parameters were statistically different among the communities, although all were within the defined normal range of the pathology laboratory. Sister chromatid exchange frequency was statistically higher in the 4.0 ppm fluoride community as compared to the other communities. Because of the higher SCE frequency in the 4.0 ppm fluoride community, a second study was performed to determine if the increased frequency was potentially related to the fluoride level of the communal water supply. Of the 58 adults recruited; 30 had used city water and 28 had used well water (< or = 0.3 ppm fluoride) as their principal water source for 30 years. Data analyses showed that the sister chromatid exchange frequency did not differ between the groups, indicating that the increased sister chromatid exchange frequency was not related to the fluoride level of the communal water. The investigation provided evidence that the long-term ingestion of water containing 4.0 ppm fluoride did not have any clinically important physiologic or genotoxic effects in healthy adults.

Total fluoride intake in children aged 3 to 4 years--a longitudinal study

Several previous studies using food consumption tables or diet records have estimated that children aged 1 to 12 years resident in fluoridated (1 ppm) areas receive, on average, between 0.05 and 0.07 mg fluoride/kg body weight from foods and drinks alone. In this study, the duplicate-diet approach, which is a more accurate method of determining nutrient intake, was used to determine if levels of fluoride intake from foods and drinks are similar to those estimated from food consumption tables or diet records. Duplicate portions of all foods and drinks consumed over 24 hours by 66 children aged 3 to 4 years resident in fluoridated and low-fluoride areas of New Zealand were collected on three separate days over a period of 12 months and analyzed for fluoride. Fluoride intake from the use and ingestion of toothpastes and fluoride supplements was also determined for each child. It was hypothesized that the total amount of fluoride received by children in low-fluoride areas from diet, toothpastes, and fluoride supplements was similar to that received by children in fluoridated areas from diet and toothpastes. The mean fluoride intake from foods and drinks alone in the low-fluoride areas was 0.008 +/- 0.003 mg/kg body weight (0.15 +/- 0.06 mg/day; n = 34) and in the fluoridated areas was 0.019 +/- 0.009 mg/kg body weight (0.36 +/- 0.17 mg/day; n = 32). The mean fluoride intake from foods and drinks and toothpastes in the low-fluoride areas was 0.027 +/- 0.012 mg/kg body weight (0.49 +/- 0.25 mg/day) and in the fluoridated areas was 0.036 +/- 0.015 mg/kg body weight (0.68 +/- 0.27 mg/day). Fluoride intake from diet alone did not exceed 0.04 mg/kg body weight (0.74 mg/day), and fluoride intake from diet and toothpaste did not exceed 0.07 mg/kg body weight (1.31 mg/day). The results suggest that levels of fluoride intake from foods and drinks alone as estimated by the duplicate-diet approach are much lower than previously estimated from food consumption tables or diet records. It was calculated that if all children in the low-fluoride areas were to take currently recommended dosages of fluoride tablets, which have been based on dietary surveys and diet records, then the total fluoride intake of some children in the low-fluoride areas would exceed that of their counterparts in the fluoridated areas. The results suggest that currently recommended dosages of fluoride tablets need to be further reduced if dental fluorosis in children is to be avoided.

Assessing fluoride concentrations of juices and juice-flavored drinks

Few studies have investigated fluoride exposures from juices and juice-flavored drinks manufactured with water. In this study, the authors analyzed 532 juices and juice drinks for fluoride. Fluoride ion concentrations ranged from 0.02 to 2.80 parts per million, in part because of variations in fluoride concentrations of water used in production. Children's ingestion of fluoride from juices and juice-flavored drinks can be substantial and a factor in the development of fluorosis.

Prevalence of dental fluorosis in children in Singapore

Prevalence and severity of dental fluorosis was assessed in 1739 Singaporean children aged 9, 12 and 16 yr in three different ethnic groups. All subjects had resided since birth in Singapore, which has a tropical climate. The water supply was fluoridated in 1957 at a level of 0.7 ppm. In this sample, mouth prevalence was 82.6%, tooth prevalence was 66.9%, the community fluorosis index was at 1.96; 9.2% of children had severe fluorosis and 26.2% had moderate fluorosis. There were no significant gender or racial differences. Prevalences were higher than those reported in most other studies. Due to differences in indices used and methodology, comparisons could not be made directly with other studies.

