Sociodemographic and behavioural correlates of severe dental fluorosis

Association Between Dietary Fluoride and Calcium Intake of School-Age Children With Symptoms of Dental and Skeletal Fluorosis in Halaba, Southern Ethiopia

Background

In the Ethiopian Rift Valley, ways to reduce the fluoride (F) burden from drinking water have been unsuccessful. Calcium (Ca) intake may mitigate fluorosis by binding with F ions and preventing absorption. The purpose of this study was to examine the association between Ca intake and proportion of fluorosis symptoms in school-age children in an area where F levels are known to be higher than WHO limit of 1.5 mg F/L water.

Methods

A cross-sectional survey in the Halaba zone involved 135 eligible children aged 6–13 year who were recruited to have dental fluorosis assessed by a dentist and skeletal fluorosis assessed by a physiotherapist. Dietary Ca intake was determined by 24-h recall. Food items and samples from ground wells, taps and spring water were collected for F concentration. Associations were measured using bivariate logistic regression, adjusted for known confounders.

Results

Water F averaged 5.09 mg/L. Total F intake was high, 10.57 mg/day, and Ca intake was low, 520 mg/day. Prevalence of dental fluorosis (from very mild to severe symptoms) was 73.1% for younger children (6–8 years) and 68.3 % for older children (9–13 years). The prevalence of children having symptoms of skeletal fluorosis ranged between 55.1 and 72.4%, with no apparent age difference. Dietary F intake of children was significantly positively associated with presence of dental fluorosis. Dietary Ca intake of children was significantly negatively associated with dental fluorosis. Higher than average dietary F intake significantly increased the odds of developing skeletal fluorosis symptoms when measured as inability to stretch and fold arms to touch back of head. Higher than average Ca intake was significantly associated with decreased odds of developing skeletal fluorosis measured as inability to bend body to touch the toes or floor.

Conclusions

High dietary F, as expected, was associated with fluorosis in children. In the presence of higher Ca intake (>520 mg/day) some fluorosis symptoms were mitigated. There is a need to improve Ca intakes as all were below recommended levels, and this nutritional strategy may also reduce burden of excess F.

Association of Dietary Calcium Intake with Dental, Skeletal and Non-Skeletal Fluorosis among Women in the Ethiopian Rift Valley

Fluorosis is a major public health problem in the Rift Valley of Ethiopia. Low calcium (Ca) intake may worsen fluorosis symptoms. We assessed the occurrence of fluorosis symptoms among women living in high-fluoride (F) communities in South Ethiopia and their associations with dietary Ca intake. Women (n = 270) from two villages provided clinical and questionnaire data. Dental fluorosis examination was done using Dean’s Index, and skeletal and non-skeletal fluorosis assessment was carried out using physical tests and clinical symptoms. Daily Ca intake was estimated by a food frequency questionnaire. Food, drinking water and beverage samples were analyzed for F level. Many subjects (56.3%) exhibited dental fluorosis. One-third of the women were unable to perform the physical exercises indicative of skeletal fluorosis; about half had ≥2 symptoms of skeletal/non-skeletal fluorosis. The average F level in drinking water sources was ~5 mg/L. The F content in staple food samples varied from 0.8–13.6 mg/kg. Average Ca intake was 406 ± 97 mg/day. Women having ≤400 mg/day Ca intake had ~3 times greater odds of developing skeletal rigidity with joint pains [AOR = 2.8, 95%CI: 1.6, 5.0] and muscular weakness [AOR = 2.9, 95%CI: 1.3, 6.3] compared to those with higher intakes. No association of calcium intake was seen with dental fluorosis. As low dietary Ca intake was associated with symptoms related to skeletal and non-skeletal fluorosis, this warrants nutritional intervention on calcium intakes in this setting.

Hydrogeogenic fluoride in groundwater and dental fluorosis in Thai agrarian communities: a prevalence survey and case-control study

Background

Dental fluorosis can be a disease of social inequity in access to safe drinking water. This dental public health issue becomes prominent in socially disadvantaged agrarian communities in fluoride endemic areas where the standard irrigation system is unavailable and groundwater containing natural fluoride is the major drinking water source. This study aimed to determine the prevalence and severity of dental fluorosis in children and to evaluate its association with fluoride in groundwater in the aforementioned setting in Thailand.

