Fluoridation Effects on
Skeletal and Dental Health: A United States and International Review
Kimberly Draper RN, BSN,
Veronica Farrell RN, BSN, Kathleen Fitzgerald RN, BSN, James Kirby RN, BSN, and
Robert Nelson RN, BSN
Abstract
Introduction
Since its
conception fluoridation of the water supply has been a controversial issue.
The Centers for Disease Control and Prevention (CDC) cites water
fluoridation as one of the ten most important public health achievements of the
21st century in regards to the decrease in dental caries (CDC,
2013). However, some still question its effectiveness, morality and
safety. There are two governmental bodies that oversee water
fluoridation: The Environmental Protection Agency and the CDC (CDC, 2013). The
EPA’s role is to assure that the fluoride concentration in the drinking water
remains under the maximum contaminant level goal, this is the level at which no
adverse health effects from fluoride are estimated to occur (National Research
Council, 2006). This was decreed by the Safe Drinking Water Act of 1974.
It is not the role of the EPA to determine the level of fluoride
necessary for caries prevention (National Research Council, 2006). The level of
fluoride correlated with decreased caries is determined by the CDC (CDC, 2013).
Currently more
than 204 million Americans consume fluoridated water in concentrations thought
to be effective in preventing dental caries (CDC, 2013). The current
recommendations are for a fluoride concentration of 0.7 to 1.2milligrams/liter
(CDC, 2013). Adding fluoride to the water supply was thought to be an easy,
cost-effective measure in reducing caries rates, especially in marginal
populations (CDC, 2013). It is important to note that the concept of water
fluoridation affects a multitude of people in the United States; understanding
its effect on the human body is an important public health issue. It is
impossible to know the weight, water, other beverage
consumption, food intake,
medical history and concurrent medications of all individuals consuming
fluoridated water, thus making it difficult to estimate total daily fluoride
intake and its effects.
Understanding the risks
and benefits associated with the effects of fluoride on skeletal and dental
health is relevant for nurses to understand due to its long-lasting effects and
contributions to possibly increasing fracture risks and weakening the quality
of bones. More importantly, this review of fluoridation demonstrates the
ambiguity of the results found and stresses that more high quality,
evidence-based research should be done in order to determine the effects of
fluoridating water and its impact on all Americans who drink water from a
fluoridated water supply. The purpose of this paper is to review current
articles examining the health effects of fluoride. When ingested from the water
supply the effects are systemic, however, this review is specific to bone and
dental outcomes in regards to fluoride consumption. The clinical significance
of the review indicates that there is a knowledge gap related to the risks and
benefits associated with fluoride and skeletal and bone health.
Methods
Research studies were
gathered after developing a database of search words that were placed into
CINAHL, EBSCO, ProQuest, and PubMed. These studies were used to compile
and analyze the research question of: Fluoridation Effects on Skeletal and
Dental Health: A United States and International Review
The key search words utilized
were: fluoride, dental caries, bone, health, and fluoridated water.
The pertinent literature was used was from eighteen articles, dated 2006-2014,
four articles were dropped due to their late year of printing, one was
discarded because it focused on neurotoxicity effects on patients more than
orthopedic responses from long term consumption of fluoride. Studies
other than that of bone and tooth health were excluded from this research
project. Sample demographics included; age groups from pediatrics to
geriatrics of both males and females of several countries. Articles were
gathered from several worldwide points of research, providing a common global
effect of fluoride on bone.
Countries included for the
study research were from, Australia, China, England, Germany, Great Britain,
India, USA, Netherlands, and South Africa. Considerations of fluoride
intake via oral fluids, water, and supplements as well as external, such as
fluoridated toothpaste and manual application of rinses were included. It was
discovered that there is no method of determining an accurate intake of fluoride
for any particular person. Variables such as volumes of fluorinated fluid
a person consumes, what medications they were taking that contained fluoride,
and if they took fluoride supplements or a rinse was a common confounder in our
research.
