Adair 1999.

Methods	FLUOROSIS STUDY Country of study: USA Geographic location: Warren County, Georgia Year of study: not stated Year of change in fluoridation status: not stated Study design: cross‐sectional
Participants	Inclusion criteria: children attending sole elementary and middle schools in study area Exclusion criteria: children whose homes were served with well‐water. Other sources of fluoride: parents completed questionnaire regarding dentifrice use, home water source and current use of systemic fluoride supplements; all subjects received school water fluoridated at 0.5 ppm Other sources of fluoride: not stated Social class: not stated Ethnicity: not stated Residential history: not considered Other confounding factors: not stated
Interventions	Group 1: 0.5‐1.2 ppm (both natural and artifical fluoridation) Group 2: < 0.1 ppm (natural fluoridation)
Outcomes	Dental fluorosis (Dean's Index); caries data collected but not presented in this review due to study design Age at assessment: 8‐10 and 11‐13 years
Funding	NIDR Grant DE‐06113
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Sampling	Unclear risk	Participants were children attending the sole elementary and middle/high schools in Warren county. There was insufficient detail reported to determine how selection took place
Confounding	High risk	SES was not accounted for
Blinding of outcome assessment (detection bias) All outcomes	High risk	Insufficient information
Incomplete outcome data (attrition bias) All outcomes	Low risk	Data for over 80% of participants were reported
Selective reporting (reporting bias)	High risk	Outcome of interest reported. However, data were not presented clearly enough to be considered reliable
Other bias	High risk	Exposure to fluoride water could not be controlled for. Some children had fluoride water at school across groups. Some had non‐fluoridated well‐water at home