Methods

A cross-sectional survey of 289 children in Nakhon Pathom Province was conducted in 2015. Children with very mild to severe fluorosis were regarded as ‘cases’ while their counterparts were ‘controls’ for a subsequent case–control study. Records of fluoride concentrations in groundwater used for household supply corresponding to resident and number of years by age of each child during 2008–2015 were retrieved. Other exposure variables were measured using a questionnaire. Prevalence ratio (PR), a measure indicating the relative effect of different levels of fluoride on dental fluorosis, was obtained from Poisson regression with robust standard error.

Result

There were 157 children with very mild to moderate dental fluorosis (54.3% prevalence). The univariable analysis revealed that the prevalence of dental fluorosis among children with fluoride concentrations in water sources of 0.7–1.49 (index category 1) and ≥ 1.5 ppm (index category 2) was 1.62 (95% CI; 0.78, 3.34) and 2.75 (95% CI; 1.42, 5.31) times the prevalence among those with fluoride < 0.7 ppm (referent category). After adjusting for all covariates, the adjusted prevalence ratios in both index categories were 1.64 (95% CI; 0.24, 11.24) and 2.85 (95% CI; 0.44, 18.52) which were close to their corresponding crude estimates. Since the magnitude of confounding, measured by (PR_crude–PR_adjusted)/PR_adjusted, were less than 10% for both index categories; this indicated the limited confounding effect of all covariates.

Conclusions

In fluoride endemic areas, groundwater containing natural fluoride utilized for household consumption resulted in high dental fluorosis prevalence, particularly in the groundwater with fluoride concentrations of ≥ 1.5 ppm.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01902-8.

Factors associated with dental fluorosis among Malaysian children exposed to different fluoride concentrations in the public water supply

OBJECTIVES

To determine the prevalence of dental fluorosis, and factors associated with its occurrence in two cohorts of children exposed to different fluoride concentrations in the Malaysian water supply.

METHODS

A cross-sectional study was conducted among lifelong residents (n = 1,155) aged 9 and 12 years old living in fluoridated and nonfluoridated areas. Malaysian children aged 12 years were born when the level of fluoride in the public water supply was 0.7 ppm while those aged 9 years were born after the level was reduced to 0.5 ppm. Fluorosis was blind scored using standardized photographs of maxillary central incisors using Dean's criteria. Fluoride exposures and other factors were assessed by parental questionnaire. Data were analyzed using descriptive statistics, Chi-squared analyses, and logistic regression.

RESULTS

Fluorosis prevalence was lower (31.9 percent) among the younger children born after the reduction of fluoride concentration in the water, compared to a prevalence of 38.4 percent in the older cohort. Early tooth brushing practices and fluoridated toothpaste were not statistically associated with fluorosis status. However, the prevalence of fluorosis was significantly associated with parents' education level, parents' income, fluoridated water, type of infant feeding method, age breast feeding ceased, use of formula milk, duration of formula milk intake, and type of water used to reconstitute formula milk via simple logistic regression. Fluoridated water remained a significant risk factor for fluorosis in multiple logistic regression.

CONCLUSIONS

Fluorosis was lower among children born after the adjustment of fluoride concentration in the water. Fluoridated water remained as a strong risk factor for fluorosis after downward adjustment of its fluoride concentration.

Prevalence of dental fluorosis in regions supplied with non-fluoridated water in the Brazilian territory: a systematic review and meta-analysis

This systematic review and meta-analysis aimed to estimate and compare the prevalences of dental fluorosis in Brazilian cities supplied with non-fluoridated water and in locations that uses groundwater. In December of 2016, cross-sectional studies were searched in eight databases, including the "grey literature". The prevalences were estimated through a mixed random effects model considering the locations as subgroups. The heterogeneity among the studies was assessed with I2 statistics and the Cochran's Q test. A total of 1038 records were found, from which only 18 articles met the inclusion criteria and were subjected to analysis. The meta-analytic model estimated a prevalence of dental fluorosis of 8.92 % (95 % CI: 5.41 % to 14.36 %) in cities supplied with non-fluoridated water, and of 51.96 % (95 % CI: 31.03 % to 72.22 %) in cities supplied by artesian wells. The heterogeneity among the studies was high: I2 = 95 % (p < 0.01) in the first subgroup of cities and I2 = 98 % (p < 0.01) in the second subgroup. The prevalence was significantly higher (p < 0.001) in populations exposed to artesian well water, indicating that the presence of natural fluoride at high concentrations represents a risk factor for the occurrence of dental fluorosis.

