Prevalence of dental fluorosis in children from non-water-fluoridated Halmstad, Sweden: fluoride toothpaste use in infancy

Topical fluoride as a cause of dental fluorosis in children

BACKGROUND

This is an update of a review first published in 2010. Use of topical fluoride has become more common over time. Excessive fluoride consumption from topical fluorides in young children could potentially lead to dental fluorosis in permanent teeth.

OBJECTIVES

To describe the relationship between the use of topical fluorides in young children and the risk of developing dental fluorosis in permanent teeth.

SEARCH METHODS

We carried out electronic searches of the Cochrane Oral Health Trials Register, CENTRAL, MEDLINE, Embase, three other databases, and two trials registers. We searched the reference lists of relevant articles. The latest search date was 28 July 2022.

SELECTION CRITERIA

We included randomized controlled trials (RCTs), quasi-RCTs, cohort studies, case-control studies, and cross-sectional surveys comparing fluoride toothpaste, mouth rinses, gels, foams, paint-on solutions, and varnishes to a different fluoride therapy, placebo, or no intervention. Upon the introduction of topical fluorides, the target population was children under six years of age.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane and used GRADE to assess the certainty of the evidence. The primary outcome measure was the percentage prevalence of fluorosis in the permanent teeth. Two authors extracted data from all included studies. In cases where both adjusted and unadjusted risk ratios or odds ratios were reported, we used the adjusted value in the meta-analysis.

MAIN RESULTS

We included 43 studies: three RCTs, four cohort studies, 10 case-control studies, and 26 cross-sectional surveys. We judged all three RCTs, one cohort study, one case-control study, and six cross-sectional studies to have some concerns for risk of bias. We judged all other observational studies to be at high risk of bias. We grouped the studies into five comparisons. Comparison 1. Age at which children started toothbrushing with fluoride toothpaste Two cohort studies (260 children) provided very uncertain evidence regarding the association between children starting to use fluoride toothpaste for brushing at or before 12 months versus after 12 months and the development of fluorosis (risk ratio (RR) 0.98, 95% confidence interval (CI) 0.81 to 1.18; very low-certainty evidence). Similarly, evidence from one cohort study (3939 children) and two cross-sectional studies (1484 children) provided very uncertain evidence regarding the association between children starting to use fluoride toothpaste for brushing before or after the age of 24 months (RR 0.83, 95% CI 0.61 to 1.13; very low-certainty evidence) or before or after four years (odds ratio (OR) 1.60, 95% CI 0.77 to 3.35; very low-certainty evidence), respectively. Comparison 2. Frequency of toothbrushing with fluoride toothpaste Two case-control studies (258 children) provided very uncertain evidence regarding the association between children brushing less than twice per day versus twice or more per day and the development of fluorosis (OR 1.63, 95% CI 0.81 to 3.28; very low-certainty evidence). Two cross-sectional surveys (1693 children) demonstrated that brushing less than once per day versus once or more per day may be associated with a decrease in the development of fluorosis in children (OR 0.62, 95% CI 0.53 to 0.74; low-certainty evidence). Comparison 3. Amount of fluoride toothpaste used for toothbrushing Two case-control studies (258 children) provided very uncertain evidence regarding the association between children using less than half a brush of toothpaste, versus half or more of the brush, and the development of fluorosis (OR 0.77, 95% CI 0.41 to 1.46; very low-certainty evidence). The evidence from cross-sectional surveys was also very uncertain (OR 0.92, 95% CI 0.66 to 1.28; 3 studies, 2037 children; very low-certainty evidence). Comparison 4. Fluoride concentration in toothpaste There was evidence from two RCTs (1968 children) that lower fluoride concentration in the toothpaste used by children under six years of age likely reduces the risk of developing fluorosis: 550 parts per million (ppm) fluoride versus 1000 ppm (RR 0.75, 95% CI 0.57 to 0.99; moderate-certainty evidence); 440 ppm fluoride versus 1450 ppm (RR 0.72, 95% CI 0.58 to 0.89; moderate-certainty evidence). The age at which the toothbrushing commenced was 24 months and 12 months, respectively. Two case-control studies (258 children) provided very uncertain evidence regarding the association between fluoride concentrations under 1000 ppm, versus concentrations of 1000 ppm or above, and the development of fluorosis (OR 0.89, 95% CI 0.52 to 1.52; very low-certainty evidence). Comparison 5. Age at which topical fluoride varnish was applied There was evidence from one RCT (123 children) that there may be little to no difference between a fluoride varnish application before four years, versus no application, and the development of fluorosis (RR 0.77, 95% CI 0.45 to 1.31; low-certainty evidence). There was low-certainty evidence from two cross-sectional surveys (982 children) that the application of topical fluoride varnish before four years of age may be associated with the development of fluorosis in children (OR 2.18, 95% CI 1.46 to 3.25).

