Associations Between Exposure to Fluoridated Drinking Water and Dental Caries Experience among Children in Two Australian States

Objectives : This study assessed associations between exposure to fluoride in water and dental caries experience among children in two Australian states. Methods : Cross-sectional data were obtained from 9, 690 South Australian children aged 5–15 years and 10, 195 Queensland children aged 5–12 years. School dental service practitioners recorded DMFS and dmfs data. A questionnaire to parents gained information about residential history that was used to calculate children's percent of lifetime exposed to fluoridated water. Results : Greater exposure to fluoride in water was associated with lower dmfs and DMFS in both states (P<. 01), although in South Australia the effect for DMFS was statistically significant only after controlling for extent of unknown fluoridation exposure and for fluoride supplements. Caries-fluoridation associations were stronger for dmfs compared with DMFS and for Queensland (5% of population fluoridated) compared with South Australia (70% of population fluoridated). Effects for DMFS persisted after controlling for socioeconomic factors. Conclusions : Fluoridation was associated with lower caries experience. The weaker association with DMFS in South Australia may be due to less caries and more fissure sealants in that state, and is consistent with a "diffusion" effect, whereby a high proportion of the population exposed to fluoridation diminishes differences among exposure groups.     

Effectiveness of Water Fluoridation

The efficacy of communal water fluoridation in reducing dental caries has been reviewed based on surveys conducted in the last decade of caries prevalence in fluoridated and nonfluoridated communities in the United States as well as in Australia, Britain, Canada, Ireland, and New Zealand. The efficacy is greatest for the deciduous dentition, with a range of 30–60 percent less caries in fluoridated communities. In the mixed dentition (ages 8 to 12), the efficacy is more variable, about 20–40 percent less caries. In adolescents (ages 14–17), it is about 15–35 percent less caries. Current data on caries prevalence in adults and seniors are extremely limited and include several populations living in communities with higher than optimal fluoride levels. For these adults and seniors, a range of 15–35 percent less caries would also apply. Viewed in toto, the current data for children, adolescents, adults and seniors show a consistently and substantially lower caries prevalence in fluoridated communities. For an accurate measurement of the efficacy of water fluoridation in reducing dental caries, it is essential that only persons with a record of continuous or long-term residency in fluoridated versus nonfluoridated areas be included in such assessments. Because of the high geographic mobility in our society and the widespread use of fluoride dentifrices, supplements, and other topical fluoride agents, such comparisons are becoming more difficult to conduct. Accordingly, the effectiveness (rather than the efficacy) of water fluoridation has decreased as the benefits of other forms of fluoride have spread to communities lacking optimal water fluoridation.     

Influence of exposure to fluoridated water on socioeconomic inequalities in children's caries experience

Abstract This study aimed to evaluate inequalities in children's dental caries experience among socioeconomic status (SES) groups and to investigate effects of exposure to fluoride in water on those inequalities. Cross-sectional data were obtained from 6704 Queensland children aged 5–12 years and 6814 South Australian children aged 5–15 years. School dental therapists and dentists recorded dmfs and DMFS data. A questionnaire to parents sought information about household SES and each child's lifetime exposure to fluoridated drinking water. SES, fluoride exposure and multiplicative interactions between the two were used as explanatory variables in least squares models in which dmfs and DMFS were dependent variables. Additive interactions were evaluated by calculating the excess rate of disease. In both states, children from low SES groups (categorized by household income or parental education) had higher mean dmfs and DMFS values than children from high SES groups (p<0.01). Independent effects of income and education remained significant (p<0.01) after controlling for exposure to fluoride in drinking water. In Queensland, there was a significant multiplicative interaction whereby SES inequalities were lower among children exposed to fluoride: dmfs ratios between low-and high-income groups ranged among ages from 1.54 to 3.56 for children with no exposure to fluoride and from 0.84 to 2.07 for children with lifetime exposure to fluoride. Multiplicative interactions were not statistically significant in South Australia or when DMFS was the dependent variable. However, additive interactions were consistent and most pronounced for deciduous teeth in both States. Absolute differences in caries experience between low and high SES children were greater among non-exposed groups due to the higher underlying levels of caries experience of children with no exposure to fluoride in water.     

