Should the drinking water of Truro, Nova Scotia, be fluoridated? Water fluoridation in the 1990s

An epidemiological assessment of differences in caries and fluorosis prevalences between children in Truro (< 0.1 ppm) and Kentville (fluoridated at 1.1 ppm in 1991), Nova Scotia, Canada, was completed in 1991. Out of a total of 429 children, in grades 5 and 6, in the two towns in 1991, 219 (51%) were examined. Parents answered a self‐administered questionnaire investigating the sources of drinking water used by the children since birth, residence history, use of fluoride supplements, dentifrices, and other fluoride products during the first 6 yr of the life. The examination criteria differentiated between non‐cavitated and cavitated carious lesions. Dental fluorosis was measured using the TSIF index. Examiner agreement was excellent. Of the children examined, 80 (36.5%) drank water (fluoridated or non‐fluoridated) from municipal water systems during the first 6 yr of life. The children were assigned into five groups based upon residence history and exposure to fluoridated water during the first 6 yr of life. The percentage difference in mean DMFS scores between children in the fluoridated and non‐fluoridated groups is 17% (delta DMFS1 =0.7) when non‐cavitated carious lesions are included and 39% (delta DMFS2= 1.1) when they are excluded. The differences are not statistically significant. The significant risk factors associated with the DMFS1 and DMFS2 scores identified by a stepwise multiple regression analysis are: education level of the father, gender, and number of years of reported use of toothpaste during the first 6 yr of life. Dental fluorosis (mainly TSIF score of 1) was present in 41.5% and 69.2% of the children in the non‐fluoridated and fluoridated groups, respectively. Residence in a fluoridated area and the educational status of the mothers were positively associated with fluorosis status. It was concluded that water fluoridation be recommended as a part of an overall plan to educate the public and the medical and dental professions with respect to the proper and safe use of fluoride products. Determination of an optimal concentration of fluoride to be added to the water should take into account all potential major sources of systemic fluoride intake during the first 6 yr of life, including foods and beverages.