Sociodemographic and behavioural correlates of severe dental fluorosis.

OBJECTIVES: The aim of this study was to identify sociodemographic and behavioural factors associated with the prevalence of severe dental fluorosis in moderate- and high-fluoride areas of the Ethiopian Rift Valley. METHODS: Three hundred and six adolescents (12-15 years) and 233 mothers participated in the study. The children were examined for dental fluorosis according to the Thylstrup-Fejerskov Index (TFI). The children and their mothers were subsequently interviewed. Sixty mothers had more than one participating child. In order to perform a paired parent/child analysis, a total of 73 younger siblings had to be excluded. RESULTS: Among the remaining 233 children, the prevalence of severe dental fluorosis (TFI >or= 5) was 24.1% and 75.9% in the moderate- and high-fluoride areas, respectively. According to bivariate as well as multivariate analyses, a number of sociodemographic and behavioural factors were related to severe fluorosis. The odds for having severe fluorosis varied according to the fluoride concentration of the drinking water, age, consumption of tea, length of breastfeeding and method of storing water. The adjusted odds ratios ranged from 2.6 to 26.1. Breastfeeding for > 18 months and the use of clay pots for storing drinking water helped protect against severe dental fluorosis. Bivariate analyses indicated that being male and consuming fish might be associated with higher TFI scores. CONCLUSION: In order to avoid dental fluorosis, low-fluoride drinking water should be provided in the relevant villages. A prolonged period of breastfeeding, the use of clay pots for storing water, and possibly a reduced intake of tea and whole fish in infants might also help to avoid severe fluorosis in children growing up in traditionally fluoride-endemic areas.

Dental fluorosis in primary teeth: a study in rural schoolchildren in Shaanxi Province, China.

OBJECTIVE: The aim of this study was to assess the prevalence and severity of fluorosis in the primary dentition of 7-8-year-old Chinese schoolchildren in areas with fluoride concentrations in the drinking water ranging from 0.35 to 7.6 mg L-). SUBJECTS AND METHODS: Four hundred and seventy-two children from 13 different schools were divided into four groups according to the fluoride concentration of the drinking water: (A)

Fluoride, calcium and magnesium intake in children living in a high-fluoride area in Ethiopia. Intake through food.

OBJECTIVE: The aim of this study was to assess the daily dietary fluoride intake in children living in two neighbouring villages in the Wonji Shoa Sugar Estate, a rural part of the Ethiopian Rift Valley. METHODS: The villages depended on water from different sources: Village A used either river water (Awash River, with 1.8 mg F(-)/L) or ground water (2.1 mg F(-)/L), while village K was served ground water with 14 mg F(-)/L. Fifteen fully weaned children below the age of 5 years were selected in each of the villages. Over a four-day period the total food intake for these children was assessed by using a duplicate portion technique. The food was analysed for fluoride by using a fluoride ion-selective electrode after the dry ashing. Furthermore, the energy of the food was measured, as well as the calcium and magnesium contents (atomic absorption spectrometry after microwave digestion with nitric acid and hydrogen peroxide). The mothers gave a description of the ingredients used for preparing the food. Relevant background information concerning food habits, etc. was collected through a food frequency questionnaire. RESULTS: This study shows that considerable amounts of fluoride may be retained in food prepared on high-fluoride water. In village A, food contributed 2.3 mg F(-)/day, while a dietary fluoride intake of 4.8 mg/day was found in children in village K. Interestingly, the sevenfold higher fluoride concentration of the water used for food preparation in village K compared to village A, gave only a doubling in fluoride intake through food. Calcium intake was relatively low while magnesium intake was above the recommended level. CONCLUSION: As the energy intake by both groups was low, some systematic underreporting might be suspected. Thus, the fluoride intake in the group may be even higher than what was actually found in this study.

Fluoride intake in children living in a high-fluoride area in Ethiopia - intake through beverages.