Exposure to water fluoridation and caries increment

OBJECTIVE: The objective of this cohort study was to examine the association between exposure to water fluoridation and the increment of dental caries in two Australian states: Queensland (Qld)--5 per cent fluoridation coverage; and South Australia (SA)--70 per cent fluoridation coverage. METHOD: Stratified random samples were drawn from fluoridated Adelaide and the largely non-fluoridated rest-of-state in SA, and fluoridated Townsville and non-fluoridated Brisbane in Qld. PARTICIPANTS: Children were enrolled between 1991 and 1992 (SA: 5-15 yrs old, n = 9,980; Qld: 5-12 yrs old, n = 10,695). Follow-up caries status data for 3 years (+/- 1/2 year) were available on 8,183 children in SA and 6,711 children in Qld. MAIN OUTCOME MEASURES: Baseline data on lifetime exposure to fluoridated water, use of other fluorides and socio-economic status (SES) were collected by questionnaire, and tooth surface caries status by dental examinations in school dental service clinics. RESULTS: Higher per cent lifetime exposure to fluoridated water (6 categories: 0;1-24; 25-49; 50-74; 75-99; 100 per cent) was a significant predictor (ANOVA, p < 0.01) of lower annualised Net Caries Increment (NCI) for the deciduous dentition in SA and Qld, but only for Qld in the permanent dentition. These associations persisted in multiple linear regression analyses controlling for age, gender, exposure to other fluorides and SES (p < 0.05). CONCLUSIONS: Water fluoridation was effective in reducing caries increment, even in the presence of a dilution effect from other fluorides. The effect of fluoridated water consumption was strongest in the deciduous dentition and where diffusion of food and beverages from fluoridated to non-fluoridated areas was less likely.     

Caries prevalence and length of residency in fluoridated and non-fluoridated communities

The caries experience of grade 6 Canadian schoolchildren was examined related to length of residence in non-fluoridated Camrose (0.23 ppm) and adjacent fluoridated Wetaskiwin (1.08 ppm). The mean age was 11.94 +/- 0.65 years, 115 being examined in Camrose and 89 in Wetaskiwin. The mean DMFT and DMFS values were similar in both the non-fluoridated and fluoridated communities with DMFT of 2.39 and 2.65 and DMFS of 3.40 and 3.54, respectively. When a minimum 5-year residency requirement was imposed, the data changed, showing for those children with 5-year residency DMFT values of 2.43 and 2.26 and DMFS values of 3.35 and 2.79, respectively, for non-fluoridated Camrose and fluoridated Wetaskiwin. Although the fluoridated community had 17% less surfaces with caries, differences between the fluoridated and non-fluoridated communities were not statistically significant. Within the fluoridated community, differences in DMFT and DMFS between children resident less than 5 and greater than 5 years were statistically significant (DMFT p less than 0.05; DMFS p less than 0.01). When comparing regions where adjacent communities exist, with and without water fluoridation, and in making decisions on fluoride supplementation levels for children who have changed residency to such communities, it is important that this type of information is taken into account.     

Relationship of caries with socioeconomic status in 14-year-old children from communities with different fluoride histories

Abstract The aim of this study was to describe the caries prevalence of 14-yr-old children living in two fluoridated communities, a non-fluoridated community, and a community that discontinued fluoridation 5 yr before the children were examined and to relate the caries prevalence to socio-economic status. Clinical examinations were completed on 413 children of whom 227 had been continuously resident in their towns. Children living in the fluoridated communities had significantly lower mean CMFT and DMFS scores than those in the non-fluoridated town. The children from the town that had discontinued fluoridation 5 yr earlier had mean DMFT and DMFS score that occupied an intermediate position. The differences were greater when only the continuous residents were examined. There were significant differences in the mean DMFT and DMFS when comparing socioeconomic status and fluoridation of the water supply. No interaction effect was demonstrated between these two factors.     

