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Cavity rates and dental fluorosis in Canada - DMFT - Decayed, Missing, Filled Teeth
Are the claimed benefits of fluoride ingestion in Canada over-rated?
A Review by Foulkes RG, "Investigation of inorganic fluoride and its effect on the occurrence of dental caries and dental fluorosis in Canada - final report", Fluoride, 1995 Aug, 28:3, 146-148
[editor's note: Health Canada awarded a fluoridation review contract to to well-known proponents who had all publicly endorsed fluoridation at a prior workshop sponsored by fluoridated toothpaste manufacturers. Some had received grants from these manufacturers and one was the editor of a dental newsletter sponsored by the toothpaste manufacturer. HC's Health Protection Branch did NOT publish this "review" by promoters]
This report was prepared for Health Canada under a research contract by dentists holding senior appointments in Canadian universities. It is a collection of five "working papers" and suffers from lack of editing and an executive summary.
The authors at the outset affirm their belief in the "unique advantages" of water fluoridation, and that these advantages must be part of the review. Their chief task, however, was to achieve the objectives established for them by Health Canada.
Dose response in prevention of caries and dental fluorosis
The studies of the efficacy of fluoride in the reduction of dental caries are selected. Large population studies showing negative relationships are omitted. In spite of this advantage, the authors could not find significant studies in either the US or Canada to support their belief in "benefit'. The most acceptable study, in their view, is the 1986-1987 dental survey of US schoolchildren carried out by the US National Institute of Dental Research. However, this study showed a comparable decline in caries in both fluoridated and non-fluoridated populations, and the differences were not significant.
As a result of the lack of contemporary supportive data, the authors base all of their major responses on the 1940s data of Trendley Dean's study of 21 cities as modified by Eklund's and Striffler's study (1980) that added further 1940s data from an additional 20 cities. From the curve derived from these data, the authors establish the "optimal intake" (ie, the concentration, in water, to give maximum benefit with minimal dental fluorosis) as a range of 0.8-1.2 ppm. The authors reason that because of the small amount of fluoride present in food at the time of Dean's study, this same range can be accepted to represent the optimal in terms of total fluoride intake in milligrams per day in the age group (12-14 years) studied by Dean. In brief, this report argues that Dean's original curve, modified slightly by Eklund and Striffler, is valid today provided that the abscissa is changed from ppm fluoride in water to milligrams of fluoride ingested from all sources.
The recommended total intakes in ugm fluoride/kg bw/day, as requested by Health Canada are calculated from the 1940s data. For the age group 7 months - 4 years of age, they recommend 56-81 ugm fluoride/kg bw/day. This exceeds, at the upper end, the "generally applied standard" of 70 ugm/kg/day (NRC 1993).
At this range, the authors are satisfied with a prevalence "very mild" and "mild" dental fluorosis of 16-26%.
Total Fluoride Intake
Estimates prepared by the Canadian Environmental Health Directorate in 1992 of fluoride ingestion for various routes of exposure may have been the data presented to the authors. These show that total fluoride ingested from ambient air, food, soil, and drinking water by the 7 month-4 year age group (average weight 13 kg) in ugm fluoride/kg bw/day is 67.25-100.42 in "fluoridated" areas and 25.41-36.42 in "non-fluoridated" areas. Estimates of the fluoride ingestion from twice daily use of fluoride dentifrice presented in the Environmental Health study is, for the same age group, 20-60 ugm/kg/day This compares to 18.5-43.1 ugm fluoride/kg bw/day m the report under review. Using the upper range (43.1) for this age group, total fluoride ingestion, including dentifrice, in ugm/kg bw/day is 143.52 in "fluoridated" and 79.52 in "non-fluoridated" groups. Use of fluoride supplements (1993 recommendation) by the latter would increase the fluoride intake by a further 15.8 ugm/kg bw/day for a possible total of 95.31 ugm/kg bw/day. If these calculations are correct, total fluoride intake for this important age group exceeds the recommended standard of 81 ugm/kg bw/day in both "fluoridated" and ''non-fluoridated" groups.
2) Recommended total intakes shown in the report and derived from Dean's data should apply provided that all sources of fluoride are considered, including dentifrices.
3) The recommendations of the April 1992 Canadian Workshop on Fluorides as recorded in the Journal of the Canadian Dental Association (59 272-279 1993) are supported. These include: a new dosage schedule for fluoride supplements; smaller "pea size" and pediatric (500 ppm) dentifrice.
Health Canada may have been motivated by concern about the obvious increase in fluoride ingestion in both "fluoridated" and "non-fluoridated" communities created by the addition of fluoride to drinking water and the importation of foods and beverages prepared in "fluoridated" areas. It may also have been motivated by concern over additional fluoride from dental products and the rising rate of dental fluorosis, which they term "an adverse dental health effect".