INTRODUCTION: The present study was conducted in Wonji Shoa, a sugar estate in the Ethiopian Rift Valley. Drinking water in the area is provided either by the Awash River or by high-fluoride ground water wells. Defluoridation plants have been installed, but are not in regular use, and fluorosis, dental as well as skeletal, is endemic. The aim of this study was to assess daily fluoride intake from drinking water and beverages in children from neighbouring villages with varying fluoride concentration in the drinking water. SUBJECTS AND METHODS: Thirty families were selected from two of the plantation villages (A and K). The criterion for being included in the project was the presence in the household of at least one child, fully weaned and below the age of 5 years. For sampling of beverages, the duplicate portion technique was used. The fluoride concentration in the beverage samples was determined using standard methods, using a fluoride ion-selective electrode. RESULTS: Ten of the selected households in Village A fetched water from the Awash River (1.8 mg F-/L) while five relied upon water from a local well (2.1 mg F-/L). All 15 households in Village K used water from a local well with fluoride concentration of 14.4 mg/L. The mean daily fluoride intake from drinking water and beverages during the four days, varied from 1.2 to 1.5 mg and 5.9 to 8.8 mg in Village A and K, respectively. Low variety in types of beverages consumed was reported both during the study period and through the questionnaire. Only local water was used for beverage preparation. Children who consumed milk had a reduced fluoride intake. Tea, which was part of the children's diet, was not found to be a main source of fluoride. CONCLUSION: A2n effective defluoridation of the drinking water or a change of water source would seem to be the only options for avoidance of dental and possibly skeletal fluorosis.

Dental caries among 10- to 14-year-old children in Ugandan rural areas with 0.5 and 2.5 mg fluoride per liter in drinking water.

The purpose of this study was to report on dental caries among Ugandan children residing in rural areas with either a low or high fluoride concentration in the drinking water, and to assess factors associated with caries. A random sample of 481 children aged 10-14 years was selected from Mpondwe (n = 81) and Kyabayenze (n = 82) in the Kasese district with 0.5 mg and from Mutolere/Kagera (n = 163) and Kabindi (n = 155) in Kisoro with 2.5 mg fluoride/l in the drinking water. The children were examined for caries using the DMFT index as described by the World Health Organization in 1987. The mean DMFT was 0.34 in the whole material. In one low fluoride area, Kyabayenze, all children were caries-free compared to 75% to 86% in the other areas. In Kyabayenze, tea with sugar was taken significantly less frequently than in the other low-fluoride area. In the high-fluoride district, age and consumption of tea with sugar were positively and significantly correlated with caries. Multivariate analyses showed age to be the only significant risk indicator.

Age as a determinant of severity of dental fluorosis in children residing in areas with 0.5 and 2.5 mg fluoride per liter in drinking water.

The purpose of this study was to investigate the influence of age on the severity of dental fluorosis in children exposed to drinking water with either low or high fluoride concentrations. The children selected for this study were aged 10-14 years, with 28 permanent teeth and at least 1 tooth pair with fluorosis. The children were permanent residents of districts in western Uganda with either 0.5 mg (n = 33) or 2.5 mg fluoride/l in drinking water (n = 186). All vestibular tooth surfaces were examined for fluorosis using the modified Thylstrup and Fejerskov (TF) index. In the high fluoride community, the proportion of teeth per child with TF scores > or = 4, and > or = 5 was significantly higher among children aged 13-14 years compared to those aged 10-12 years. Children's chronological age correlated positively and significantly with the median TF scores for all teeth, including early erupting (first molars and incisors) and late erupting teeth (canines, premolars and second molars). In linear regression analyses, the median TF score for all teeth, as well as for early erupting and late erupting teeth, increased significantly with age. On the other hand, in the low fluoride community there was no significant association between age and the severity of fluorosis. This study showed a significant increase in the severity of fluorosis with increasing age in a high fluoride community, whereas no change in severity with age was observed in a low fluoride community.

Weaning food and magadi associated with dental fluorosis in Northern Tanzania.