Oral diseases and socio-demographic factors in adolescents living in Maasai population areas of Tanzania: a cross-sectional study

Background

Oral diseases may cause serious health problems, especially in socially disadvantaged populations and in low-income countries. In populations living in the rural areas of Tanzania there is paucity of reports on oral health. The study aim was to estimate the prevalence, severity and socio-demographic distribution of oral diseases/conditions in adolescents living in Maasai population areas of Tanzania and to compare oral diseases/conditions between Maasai and non-Maasai ethnic groups.

Methods

A total of 23 schools were randomly selected from 66 rural public primary schools in Monduli and Longido districts, Tanzania. All pupils in the selected classes, 6th grade, were invited to participate in the study. A total of 989 were invited and 906 (91.6%) accepted the invitation and completed an interview and a clinical oral examination.

Results

Out of 906 study participants (age range 12–17 years), 721(79.6%) were from Maasai and 185 (20.4%) from non-Maasai ethnic groups. Prevalence of poor oral hygiene, gingival bleeding, dental caries experience (DMFT> 0), dental fluorosis TF grade 5–9, dental erosion (into dentin), tooth wear (into dentin) and TMD was 65.6, 40.9, 8.8, 48.6, 1.9, 16.5 and 11.8%, respectively. Multiple variable logistic regression analysis revealed that, girls (OR = 2.0) and participants from Longido (OR = 2.6) were more likely to present with good oral hygiene (p < 0.05). Adolescents from Monduli (OR = 1.7), males (OR = 2.1), being born within Arusha region (OR = 1.9) and Maasai (OR = 1.7) were more likely to present with gingival bleeding (p < 0.05). DMFT> 0 increased by age (OR = 2.0) and was associated with non-Maasai ethnic group (OR = 2.2), (p < 0.05). Adolescents from Monduli district (OR = 10.0) and those born in Arusha region (OR = 3.2) were more likely to present with dental fluorosis (p < 0.05). Dental erosion was more common among non-Maasais (OR = 2.0) as well as having mother with high education (OR = 2.3), (p < 0.05).

Conclusions

Oral diseases like dental caries and dental erosion were less common, but gingival bleeding, dental fluorosis, tooth wear and TMD were common findings in adolescents attending primary schools in the Maasai population areas of Tanzania. Notable differences between Maasai and non-Maasai ethnic groups and certain correlations to sociodemographic factors were detected. Our findings can be utilized by policy makers in the planning of oral health programs in public primary schools of Maasai population areas of Tanzania.

Biomarkers of chronic fluoride exposure in groundwater in a highly exposed population

This study examined the relation between fluoride (F-) concentrations in fingernail clippings and urine and the prevalence and severity of enamel fluorosis (EF) among Ethiopian Rift Valley populations exposed to high levels of F- in drinking water. The utility of fingernail clippings as a biomarker for F- exposure and EF was also assessed for the first time in a high-F- region. The study recorded the EF status of 386 individuals (10 to 50years old), who consume naturally contaminated groundwater with widely varying F- concentration (0.6-15mg/L). The mean F- concentrations among residents of communities with primary reliance on groundwater were 5.1mg/kg (range: 0.5-34mg/kg) in fingernails and 8.9mg/L (range: 0.44-34mg/L) in urine. We show strong positive correlations between F- in drinking water and 12-hour urinary excretion (r=0.74, p<0.001, n=287), fingernail F- content (r=0.6, p<0.001, n=258), and mean individual measures of EF severity as measured using the Thylstrup and Fejerskov (TF) Index (r=0.42, p<0.001, n=316). The data indicate that both fingernail and urine measures are good biomarkers for F- exposure and EF outcomes, the latter being slightly more sensitive. Cases of moderate/severe EF were significantly more common among younger subjects (10 to 15years old) than older subjects (mostly >25years old) (p<0.001), consistent with their greater exposure to F- during early childhood, which is the only period of life the enamel is at risk of fluorosis. In this younger population, EF may be useful as a biomarker for identifying individuals with other potential health effects that depend on a specific age window of susceptibility. The finding of exceptionally high F- concentrations in water, fingernail clippings and urine in this region should motivate further investigations of other potential health consequences such as bone disease and abnormalities in the function of the neurological and endocrine systems.