AUTHORS' CONCLUSIONS

Most evidence identified mild fluorosis as a potential adverse outcome of using topical fluoride at an early age. There is low- to very low-certainty and inconclusive evidence on the risk of having fluorosis in permanent teeth for: when a child starts receiving topical fluoride varnish application; toothbrushing with fluoride toothpaste; the amount of toothpaste used by the child; and the frequency of toothbrushing. Moderate-certainty evidence from RCTs showed that children who brushed with 1000 ppm or more fluoride toothpaste from one to two years of age until five to six years of age probably had an increased chance of developing dental fluorosis in permanent teeth. It is unethical to propose new RCTs to assess the development of dental fluorosis. However, future RCTs focusing on dental caries prevention could record children's exposure to topical fluoride sources in early life and evaluate the dental fluorosis in their permanent teeth as a long-term outcome. In the absence of these studies and methods, further research in this area will come from observational studies. Attention needs to be given to the choice of study design, bearing in mind that prospective controlled studies will be less susceptible to bias than retrospective and uncontrolled studies.

‘Hidden Hot Springs’ as a Source of Groundwater Fluoride and Severe Dental Fluorosis in Malawi

Hidden hot springs likely impact rural water supplies in Malawi’s Rift Valley with excess dissolved fluoride leading to localised endemic severe dental fluorosis. Predicting their occurrence is a challenge; Malawi’s groundwater data archive is sporadic and incomplete which prevents the application of standard modelling techniques. A creative alternative method to predict hidden hot spring locations was developed using a synthesis of proxy indicators (geological, geochemical, dental) and is shown to be at least 75% effective. An exciting collaboration between geoscientists and dentists allowed corroboration of severe dental fluorosis with hydrogeological vulnerability. Thirteen hidden hot springs were identified based on synthesised proxy indicators. A vulnerability prediction map for the region was developed and is the first of its kind in Malawi. It allows improved groundwater fluoride prediction in Malawi’s rift basin which hosts the majority of hot springs. Moreover, it allows dentists to recognise geological control over community oral health. Collaborative efforts have proven mutually beneficial, allowing both disciplines to conduct targeted research to improve community wellbeing and health and inform policy development in their respective areas. This work contributes globally in developing nations where incomplete groundwater data and vulnerability to groundwater contamination from hydrothermal fluoride exist in tandem.

The association between the prevalence of dental fluorosis and the socio-economic status and area of residence of 12-year-old students in Uruguay

Objective: This study investigates the association between the prevalence and severity of dental fluorosis, the socio-economic status (SES) and area of residence among 12-year-old schoolchildren in Uruguay.Material and methods: The study was descriptive, cross-sectional, explanatory and observational. Subjects considered eligible were born in 1999 and had their parents' or guardian's prior consent. A questionnaire was used to identify SES according to Centro de Investigaciones Económicas Institute on four levels. Dental fluorosis was determined using the Thylstrup-Fejerskov (TF) index.Results: Of the 1544 students examined, 45.0% showed dental fluorosis. A TF index 1-2 was recorded in 29.3% of the subjects, TF 3 in 20.9%, TF 4 in 6.7% and TF 5-9 in 2.1%. In area 1 (the capital Montevideo city), 84.8% of the subjects had dental fluorosis, a value that was significantly higher than in the inland region (area 2, 24.4%) and border departments (area 3, 22.5%) (x² = 27.92, p < .0001). Students from families with a low socio-economic level showed less prevalence of dental fluorosis than those with a high level (x² = 14.58, p = .002).Conclusion: Significant differences exist in the prevalence of dental fluorosis in relation to place of residence and socio-economic level.

Current Guidance for Fluoride Intake: Is It Appropriate?

The purpose of this report is to examine critically the appropriateness of the current guidance for fluoride intake in the population (0.05-0.07 mg F/kg bodyweight/d), consider whether changes to the current guidance are desirable, and suggest further research that will strengthen the evidence base for future decisions on guidance/advice in this area. The benefits and the risks of using fluoride particularly concern preschool children because it is at this age that excessive fluoride intake may result in dental fluorosis. Data from mostly cross-sectional studies show a wide variation in exposure and a considerable variation in the amount of fluoride ingested. Fluorosis, mostly mild, is commonly observed. For considering changes in current guidance, there is a need for more knowledge on the relationship between exposure to fluoride at an early age and the development of fluorosis. For that, prospective epidemiological studies with sufficiently large and representative samples of children are required. It is also important to study children in communities both with and without water fluoridation and to include populations where salt or milk fluoridation is used. There is also a need for professional agreement on acceptable levels of mild and moderate/severe fluorosis and a more comprehensive knowledge on the appreciation of mild fluorosis among the public.