A cross-sectional study of 143 children aged 10-14 years was carried out to identify factors associated with the severity of dental fluorosis in 2 areas (Moshi/Kibosho: n = 63/80) with fluoride (F) concentrations < 0.4 mg F/L in the drinking water. Dental fluorosis was recorded under field conditions using the Thylstrup and Fejerskov index (TFI). The score on tooth 21 was used to indicate the severity. The prevalence of dental fluorosis in Moshi at TFI score > or =1 was 60% and at TFI score > or =5 it was 10%. The corresponding values in Kibosho were 100% and 34%, respectively. Background variables pertained primarily to the child's first 6 years of life. In Moshi and Kibosho, 65% and 97% of children, respectively, used magadi, a fluoride-containing food tenderizer. In Moshi, the risk of having TFI score > or =2 was significantly higher among users of magadi (odds ratio (OR) = 5). Kiborou, a traditional homemade weaning food (porridge) cooked with magadi, was used only in Kibosho. Users of kiborou (36%) were at significantly higher risk (OR = 3) of developing fluorosis at severity TFI > or =4 than the users of lishe, another type of weaning food. All children in Moshi and 64% in Kibosho used lishe, which is cooked without magadi. Magadi and kiborou were significant risk indicators. Thus, it seems that the unexpectedly high prevalence of dental fluorosis and the observed differences in fluorosis prevalence and severity may be partly explained by F exposure from magadi.

An attempt to explain why Tanzanian children drinking water containing 0.2 or 3.6 mg fluoride per liter exhibit a similar level of dental fluorosis.

The aim of this study was to identify factors that might explain the similar level of prevalence and severity of dental fluorosis in two neighboring areas in Tanzania: Kibosho; 0.2 mg fluoride/l, n = 96 and Arusha; 3.6 mg fluoride/l in drinking water, n = 80. Subjects aged 8-16 years were examined for dental fluorosis using the Thylstrup and Fejerskov Index (TFI). Based on the score on the upper left central incisor, the prevalence was not significantly different between the communities (TFI > or = 1). The severity, however, was significantly higher in Arusha. The areas had different food habits, e.g., type of weaning food used, and the use of magadi, a fluoride containing salt. In Arusha, 99% of the children had been given lishe, which is a magadi-free weaning food. Conversely in Kibosho, 61% used lishe while 39% used the magadi-containing weaning food kiborou. Magadi was used as food tenderizer in 'adult food' by 98% in Kibosho and 45% in Arusha. Residential area and use of magadi explained 5% of the variance in TFI scores in inter-area analyses. In intra-area analyses, weaning food in Kibosho and use of magadi in Arusha had a significant effect, but the total explained variance was only 5 and 4%, respectively. Apart from fluoride in the drinking water, other sources of fluoride such as use of magadi in weaning food (kiborou) and in the adult food may partly explain the high prevalence and severity of dental fluorosis in the community with 0.2 mg fluoride per liter in the drinking water.

Dental variables associated with differences in severity of fluorosis within the permanent dentition.

The aim of this study was to assess the influence of age at start, duration, and completion of enamel formation, as well as of tooth-eruption age and enamel thickness on the severity of dental fluorosis within the permanent dentition. The material comprised Ugandan children (n = 219), aged 10-14 years, with 28 teeth and at least 1 tooth with fluorosis. The children were permanent residents in districts with either 0.5 mg or 2.5 mg fluoride/l in the drinking water. Fluorosis was assessed on the vestibular surfaces of all teeth using the modified Thylstrup and Fejerskov (TF) index. In order to relate fluorosis to the dental variables, the material was divided into a test group (n = 103), with fluorosis on all teeth, and a reference group (n = 116), with fluorosis on up to 27 teeth. The reference group was used to confirm or refute the findings in the test group. Paired comparisons showed significantly higher median TF scores for the late than for the early mineralizing and erupting teeth. In multiple regression analyses, the age at start, duration, and completion of enamel formation as well as tooth eruption was significantly related to the severity of fluorosis after controlling for enamel thickness (P < 0.05, n = 14). The effect (R2change) of the dental variables on the variation in severity of fluorosis within the dentition was in decreasing order: the duration of enamel formation, age at completion of enamel formation, tooth-eruption age, and the start of enamel formation.

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.

Perceptions of susceptibility to oral health hazards: a study of women in different cultures.

