Fluoridation promoters claim that fluoridation benefits adults as well as children, even though recent studies, such as Armfield and Spencer, show that any temporary difference in tooth decay rates in children (caused by a delay in tooth eruption) disappears by age 12 to 15. How fluoridation magically becomes beneficial again in adulthood is not explained.

According to a 2001 review by the Ontario Ministry of Health and Long Term Care (Locker 2001), “The absence of adults from water fluoridation studies is difficult to explain… Whatever the reason, it must be regarded as a major limitation in the research effort to date.”

Nevertheless, promoters quote a small number of unreliable studies to support their claim. The latest is Griffin, 2007, which was a review of the unreliable research; not research itself. It was commissioned by the US fluoridation promoter, the Centers for Disease Control. Griffin’s opening statement is “To date, no systematic reviews have found fluoride to be effective in preventing dental caries in adults.” Echoing the York Review it continues: “There is a clear need for further well designed studies on the effectiveness of fluoride among adults.”

To date the only actual research the NZ fluoridation lobby has cited to support its claim that fluoridation benefits adults is Hunt Aldridge and Beck 1989. This actually found, at the outset of the study, no difference in decay rates after 30 to 40 years of exposure to fluoride.

Griffin 2007

(S O Griffin, E Regnier, P M Griffin, V Huntley (2007) “Effectiveness of Fluoride in Preventing Caries in Adults”, Journal of  Dental Research 86(5): 410 – 415)

Griffin is not research: it is a review of research. But only research published in English. It is not a systematic review, hence fails to meet Ministry of Health’s specifications. Virtually all of the studies were published before the York Review, yet the York reliability rating is not quoted for any study. Neither does this review include the two studies from 2006 and 2007 that specifically found no benefit to adults from fluoridation, discussed below.

A representative of the new Ministry of Health-funded lobby group the NFIS (National Fluoridation Information Service) claimed in May 2011 that Griffin showed a 27% benefit to adults from water fluoridation. However Griffin does not claim this. Griffin stated that there was seemingly a reduction of about 1/2 a DMFS per year from three sources of fluoride – water, toothpaste, and professionally applied lacquers. Griffin then stated that water fluoridation accounted for 27% of this total; NOT a 27% reduction in decay. If, for example, this 1/2 DMFS was a 20% overall reduction in decay 9we do not know as Griffin does not sate this), the water fluoridation component would amount to 5.4% (20% * 27%).

But let us also do a reality check. Half a DMFS per year is 10 DMFS (mainly fillings) over 20 years. But if this is a saving of between 20% and 50% (say), there must be between 1 and 2.5 DMFS per year total. In 20 years (say from age 18 to 38) this is between 20 and 50 fillings! And between 40 and 100 by the age of 58! So even the claimed total benefit is simply not credible!

Regarding credibility, Griffin’s opening statement at page 410 is:

“To date, no systematic reviews have found fluoride to be effective in preventing dental caries in adults.”

A systematic review looks at he reliability of the research before using it. Griffin did not assess reliability – she just quoted the figures. In the case of Hunt Elderidge and Beck, the original research stated that although there were numerically less caries in the fluoridated subjects, this was within the margin of error – not statistically significant. But Griffin incorporates them anyway, and reports them as significant.

Then at pages 413 and 414 it states:

“One limitation of this review is the quality and the quantity of studies on fluoride effectiveness among adults.”

“Because of the paucity of studies, we were not able to exclude studies without blind outcome assessment.”

“There is a clear need for further well designed studies on the effectiveness of fluoride among adults.”

This is consistent with the York Review finding that there is no reliable evidence to support claims for fluoridation, and that better studies are required. In fact Griffin also states that better studies are needed.

The studies are old (only 4 post 1979). They include Hunt, Elderidge and Beck as discussed below. They include Burt and Eklund, which compared communities with 3.5 ppm fluoride with communities with 0.7 ppm and is irrelevant to fluoridation, as discussed below.

The study was funded by the Centers for Disease Control (CDC) – one of the two main US political promoters of fluoridation. This was at a time when people were asking “If fluoridation helps developing teeth in children, why are we giving it to adults?”. The CDC needed an answer. It is being quoted by the fluoridation lobby in other countries as supporting the claim of benefit for adults. It is obvious that this shoddy review was commissioned by the CDC specifically as ammunition for the fluoridation lobby, just as the tobacco companies commissioned studies “proving” smoking was “safe”.

This is a classic example of the observation made in the British Medical Journal in 2005: that the fluoridation lobby selectively quotes unreliable research to support its position.

Maupomé 2007

(Maupomé G, et al. (2007) “A comparison of dental treatment utilization and costs by HMO members living in fluoridated and nonfluoridated areas.” Journal of Public Health Dentistry 67(4):224-33.)

In 2007, this important study was published which sheds light on whether fluoridated water is effective at preventing tooth decay in adult populations. Despite a press release to the contrary, the study indicates very little, if any, benefit.