Risk of fluorosis in a fluoridated population. Implications for the dentist and hygienist

The prevalence of enamel fluorosis has increased in optimally fluoridated areas in recent years. This has led to efforts to identify the cause or causes and to make recommendations that seek to maintain the caries-preventive effectiveness of fluoride use while minimizing the risk of fluorosis. In this study, the author estimated the potential direct impact that dental practitioners could have on reducing the amount of enamel fluorosis in U.S. children. The findings suggest that dental practitioners could have an important impact on reducing the prevalence of enamel fluorosis by guiding the public toward the most appropriate use of fluoride products.

Refining the estimate of the critical period for susceptibility to enamel fluorosis in human maxillary central incisors

PURPOSE

The purpose of this study was to determine an improved estimate of the critical period for susceptibility to fluorosis in human maxillary central incisors.

METHODS

The fluorosis score, S, of the incisal (I), middle (M), and cervical (C) third divisions on the labial surface of right maxillary central incisors of subjects (a representative sample of 1,085 Hong Kong Chinese children aged 7 to 12 years surveyed in 1986) was determined according to the Chronological Fluorosis Assessment (CFA) Index. Subject data were grouped by month of birth relative to June 1978, when the designated concentration for waterborne fluoride in the community water supply was reduced from 1.0 to 0.7 mg/L. The analytical task was one of finding the correlation maximum in a system of 12 variates and adjustable parameters including the waterborne fluoride concentration, [F-], and the fluorosis score.

RESULTS

The main findings were: (1) the peak correlation of S vs [F-] for the male incisal third centered at 17.5 months after birth; (2) and six months later for females; (3) the correlation of S with [F-] is maximized for S(M) following S(I) by two months, and S(C) following S(M) by a further two months for both males and females; and (4) the critical period for exposure to fluoride is of about four months' duration for each third.

CONCLUSIONS

The maxillary central incisor, as a whole, appears most at risk to fluorosis from dietary fluoride between age 15 and 24 months for males and between 21 and 30 months for females.

The prevalence of dental fluorosis in a school-based program of fluoride mouthrinsing, fluoride tablets, and both procedures combined

OBJECTIVES

The objective of the study was to describe and compare the prevalence and severity of dental fluorosis in children who participated in an eight-year clinical trial of the effectiveness of school-based fluoride procedures according to three treatment regimens and age of regimen initiation.

METHODS

At baseline in 1981, 1,640 kindergarten and first grade children residing in a fluoride-deficient community (Springfield, OH) were assigned randomly to a group that (1) rinsed once a week with a 0.2 percent neutral NaF solution; (2) chewed, rinsed, and swallowed daily a neutral 2.2 mg NaF tablet; or (3) carried out both procedures. DMFS examinations were conducted at baseline and after two, five, and eight years of treatment. As a follow-up in 1992, fluorosis examinations using Dean's index were conducted on 448 remaining subjects.

RESULTS

Overall, the prevalence of fluorosis was 4.4 percent with 20 children classified as having some definitive level of the condition. No statistically significant differences existed in the prevalence or severity of fluorosis: (1) among the preventive regimens; (2) among children who began the regimens at ages 5, 6, or 7; or (3) by eruptive status of teeth.

CONCLUSION

These results reiterate the safety of school-based fluoride mouthrinse, fluoride tablet, or combined regimens in communities with fluoride-deficient water supplies.

Risk factors for dental fluorosis in pediatric dental patients

OBJECTIVES

Concerns have been raised recently about whether a substantial amount of dental fluorosis is resulting from the increased use of fluoride from various sources. The purposes of this study were to determine the prevalence and severity of dental fluorosis in a sample of pediatric patients seeking dental treatment in a university pediatric dental clinic and to evaluate sources of fluoride as risk factors for dental fluorosis.

METHODS

A convenience sample of 157 children aged 8 to 17 years were examined for dental fluorosis using the Tooth Surface Index of Fluorosis (TSIF). Fluoride history questionnaires assessing previous exposure to fluoride during the first eight years of life were completed by the children's parents. Fluoride exposures were compared among 54 cases and 54 matched controls using a case-control retrospective design.