UNLABELLED: People typically attribute lower health risks to themselves than to others, a phenomenon called unrealistic optimism. OBJECTIVES: The purpose of this study was to investigate how women's perceived susceptibility to tooth decay is related to information from various sources, trust in these sources and personal experience with risk factors. Comparative risk judgments for oral health hazards were also investigated. METHODS: Two samples of women were included. In 1997, a random sample of adults (n = 1190) aged 25 years, from three counties of western Norway, were invited to complete postal questionnaires at home. A total of 735 adults (62%) responded, of whom 374 (51%) were women. During July 1997, a convenient sample of 140 women, aged 15-40 years, participated in a structured interview at a Maternal Child Health clinic in Arusha town, Tanzania. RESULTS: Among the Tanzanian women, information from health workers and media, trust in these sources, symptoms of tooth decay and intake of sugared foods were significantly related to perceived risk for tooth decay. Pearson's correlation coefficients varied from r = 0.47, P < 0.001 (trust in health workers) to r = 0.20, P < 0.05 (intake of sugared foods). In both groups of women all mean ratings of comparative risk differed significantly (P < 0.001) from the midpoint of the scales (marked same risk as others), as tested by one sample t-test (test value = 0). The range of t-values was from t = -12.7 (dental fluorosis) to t = -18.2 (tooth decay) and from t = -4.9 (gum disease) to t = -8.3 (loss of teeth) among the Tanzanian and Norwegian women, respectively. CONCLUSIONS: When judging their susceptibility for tooth decay, Tanzanian women seem to consider both information from health workers and their personal risk experience. Optimism in comparative risk judgments for oral health hazards was evident among both the Tanzanian and the Norwegian women investigated. These findings are discussed in the context of implications for oral health education.

Altitude as a risk indicator of dental fluorosis in children residing in areas with 0.5 and 2.5 mg fluoride per litre in drinking water.

The purpose of this study was to assess the association between altitude and dental fluorosis among Ugandan children in two fluoride (F) districts while controlling for other factors related to fluorosis. A random sample of 481 children aged 10-14 years was examined for fluorosis using the Thylstrup and Fejerskov (TF) index. The prevalence and severity of dental fluorosis increased significantly with increase in altitude (900 vs. 2,200 m in the low- and 1,750 vs. 2,800 m in the high-F district) and in F concentration in the drinking water. In bivariate correlation analyses, F exposure from liquid (FEL), altitude, infant formula, vegetarianism and storing of drinking water in earthenware pots were significantly associated with the tooth prevalence of fluorosis (TPF), i.e. at a severity of TF score >/=1 (p<0.05); age and gender were not. The stepwise multiple linear regression explained 35 and 55% of the variance in TPF within the low- and high-F districts, respectively. The change in R2 due to FEL was 28 and 51% points compared with 5 and 4% points due to altitude. The significant effect of FEL and altitude was confirmed by multiple logistic regression analyses. Thus, although most of the variation in the prevalence and severity of dental fluorosis was explained by the F intake from liquid, altitude was a significant risk indicator after controlling for potential confounders.

Vegetarianism and dental fluorosis among children in a high fluoride area of northern Tanzania.

OBJECTIVE: The purpose of this study was to compare the prevalence and severity of dental fluorosis among vegetarian and nonvegetarian children and adolescents living in an area where dental fluorosis is endemic. DESIGN: An analytical cross-sectional retrospective study. SAMPLE AND METHODS: Children (n = 165) aged 6-18 years, from five schools in Arusha town were examined. The children had a life-long exposure to drinking water with 3.6 mg F/litre. The severity of dental fluorosis was assessed using the Thylstrup & Fejerskov Index (TFI). RESULTS: In the vegetarian group (n = 24), the prevalence of dental fluorosis (TFI score > or = 1) was 67%, while 21% had severe fluorosis (TFI score > or = 5). In the nonvegetarian group (n = 141) the prevalence of fluorosis and severe fluorosis was 95% and 35%, respectively. In bi-variate correlation analyses age, vegetarianism and a series of other factors related to childhood nutrition (meals per day, the use of home-made porridge, the use of fish, etc.) were significantly associated with the tooth prevalence of dental fluorosis (TPF, P < 0.05). Stepwise multiple linear regression analyses explained 30% of the variance in TPF; age 15% points and vegetarianism 13% points. Multiple logistic regression analysis showed that the risk of developing dental fluorosis was seven times higher among nonvegetarians than among vegetarians. CONCLUSION: The significantly lower prevalence and severity of dental fluorosis among the vegetarian group compared to the nonvegetarians would seem to be related to diet.

Risk periods in the development of dental fluorosis.