Prevalence and extent of enamel defects in the permanent teeth of 8-year-old Nigerian children

OBJECTIVES

Enamel formation is a vulnerable developmental process, susceptible to environmental influences such as excessive systemic fluoride (F) exposure and infant/childhood disease. This study determined prevalence and extent of developmental enamel defects (DDE) and dental fluorosis in 8-year-old Nigerians and explored associations with key predictors.

METHODS

A sample of 322 healthy 8-year-olds (155 males, 167 females) from primary schools in lower and higher water F areas of (i) rural and (ii) urban parts of Oyo State in south-west Nigeria (n = 4 areas) (in which the mean (SD) F concentration of community water supplies ranged from 0.07 (0.02) to 2.13 (0.64) mg F/L) were dentally examined using modified DDE (mDDE) and Thylstrup and Fejerskov (TF) indices. Drinking waters, cooking waters and toothpaste samples were analysed for F concentration using a F ion-selective electrode (F-ISE). Information on infant/childhood diseases, infant feeding and tooth cleaning practices was obtained from parents/legal guardians. Data were analysed using ANOVA, chi-square tests, Spearman correlation and binary logistic regression as appropriate.

RESULTS

Mean (SD) F concentration of actual drinking and actual cooking waters consumed by participants was 0.25 (0.20) and 0.24 (0.14) mg F/L respectively in the urban higher F area; 1.11 (1.00) and 1.16 (1.02) mg F/L, respectively in the rural higher F area (P < .05). Overall, mouth prevalence of DDE in the permanent dentition was 61.2% with a mean (SD) of 2.4 (2.2) index teeth affected. Dental fluorosis mouth prevalence was 29.8% with a mean of 2.1 (3.7) teeth affected. Prevalence and extent of DDE and dental fluorosis were greater in higher F than lower water F areas (P < .001). A weak positive correlation was seen between extent of dental fluorosis and drinking water F concentration (ρ = 0.28). The absence of infant/childhood disease was associated with a lower risk of DDE being present (P = .001), with an odds ratio of 0.43 (95% CI = 0.26, 0.71). Gender was a statistically significant (P = .014) predictor for dental fluorosis with females having a higher risk OR 1.94 (95% CI = 1.14, 3.28) of dental fluorosis than males.

CONCLUSIONS

In these Nigerian 8-year-olds (n = 322), mouth prevalence of DDE was 61.2% (mean (SD) teeth affected = 2.4 (2.2)), and a key positive predictor was a history of infant/childhood disease. With 29.8% of these children exhibiting dental fluorosis (mean (SD) teeth affected = 2.1(3.7)), drinking water F concentration was identified as a positive predictor, along with gender, with females more at risk of dental fluorosis than males.

Study of the relationship between the lifestyle of residents residing in fluorosis endemic areas and adult skeletal fluorosis

The relationship between fluorosis and the lifestyle of adult residents of areas in which fluorosis is endemic was evaluated. A cross-sectional and case-control analysis was performed to study 289 villagers living in fluorosis endemic areas who drank the local water. Subjects were divided into skeletal fluorosis and non-skeletal fluorosis groups according to whether they were afflicted with skeletal fluorosis. A semi-quantitative food frequency questionnaire, homemade lifestyle questionnaires, and general characteristics were analyzed. The factors that affected the occurrence of skeletal fluorosis were determined by generalized estimating equations. Our results showed that protective factors against skeletal fluorosis included drinking boiled water, storing water in a ceramic tank, and ingesting fruits, vitamin A, thiamine, and folic acid. Risk factors for skeletal fluorosis were overweight status and obesity, drinking tea, drinking water without storage, and ingestion of oils, fats, and phosphorus. Our results demonstrate that skeletal fluorosis has a close relationship with lifestyle.