RESULTS

Fluorosis was found in 72 percent of the children, but was generally quite mild. The risk of fluorosis was significantly greater for children who had greater exposure to fluoridated water and who used larger amounts of fluoridated toothpaste up to age eight.

CONCLUSIONS

This study provided evidence that increased use of fluoride toothpaste may be a risk factor for dental fluorosis. The results suggest prudent use of dentifrice by young children to minimize the risk of fluorosis.

Fluoride supplement use by children in fluoridated communities

OBJECTIVES

The purpose of this study is to describe patterns of inappropriate fluoride supplementation among a sample of Connecticut schoolchildren living in optimally fluoridated areas.

METHODS

Fluoride exposure histories were obtained via a written questionnaire with a response rate of 89 percent and an overall reliability of 87 percent agreement.

RESULTS

A total of 575 subjects lived the entire first eight years of life in a fluoridated community. Of these, 26.1 percent had a history of inappropriate supplementation sometime during that period, including 31.8 percent of subjects with mild to moderate fluorosis and 22.8 percent of subjects without fluorosis. There were no significant supplement history differences related to current age, sex, or socioeconomic status. Overall, 71 percent of these subjects used only vitamins with fluoride, while only 14 percent were reported to have used fluoride supplements alone. Sixty-eight percent of the subjects who were supplemented while breast feeding, continued supplementation after cessation of breast feeding.

CONCLUSIONS

These findings reinforce the need for health professionals to be targeted more aggressively at the school, residency, and private practice levels to better promote a full understanding of the proper utilization of fluoride supplements.

Proton microprobe assessment of the distribution of fluoride in the enamel and dentine of developing central incisors of sheep and changes induced by daily fluoride supplements

Ten sheep were given 0.5 mg fluoride (F) and 10 sheep 0.2 mg F/kg body wt orally for periods of 1-6 months while 8 sheep received no additional F. One incisor from each sheep was sectioned longitudinally in the midline and, using the proton microprobe, multiple scans for calcium and F were made across the enamel and dentine. F was determined by proton-induced gamma-ray emission and calcium by X-ray emission. Tooth length and hence the stage of ameloblast activity for each of the 28 teeth at the start of the experiment was determined using a tetracycline marker. In addition, the stage of enamel development of the eight control teeth (no dietary F) at the time of their extraction was assessed from their macroscopic appearance. Continuous changes in F levels occurred in both enamel and dentine throughout tooth development and also in the mature enamel and associated dentine after ameloblast regression. All scans for all stages of tooth development and all F treatments showed a high F concentration at the enamel surface. Early in the secretory phase, a wide-based F peak occupied the entire width of the enamel with a similar F peak in the dentine. In the control teeth, no consistent increase in F concentration occurred at the enamel surface during later development. When F supplements were started early in the maturation phase an increase in F concentration only at the enamel surface was recorded. When F supplements were also given during the secretory phase, higher F concentrations were recorded not only at the enamel surface but also for the inner enamel and dentine plateau. These findings, based on a small number of sheep, indicate that further research is needed to clarify the method and control of F uptake and to determine the changes in these processes during the different stages of tooth development.

The effect of sodium fluoride at prophylactic and toxic doses on renal structure and function in the isolated perfused rat kidney

