The Flaw in the Fluoridation Statistics

Dan Montgomery

September 10, 2001

The report of the York review was published on October 6, 2000. This review was done at the NHS Centre for Reviews and Dissemination at York University. It was supposed to resolve the scientific controversy over fluoridation once and for all. The reviewers used the Cochrane process for designing the review. The Cochrane process is a rigorous and statistically fair method. Peter Mansfield, PhD, was a member of the advisory committee for the review. He summarizes the findings of the York review in Water Fluoride: As much harm as good:

Fluoridation advocates and opponents alike were convinced from the start that this review would conclude, like others before it, that water fluoride is a safe and effective public health measure; but to us this seemed unlikely. The method of review was extremely rigorous, ruthlessly excluding any study that did not stand up and ranking the survivors for quality. The term "evidence-based medicine" was invented in England by an MRC scientist, and Cochrane Reviews are the fairest in the world. Furthermore, the young team responsible for this review proved very capable, fair minded and ably led - remarkably so since all were trained in an academic tradition that assumed fluoride was an unmitigated blessing.

The York review found that the difference in caries is only 15%. This is in contrast to previous claims of 25% to 60% less caries in the populations that drank fluoridated water.

Hardy Limeback, DDS, in a guest editorial in the February, 2001 issue of Fluoride, commented on the York Review:

A lot of credence has been given to the recent York review. However, a meta-analysis that mixes 50-year-old studies (pre-fluoride era) with more recent ones and then declares that fluoride has an 'average' benefit today, is obviously flawed. Actually, each and every water fluoridation study conducted to date is flawed since not a single study took into account that ingested fluoride delays tooth eruption by about a few months to over a year. 17, 18 This means that the test communities had children who were dentally younger compared to the control communities. The unerupted teeth would not be exposed to the same carbohydrate challenges and may end up with the same dental decay given the same amount of time in the oral cavity. Not a single fluoridation study has examined this problem in detail. Looking over older data, where there is less influence of the other sources of fluoride such as toothpaste, I have discovered that a delay in tooth eruption of one year would account for approximately 15% of the estimated 'benefit' of fluoridated water. This is the same 'benefit' that the York review considered to be the average benefit by lumping all the water fluoridation studies together.

The delay in tooth eruption associated with fluoridation is also mentioned in The Greatest Fraud:Fluoridation, by Philip RN Sutton. Andreas Schuld did a search of the scientific literature and found that it has been known for many years that fluorides can be a cause of hypothyroidism. The hypothyroidism causes the delay in the eruption of teeth. This scientific evidence, though substantial, was not included by the York reviewers.

Copyright 2002 Daniel A. Montgomery