Chemical quality of groundwaters and fluoride concentrations in the district of Dassa-Zoume, Southern Benin

Abstract

Like many African countries, the groundwaters of some regions in Benin have fluoride concentrations above the WHO guidelines (0.7 to 1.5 mg/L). The fluoride is useful against caries and hardens the enamel. At higher concentrations, it weakens the bones or causes crystallization points implying the appearance of arthritis deforming joint: it is fluorosis. Fluorosis is a public health problem due to its complication in bone fluorosis. It becomes an aesthetic problem and a daily concern for the patients. People discover spotted, brownish and disharmonious teeth when the patient smiles. We propose to carry out a study on a sample of the populations of the district of Dassa-Zoumè in order to evaluate the fluoride rate contained in groundwaters and the impacts on teeth. A transversal, descriptive and analytical study was conducted. It covered 1,002 pupils from 4 to 18 years of primary and secondary schools in Dassa-Zoume. The study was carried out in two phases: wells and well water extraction from Dassa-Zoume; a total of 24 boreholes were analyzed. Questionnaires directly about dental examination were administered and filled. The fluoride concentration ranged between 0.29 and 4.3 mg/L with a mean of 1.87 mg/L. The statistical analysis carried out for p <0.05 showed no correlation between the F and the four major elements (Ca2+, NO3-, NO2- and NH4+), but this correlation is positive with the evolution of pH between 6.44 and 7.08 for an average of 6.83. There was an overall prevalence of 12.2% with 95% CI: [10.2 to 14.3%], a CAD of 0.23 with 139 decayed teeth, 86 teeth absent and 01 tooth closed. The distribution of fluorosis at the sample level showed that 61.4% of the pupils had an evident fluorosis. The results of our survey showed the importance of treatment towards the Dassa-Zoume populations’ needs. Only preventive programs could reduce the number of oral diseases.