To assess the renal effects of fluoride, isolated rat kidneys were perfused in single pass mode for 120 min. Five, 15 and 50, as well as 150, 500 and 1500 mumol NaF were administered 60, 80 and 100 min after starting the perfusion, respectively. Kidneys were perfused with constant pressure (100 mmHg). The perfusate consisted of a substrate supplemented Ringer solution containing hydroxy ethyl starch (HES) to produce isoncotic conditions. Concentrations below 500 mumol/l NaF did not induce major changes in the main parameters of renal function. Only upon admixture of the highest concentration of 1500 mumol/l NaF severe changes in renal function could be observed, resulting in complete anuria and a drastic reduction of renal perfusion to 5% of control, associated with a cessation of glomerular filtration. Due to the lack in tubular load, tubular reabsorptive processes inevitably declined to zero. The morphological analysis of kidneys exhibited to 500 mumol/l NaF revealed the occurrence of vesicular material within the urinary space. These vesicles could electron microscopically be identified as membrane enclosed material of podocytic origin. The interstitium was widened. Upon admixture of 1500 mumol/l NaF, kidneys responded with a decrease of the interstitial space. Moreover, epithelial cell swelling, hydropic degeneration of all proximal and distal tubular segments, bleb formation and intraluminal casts were observed frequently. Glomerular capillaries were filled with fine precipitates and their endothelium was severely damaged. The results of our studies in the isolated perfused rat kidney (IPRK) model clearly demonstrate a direct dose dependent acute nephrotoxic effect of NaF only for extremely high doses, which, however, may be reached in human cases of severe fluoride intoxication. On the contrary, for low fluoride doses, especially for those concentrations occurring in human plasma upon cariesprophylactic intake of fluorides, no signs of direct acute nephrotoxic action could be observed in the IPRK model.

Commentary on and recommendations for the proper uses of fluoride

Fluorosis has been associated with the fluoride concentration of drinking water, use of dietary fluoride supplements, early use of dentifrices, and prolonged use of infant formula. The literature, however, does not show associations between fluorosis and use of fluoride mouthrinses, professionally applied fluorides, bottled waters, carbonated beverages, and juices. It is unwise to issue laundry lists of items that may be implicated as problem-causing when, in fact, they may not be. Although usually classified without fluorosis, children in Dean's "questionable" category would be classified with the condition if the TFI or TSIF were used. Accordingly, Dean, in 1942, really reported only 52.8 percent of children without fluorosis in Kewanee, a community with 0.9 ppm fluoride in drinking water. Because the morbidity and sequelae of dental caries have declined, undue emphasis has been placed recently on the risks of using fluoride rather than on its profound beneficial effects. Although of paramount importance, conclusions cannot be drawn on whether fluoride protects against, contributes to, or has no effect on bone fractures or is valuable in treating osteoporosis. Careful thought is required before making recommendations that may reduce health benefits because of unfounded concerns about perceived risks. There should be greater regulation of extraneous fluoride sources, rather than reliance on educational efforts or recommendations to eliminate use of highly effective preventive regimens.

Sources of fluoride intake in children

Wide variations in fluoride intake among children make estimating fluoride intake difficult. This paper discusses the various sources of fluoride intake among children, beginning with a review of the fluoride concentrations of water and other beverages, foods, and therapeutic fluoride products. A review of previous studies' estimates of fluoride intake from diet, dentifrice, fluoride supplements, fluoride mouthrinses, and gels, as well as total fluoride intake also is presented. Then, estimates of fluoride intake among young children of different age groups are summarized, and examples demonstrating the high level of variability of fluoride intake, both from individual sources and in total, are presented. Lastly, this paper discusses the implications of our current level of knowledge of children's fluoride intake, and presents recommendations for the use of fluoride for children in light of this current knowledge. The major recommendations are that: (1) the fluoride content of foods and beverages, particularly infant formulas and water used in their reconstitution, should continue to be monitored closely in an effort to limit excessive fluoride intake; (2) ingestion of fluoride from dentifrice by young children should be controlled, and the use of only small quantities of dentifrice by young children should be emphasized; and (3) dietary fluoride supplements should be considered a targeted preventive regimen only for those children at higher risk for dental caries and with low levels of ingested fluoride from other sources.

Influence of exposure to various fluoride technologies on the prevalence of dental fluorosis

An increase in the prevalence of dental fluorosis among children in North America is well documented. Published reports of the relationship between the occurrence of dental fluorosis and early exposure to various fluorides and the use of different types of infant feeding practices have begun to provide insights into possible causes for this increase. This study was designed to investigate this issue for children living in a non-fluoridated and a fluoridated community in British Columbia, Canada. Parents or guardians completed a questionnaire which detailed exposure to different types of fluorides and infant feeding practices during the first 6 yr of life. Completed questionnaires were returned and examinations were performed on 1131 children. 60% of children had dental fluorosis, and only 8% presented with scores of 2 or greater. Logistic regression analyses showed that the use of infant formula and parental educational attainment were significantly associated with the occurrence of dental fluorosis in the range of scores from 2 to 6. Despite these statistically significant findings, these variables actually had little additional predictive value beyond a chance occurrence in determining which children would have dental fluorosis.