To assess fluoridation’s effectiveness, the study examined the dental treatment costs accrued over 5 years by 51,683 members from an HMO. The HMO members, including both adults and children, lived in fluoridated and non-fluoridated communities of 3 separate regions in the Northwest. The authors, a team of pro-fluoridation researchers, state that the study shows a “small” benefit from fluoridated water which “may” have led to some cost-savings. A close inspection of their data, however, shows that this “small benefit” — if it even exists — was very small indeed.

For example, in the largest region examined in the study, representing over 75% of the HMO members surveyed (the Portland metro area of Oregon), fewer children and adults in the non-fluoridated areas required treatment than children and adults in the fluoridated areas. Moreover, the children and adults in the non-fluoridated area who sought treatment accrued lower total costs over the 5-year period than those in the fluoridated area. As noted by the authors, the “Portland metro had lower treatment costs for the non-fluoridated area…”

These findings from the Portland region are remarkable: after all, one of the most-frequently cited claims by fluoridation proponents is that every $1 spent on fluoridated water saves $80 in dental bills. In this study, the dental care costs in the largest region surveyed were lower in the areas without water fluoridation.

Even among the smaller regions in the study (Marion County, Oregon and Clark County, Washington), which produced more favorable results for the fluoridated areas, the results were still inconsistent and the benefits marginal. As the authors admit, “the effect we observed was generally small.”

One of the reasons given by the authors for why the benefit was small and inconsistent was that the population being studied was insured and had ready access to dental care and preventive procedures. However, a separate study by a University of Michigan research team (Burt, 2006) suggests that water fluoridation is equally ineffective in low-income areas as well.

Burt et al. 2006

Burt BA, et al. (2006). “Dietary patterns related to caries in a low-income adult population.” Caries Research 40(6):473-80.

This study examined a group of 800 low-income African American adults living in Detroit. Despite the fact that Detroit has been fluoridated since 1967, the authors found that tooth decay was “severe” and “extensive”, with tooth decay rates reaching as high as 99.8% for individuals aged 14 to 35 years.

What makes this Detroit study particularly interesting, is that , unlike the vast majority of studies investigating fluoridation’s effectiveness, the authors actually assessed the quantity of fluoridated tap water consumed by each individual. When they then compared the quantity of fluoridated water consumed with the rate of tooth decay, they found no relationship. In other words, ingestion of fluoridated tap water for up to 4 decades did nothing to produce better teeth in this disadvantaged population.

Earlier Studies Quoted by the NZ Ministry of Health

The Ministry of Health quotes 3 studies:

  • Thompson, 1997
  • Burt, Ismail and Eckland, 1986
  • Hunt Elderidge and Beck, 1989

Yet as we will see, not one of these studies supports the Ministry’s position, in fact the last one shows, if anything, the opposite.

Thompson 1997

(W.M. Thompson 1997: publication for the National Advisory Committee on Health and Disability entitled “Preventive Dental Strategies for Older Populations”)

Thompson did no research and simply quotes the earlier study (Burt, Ismail and Eckland, 1986). So Thompson is not an independent authority at all!

Burt and Eklund

(B. A. Burt, A. I. Ismail and S. A. Eklund “Root caries in an optimally fluoridated and a high-fluoride community” Journal of Dental Research, Vol 65, 1154-1158)

This study did not look at low fluoride communities – it compared a very high fluoride community (3.5 ppm) with a medium fluoride community (0.7 ppm). 3.5 ppm is enough for topical benefit (2ppm threshold): As we know from Arends’ study in 1989, 2ppm or higher is enough for topical benefit. So this study falls into the same error as the original proponents 50 years earlier. It is scientifically invalid to simply extrapolate a straight line back to low fluoride levels with this knowledge: the study proves nothing.

Hunt, Elderidge, and Beck 1989

(R J Hunt, J B  Eldredge, J D Beck (1989) “Effectiveness of Residence in a Fluoridated Community on the Incidence of Coronal and Root Caries in an Older Adult Population” Journal of Public Health Dentistry Vol 49:3, Summer 1989, 138 – 141.)

This study acknowledged that the number of subjects was too small and the results were not statistically significant, except one.

That conclusion was that adults received no benefit from 30 years of continuous fluoridation. (Specifically the fluoridated and non-fluoridated subjects had the same levels of decay at the beginning of the study {after 40 years of high fluoride exposure in some instances}). With more than 30 years exposure, it concluded that there was on average ½ a cavity less in the fluoridated communities.

In fact this found (at the start of the study) no difference in decay rates after 30 to 40 years of exposure to fluoride at 1 ppm. At the end of the 18 month study it claimed an apparent minor benefit but noted that it had not considered use of fluoride toothpaste, other dental treatments, or any confounding factors of any kind. The report states:

“information on other sources of fluoride, such as fluoride toothpastes and mouthrinses, was not collected. Thus it is possible that the differences in caries incidence were due to other sources of fluoride.”

It also failed to note that claiming a benefit for, say, 32 yr olds after the study, but none for 32 yr olds at the start of the study, was self contradictory.

As an interesting aside, the study notes that its results “indicate that the topical effect of currently consumed fluoridated water was not sufficient by itself to significantly reduce caries.”

The obvious question is “why would anyone take a known poison so that after 30 or 40 years they may have a 50/50 chance of saving one filling?!”