Measuring the short‐term impact of fluoridation cessation on dental caries in Grade 2 children using tooth surface indices

Abstract

ObjectivesTo examine the short‐term impact of fluoridation cessation on children's caries experience measured by tooth surfaces. If there is an adverse short‐term effect of cessation, it should be apparent when we focus on smooth tooth surfaces, where fluoride is most likely to have an impact for the age group and time frame considered in this study.MethodsWe examined data from population‐based samples of school children (Grade 2) in two similar cities in the province of Alberta, Canada: Calgary, where cessation occurred in May 2011 and Edmonton where fluoridation remains in place. We analysed change over time (2004/2005 to 2013/2014) in summary data for primary (defs) and permanent (DMFS) teeth for Calgary and Edmonton, for all tooth surfaces and smooth surfaces only. We also considered, for 2013/2014 only, the exposed subsample defined as lifelong residents who reported usually drinking tap water.ResultsWe observed, across the full sample, an increase in primary tooth decay (mean defs – all surfaces and smooth surfaces) in both cities, but the magnitude of the increase was greater in Calgary (F‐cessation) than in Edmonton (F‐continued). For permanent tooth decay, when focusing on smooth surfaces among those affected (those with DMFS>0), we observed a non‐significant trend towards an increase in Calgary (F‐cessation) that was not apparent in Edmonton (F‐continued).ConclusionsTrends observed for primary teeth were consistent with an adverse effect of fluoridation cessation on children's tooth decay, 2.5–3 years post‐cessation. Trends for permanent teeth hinted at early indication of an adverse effect. It is important that future data collection efforts in the two cities be undertaken, to permit continued monitoring of these trends.

Fluoridation cessation: More science from Alberta

“…Considering our whole work,2, 3, 4 one will find the data point in question, including our observation in Calgary between 2004/2005‐2009/2010 (precessation) and 2009/2010‐2013/2014 (largely postcessation) of a small increase in slope for deft prevalence (%>0; the worsening speeds up) in the latter relative to the former. We reasoned2 that fluoridation cessation might first affect prevalence rather than means, which are influenced by children with more severe caries.…”

“…We therefore could not examine differences in baseline (or changes) in those variables. That is an important limitation, which we acknowledged 2, 3…”

“…The observed tooth‐level decrease (improvement) in permanent decay in Calgary2 was muted when focusing on smooth‐surface caries only; for mean DMFS among those with DMFS  > 0, the direction of change became positive, although not statistically significant. We reasoned3 that this could be an early hint of an adverse effect of fluoridation cessation on permanent tooth caries, but confirmation needs additional monitoring.…”

“…We thus prepared multiple papers addressing different aspects of the study: overall trends in dental caries—tooth‐level data2 and tooth surface‐level data;3 and trends by socioeconomic indicators4 (Neurath et al [“the authors”] erroneously state that we “control” for these in the latter paper).…”

“…The authors focus on a single paper 3. We did not include the 2009/2010 data point in that paper because of its focus on tooth surface‐level data, which the 2009/2010 data point did not include.…”