Fluoride Action Network


Introduction: Dental fluorosis is endemic in the Rift Valley in Africa, especially around volcanic areas, due to the high fluoride content in daily drinking water.

Objective: This study evaluates the oral health status and types of occlusion in a school population, and to assess the possible association between dental fluorosis and other pathologies such as decay, gingivitis and periodontitis.

Material and methods: An observational study of 581 individuals recruited from a public secondary school in Arusha, Northern Tanzania was undertaken. The indices used were: the Silness & Löe Plaque Index, the Community Periodontal Index and the Decayed/Missing/Filled index. Descriptive statistical analyses were performed and a chi-square test was used to assess the associations between independent variables.

Results: Almost all the school children evaluated (96.73%) presented Angle class I dental occlusion, and 75.22% presented some degree of dental fluorosis. Most of the population (511, 87.95%) showed bleeding on probing. A moderate/high degree of some dental pathology (DMF score) was recorded in 14.46%. The association between dental fluorosis, gingival bleeding and tooth decay indicated a higher concentration of pathology in groups with more severe fluorosis (p<0.05).

Conclusion: In this large population sample, both tooth decay and gingivitis were significantly associated with moderate or severe dental fluorosis.



Dental fluorosis is endemic to the Rift Valley in Africa, especially in volcanic areas, and it has been attributed to the high fluoride content in daily drinking water. In some parts of Tanzania, and particularly in the Arusha region (close to a dormant strato volcano named Mount Meru), dental fluorosis is considered a health problem14. Although the World Health Organization (WHO) guidelines for drinking water quality recommend that fluoride concentration in the water supply should be between 0.5 and 1 mg/l,5 the fluoride content of the drinking water in Arusha is approximately 3.6mg/l.3

The Kaloleni Secondary School is a publicly-funded center located in a low-income neighborhood in the city of Arusha, where students and their families have access only to the public water supply. For these reasons, the school is an ideal setting for the study of dental fluorosis in Northern Tanzania.

Dental caries remains the world’s most prevalent disease, affecting billions of people, especially children.610 Although the number of decayed, missing and filled teeth has fallen in many countries over the last three decades, a growing number of studies have observed increases in these rates in a small section of the population, above all among lower socioeconomic groups.1014 Numerous studies have attempted to correlate caries with dental fluorosis and have reported changes in the risk of decay depending on the degree of severity of the condition.1523

Fewer studies have explored the association between dental fluorosis with periodontitis. The role of some of the etiological factors of periodontal disease such as age, gender, ethnicity, socio-economic status, lifestyle, smoking and oral hygiene has been studied in some populations in India24,25 but the effect of fluoride on periodontal tissue remains controversial, even though its association with tooth decay is well established.26 The epidemiological data regarding the periodontal status of individuals living in areas with highly fluoridated water are inconsistent. As regards malocclusion, few recent investigations have analyzed and classified dental occlusion in school populations in northern Tanzania.2729

The objectives of the study were, on the one hand, to evaluate the oral health status and types of occlusion in this population, and to assess the possible association between dental fluorosis and other pathologies such as decay, gingivitis and periodontitis…


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**Full text study online at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7750069/