In order to study the age-related susceptibility to dental fluorosis, 40 children who had been lifelong consumers of moderate- to high-fluoride water (0.55-8.48 mg F/l) were examined, as well as a group of older siblings (n = 40) who were born 6 months to 6 years before the fluoride-containing drinking water was introduced to the household. Background information was obtained through a structured questionnaire. Dental fluorosis was scored according to the TF index. Among the 80 children examined, the permanent incisors were erupted in 66, while 67 had permanent first molars present. As compared to their older siblings, the prevalence of dental fluorosis was significantly higher in the children who had consumed moderate-to high-fluoride water throughout their lives. In a multiple regression analysis, the variable "age when introduced to moderate- to high-fluoride water" came out as the only significant risk factor associated with dental fluorosis. This variable was divided into three categories according to the first exposure to moderate- to high-fluoride drinking water (1) 0-12 months of age, (2) 13-24 months of age and (3) after 24 months of age. Category 3 was used as the reference group. Fluoride exposure starting during the 1st year of life showed the highest odds ratio as compared to exposure only after 2 years of age. The findings indicate that early mineralizing teeth (central incisors and first molars) are highly susceptible to dental fluorosis if exposed to fluoride from the first and--to a lesser extent--also from the 2nd year of life.

[Ground water and health. Reflections based on analysis of water specimens from Hordaland and Vestfold]. / Grunnvann og helse. Refleksjoner på grunnlag av analyse av vannprøver fra Hordaland og vestfold.

Basically, Norway has an ample supply of water. The quality of Norwegian drinking water, however, is threatened, not the least because of pollution of surface water reservoirs. Ground water is better protected against pollution, and sub-surface water sources are being exploited more than before. At present, less than 15% of the Norwegian population uses ground water for household purposes, but the percentage is increasing rapidly Ground water is (normally) clean and has a good taste. A large number of elements can be traced in ground water; some of them in concentrations of significance for human health. The present paper reports elemental analyses of 150 water samples from ground water reservoirs in rock, collected in Vestfold (Eastern Norway) and Hordaland (Western Norway). Sixty-four elements were assessed using modern equipment such as ICP-MS. In most cases the chemical composition of the water was well within the limits set for good quality drinking water. For some of the elements one or more of the results exceeded the "highest acceptable concentrations" as defined by the Norwegian health authorities. This was the case for Al, As, Ba, Ca, Cd, F, Fe, Hg, K, Mg, Mn, Na, P, Pb, Rn and Zn. No drinking water standards have been established for Be, Mo, Th and U, which are of clear significance to the health. More research is needed to assess the relationship between drinking water chemistry and human health. The authors call for a systematic analysis of all Norwegian ground water wells, and emphasise the need for regular quality control, even of small, private water supplies.

Caries and dental fluorosis in a 0.25 and a 2.5 ppm fluoride area in the Sudan.

The purpose of this study was to assess the caries prevalence of children living in areas with either 0.25 or 2.5 ppm fluoride in the drinking water, and to relate caries experience to the severity of dental fluorosis. The children, aged 6-16 years (mean 11.3 years), were lifelong residents of their rural villages. The severity of dental fluorosis in the maxillary central incisors, assessed by Deans index, was 1.4 +/- 0.9 (n = 59) and 2.3 +/- 0.9 (n = 65) in the 0.25 and 2.5 ppm areas, respectively. There was no significant difference in DMFT between children from the two areas (2.6 +/- 2.3 n = 59 versus 2.1 +/- 2.3, n = 65). In the low-fluoride area 75% of the children had decayed permanent teeth compared to 66% in the high-fluoride area. In the primary teeth, however, both the caries prevalence and the dmft were significantly lower in the 2.5 ppm area than in the low-fluoride area. Stepwise, multiple, linear regression analyses, including all children, showed a significant effect of age on DMFT (30% of the variance explained), but no explanatory effect of fluoride in drinking water, severity of dental fluorosis, or gender. Regression analyses based on children in the 2.5 ppm area alone, showed significantly higher DMFT by increased severity of dental fluorosis. In children with a mixed dentition (n = 66), there was no association between caries in the primary and permanent teeth.

Variability in fluoride content of subsurface water reservoirs.