The authors of the report express concern that water fluoridation may be threatened. By virtually ignoring the increase of fluoride in food and beverages associated with water fluoridation, they concentrate on "discretionary sources" in their recommendations in addition to suggesting that fluoridation levels be decided by regional officials on the basis of caries prevalence, a vague procedure at best.
The most prominent feature of this report is the admission of the authors that they could find no contemporary data to support the fluoride-caries hypothesis so that they were forced to base their responses on 1940s data that are more mythical than factual. Examination of the pivotal figures for a recommended range of total intake (all sources), the optimal level for fluoridation and their acceptance of a 16-26% prevalence of "very: mild" to "mild" dental fluorosis leads to a serious conclusion: the authors began the report with a determination to recommend maintenance of the status quo and selected their data accordingly. This report appears to qualify as an example of the "tainted truth".
NOTE: excerpts are reproduced below from this Canadian "review" -- chapter by: Ismail AI, "Dental caries, fluorosis, and fluorides". Some of the other Canadian studies mentioned in this Chapter are on this web page in abstract form.
There were no statistically significant differences in caries prevalence of the children between Camrose and Wetaskiwin (40). When only children with at least 5 years of residency in their community were compared with those from the fluoridated community, they had a 17% lower mean number of DMFS scores (decayed, missing, and filled tooth surfaces). This difference was not statistically significant. Within the fluoridated community children with less than 5 years of residency had a 44% higher mean number of DMFS scores than those with more than 5 years of residency. [emphasis added and comment: a higher DMFS score is meaningless if it's not statistically significant or clinically relevant (see below)]
Another study in British Columbia which included children between 6 and 14 years of age also found no statistically significant difference in mean DMFS scores (35% higher in the non-fluoridated group or equivalent to 0.88 DMFS). The overall prevalence of fluorosis was 60% with 55% of children in the nonfluoridated city of Vernon (<0.1 mg/L) having fluorosis compared with 65% in the fluoridated city of Kelowna (1.2 mg/L). Only 8% of the children had a score higher than a 2 on the TSIF scale of fluorosis Interestingly, between 1 and 2 years of age, 75% of the children reported use of a fluoridated dentifrice and by the age of 3 years, 93% reported its use.
In summary, Canadian studies carried out in the 1980s show that differences in caries prevalence between fluoridated and non-fluoridated children who were born and lived the first 6 years of their lives in their communities ranged between 17% and 39%. The difference in absolute terms is less than 1 DMF tooth surface. [and were not statistically significant - emphasis added]
BETWEEN CALGARY & EDMONTON
Calgary's tooth decay rate for 13-year olds may have been lower at the time of our provincial dental survey in 1985 than fluoridated Edmonton children. After comparing Calgary's Health Authority's internal reports with Edmonton's reports, in 1984, 1985, and 1986, it is clear that Calgary children had comparable and lower caries-free rates than did fluoridated Edmonton children. At the time of the province-wide dental survey in 1985, Edmonton children had been fluoridated their whole lives.
The published report of the Alberta Survey showed a mean DMFT rate for 13-year old children of 2.90 for Calgary and Edmonton combined. The OMISSION of the individual rates for the two cities appears to be DELIBERATE! After recently reviewing Edmonton Board of Health's (EBH) annual reports, I discovered that the DMFT rate for Edmonton children in the provincial survey was 2.80. This compares with their own internal survey of 2.885. Since there were only two cities in the metropoliton category in the Alberta survey, and because the EBH's Annual Report (page 56) listed the DMFT rate as 2.80, the MEAN DMFT rate can be calculated for Calgary children from both these reports. It's 2.9955!
With the traditionally accepted margin of error factored into the provincial survey (+ or - 0.5 DMFT), Calgary children had comparable DMFT rates. This information was known by our local health authorities, yet they promoted fluoridation for Calgary in 1989 anyway! In fact, Calgary Health Services' 1986 Annual Report stated this: "The 1986 Alberta Dental Survery Report shows that dental health, measured by decayed, filled and missing teeth in children aged 13, continues to imporve even in non-fluoridated communities such as Calgary."
Gray AS, Fluoridation: time for a new baseline? J Canadian Dental Association, 1987, 53:10 763-765.
A review of current findings in British Columbia and also in other localities indicates that DMF rates in children are falling drastically in non-fluoridated areas as well as fluoridated areas. The current statements of our profession in support of fluoridation do not appear to take these changes into account. It is timely for the profession to take the lead in deciding what is scientifically appropriate to tell communities that may consider installing fluoridation equipment and hold fluoridation referendums in the late 1980's.