The research questions were
addressed utilizing content analysis to identify study characteristics. Such
characteristics included conceptual and theoretical framework used to form this
presentation. Five members of our group gathered, reviewed, and collaborated
on the appropriate studies to include out of the original 23 studies gathered
from our searches.
Results
The
results of human exposure to fluoride varied greatly across the studies
reviewed. Phipps (2000) found that women with continuous exposure to
fluoride experienced 31% less hip fractures (P = 0.028) and 27% less vertebral
fractures (P = 0.033). There was an increased risk of wrist fractures (P=0.051)
and a decreased risk of humerus fractures (P=0.387), however such results were
not statistically significant. Li (2001) found that long-term exposure to water
with fluoride levels greater than 4.32 part per million (ppm) increased the
risk for hip fractures among Chinese subjects. Long-term exposure to water with
fluoride levels of 1.00-1.06 ppm significantly lowered the risk of bone
fracture (p< 0.05). Pizzo (2007) suggests topical fluoride reduces
caries in industrialized and developing countries.
Vestergaard
(2008) found that fluoride treatment increased hip and spine bone mineral
density by 2.1% (95% confidence interval (CI): 0.9%, 3.4%, p<0.01, n=1,434)
and 7.9% (95% CI: 5.4%, 10.5%, p<0.001, n=1,774) respectively. A longer
duration of fluoride treatment was associated with an increase in spinal bone
mineral density (5.04 +/‐ 2.16 per
cent per year of treatment). Sub-group analysis showed a statistically
significant reduction in both vertebral (odds ratio (OR) 0.28; 95% CI: 0.09,
0.87, six studies, n=593) and non-vertebral fractures (OR 0.52; 95% CI: 0.28,
0.76, six studies, n=768) when the daily dose of fluoride was 20 mg or less.
Higher doses of fluoride was associated with an increase in vertebral and
non-vertebral fractures, however, this was not a statistically significant
finding.
Bassin, Wypij, Davis, and Mittleman (2006)
found males (but not females) exposed to fluoride in their drinking water
during childhood were at increased risk of developing osteosarcoma before age
20 (OR 5.46; 95% CI: 1.50, 19.90). Levy and Leclerc (2012) found the increased risk of
osteosarcoma in American males versus female aged 15-19 (p<0.001) was not
related to the fluoridation status in their respective states. Blakey et al.
(2014) found similar results to that of Levy and Leclerc (2012) whereby in Great Britain, no
relationship between water fluoridation and osteosarcoma was found (relative
risk (RR) per one ppm increase in the level of fluoride = 1.001; 90% CI:
0.871, 1.151). A connection between water fluoridation and Ewing’s sarcoma was
also unable to be found (RR = 0.929; 90% CI: 0.773, 1.115). Additionally,Chachra, Limeback, Willett, and
Grynpas (2010), Levy et al. (2014), and Jones, Riley, Couper, and Dwyer (2008)
did not find enough evidence to suggest an association between water
fluoridation and negative bone health.
Odiyo and
Makungo (2012) found an increased incidence of dental fluorosis in African
households that use groundwater with levels of fluoride exceeding 1.5 mg/l. Similarly,
Wondwossen, Astrom, Bjorvatn, and
Bardsen (2004) found a 91.8% and 100% increase in dental fluorosis
among Ethiopian children who drank water with fluoride levels of 0.3–2.2 mg/l
and 10–14 mg/l respectively. Kakumanu (2013) found a serum fluoride
level of 0.43 mg/l or fluoride intake of greater than 20 mg per day (about
100-150 tea bags) can lead to skeletal fluorosis. . Chen et al. (2013) Fluoride
intake of 3.475mg/L, on average, over a long period of time (~10yrs) causes
dental fluorosis, changes in bone metabolism, and bone damage among children of
Chinese villages.
As a
result of a literature review, Harding and O’Mullane (2013) found between 1983 and 1984,
dental caries had decreased at a greater rate in fluoridated communities since
the 1970 initiation of fluoride in drinking water in Ireland at 0.8-1.0 ppm.