Groundwater may contain high concentrations of fluoride. In most countries, however, information on the fluoride content is scarce and anecdotal. The aim of the present study was to make a comprehensive assessment of F- in the groundwater of a representative area of Norway, thereby establishing a more solid basis for appropriate health counseling. Relevant technical information was collected, together with water samples from 1063 underground water sources in 31 municipalities in the county of Hordaland. One thousand and two water samples were analyzed for F- and pH with an F(-)-selective electrode and a pH electrode, respectively. Mean F- was 0.30 mg/l (range, < 0.02-9.48). Fourteen per cent of the wells contained water with F- levels > or = 0.50 mg/l. In three municipalities well water had a mean F- concentration > 0.07 mg/l; in one instance the mean was as high as 1.45 mg/l. In 10 municipalities maximum F- values were > 1.50 mg/l. F- values showed a positive correlation with the pH of the water and the depth of the wells (P < 0.01) and a negative correlation with the age of the well (P < 0.05). The results indicated that low-capacity wells deliver water with a higher F- value than high-capacity wells. This trend, however, was not statistically significant. The results show that high-F groundwater is prevalent and emphasize that information on domestic water supply must be available before supplementary fluoride is prescribed for caries prophylactic purpose.

Radon, fluoride and 62 elements as determined by ICP-MS in 145 Norwegian hard rock groundwater samples.

Hard rock groundwater (145) samples collected from private drinking water wells in the environs of Oslo and Bergen were analysed for their radon and fluoride contents. A further 62 elements were determined by inductively coupled plasma mass spectrometry (ICP-MS). For 59 elements, more than 50% of all concentration values were above the detection limit. Characteristic differences between the Oslo- and Bergen-dataset can be shown to be related to host rock lithology. Variation in element contents generally spans 2-6 orders of magnitude. Concentrations of several elements (e.g. Ba, F, Fe, Mn, Na, Rn) exceed current drinking water action levels in a significant number of cases. High levels of other parameters such as Be, Mo, Th and U, which could have an impact on health, were observed. There are no Norwegian action levels currently defined for these elements. The economic and toxicological impacts of these findings require urgent assessment.

Musculoskeletal symptoms among dentists in a dental school.

A cross-sectional study of symptoms from the musculoskeletal system among employees in a school of dentistry was performed. A questionnaire was answered by 139 dentists, dental auxiliaries and office workers, e.g. 68% of the employees. The answers from the dentists were compared to the answers from all the other employees. No significant differences in musculoskeletal symptoms between the dentists and the other employees were found. Female dentists reported more musculoskeletal symptoms than did male dentists. No difference was found comparing the occurrence of musculoskeletal symptoms among female dentists and females in the reference group. This indicates that the symptoms are not related to the work as a dentist, but to female working conditions in general or to factors outside work.

Prevalence of dental fluorosis in Sudanese children from two villages with 0.25 and 2.56 ppm fluoride in the drinking water.

Dental fluorosis is endemic in Eastern Africa and a high prevalence has been found even in low-fluoride (approximately 0.5 ppm) areas. Substantial seasonal changes in the fluoride content of water have also been reported. The aim of the present study was to ascertain, through one year, the fluoride concentration in water from two underground reservoirs in Sudan, in Treit el Biga (TeB) and Abu Groon (AG), and to assess dental fluorosis in children aged 7-16 years who had been lifelong residents. The water in one of the reservoirs (TeB) was shown to have a low, very stable fluoride concentration (0.25 ppm SD 0.04) whereas the other (AG) had a tenfold higher, and slightly varying, fluoride concentration (2.56 ppm SD 0.26). Dental fluorosis was recorded on maxillary central incisors according to Dean's index. In TeB 91% of the children showed signs of dental fluorosis whereas in AG all children had fluorotic teeth. The Community Fluorosis Index in TeB and AG was 1.40 and 2.44, respectively. There was a significantly higher degree of fluorosis in boys than in girls in the low-fluoride area. In TeB, older boys tended to have more fluorosis than younger boys; the difference, however, was not statistically significant. No significant sex or age differences in fluorosis were found in AG. In both villages great inter-individual variations in dental fluorosis were recorded. The prevalence and severity of dental fluorosis in TeB was higher than that previously reported in areas with similar fluoride concentrations in the drinking water.