BOH Agenda 032520 - Laserfiche WebLink

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Conversely, it is almost inevitable that some of the fluoride in toothpaste and other topically- applied products is swallowed , and if that occurs in childhood , it contributes to the pre - eruptive mechanism of caries prevention . However, the amount of fluoride swallowed during tooth brushing varies considerably among children , 3 making it difficult to quantify the overall contribution of toothpaste to pre - eruptive effects of fluoride occurring in the population . 1 . 3. 2 Evolution of evidence concerning the relative contribution of pre- and post-eruptive effects According to the biological reasoning outlined above , fluoride in drinking water can , in principle, prevent dental caries via a pre - eruptive mechanism , post-eruptive mechanism , or both mechanisms . Scientific thinking has changed considerably over the decades as to the relative contribution of each mechanism , reflecting the evolution in research about dental health effects of fluoride itself. By the middle of the 20th century, it was assumed that that the caries- preventive effect of fluoridated drinking water was due entirely to pre -eruptive mechanisms . The evolution of this thinking aligned with sequence of discoveries about fluoride and dental health made in the first half of the century .4 In summary : ( i ) Colorado brown stain was found to be endemic in some communities, but absent in others; ( ii ) co - incidentally, where Colorado brown stain was endemic, rates of dental caries were noticeably lower; ( iii ) further studies established that Colorado brown stain was attributable to the community' s drinking water, specifically in children who had consumed the drinking water since birth ; ( iv ) high concentrations of fluoride in the drinking water were then isolated as the cause of Colorado brown stain, which was renamed dental fluorosis; (v) further studies established that lifetime exposure to lower levels of fluoride in drinking water of around 1 mg/ L F was associated with lower rates of dental caries compared to a negligible concentration, and with little significant dental fluorosis; ( vi ) in subsequent intervention studies that added around 1 mg/ L F to drinking water, dental caries experience was lessened in cohorts born after implementation of fluoridation ; ( vii ) by then , it had been established that high concentrations of fluoride in drinking water affected the developing teeth to cause dental fluorosis seen in epidemiologic studies ; ( viii ) by deduction , it was reasonable to believe that caries preventive benefits of lower concentrations of fluoride in drinking were likewise due to its effects on the developing enamel . In fact, there was already some evidence to question the assumption that fluoride prevented caries solely be a pre - eruptive mechanism . In the Grand - Rapids study, caries experience of 16 year olds 10 years after implementation of fluoridation was lower than the level seen prior to fluoridation . Commenting on the significance of this finding, Arnold alluded to a post-eruptive effect of water fluoridation noting " It is to be remembered that these children in most cases were those who presumably had the coronal portion of their permanent teeth already calcified when fluoridation started . i5 By the 1960s, the premise that fluoridated water prevented caries predominantly via a pre -eruptive mechanism was being challenged by biological studies . In one study of 36 premolar teeth extracted for orthodontic reasons, there was little correlation between fluoride concentration of surface enamel and caries experience of the study participants ' other teeth . 6 Although a larger study reported an inverse correlation , ' the finding cast into doubt the prognostic importance of fluoride' s incorporation into surface enamel . This was around the time that randomized controlled trials