Investigating the Role of Genetic Predisposition and High-Fluoride Water Exposure in Dental Fluorosis among Individuals Born and Raised in Naivasha, Kenya.

Abstract Background: High fluoride is popular for causing dental fluorosis worldwide. However, studies on combined effects of genetic predisposition with lifelong fluoride exposure on the severity of dental fluorosis have not been carried out at individual levels. This study aims to investigate the role of environmental factors combined with genetic factors at individual level on severity of dental fluorosis. Objectives: To investigate the role of genetic predisposition and high-fluoride water exposure on the severity of dental fluorosis. This will be carried out by determining the prevalence of dental fluorosis, identifying specific genetic markers, quantifying lifelong fluoride exposure using non-invasive biomarkers, and determining the association between these factors and severity of fluorosis. Methodology: This is a cross-section analytical study conducted in Naivasha sub-county of Nakuru, Kenya. The study population consists of children aged 6-18 year who were born and raised in the region. The calculated sample size is 384, however, the high cost of genetic and biomarkers analyses directs the study to focus on a more feasible and effective sample of 150 participants which is sufficient to achieve the chief objective of the study. Data Collection: Data will be collected through structural questionnaire tailored to achievement of the objectives of this study, clinical assessment where dental fluorosis will be examined by using Dean’s Fluorosis Index, water sampling for analysis of fluoride concentration and therefore, environmental exposure, biological samples (hair and nail for measuring cumulative, long-term fluoride exposure at individual level, urine for measuring recent, short-term fluoride exposure, saliva for genetic analysis to identify single nucleotide polymorphisms (SNPs) associated with individual fluoride metabolism and susceptibility to fluorosis. Data Analysis: The collected data will be analyzed using statistical tools (SPSS, R or excel). This analysis includes a descriptive statistic to determine the prevalence of dental fluorosis within the study population, and inferential statistics through multiple regression analysis to determine the association between the genetic markers, cumulative fluoride exposure (hair/nails), and the severity of dental fluorosis while controlling for confounding variables. Keywords: Dental Fluorosis, Genetic Predisposition, Dean's Fluorosis Index, single nucleotide polymorphisms (SNPs), Fluoride Exposure