Violation
A study has been conducted comparing rates of dental caries in 25 cities with differing levels of fluoride in the water supply. This study is a/an
ecological study.
case series.
community trial.
cross-sectional study.
A study has been conducted comparing rates of dental caries in 25 cities with differing levels of fluoride in the water supply. This study is a/an
ecological study.
case series.
community trial.
cross-sectional study.