Fluoride exposure from groundwater as reflected by urinary fluoride and children's dental fluorosis in the Main Ethiopian Rift Valley

This cross-sectional study explores the relationships between children's F(-) exposure from drinking groundwater and urinary F(-) concentrations, combined with dental fluorosis (DF) in the Main Ethiopian Rift (MER) Valley. We examined the DF prevalence and severity among 491 children (10 to 15 years old) who are life-long residents of 33 rural communities in which groundwater concentrations of F(-) cover a wide range. A subset of 156 children was selected for urinary F(-) measurements. Our results showed that the mean F(-) concentrations in groundwater were 8.5 ± 4.1 mg/L (range: 1.1-18 mg/L), while those in urine were 12.1±7.3 mg/L (range: 1.1-39.8 mg/L). The prevalence of mild, moderate, and severe DF in children's teeth was 17%, 29%, and 45%, respectively, and the majority (90%; n=140) of the children had urinary F(-) concentrations above 3 mg/L. Below this level most of the teeth showed mild forms of DF. The exposure-response relationship between F(-) and DF was positive and non-linear, with DF severity tending to level off above a F(-) threshold of ~6 mg/L, most likely due to the fact that at ~6 mg/L the enamel is damaged as much as it can be clinically observed in most children. We also observed differential prevalence (and severity) of DF and urinary concentration, across children exposed to similar F(-) concentrations in water, which highlights the importance of individual-specific factors in addition to the F(-) levels in drinking water. Finally, we investigated urinary F(-) in children from communities where defluoridation remediation was taking place. The lower F(-) concentration measured in urine of this population demonstrates the capacity of the urinary F(-) method as an effective monitoring and evaluation tool for assessing the outcome of successful F(-) mitigation strategy in relatively short time (months) in areas affected with severe fluorosis.

Dental fluorosis in populations from Chiang Mai, Thailand with different fluoride exposures - paper 1: assessing fluorosis risk, predictors of fluorosis and the potential role of food preparation

Background

To determine the severity of dental fluorosis in selected populations in Chiang Mai, Thailand with different exposures to fluoride and to explore possible risk indicators for dental fluorosis.

Methods

Subjects were male and female lifetime residents aged 8–13 years. For each child the fluoride content of drinking and cooking water samples were assessed. Digital images were taken of the maxillary central incisors for later blind scoring for TF index (10% repeat scores). Interview data explored previous cooking and drinking water use, exposure to fluoride, infant feeding patterns and oral hygiene practices.

Results

Data from 560 subjects were available for analysis (298 M, 262 F). A weighted kappa of 0.80 was obtained for repeat photographic scores. The prevalence of fluorosis (TF 3+) for subjects consuming drinking and cooking water with a fluoride concentration of <0.9 ppm was 10.2%. For subjects consuming drinking and cooking water >0.9 ppm F the prevalence of fluorosis (TF 3+) rose to 37.3%. Drinking and cooking water at age 3, water used for infant formula and water used for preparing infant food all demonstrated an increase in fluorosis severity with increase in water fluoride level (p < 0.001). The probability estimate for the presentation of aesthetically significant fluorosis was 0.53 for exposure to high fluoride drinking (≥0.9 ppm) and cooking water (≥1.6 ppm).

Conclusions

The consumption of drinking water with fluoride content >0.9 ppm and use of cooking water with fluoride content >1.6 ppm were associated with an increased risk of aesthetically significant dental fluorosis. Fluoride levels in the current drinking and cooking water sources were strongly correlated with fluorosis severity. Further work is needed to explore fluorosis risk in relation to total fluoride intake from all sources including food preparation.