Excerpt: The type of caries now seen in British Columbia's children of 13 years of age, is mostly the pit and fissure type. Knudsen in 1940, suggested that 70 percent of the caries in children was in pits and fissures. Recent reports indicated that today, 83 per cent of all caries in North American children is of this type. Pit and fissure cavities aren't considered to be preventable by fluorides, they are prevented by sealants. [emphasis added]
Ismail AI, Shoveller J, Langille D, MacInnis WA, McNally M, Should the drinking water of Truro, Nova Scotia, be fluoridated? Water fluoridation in the 1990s, Community Dental Oral Epidemiology, 1993, 21:118-125
An epidemiological assessment of differences in caries and fluorosis prevalences between children in Truro (< 0.1 ppm) and Kentville (fluoridated at 1.1 ppm in 1991), Nova Scotia, Canada, was completed in 1991. Out of a total of 429 children, in grades 5 and 6, in the two towns in 1991, 219 (51%) were examined. Parents answered a self-administered questionnaire investigating the sources of drinking water used by the children since birth, residence history, use of fluoride supplements, dentifrices, and other fluoride products during the first 6 yr of the life. The examination criteria differentiated between non-cavitated and cavitated carious lesions. Dental fluorosis was measured using the TSIF index. Examiner agreement was excellent. Of the children examined, 80 (36.5%) drank water (fluoridated or non-fluoridated) from municipal water systems during the first 6 yr of life. The children were assigned into five groups based upon residence history and exposure to fluoridated water during the first 6 yr of life. The percentage difference in mean DMFS scores between children in the fluoridated and non-fluoridated groups is 17% (delta DMFS1 = 0.7) when non-cavitated carious lesions are included and 39% (delta DMFS2 = 1.1) when they are excluded. The differences are not statistically significant. The significant risk factors associated with the DMFS1 and DMFS2 scores identified by a stepwise multiple regression analysis are: education level of the father, gender, and number of years of reported use of toothpaste during the first 6 yr of life. Dental fluorosis (mainly TSIF score of 1) was present in 41.5% and 69.2% of the children in the non-fluoridated and fluoridated groups, respectively. Residence in a fluoridated area and the educational status of the mothers were positively associated with fluorosis status. It was concluded that water fluoridation be recommended as a part of an overall plan to educate the public and the medical and dental professions with respect to the proper and safe use of fluoride products. Determination of an optimal concentration of fluoride to be added to the water should take into account all potential major sources of systemic fluoride intake during the first 6 yr of life, including foods and beverages.
Ismail AI, et al., Prevalence of Dental Caries and Dental Fluorosis in Students, 11-17 Years of Age, in Fluoridated and Non-Fluoridated Cities in Quebec, Caries Research, 1990, 24, 290-297
The purpose of this study was to evaluate the difference in dental caries and fluorosis prevalence in 936 randomly selected life-long residents selected from public and private schools in Trois-Rivières (1.0 ppm F in 1987) and Sherbrooke (< 0.1 ppm F), Que., Canada. Students, 11-17 years of age, were examined for dental caries using the National Institute for Dental Research criteria and for dental fluorosis using the Tooth Surface Index of Fluorosis. Because of an inconsistent fluoridation history in Trois-Rivières, comparisons were carried out between two age strata: students 11-14 years of age who consumed for a longer duration suboptimally [see blunder below] fluoridated water than those in the second stratum: students 15-17 years of age. Only public school students, 15-17 years of age, from Trois-Rivières had significantly lower mean filled surface and decayed, missing, and filled tooth surface (DMFS) scores (28 and 24%, respectively) than similar students in Sherbrook. Among private school students, differences were not found, except in the youngest age group in Sherbrook who had significantly lower mean DMFS than similar students from Trois-Rivières. The prevalence of fluorosis was 45.6% and 58.0% in Trois-Rivières public and private schools, respectively, and 31.1% and 30.1% in Sherbrooke public and private schools, respectively. The use of fluoride tablets was significantly associated with fluorosis. This study showed that water fluoridation benefitted students from public schools and that risk factors for dental fluorosis were the use of fluoridated water and fluoride tablets.
