Table 1 Eligibility criteria

− Country and setting: Ethiopian rift valley

− The article did not contain original data or observations

− Study design: Cross-sectional

− Study subjects were not humans

− Measurement: The concentration of fluoride in ground water and prevalence of dental fluorosis

− Fluoride concentration was not measured or estimated

− Types of article: Peer-reviewed and published in English language

− Dental fluorosis was not reported using the three-severity level

− Publication year: up to December, 2018

− The mean and standard deviation of Fluoride concentration was not reported

− Undertook laboratory works: Reported type of laboratory tests and the respective result

− Being a review study

− Measurable outcomes: dental fluorosis (Dean’s index)

− Being none related to fluoride in ground water supplies and dental fluorosis