Factors associated to endemic dental fluorosis in Brazilian rural communities

The present paper examines the relationship between hydrochemical characteristics and endemic dental fluorosis, controlling for variables with information on an individual level. An epidemiological survey was carried out in seven rural communities in two municipalities in the state of Minas Gerais, Brazil. The Thystrup & Fejerskov index was employed by a single examiner for the diagnosis of dental fluorosis. A sampling campaign of deep groundwater in the rural communities of interest was carried out concomitantly to the epidemiological survey for the determination of physiochemical parameters. Multilevel modeling of 276 individuals from seven rural communities was achieved using the non-linear logit link function. Parameters were estimated using the restricted maximum likelihood method. Analysis was carried out considering two response variables: presence (TF 1 to 9) or absence (TF = 0) of any degree of dental fluorosis; and presence (TF ≥ 5—with loss of enamel structure) or absence of severe dental fluorosis (TF ≤ 4—with no loss of enamel structure). Hydrogeological analyses revealed that dental fluorosis is influenced by the concentration of fluoride (OR = 2.59 CI95% 1.07–6.27; p = 0.073) and bicarbonate (OR = 1.02 CI95% 1.01–1.03; p = 0.060) in the water of deep wells. No other variable was associated with this prevalence (p > 0.05). More severe dental fluorosis (TF ≥ 5) was only associated with age group (p < 0.05). No other variable was associated to the severe dental fluorosis (p > 0.05). Dental fluorosis was found to be highly prevalent and severe. A chemical element besides fluoride was found to be associated (p > 0.05) to the prevalence of dental fluorosis, although this last finding should be interpreted with caution due to its p value.

Caries and dental fluorosis in a western Saharan population of refugee children

The aim of this study was to investigate the relationship between dental fluorosis and dental caries among western Saharan refugee children. The western Saharan child population is characterized by adverse living conditions, an unbalanced diet, poor oral hygiene habits, and a concentration of fluoride in the drinking water of around 2 p.p.m. (2 mg l(-1)). A sample consisting of 360 children, 6-7 yr of age, and 212 children, 11-13 yr of age, was obtained from four refugee camps (Smara, Awsard, El-Aaiun, and 27-February) situated in the vicinity of Tindouf (southern Algeria). The children were examined using the World Health Organization criteria for caries diagnosis and Dean's index for fluorosis. The decayed, missing or filled teeth (DMFT) score was 0.48 in the 6-7-yr-old children and 1.69 in the 11-13-yr-old children, with a caries prevalence (DMFT > 0 or decayed and filled primary teeth (dft) > 0) of 47.2% and 63.2%, respectively. Among the 6-7 yr-old children examined, 36.9% were free of fluorosis, 15.6% presented moderate fluorosis, and 7.8% presented severe fluorosis. Among 11-13 yr-old children, only 4.2% were free of fluorosis, 30.2% exhibited moderate fluorosis, and 27.4% presented severe fluorosis. The mean DMFT, decayed permanent teeth (DT), and caries prevalence (DMFT > 0 and DMFT or dft > 0) scores were significantly higher among the children affected by severe fluorosis, suggesting that severe fluorosis might increase the susceptibility to dental caries.

Perception of dental fluorosis and other oral health disorders by 12-year-old Brazilian children

AIM

The aim of this study was to verify the perception of dental fluorosis as an oral health problem by 12-year-old Brazilian children and to evaluate if they were able to detect other oral disorders.

METHODOLOGY

The sample consisted of 401 schoolchildren. Firstly, clinical examinations were performed using a visual method under natural light. After that, children answered a questionnaire with the purpose of assessing the self-perception of their oral health problems. Next, the volunteers were shown a photo album containing 24 photographs, and had to match each photo with a severity scale.

RESULTS

The prevalence of fluorosis was 18.2%; 81.8% of this total in fluorosis scale T-F 1. Of the 401 children, 48.9% (n = 196) answered oral health problems related to concerns, such as aesthetic appearance or pain. Among them, only two children, both with fluorosis T-F 2, correlated their problems with the presence of stained teeth. As regards the photo album analysis, the children considered photos showing fluorosis T-F 7-9 as the most severe, whereas the photo of an orally healthy patient was considered the least severe.

CONCLUSION

Children did not show negative perception of dental fluorosis, except for dental fluorosis at severe levels (T-F 7-9), and were mainly able to detect aesthetic or pain-related problems.