[editor's note: In order to explain away their contrary study findings for the "benefits" of fluoridation in the 11-14 year-olds, these authors claim that their study is confounded because for "many years between 1970 and 1987" Trois-Rivières had "sub-optimal" fluoridation. They define "optimal" as water containing between 1.1 ppm and 1.7 ppm fluoride. This is WRONG! The so-called "optimal" fluoride levels are 0.7 ppm -1.2 ppm! If one looks at their graph of fluoride levels for Trois-Rivières, the levels were rarely below "optimal" concentrations. Emphasis above added]
Johnston DW, Grainger RM, Ryan RK, The Decline of Dental Caries in Ontario School Children, J Can Dent Assn, 1986, 5, 411-417
Dental Caries prevalence data collected in Ontario health units from 1951 to 1956 and data collected by almost 100 examiners in Ontario health units during the years 1972 to 1984 for children aged five, seven, nine, 11 and 13 years are analyzed by various statistical methods to determine the rate of decline of caries over these years. The provincial average rate of decline in the last two decades is in the order of 50 per cent and there is no apparent evidence that this is lessening. Retro-projections suggest that the decline from previously known levels began in the late 1950s to early 1960s [before the introduction of fluoridated toothpastes and before widespread fluoridation was adopted]. By the middle of the 1990s, projections indicate that in many areas of the province, less than 10 per cent of seven-year-old children will have experienced tooth decay. The rate of decline is not uniform throughout the province, and in the areas that were lowest in 1984 it is two to three times more rapid than in areas which are still high. This decline in tooth decay appears to be in addition to the benefit provided by fluoridation. It is suggested that the reduction in the need to treat dental caries and its sequelae will bring about marked changes in the future pattern of the practice of dentistry. [emphasis & comment added]
[Excerpts:] Intuitively, if the decline of caries follows the statistical curves that have been observed in the past for infectious diseases such as diphtheria and tuberculosis, it might be expected that a reversed sigmoid curve i.e., a slow decline at first, followed by a relatively linear rapid decline, ending with a drawn-out decline at a very low level would be appropriate.
[in naturally fluoridated areas] ...there has been a further decline in caries similar to that in other parts of the province over the years 1972 to 1984. Whatever is causing the drop in dental caries seems to act independently and provides extra protection beyond the 50 to 60 per cent attributable to fluoridation.
[editor's note: Whatever is causing this precipitous drop in naturally fluoridated areas obviously cannot be attributable to ingesting fluoride if a further decay decline has occured]
Cause of the Caries Decline
It is difficult to attribute the decline in dental caries to any specific factor(s). Whether one factor was the main trigger or whether the decline is due to a combination of all, or other factors not identified, remains a matter of conjecture and must be the aim of future intensive research. Some of the events which the authors suggest may have influenced the drop are listed below.
All the above factors are ongoing and unlikely to change and their possible joint influence on dental caries is likely to persist and possibly intensify.
[editor's note: this study also revealed that the highest caries rates are in Northern Ontario and the lowest in South Ontario. Differences in decay rates could be partially due to the fact that the average number of hours of daily sunlight would be higher in S. Ontario. Full spectrum lighting is known to reduce tooth decay. Sunlight would act in a similar manner (vitamin D is formed in the skin with exposure to sunlight. See related articles:]
Maupome G, Clark DC, Levy SM, Berkowitz J. Patterns of dental caries following the cessation of water fluoridation. Community Dent Oral Epidemiol 2001 Feb;29(1):37-47. Faculty of Dentistry, University of British Columbia, Vancouver, Canada. Email: firstname.lastname@example.org
OBJECTIVES: To compare prevalence and incidence of caries between fluoridation-ended and still-fluoridated communities in British Columbia, Canada, from a baseline survey and after three years.
METHODS: At the baseline (1993/4 academic year) and follow-up (1996/7) surveys, children were examined at their schools. Data were collected on snacking, oral hygiene, exposure to fluoride technologies, and socio-economic level. These variables were used together with D1D2MFS indices in multiple regression models.
RESULTS: The prevalence of caries (assessed in 5,927 children, grades 2, 3, 8, 9) decreased over time in the fluoridation-ended community while remaining unchanged in the fluoridated community. While numbers of filled surfaces did not vary between surveys, sealed surfaces increased at both study sites. Caries incidence (assessed in 2,994 life-long residents, grades 5, 6, 11, 12) expressed in terms of D1D2MFS was not different between the still-fluoridating and fluoridation-ended communities. There were, however, differences in caries experienced when D1D2MFS components and surfaces at risk were investigated in detail. Regression models did not identify specific variables markedly affecting changes in the incidence of dental decay.
CONCLUSIONS: Our results suggest a complicated pattern of disease following cessation of fluoridation. Multiple sources of fluoride besides water fluoridation have made it more difficult to detect changes in the epidemiological profile of a population with generally low caries experience, and living in an affluent setting with widely accessible dental services. There are, however, subtle differences in caries and caries treatment experience between children living in fluoridated and fluoridation-ended areas.
Paynette M, Plante R, L'Heureux JB, Comparison of dental caries and oral hygiene indices For 13-14 Year Old Quebec Children between 1977 and 1984, J. Canadian Dental Assn, 1988, 54:3, 183-189Abstract: ...The most interesting conclusions are: a 33 per cent decline in dental caries prevalence; a 50 per cent increase in treatment level; a 40 per cent reduction in treatment need; a five-fold reduction in tooth mortality rate; significant differences in the DMFT index between ethnic groups and residential status no longer exist; a slight improvement in the oral hygiene condition. Water fluoridation is still associated with significantly lower dental decay.
Editor's notes:This publication is a classic example of the unscientific nature of the pro-fluoridation bias. The authors reveal that: