A comparison of dental fluorosis in adult populations with and without lifetime exposure to water fluoridation

Objectives: There is a lack of evidence on the proportion and severity of fluorosis in adult populations exposed and not exposed to fluoridated water over their lifetimes. The aim of this study was to compare the proportion and severity of fluorosis in adults with lifetime exposure to water fluoridation with a non-exposed sample. A secondary aim was to report the gradient of fluorosis severity by age. Methods: A cross-sectional study recruited a sample with lifetime exposure to water fluoridation and a matched, non-exposed group. 580 participants, aged 18 to 52 years (mean 34.3, SD 9.4) and 64% female, were recruited in general dental practices located in fluoridated (Birmingham and County Durham) and non-fluoridated areas (Manchester). Three digital images were taken of their incisors and an experienced examiner who was blind to exposure status viewed the images remotely and allocated fluorosis scores using the Thylstrup and Fejerskov (TF) scale. Results: At TF ≥ 1 (any fluorosis), a significantly higher proportion of participants from the fluoridated area had fluorosis (F 39% NF 21.3%, p<0.001), at the threshold TF ≥ 3 (“aesthetic concern”), the difference was no longer statistically significant (F 4.1%, NF 2.2%, p=0.25). There was a gradient by age, whereby fluorosis was highest in the youngest and lowest in the oldest age group. Conclusions: Although fluorosis is more common in adults with lifetime exposure to water fluoridation than those with no exposure, the aesthetic impact of fluorosis seems to diminish with age.