Volume 8 • 2021 • Issue 5

Study Shows Long-Term Effects of Ending Fluoridation Authors: Lindsay McLaren, Steven K. Patterson, Peter Faris, Guanmin Chen, Salima Thawer, Rafael Figueiredo, Cynthia Weijs, Deborah McNeil, Arianna Waye, Melissa Potestio Objective: To examine the effect of fluoridation cessation on childhood dental caries by comparing populations in Calgary, where fluoridation ended in 2011, and Edmonton, where the water is fluoridated. Participants: Researchers studied grade 2 students about 7 years after fluoridation cessation in Calgary. These children were born after cessation occurred. A group of grade 2 students in Edmonton were also included as a sample of children who were born and grew up drinking from a fluoridated municipal water supply. Method: Data collection included a dental examination conducted in school by calibrated teams consisting of a dental hygienist and a clerk, a questionnaire completed by parents, and fingernail clippings from a small subsample. Analysis: The researchers examined dental caries experience in the two groups of grade 2 students, including: • deft: the sum of the number of decayed, extracted due to caries, and filled teeth among the primary teeth • DMFT: the sum of the number of decayed, missing due to caries, and filled teeth among the permanent teeth • Smooth surface caries based on the defs and DMFS (decayed, extracted/missing, and filled surfaces), because fluoride tends to help prevent smooth surface caries more so than other kinds The research team compared these measures in the two populations in 2018–19, and to measures gathered from similar samples in pre-cessation and early post-cessation surveys. In addition, they evaluated whether differences were likely to reflect fluoridation cessation in Calgary, rather than other confounding factors. Results: The prevalence of caries in the primary teeth was significantly higher in Calgary than in Edmonton, which suggests that ending fluoridation negatively impacted children’s oral health. For example, crude deft prevalence was 64.8% in Calgary and 55.1% in Edmonton. These differences were consistent and robust, and they persisted with adjustment for potential confounders. Findings for permanent teeth were less consistent, which likely reflect that grade 2 students have only had permanent teeth for a short time. 38 | 2021 | Issue 5