Absorption and retention of dietary and supplemental fluoride by infants

There is a widespread belief that an adequate intake of fluoride during the pre-eruptive stage of enamel formation (i.e., from the diet in frequent small doses throughout the day) will be protective against caries in later life. To obtain data on bio-availability and retention of fluoride in one age group (infants), we studied 3 treatment regimens: In Regimen A, small amounts of fluoride were obtained from the diet in frequent doses throughout the day; in Regimen B, a fluoride supplement (0.25 mg) was given once each day with a feeding; Regimen C was similar to regimen B except that the fluoride supplement was given 1 h before a feeding. For the 3 regimens, the respective mean absorptions of fluoride were 90.1, 88.9, and 96.0% of intake, and the respective retentions were 12.5, 47.1, and 52.3% of intake. Neither the difference in absorption nor the difference in retention between regimens B and C was statistically significant. By subtracting the background urinary excretion of fluoride (i.e., excretion of fluoride while diet was the sole source of fluoride) from the excretion after administration of the fluoride supplement, we calculated that 68.1% of the supplement was retained in Regimen B and 73.0% of the supplement in Regimen C. The difference was not significant.

Review of fluoride exposures and ingestion

The literature on fluoride intake/ingestion was reviewed critically to determine the current exposure to fluorides for children living in non-fluoridated and fluoridated areas in North America. Fluoride from all sources except mouthrinses and professionally applied topical fluorides was considered, including ingestion from foods and beverages, as well as intake from the use of fluoride dentifrice and dietary fluoride supplements. Data from all of these sources were used to produce estimates of mean daily ingestion. Studies consistently have identified substantial variation in ingestion among individuals. These analyses demonstrated that a substantial proportion of individuals had exposure or ingestion well beyond that of the mean for each source, and often 10-20% received up to several times as much exposure as the mean. Some children probably ingest sufficient fluoride from a single source to exceed the "optimal" fluoride intake recommended from all sources, and are therefore at increased risk of fluorosis. This review highlighted the substantial variation and complexity of fluoride ingestion. Appropriate consideration of these aspects is warranted in efforts to ensure a margin of safety favoring dental caries prevention while limiting objectionable fluorosis.

Dental fluorosis: its use as a biomarker

Several epidemiological studies, beginning with those of Dean and co-workers in the 1940's, clearly demonstrate the relationship between dental fluorosis in humans and the level of fluoride in water supplies. These studies and others have shown that, in a population, there is a direct relationship among the degree of enamel fluorosis, plasma and bone fluoride levels, and the concentration of fluoride in drinking water. However, dental fluorosis is a reflection of fluoride exposure only during the time of enamel formation, somewhat limiting its use as a biomarker. In addition, the degree of fluorosis is dependent not only on the total fluoride dose, but also on the timing and duration of fluoride exposure. At the level of an individual response to fluoride exposure, factors such as body weight, activity level, nutritional factors, and the rate of skeletal growth and remodeling are also important. These variables, along with an individual variability in response to similar doses of fluoride, indicate that enamel fluorosis cannot be used as a biological marker of the level of fluoride exposure for an individual.

Strategies for improving the assessment of dental fluorosis: focus on optical techniques

In its milder forms, enamel fluorosis is characterized clinically by diffuse opacities. The appearance is due to optical properties of a subsurface or surface porous layer with lower mineral content. These areas usually have texture and color similar to those of initial caries lesions but generally another shape and location. Therefore, several optical methods, previously used to diagnose initial caries lesions, were applied to fluoride-induced opacities on extracted premolars and on incisors of four subjects in vivo. These methods included light-scattering measurements, white light illumination, violet light illumination, ultraviolet illumination, and laser fluorescence. Video images were captured with a charge-coupled-device (CCD) camera, digitized, and computer-processed. It is concluded that the light-scattering monitor can be used for the determination of the local porosity of fluorotic enamel and that the laser fluorescence method might be developed into a method applicable for the assessment of the severity of enamel fluorosis.