Evaluating oral health promotion activity within a general dental practice

The prevention of the common dental diseases is fundamental to modern day general dental practice. Oral health promotion (OHP) is therefore key to facilitating health outcomes within organisations. The literature surrounding OHP stresses the importance of evaluation in order to assess the effectiveness of OHP activities. This paper describes the evaluation of OHP within a general dental practice setting. Early attendance, the use of adult toothpastes during childhood and consequential fluorosis are investigated. A small service evaluation study of 100 consecutive patients was undertaken. The results support the ongoing promotion of early attendance and the use of toothpastes with adequate fluoride levels. There was no evidence of unsightly fluorosis in the sample studied.

Estimation of toothpaste fluoride intake in preschool children

The objective of this study was to estimate the intake of toothpaste fluoride used by children aged 2 to 6 years (n=87) treated at a hospital of a medium-sized city (Campina Grande, PB) in the Northeastern region of Brazil. Data regarding sociodemographic characteristics of families and children's toothbrushing were collected from questionnaire-based interviews with parents/guardians, and the amount of fluoride used during toothbrushing was estimated using a precision scale for assessment of the risk of dental fluorosis, considering a cutoff value of 0.07 mgF/kg body weight/day. Fluoride content in the toothpastes was analyzed using a specific fluoride electrode. Data were analyzed using descriptive and inferential statistics using the chi-square and Fisher's exact tests (α=0.05). Considering the use of the derice, the risk of fluorosis in the children was 19.5%. There was significant association (p<0.05) between the risk of fluorosis, brushing frequency, type of derice and who performed the child's oral hygiene. It was concluded that a high percentage of children in the studied sample used toothpaste inappropriately and were at risk of developing dental fluorosis.

Prevalence of dental fluorosis in children taking part in an oral health programme including fluoride tablet supplements from the age of 2 years

AIM

To investigate the prevalence of dental fluorosis in children who had participated in an oral health programme between the ages 2-5 years, including fluoride tablets from the age of 2 years.

DESIGN

The study group consisted of 135 10- to 11-year-old children who had participated in the programme, including parent education, tooth-brushing instruction and prescribed fluoride tablets (0.25 mg NaF) (2-3 years: 1 tablet/day; 3-5 years: 2 tablets/day). The prevalence of dental fluorosis in the study group was compared with that in a nonintervention reference group consisting of 129 children of the same ages. The analysis was based on photos of the permanent maxillary front teeth using the Thylstrup & Fejerskov (TF) Index.

RESULTS

No statistically significant difference in prevalence of dental fluorosis was seen between the two groups. Forty-three percent of the children in the study group and 38% in the reference group had fluorosis, the majority of a mild nature (TF-score 1). None had a TF score above 2. The pattern was the same after correction for parent reported intake of tablets at 3 and 5 years of age.

CONCLUSION

Introduction of fluoride tablets at the age of 2 years did not result in increased prevalence of dental fluorosis.

Topical fluoride as a cause of dental fluorosis in children

BACKGROUND

For many years, topical use of fluorides has gained greater popularity than systemic use of fluorides. A possible adverse effect associated with the use of topical fluoride is the development of dental fluorosis due to the ingestion of excessive fluoride by young children with developing teeth.

OBJECTIVES

To describe the relationship between the use of topical fluorides in young children and the risk of developing dental fluorosis.

SEARCH STRATEGY

Electronic search of the Cochrane Oral Health Group Trials Register, CENTRAL, MEDLINE, EMBASE, BIOSIS, Dissertation Abstracts and LILACS/BBO. Reference lists from relevant articles were searched. Date of the most recent searches: 9th March 09.

SELECTION CRITERIA

Randomised controlled trials (RCTs), quasi-RCTs, cohort studies, case-control studies and cross-sectional surveys, in which fluoride toothpastes, mouthrinses, gels, foams, paint-on solutions, and varnishes were compared to an alternative fluoride treatment, placebo or no intervention group. Children under the age of 6 years at the time topical fluorides were used.

DATA COLLECTION AND ANALYSIS

Data from all included studies were extracted by two review authors. Risk ratios for controlled, prospective studies and odds ratios for case-control studies or cross-sectional surveys were extracted or calculated. Where both adjusted and unadjusted risk ratios or odds ratios were presented, the adjusted value was included in the meta-analysis.

MAIN RESULTS

25 studies were included: 2 RCTs, 1 cohort study, 6 case-control studies and 16 cross-sectional surveys. Only one RCT was judged to be at low risk of bias. The other RCT and all observational studies were judged to be at moderate to high risk of bias. Studies were included in four intervention/exposure comparisons. A statistically significant reduction in fluorosis was found if brushing of a child's teeth with fluoride toothpaste commenced after the age of 12 months odds ratio 0.70 (random-effects: 95% confidence interval 0.57 to 0.88) (data from observational studies). Inconsistent statistically significant associations were found between starting using fluoride toothpaste/toothbrushing before or after the age of 24 months and fluorosis (data from observational studies). From the RCTs, use of higher level of fluoride was associated with an increased risk of fluorosis. No significant association between the frequency of toothbrushing or the amount of fluoride toothpaste used and fluorosis was found.

