SYTTY
IMPACT OF HIGH WATER FLUORIDE ON HEALTH.
A PRELIMINARY STUDY
Project leader: Markku Larmas, University of Oulu, Institute
of Dentistry, P.O.Box 5281,
FIN-90014 University of Oulu, Finland, tel. +358-8-5385510, e-mail:
Markku.Larmas@oulu.fi
| PUBLICATIONS |
| TIIVISTELMÄ SUOMEKSI |
Financing SYTTY organisation: The Academy of Finland, The Ministry
of Agriculture and Forestry
Funding from SYTTY / Total funding of project (€): 48774
/ 74002
Person-months of work funded by SYTTY / Total person-months of work:
10,5 / 18,2
KEY WORDS: fluoride, water, dental health, connective tissue
EXTENDED ABSTRACT
1 Introduction
The inverse relationship between the fluoride (F) concentrations of drinking water and the prevalence of dental caries has stimulated extensive research aimed at determining the optimum level of F ingestion required to obtain the maximum protection against dental caries with the least risk of producing dental fluorosis or fluorosis of the skeleton. The optimum level of F for dental health, recommended by WHO, is 1 ppm in drinking water. The maximum level permitted by EU is 1.5 ppm.
Owing to the universal presence of F in the earth's crust, all water contains F in varying concentrations. In Finland most of the drinking water contains F 0.1 - 0.3 ppm that is significantly less than recommended for dental health. On the other hand, there are certain areas (rapakivi areas) in which the F concentration of drinking water exceeds 1.5 ppm. Although as high as 3 - 4 ppm F concentrations have been measured from drinking water in Finland, dental fluorosis is not any big problem probably due to the fact that because of the climate conditions water consumption is not very high. The fluoride of drinking water is commonly the largest single contributor to the daily fluoride intake. The estimated F intake through Finnish food is only about 0,5 mg/day.
An increasing number of pharmaceutical products contain fluorides in organic or inorganic form. Practically all dentifrices used in Finland today contain 1.0 - 1.5 g F per kilogram. The swallowing of fluoride dentifrices is of particular concern with regard to small children. Several reports during the last few years have shown that the amount of toothpaste ingested by children aged 2-5 years may range from 0.1 to 2.0 g with a mean 0.5 g.
Basing on the increased consumption of fluoridated tooth pastes and various forms of F-therapy provided in health centers in Finland the average fluoride intake has increased during the past two decades. This increase fits very well with the significant reduction of dental caries in terms of DMF (Decayed, Missing, Filled teeth) values. At the age of 12 years the lowest DMF values of EU have been reached in Finland.
On the other hand, the number of subjects directed to early retirement because of musculoskeletal disorders or symptoms has increased in Finland from 5620 in 1980 to 9557 in 1987. The main reasons for the early retirement were back diseases and arthrosis whereas rheumatoid arthritis has been about the same during the period. One special feature in the prevalence of various back diseases in Finland is the fact that in a restricted area of Kymi, the prevalence of retirement due to back diseases is reported to be relatively high. Kymi region is located on the Viborg rapakivi high fluoride area. These observations on disease prevalence led to the hypothesis that fluoride ion may have a role in health and disease of all calcified tissues.
The aim of the present study is to create new scientific observations on the relationship between fluoride in drinking water and oral and musculoskeletal health. It is based on some preliminary observations on similarities in the prevalence of good oral health situation in areas where the prevalence of musculoskeletal symptoms seems to be the opposite. The dental health data flied in the patient records in Finland are followed retrospectively (longitudinally) for oral health situation in certain age ' cohorts in fluoride and non-fluoride areas. Finland is an excellent piece for this kind of research in that sense that the hydrogeochemical map of Finland is accurate and detailed. Therefore fluoride content in drinking water in different regions can be followed. Combining (1) the knowledge of the hydrogeochemical maps of Finland, (2) the accurate longitudinal dental health surveys, and (3) collecting standardized questionnary information for the analysis of musculoskeletal symptoms and in the positive cases, and (4) evaluation of the objective findings in the files of public health system, all this will provide new scientific information on the role of F in dental and musculoskeletal health.