Trends in prevalence of dental fluorosis in North America

This review of the literature was undertaken to demonstrate the changing trends in the prevalence of dental fluorosis in North America. Using Dean's early work to establish a baseline for the prevalence of dental fluorosis, results of more recent prevalence surveys were used to establish a range for the occurrence of dental fluorosis today. These results suggest that the prevalence of dental fluorosis now ranges somewhere between 35% and 60% in fluoridated communities and between 20% and 45% in nonfluoridated areas, depending on the influence of different local conditions. While the increase has occurred primarily in the very mild and mild categories of dental fluorosis, there is also some evidence that the prevalence is increasing in the moderate and severe classifications as well.

Water fluoridation: current effectiveness and dental fluorosis

This paper reviewed the literature on the evidence for water fluoridation's effectiveness under current conditions of multiple fluoride use at recommended and at reduced concentrations, the extent of dental fluorosis at different fluoride concentrations, and the "halo" effect of water fluoridation. Using the relative difference in dental caries between communities with low and optimal water fluoride as an indicator, the effectiveness of water fluoridation has decreased over time as the use of other fluorides has increased. Thus the effectiveness of water fluoridation alone cannot now be determined. Compared to the early fluoridation studies, the differences in dental caries and fluorosis prevalence between fluoridated and non-fluoridated areas have markedly narrowed. Both the prevalence and severity of dental fluorosis have increased since 1945; however, the portion of fluorosis due to water fluoridation is now less (40%) than that attributed to other fluoride sources (60%). Research also suggests that the "halo" effect of community water fluoridation may result in a significantly greater intake of fluoride for people in non-fluoridated communities. This review recognized that since water fluoridation has unique advantages from the perspectives of distribution, equity, compliance and cost-effectiveness over other fluoride technologies, it remains as the fundamental base for caries prevention. The increasingly greater contribution that other sources of fluoride make to dental fluorosis suggests that these sources of fluoride, many of which are used on an elective basis, should be more closely examined for needed changes.

Review of fluorosis risk of self-applied topical fluorides: dentifrices, mouthrinses and gels

The literature on the risks of dental fluorosis and the benefits from the use of fluoride dentifrices, mouthrinses and self-applied gels has been briefly reviewed. While there are several studies that have investigated the impact of dentifrices on the development of dental fluorosis, results are mixed. Although there is far less research investigating the relationship between the use of mouthrinses and dental fluorosis, the available evidence generally fails to identify this technology as one of the major causes of dental fluorosis. Although there is little direct evidence to suggest that the use of self-applied fluoride gels contributes to the development of dental fluorosis, ingestion of fluoride from these systems is of genuine concern and their use by preschool age children is not recommended.

Research in dental health education and health promotion: a review of the literature

This article presents a review of research in dental health education and health promotion. In the period 1982 to 1992, a total of 57 studies evaluating the effectiveness of interventions to alter individuals' behavior related to dental health were identified. Combining the results of these 57 studies with descriptive articles published over the same period, it appears that dental health education can result in improvements in objective measures of dental health behaviors and actual oral health measures, but has only limited success in changing attitudes towards dental issues and achieves only short-term gains in knowledge. The limited use of theoretical frameworks, poor statistical analyses, the use of convenient samples and the short post-intervention follow-up periods diminish the contribution of this research to the development of dental health policy and the formation of strategies to improve the health of communities.

Factors associated with the use of fluoride supplements and fluoride dentifrice by infants and toddlers

Dental fluorosis may be associated with the inappropriate use of fluoride dentifrices and/or dietary fluoride supplements by young children, especially for those who consume optimally fluoridated water. Studies to date have used retrospective designs that rely on anamnestic responses of adults to determine fluoride exposures in their children. The 1986 National Health Interview Survey (NHIS) collected information on current use of fluoride-containing dental products (dentifrices, drops, tablets, and mouthrinses) by all household members during home interviews. This report contains information obtained from adults for 1,996 children younger than two years of age. Nearly half of the children used fluoride dentifrices or dietary fluoride supplements. Eleven percent of the children younger than one year of age and nearly 60 percent of children between one and two years of age reportedly used a fluoride toothpaste. Dietary fluoride supplements were used about equally in these age groups (about 16%). The use of a fluoride dentifrice was similar across racial-ethnic groups, but the use of dietary fluoride supplements was less among blacks and Hispanics. A significantly higher proportion of children whose respondent knew the purpose of water fluoridation used some type of fluoride product. Because young children tend to swallow dentifrices, the findings of this study suggest the need for educational programs targeted to parents and health care providers regarding the appropriate use of fluorides and the risk of fluorosis when they are used inappropriately.

Perceptions of dental fluorosis

Mild dental fluorosis has long been accepted as a side-effect of water fluoridation and, more recently, has been recognized as a consequence of the use of other fluoride-based caries-preventive strategies. Traditionally, dental health professionals have not seen this as being of public health importance, but members of the public have not been asked their opinion. The purpose of the present study was to gather the opinions of lay groups concerning the appearance of the teeth of children with various degrees of fluorosis. Twenty-eight children, born in 1978, who had earlier participated in a study of fluorosis in Perth (Western Australia), allowed 110 observers to look at their upper central incisors under good viewing conditions. Fluorosis in these teeth ranged from TF score 0 (no fluorosis) to TF score 3. The observers were university students, parents, public servants, or dentists. They responded to statement items about the appearance of the teeth. The results, based on just over 3000 responses, showed that lay and dental observers could distinguish between different fluorosis levels. In response to a statement that the teeth appeared pleasing, a large majority agreed when the TF score was 0, but agreement declined as the TF score increased; when the TF score was 3, most people disagreed. Similarly, observers felt that the appearance would increasingly embarrass the child as the TF score increased. Observers, except the dentists, tended to feel that higher TF scores indicated neglect on the part of the child.(ABSTRACT TRUNCATED AT 250 WORDS)

Fluoride supplements in caries prevention: a literature review and proposal for a new dosage schedule

Fluoride supplements have contributed significantly to caries prevention; however, better information about the dynamic nature of fluoride's effect on caries has made a reappraisal desirable. It seems, from a review of the literature, that the benefit from supplement use that can be expected today in populations in low-fluoride areas is small. Possible reasons include the low caries incidence in children of recent years. Few people are willing to use supplements with sufficient regularity to achieve an effect. The principal mode of action of fluoride in supplements, topical exposure of teeth to fluoride, can be achieved with toothpastes and other means. Supplement use has been associated with dental fluorosis in children. This is displeasing to look at and may put at risk the undoubted benefits of water fluoridation if the public associates fluoride with negative cosmetic effects. This reason alone should be sufficient to compel a reconsideration of existing recommendations. An appropriate new dosage schedule for fluoride supplements should be aimed only at identifiable high caries-risk individuals, not at groups defined by age or residence and should result in much lower fluoride intake in the age span birth-eight years than many current recommendations. It should start at six months or later, expressly recommend lozenges rather than tablets for swallowing to maximize the topical effect, stipulate that the maximum fluoride ion content of a tablet be 0.50 mg to reduce the chances of fluorosis and overconsumption, and have no upper age limit, as caries risk may occur at any age. A dosage schedule meeting these requirements is proposed.

Fluoride intake from beverage consumption in a sample of North Carolina children

Since the 1940's, the prevalence of dental fluorosis has increased in the US, concomitant with a reduction in dental decay. These changes have been attributed in part to the widespread use of systemic and topical fluorides. Various sources of increased systemic fluoride exposure have been investigated. However, little is known regarding fluoride intake from beverages in a sample of children of ages susceptible to dental fluorosis. The purpose of this study was to estimate the amount of fluoride ingested from beverages by a sample of North Carolina (NC) children of ages 2-10 years. Data on beverage consumption were collected by means of a diary format. A questionnaire was included so that demographic information and self-assessment on the accuracy of the diaries could be obtained. Beverages reported in the diaries were purchased, and their fluoride content was assayed. Daily total fluid intake ranged from 970 to 1240 mL, and daily beverage consumption ranged from 585 to 756 mL. The estimated mean daily fluoride intakes from beverages for children 2-3, 4-6, and 7-10 years of age were 0.36, 0.54, and 0.60 mg, respectively.