AUTHORS' CONCLUSIONS

There should be a balanced consideration between the benefits of topical fluorides in caries prevention and the risk of the development of fluorosis. Most of the available evidence focuses on mild fluorosis. There is weak unreliable evidence that starting the use of fluoride toothpaste in children under 12 months of age may be associated with an increased risk of fluorosis. The evidence for its use between the age of 12 and 24 months is equivocal. If the risk of fluorosis is of concern, the fluoride level of toothpaste for young children (under 6 years of age) is recommended to be lower than 1000 parts per million (ppm).More evidence with low risk of bias is needed. Future trials assessing the effectiveness of different types of topical fluorides (including toothpastes, gels, varnishes and mouthrinses) or different concentrations or both should ensure that they include an adequate follow-up period in order to collect data on potential fluorosis. As it is unethical to propose RCTs to assess fluorosis itself, it is acknowledged that further observational studies will be undertaken in this area. However, attention needs to be given to the choice of study design, bearing in mind that prospective, controlled studies will be less susceptible to bias than retrospective and/or uncontrolled studies.

Photographic assessment of fluorosis in children from naturally fluoridated Kungsbacka and non-fluoridated Halmstad, Sweden

OBJECTIVES

To assess levels of fluorosis and fluorosis of esthetic concern in children from a naturally fluoridated and a non-fluoridated area of Sweden, and to determine the relative contributions of fluoridated water, parental educational level, and infant oral health-related behaviors.

METHODS

A parental questionnaire collected information concerning child F-supplement and F-dentifrice usage histories, and socio-economic status. Photographic examination of 1336 subjects (F=791; N-F=545) was undertaken. Fluorosis was assessed (blind to F-exposure) in a random sample (n=250) of 35 mm slides by four dental and two lay "jurors" (with 10% random repeat-viewing for inter-observer and intra-observer agreement). Four outcomes were assessed on each slide: fluorosis at any level, fluorosis of esthetic concern, acceptability of appearance, and treatment needs. Ordinal logistic regression models were used to determine significant determinants.

RESULTS

For presence of fluorosis of esthetic concern, majority jury agreements (>3 of 6) were seen in only 2.3% (N-F) and 13.4% (F) pupils (p<0.001), albeit jurors unanimously scored only 13 F and 2 N-F exposed children as having esthetically unacceptable fluorosed teeth (p<0.001). The over-riding significant factor in terms of fluorosis of esthetic concern was exposure to water fluoridation in infancy in both unadjusted and adjusted models.

CONCLUSIONS

The important factor in relation to fluorosis of esthetic concern was explained by exposure to fluoridated water in infancy, and was not explained by age, sex, level of parental education or early childhood oral health behaviors. However, prevalence of this condition was relatively low. These findings should inform policies on appropriate total fluoride exposure levels during infancy.

Dental fluorosis in cohorts born before, during, and after the national salt fluoridation program in a community in Mexico

OBJECTIVE

To determine the prevalence and severity of dental fluorosis, as well as factors associated with its occurrence, in seven cohorts of children before and after the implementation of a fluoridated salt program in 1991.

MATERIAL AND METHODS

A cross-sectional study was carried out in 1,373 children aged from 6 to 12 years in Campeche, Mexico. Data were collected by means of a questionnaire administered to mothers and a dental examination of the children. Modified Dean's criteria were used to diagnose dental fluorosis. A multivariate logistic regression model was used to evaluate the relationship between dental fluorosis and independent variables.

RESULTS

The prevalence of dental fluorosis was 51.9%. The most common degree of dental fluorosis was very mild, with 84.7%, followed by mild, moderate, and severe with 13.1%, 1.7%, and 0.6%, respectively. The multivariate model adjusted by number of additional sources of fluoride, age at the beginning of use of toothpaste, and level of schooling of the mother, showed that children born in 1990 (OR = 1.74; CI 95% = 1.36-2.22), 1991 (OR = 4.03; CI 95% = 2.58-6.28), and 1992 (OR = 10.41; CI 95% = 5.77-18.78) were more likely to have dental fluorosis than those born in the period 1986-1989. The frequency of toothbrushing (OR = 1.63; CI 95% = 1.37-1.95) was also associated with dental fluorosis.

CONCLUSIONS

A close relationship was found between exposure to toothpaste and dental fluorosis. Implementation of the fluoridated salt program greatly increased the risk of fluorosis.