Fluoridation and social equity

The overall reduction in caries prevalence and severity in the United States over recent decades is largely due to widespread exposure to fluoride, most notably from the fluoridation of drinking waters. Despite this overall reduction, however, caries distribution today remains skewed, with the poor and deprived carrying a disproportionate share of the disease burden. Dental caries, like many other diseases, is directly related to low socioeconomic status (SES). In some communities, however, caries experience has now diminished to the point where the need for continuing water fluoridation is being questioned. This paper argues that water fluoridation is still needed because it is the most effective and practical method of reducing the SES-based disparities in the burden of dental caries. There is no practical alternative to water fluoridation for reducing these disparities in the United States. For example, a school dental service, like those in many other high-income countries, would require the allocation of substantial public resources, and as such is not likely to occur soon. But studies in the United States, Britain, Australia, and New Zealand have demonstrated that fluoridation not only reduces the overall prevalence and severity of caries, but also reduces the disparities between SES groups. Water fluoridation has been named as one of the 10 major public health achievements of the 20th century by the Centers for Disease Control and Prevention, and promoting it is a Healthy People objective for the year 2010. Within the social context of the United States, water fluoridation is probably the most significant step we can take toward reducing the disparities in dental caries. It therefore should remain as a public health priority.     

Association between infant formula feeding and dental fluorosis and caries in Australian children

Objective: The objective of this study was to evaluate associations between patterns of infant formula feeding and dental fluorosis and caries in a representative sample of Australian children. Methods: A population‐based study gathered information on fluoride exposure in early childhood. Information on infant formula feeding and fluoridation status was used to group children: three groups in nonfluoridated areas (formula nonuser, user for ≤6 months, and user for 6+ months) and four groups in fluoridated areas (nonuser, user with nonfluoridated water, user with fluoridated water for ≤6 months, and user with fluoridated water for 6+ months). Children aged 8‐13 years were examined for fluorosis using the Thylstrup and Fejerskov (TF) Index. Primary tooth caries experience recorded at age 8‐9 years was extracted from clinical records. Fluorosis cases were defined as having TF 1+ on maxillary incisors. Fluorosis prevalence and primary caries experience were compared across formula user groups in multivariable regression models adjusting for other factors. Results: Total sample was 588 children. Children in fluoridated areas had higher prevalence of very mild to mild fluorosis, but lower caries experience than those in nonfluoridated areas. Among children in nonfluoridated areas, formula users for 6+ months had significantly higher prevalence of fluorosis compared with nonusers. There was no significant difference in fluorosis prevalence among the formula users in fluoridated areas. Among children in fluoridated areas, formula users with nontap water had higher caries experience. Conclusion: Infant formula use was associated with higher prevalence of fluorosis in nonfluoridated areas but not in fluoridated areas. Type of water used for reconstituting infant formula in fluoridated areas was associated with caries experience.     

Plaque fluoride and mutans streptococci in plaque and saliva before and after discontinuation of water fluoridation

Our aim was to compare plaque fluoride and the level of mutans streptococci in saliva and plaque before and 1 and 2 years after discontinuation of water fluoridation in Kuopio, Finland. For comparison, a low-fluoride community was included in the study. Pooled plaque and saliva were collected from a random sample of 12-year-olds in both communities ( n =139). Enumeration of mutans streptococci in plaque was made on MSB agar and the level of salivary mutans streptococci was measured using the Strip mutans® method. Fluoride was analyzed using a fluoride specific electrode. Caries, gingival status, fluoride varnish applications and self-reported oral health habits were recorded at baseline. Before discontinuation of fluoridation. the level of mutans streptococci in saliva was significantly lower in the fluoridated than in the non-fluoridated community. The difference in plaque mutans streptococci was not statistically significant. After discontinuation of water fluoridation, there was a significant shift towards elevated values of salivary mutans streptococci in the fluoridated community, but the level of mutans streptococci in plaque remained at the baseline level. There was no significant difference between the communities in the fluoride content of plaque either before or after discontinuation of fluoridation. From the background factors, only caries scores (higher in the non-fluoridated community) and oral hygiene (better in the non-fluoridated community) were significantly different between the communities.     