The need for toothpastes with lower than conventional fluoride concentrations for preschool-aged children

Since 1945, when community water fluoridation was first implemented in the United States, not only has the procedure grown to cover more than half of the US population, but the development and use of other fluoride methods have expanded greatly. A concomitant, dramatic decrease has occurred in the caries prevalence of US school-aged children. Recent studies indicate, however, that the prevalence and, to a lesser extent, the intensity of dental fluorosis have increased in schoolchildren in both fluoridated and fluoride-deficient areas. Several studies show that young children inadvertently ingest sizable proportions of toothpaste during toothbrushing. Although ingestion of fluoride toothpastes by preschool-aged children may not be the major contributor to the increase in fluorosis, the findings of at least four studies suggest that the use of fluoride toothpastes by young children is a risk factor. The direct dose-response relation between effectiveness and fluoride concentration of toothpastes is far from clear-cut and, at best, is weak. Thus, considering today's reduced risk of caries, it is timely to market fluoride toothpastes in the US with 400-500 ppm fluoride for preschool-aged children, who are still at risk for developing fluorosis, as has been done in several other countries. Dental public health authorities must work with toothpaste manufacturers, professional organizations, and regulatory agencies to facilitate the approval and marketing of such pediatric fluoride toothpastes.

Evaluation of appropriate use of dietary fluoride supplements in the US

Recent epidemiologic and related evidence suggests the following trends: 1. the prevalence of caries continues to decline in children of the US and several other developed countries; 2. the prevalence of mild dental fluorosis is increasing; 3. the majority of the cariostatic effects of fluoride are topical; and 4. dietary fluoride supplements are a risk factor for dental fluorosis. These trends, and the scientific evidence on fluoride and fluorosis, suggest that it is time to re-evaluate the use of dietary fluoride supplements. This paper examines the evidence for each of the four trends and the use of fluoride supplements in caries prevention today.

Factors affecting the ingestion of fluoride dentifrice by children

Several factors affecting the amount of fluoride ingested during toothbrushing by 2- to 7-year-old children were investigated. The specific purpose of this study was to determine the contribution of age, the amount of dentifrice used, and rinsing after brushing to the variation in the ingestion of fluoride dentifrice. Four hundred and five children brushed their teeth in front of a portable sink. The tubes of dentifrice in gel (0.24% NaF) were weighed before and after use to determine the amount of toothpaste used. The fluoride content of the collected liquids was determined with a fluoride-ion-specific electrode. The amount of fluoride ingested was derived by determining the difference between the amounts used and recovered. The amount of dentifrice used, the age, and the rinsing habits, entered in a multiple regression model, explained up to 66 percent of the total variation in the amount of fluoride ingested. The amount of dentifrice used accounted by itself for 60 percent of the total variation. Therefore, these results indicate that the quantity of dentifrice used was the most important factor affecting the ingestion of fluoride through toothbrushing by young children.

Current regulations and recommendations concerning water fluoridation, fluoride supplements, and topical fluoride agents

In recent years, an increase in the prevalence of dental fluorosis, mostly of the very mild to mild category, has been seen in the United States. This paper therefore discusses the safety of dental fluoride products, primarily with respect to the risk of dental fluorosis due to chronic ingestion of these products by pre-school children. No change is indicated in the optimal fluoride level (0.7 to 1.2 ppm) for water fluoridation. A reduction in the dosage of fluoride supplements is recommended for children aged from three to six years (14.5 to 22 kg body weight) residing in communities with less than 0.7 ppm F. Physicians, pharmacists, and dentists need to be better educated in correctly prescribing fluoride supplements; such prescriptions should be based on the fluoride concentration of the domestic water supply and the child's weight/height/age. No change is recommended in the concentration of fluoride used in dentifrices and mouthrinses. The US Food and Drug Administration should require more explicit labeling of fluoride products with regard to avoidance of ingestion, use of small amounts, and need for supervised use by pre-school children. The efficacy of water fluoridation, fluoride supplements, and topical fluoride agents has been amply documented elsewhere.