Recurrent low pain back (LBP) episodes are common in the working-age population, and the history of back problem is often quite long. Although low back diseases are most prevalent in middle age, symptoms frequently begin in adolescence. About 17 % of school children report disabling LBP during the previous year, which makes this kind of analysis reasonable in even relatively young age cohorts. The objective findings are made of diseases leading to hospitalisation, i.e. low back pain altogether (2%), lumbal disc disease (1.2 %), herniated nucleous purposes (0.8) (the incidence rases of which at 28 years of age are given in parentheses).
2 Methods
Study areas
In the 1980's in Finland a hydrogeochemical mapping project was conducted
in which about 6000 water samples were collected from springs and from
wells, and analysed for the main cationic and anionic components including
fluorides.
The study cohorts are selected from subjects born in 1930, 1940, 1950, or 1960 and lived the whole of their lives on that area. The study towns will be Laitila on the rapakivi area. The reference area will be the permanent residents of the non-fluoride villages of the rapakivi area and Somero with non-fluoridated piping.
Dental health
Retrospective dental health data is collected from the cohorts (born
1960, 1970, 1980) from the files of the public health system. The subjects
should have visited dental dentist regularly (annually) from 6 to 20+ years.
The information needed is transferred directly to a portable computer in
the dental office. Before that the permission of the Ethical Committee
of the University of Oulu and health authorities involved was obtained
and all the regulations of the national authorities are followed in handling
the data.
From these patient records the time of tooth eruption of each individual permanent tooth is established for each study location. Comparisons between genders, geographical location, different preventive measures and strategies of treatment are performed.
Dental health is determined on each tooth surface at the stages when dentist is making the filling due to dental caries. Fillings due to fractures, aesthetic or technical reasons are excluded, which is a real advantage to all other studies by now. Thus the advanced dental caries is the only parameter followed.
Musculoskeletal disorders
In a self-administered standardized questionnaire the subjects will
be asked to indicate their musculoskeletal symptoms (28). Neck and shoulder
pain, arm pain, low back pain and sciatic pain, hip and knee pain will
be asked all separately. The questions made will indicate how severe the
symptoms have been, in what age the symptoms have occurred, how the symptoms
have occurred during the last year and during the 7 last days and how much
the symptoms have affected the activities of the daily life (29).
Age, sex, weight, height, occupation, work satisfaction, previous musculosceletal injuries, workload, smoking will be asked.
The "objective" determination of the occurrence of symptoms and/or the treatment of the disorder is performed from the patient record files of the primary health care system and/or files of the secondary health care system of the study region.
Statistics
A sophisticated time dependent regression analysis will then be applied
to explain the possible differences between the study locations as well
as to determine the relative importance of the various factors. Comparison
of oral health and symptoms of musculoskeletal system will be performed
using time dependent regression analysis.
3 Results and discussion
A questionnaire was sent to altogether 1128 subjects in the towns of Hamina and Laitila (high fluoride area) and in Somero (low fluoride area). The questionnaire was sent to all subjects born in 1930-31, 1940-41, 1950-51, 1960-61, and 1970-71 who had lived all their lives in the same area. The subjects were selected from the files of National Social Security Register so that all subjects who were born in their present residence were considered to be permanent residents of the towns involved. The number of responses obtained from 695 subjects. In addition oral health of all subjects in Laitila born 1970 or 1980 and who still are living in the area were recorded to computers from the dental records of the health centre.
The effect of high endemic fluoride on dental health was beneficial. Dental caries was still declining in each tooth in Laitila in the 1980 cohort although it is known that caries in second molars and molars is increasing in other parts of Finland. The study indicates that the high fluoride still is beneficial in circumstances where other preventive measures are overruled the low fluoride effect.
There were no significant differences in the prevalence of mineralized connective tissue disorders between fluoride and non-fluoride areas. Some significant differences were occasionally observed in symptoms but they were occasional and sometimes controversial. The prevalence of one chronic disease was abnormally high in Laitila but because the observation needs confirmation, its publication is delayed. The analysis is under progression.
4 Conclusions
High fluoride is beneficial for dental health but may have adverse affects
on general health. The latter needs further confirmation.