Community fluoridation status and caries experience in children

OBJECTIVE: This study compares dental caries experience in fluoridated and nonfluoridated communities. METHODS: A dental health survey designed to collect data on caries experience and treatment needs for community-specific public health planning purposes was conducted in public elementary schools during the 1996-97 school year. Oral examinations of 17,256 children were completed, representing 93 percent of children residing in 62 East Tennessee communities. RESULTS: The analysis showed that water fluoridation was significantly related to caries experience in the primary (dfs) and permanent (DMFS) dentitions and to the proportion of caries-free children in the primary and permanent dentitions. When the data were adjusted for socioeconomic status, race, and age, caries levels were 21 percent lower in the primary dentition and 25 percent lower in the permanent dentition in fluoridated communities than in nonfluoridated communities. In addition, the proportion of children who were caries free was larger in fluoridated as compared with nonfluoridated communities by 19 percent in the primary dentition and 6 percent in the permanent dentition. CONCLUSION: Although the design of the study prevented the collection of individual fluoride and residency histories, findings suggest there was substantially lower caries experience in fluoridated communities than in nonfluoridated communities.     

Relationships between exposure to additional fluoride, social background and dental health in 7-year-old children

The relationship between social background, water fluoridation, use of fluoride tablets and dmf scores was studied in a birth cohort of 7-yr-old New Zealand children. This analysis showed that the level of exposure to additional fluoride was a complex variable influenced by at least three factors: the use of fluoride toothpaste; the child's length of residence in a fluoridated area; the length of time for which the child had been provided fluoride tablets. Log linear modelling of the data suggested the presence of a relatively complex relationship between exposure to additional fluoride, social background and dental health. First, both duration of residence in a fluoridated area and the provision of fluoride tablets made significant net contributions to the variability in the dmf score. However, exposure to additional fluoride from these sources was differentially influenced by social background: while there were relatively strong associations between social background and the use of fluoride tablets, there was no significant association between duration of residence in a fluoridated area and social background. Finally, independently of an association with exposure to additional fluoride, family social background made a significant net contribution to the variability in dmf scores.     

Water fluoridation: current effectiveness and dental fluorosis

Abstract – 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 arc used on an elective basis, should be more closely examined for needed changes.     

Prevalence and severity of dental caries in adolescents aged 12 and 15 living in communities with various fluoride concentrations

OBJECTIVES: To determine the experience, prevalence, and severity of dental caries in adolescents naturally exposed to various fluoride concentrations. METHODS: A cross-sectional census was conducted on 1,538 adolescents aged 12 and 15 years living at high altitude above sea level (> 2,000 m or > 6,560 ft) in above-optimal fluoridated communities (levels ranging from 1.38 to 3.07 ppm) of Hidalgo, Mexico. Sociodemographic and socioeconomic data were collected using questionnaires. Two previously trained and standardized examiners performed the dental exams. RESULTS: Caries prevalence was 48.6 percent and mean of decay, missing, and filling teeth (DMFT) for the whole population was 1.15 +/- 1.17. In terms of severity, 9.6 percent of the adolescents had DMFT > or = 4, and 1.7 percent had > or = 7. The significant caries index (SiC) was 2.41 in the group of 12-year-olds, and 3.46 in the 15-year-olds. Higher experience and prevalence were observed in girls, in children with dental visit in the past year, those in the wealthiest socioeconomic status (SES) (quartiles 2, 3, and 4), those whose locale of residence is in San Marcos and Tula Centro, and in fluorosis-free children and those with moderate/severe fluorosis. In an analysis of caries severity (DMFT > or = 4), both adolescents with very mild/mild and moderate/severe dental fluorosis have higher caries severity. CONCLUSIONS: The results indicated that caries experience, prevalence, and severity as well as SiC index among 12- and 15-year-old adolescents were relatively low. Sociodemographic and socioeconomic variables commonly associated with dental caries were also observed in Mexican adolescents. Unlike other studies, we found that caries increased with higher SES. Fluoride exposure (measured through fluorosis presence) does not appear to be reducing the caries prevalence (DMFT > 0) or caries severity (DMFT > or = 4) in these high-altitude communities.     

