FLUORIDATION:
No significant caries reduction with ingestion.
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There is already a consensus including CDC, Cochrane Collaboration, the Iowa Fluoride Study and others that fluoride’s effectiveness in preventing cavities is mainly topical (not swallowed).
According to most major sources, estimates of fluoridation effectiveness amount to at most a reduction of only one-half cavity per child. Low end estimates find no significant reduction at all. Children aged 6-17 average 2.1 cavities in their permanent teeth (1):
Cochrane Collaboration (2) (2015): 26% (0.5 cavity per child)
CDC (3) (2018): 25% (0.5 cavity per child)
Iowa Fluoride Study (4) (2018): No significant reduction
World Health Organization data (5) (2005): No evidence of fluoridation’s effectiveness
The Cochrane Collaboration is considered the gold standard of evaluating effectiveness. It said the cavity reduction referenced above was “based predominantly on old studies and may not be applicable today.”
“Over 97% of the 155 studies were at a high risk of bias, which reduces the overall quality of the results… We did not identify any evidence… to determine the effectiveness of water fluoridation for preventing caries in adults… There is insufficient evidence to determine whether water fluoridation results in a change in disparities in caries levels across socio-economic status.”
The Iowa Fluoride Study (IFS), funded by the National Institutes of Health, is the most comprehensive, ongoing research project in the U.S., the only one measuring all sources of fluoride ingestion. The 2018 study from IFS referenced above found no significant correlation between ingested fluoride and cavity reduction, further validating a 2009 study(6) from IFS that stated:
“ … achieving a caries-free status may have relatively little to do with fluoride intake (emphasis in the original) … recommending an ‘optimal’ fluoride intake is problematic.”
Finally, World Health Organization data show cavity rates in children (age 12) have dropped as much in nations that don’t fluoridate (darker solid lines) as in nations that do (red/yellow dotted lines). (Graph below.)
Slade et al, 2018, Journal of Dental Research, https:// www.ncbi.nlm.nih.gov/pubmed/29900806
Cochrane Collaboration, 2015, https://www.cochrane.org/CD010856/ ORAL_water-fluoridation-prevent-tooth-decay
CDC, 2018, https://www.cdc.gov/fluoridation/index.html
Curtis et al, 2018, Journal of Public Health Dentistry, https:// www.ncbi.nlm.nih.gov/pubmed/29752831
Neurath, 2005, Fluoride, http://www.fluorideresearch.org/384/files/ 384324-325.pdf
Warren et al, 2009, Journal of Public Health Dentistry, https:// www.ncbi.nlm.nih.gov/pubmed/19054310