Pendrys 1989.

Methods	Case‐control study in non‐fluoridated areas in Massachusetts and Connecticut, US.
Participants	1242 fluorosis examinations, undertaken in schools, of 11 to 14 year olds (born between 1972 and 1975). 850 cases and controls selected. 680 (80%) questionnaires on exposure returned.
Interventions	Exposure: fluoride supplements (drops or tablets) during each of the first 6 years of life; fluoride toothpaste use during each of the first 6 years of life.
Outcomes	FRI.
Notes	Intra‐ and inter‐examiner reliability of fluorosis examinations checked (Kappa ranging from 0.76 to 1.0).