Dental caries experience in schoolchildren in fluoridated and non-fluoridated communities in Western Australia

A cross-sectional survey was undertaken in 1987 to measure the difference in caries experience in schoolchildren between a fluoridated (0.8 mg/L F-) and a non-fluoridated region (0.1-0.4 mg/L F-). 3436 children aged 5-15 yr were examined. Children in the non-fluoridated region had a higher caries experience than those in the fluoridated region. Mean differences were 1.06 dfs (95% CI = 0.66 to 1.47, P less than 0.001) and 0.48 DFS (95% CI = 0.23 to 0.72, P less than 0.001). After adjusting for potential confounding factors (fluoride tablet consumption, socioeconomic status, number of fissure-sealed surfaces, and mobility between regions) the relative risk of not being caries-free in the non-fluoridated region compared with the fluoridated region was 1.43 (95% CI = 1.21-1.70, P less than 0.0001) for the primary dentition and 1.39 (95% CI = 1.18-1.63, P less than 0.0001) for the permanent dentition.     

Consumption of nonpublic water: implications for children's caries experience

There are concerns that the consumption of unfluoridated bottled and tank water may put children at increased risk of developing caries. OBJECTIVES: The aim of this study was to investigate the relationship between nonpublic water consumption (either from bottles or rainwater tanks) and socioeconomic status (SES) and both deciduous and permanent caries experience. METHODS: A random sample of children enrolled in the School Dental Service of South Australia participated in the study (response rate = 71.8%, n = 9988). RESULTS: Forty-five per cent of children had greater than 50% lifetime consumption of nonpublic water while 36% of children had 0% lifetime consumption. Increased use of nonpublic water occurred for children from lower socioeconomic groups, two-parent families and children from nonmetropolitan areas, with these results most likely a result of the residential location of the children. Multivariate modelling revealed a significant positive relationship between deciduous caries experience and consumption of nonpublic water, even after controlling for the age and sex of the child, SES and residential location. This relationship was significant only for those children with 100% lifetime availability of fluoridated water. The effect of consumption of nonpublic water on permanent caries experience was not significant. It is postulated that these findings may result from the lower caries activity in the permanent dentition of children aged 10-15 and possible dietary confounders. CONCLUSION: Recommendations are made for the addition of fluoride to bottled water, especially with regard to the oral health of younger children.     

Decision-making for national programs of community fluoride use

Every community, region or country with a high or rising prevalence of dental caries should implement a caries-preventive program that automatically brings the benefits of systemic and topically applied fluoride to the entire population. The fluoridation of community water supplies or salt fulfills the requirements of providing safe, effective protection from dental caries at reasonable cost. The use of dietary fluoride supplements or fluoridated milk does not meet the requirements of a comprehensive national or community program because compliance is poor or only selected age groups are targeted. Water fluoridation is ideal for countries, regions or communities with many central water supplies or where salt production or distribution is not centralized or easy to control. Water fluoridation also has advantages where many areas exist with natural water fluoride concentrations at optimal or greater than optimal concentrations. Salt fluoridation is ideal for countries or regions with few, potable central water supplies in which salt production and distribution are centralized and easily controlled. Concentrations of fluoride for water fluoridation range from 0.5 to 1.2 parts per million (ppm) parts of water depending on climate and dietary practices. The concentration for fluoridation of salt is approximately 200 to 250 mg fluoride per kg of salt, also depending on dietary practices. Properly fluoridated salt should produce levels of urinary fluoride excretion similar to those found in communities with fluoridated water. Benefits of the two methods are similar. Salt fluoridation may be done more cheaply.     

Reduction of caries in rural school-children exposed to fluoride through a milk-fluoridation programme in Araucania, Chile

OBJECTIVE: To assess the effectiveness of a dental caries prevention programme on the permanent dentition of Chilean rural schoolchildren using fluoridated powdered milk and milk derivatives. BASIC RESEARCH DESIGN: The fluoridated products were delivered to 35,000 schoolchildren in the rural areas of the Ninth Region in Chile using the standard School Feeding Programme (PAE). The daily fluoride dose from milk fluoridated products was estimated at 0.65 mg/day, during approximately 200 schooldays/year. Cross-sectional samples of schoolchildren aged 6, 9 and 12 years from study communities and from positive control communities (ongoing APF-gel programme) were examined at the start of the study in November 1999 and after 36 months. RESULTS: No significant differences were found for the DMFT and dmft indices among 6-year-olds in the study and positive control groups either at baseline or 36 months later. Significant reductions (range 24-27%) were observed in the DMFT index in 9 and 12-years-olds of the study communities when clinical data at baseline, in the absence of a fluoridated preventive programme, were compared to those obtained after 36 months of receiving fluoridated milk products. Upon the follow-up examination, the DMFT indices of schoolchildren aged 9 and 12 years old receiving fluoridated milk were not significantly different from those of the positive control comparison group of the APF-Gel programme. CONCLUSIONS: Considering the relative costs and technical difficulties involved in both caries preventive programmes, it appears that in rural Chilean communities, fluoridation of powdered milk and milk derivatives is an effective alternative caries prevention programme in areas where either water fluoridation or other community delivered programmes are difficult to apply.     

Patterns of dental caries following the cessation of water fluoridation

OBJECTIVES: To compare prevalence and incidence of caries between fluoridation-ended and still-fluoridated communities in British Columbia, Canada, from a baseline survey and after three years. METHODS: At the baseline (1993/4 academic year) and follow-up (1996/7) surveys, children were examined at their schools. Data were collected on snacking, oral hygiene, exposure to fluoride technologies, and socio-economic level. These variables were used together with D1D2MFS indices in multiple regression models. RESULTS: The prevalence of caries (assessed in 5,927 children, grades 2, 3, 8, 9) decreased over time in the fluoridation-ended community while remaining unchanged in the fluoridated community. While numbers of filled surfaces did not vary between surveys, sealed surfaces increased at both study sites. Caries incidence (assessed in 2,994 life-long residents, grades 5, 6, 11, 12) expressed in terms of D1D2MFS was not different between the still-fluoridating and fluoridation-ended communities. There were, however, differences in caries experienced when D1D2MFS components and surfaces at risk were investigated in detail. Regression models did not identify specific variables markedly affecting changes in the incidence of dental decay. CONCLUSIONS: Our results suggest a complicated pattern of disease following cessation of fluoridation. Multiple sources of fluoride besides water fluoridation have made it more difficult to detect changes in the epidemiological profile of a population with generally low caries experience, and living in an affluent setting with widely accessible dental services. There are, however, subtle differences in caries and caries treatment experience between children living in fluoridated and fluoridation-ended areas.     

The Pre-and Posteruptive Effects of Fluoride in the Caries Decline

The widespread availability of fluoride from many sources is accepted as a major reason for the caries decline among children in developed countries. There is still controversy, however, about its principal mode of action. This article reviews the evidence on fluoride's preeruptive and posteruptive effects, and suggests reasons for its continuing role in the caries decline. Early fluoridation studies accepted that fluoride acted preruptively through incorporation into developing enamel; but further research could not explain why fluoride levels were not clearly higher in enamel exposed to fluoride, nor why there were no clear correlations between caries experience and enamel fluoride concentration. Instead, considerable evidence suggests that fluoride acts mainly, though not entirely, through posteruptive remineralization of demineralized enamel. Caries experience has declined in nonfluoridated as well as in fluoridated areas, though DMF scores are still consistently lower in fluoridated areas. Posteruptive remineralization effects are seen from fluoridated drinking water as well as with fluoride from other sources. The continuing caries decline, beyond the level suggested by early fluoridation field trials, can be attributed either to more efficient remineralization or to long-term, intraoral ecological change, or to both.     

Dental caries and fluorosis among children in a rural Georgia area

PURPOSE: This IRB-approved study compared the caries experience, fluorosis prevalence, and plaque and salivary fluoride concentrations ([F]) in middle school (MS; N = 51) and elementary school (ES; N = 144) children residing in nonfluoridated and fluoridated communities in rural Georgia. All participants were exposed to fluoridated water at school (0.5-1.2 ppm), some received that level at home, and others received home water with < 0.1 ppm F. METHODS: Subjects' parents completed a questionnaire regarding fluoride exposure. Children were examined at school by two calibrated dentists. RESULTS: No significant differences were seen in DMFS+dfs between children with or without fluoridated home water, nor for those with or without fluorosis. MS children with non-fluoridated home water had lower mean salivary [F] values than MS children with fluoridated home water. No differences were found among MS and ES children in mean plaque [F] for those with or without fluorosis. CONCLUSIONS: Home water fluoridation had little effect on the variables measured. These findings appear to be due to fluoride exposure from fluoridated dentifrices, fluoridated drinking water at school, and the fluoride "halo" effect.