When re-assessed in 2002, a similar finding of decreased caries in fluoridated
communities was present. However, rates of dental fluorosis increased at a
greater rate in communities with fluoridated water than those with
non-fluoridated water.
Discussion
Dentist Frederick McKay, in the dawn of the 20th century,
initiated the water fluoridation research that continues through the present
day.30,35 Dr McKay was inquisitive regarding the distinctive
brown stains he was noticing on the teeth of many of his Colorado
patients. Distinctive brown stains that were evidently highly resistant to
caries lesions. Dr. McKay referred to these stains as “mottled enamel”. Dr
McKay subsequently found mottled enamel in other communities throughout the
United States.5,29-30 Inquisition formulated the hypothesis
that something in the drinking water was responsible for the caries resistant
mottled enamel. Chemist H.V. Churchill took up the mantel in the 1930’s
conducting water analysis and subsequently identifying fluoride as the
etiological agent of the mottled enamel. The term mottled enamel would then be
replaced with enamel fluorosis.5,29-30 Joining these efforts
was a Public Health scientist named H. Trendley Dean, who initiated a series of
epidemiological investigations to test the hypothesis that increased fluoride
concentration in water supplies was associated with a reduction in caries
prevalence.5 During this time period, the so-called 21-City
study conducted in Colorado, Illinois and Ohio confirmed this inverse
relationship between increased fluoride concentration in drinking water and caries
prevention. When fluoride levels were found to be up to 1.0 ppm in drinking
water, researchers observed a lower prevalence of fluorosis
(10-12%) and even the 10-12% was considered a very mild fluorosis. On the
contrary, fluorosis increased when the fluoride in drinking water exceeded the
10. ppm level.5,29 These early findings became the genesis for
the creation of community water fluoridation programs in the United States and
Canada.6
Over ten years later, Grand Rapids Michigan became
the first city in the world to manipulate the public water supply raising the
fluoride level to 1 ppm. 5,29 Around this time, the town
of Aurora Illinois (whose water was naturally fluoridated at 1.4 ppm) and the
town of Muskegon Missouri (the experimental control) became subjects in a
clinical study on the effects of water fluoridation on caries.5,19
Joining this important research was Newburgh, NY and Kingston NY as the
control city. Followed in 1946, with Wvanston, Illinois and Oak Park, Illinois
as the control, and in Ontario Canada Brantford and Sarnia as control and
naturally fluoridated Stratford. Six years later it was reported
that the children living in Grand Rapids developed caries during the period of
water fluoridation at a rate half of the rate of the children
living in Muskegon (the experimental control town) and had similar levels
to those seen in Aurora (naturally fluoridated town).9 Subsequent
sequential cross-sectional investigations over 13-15 years demonstrated a
caries reduction of 50-70% in children living within the fluoridated
communities.5 Motivated by these long-term community studies,
the introduction of water fluoridation gained momentum in the USA and in a
number of other countries throughout the world.6,19,29
Since the 1950’s within the United States, as well as
throughout the world, there has existed a dissenting voice resisting the
fluoridation of community water. This dissenting voice has been expressed
within a multitude of organizations opposed to the addition of fluoride in the
public water systems. Principled concern included the issue of freedom of
choice, as well as perceived and potential risks to human health posed by
fluoride.8,31 Conflicting studies linking/not linking fluoride
to numerous disease states, cancer, Downs’ syndrome, intelligence, and an
increase in fracture rate have created public confusion.28-29,31 Presently,
a multitude of particularly European countries do not or no
longer maintain water fluoridation schemes on grounds of a believed
violation of medical ethics. The argument involves Silico-fluorides being
used in water fluoridation being regarded as the addition of an unlicensed
medical substances being added to the water, and as a human rights
argument. Silico-fluorides being administered to large populations without
informed consent or medical supervision.8,13,19
Water Fluoridation In The World
Current estimates place over 300 million people in 39
countries worldwide residing in communities depended on water supplies being
fluoridated.3,29 Here in the United States in excess of 170
million people (67% of the population) currently reside in communities
enhancing their water supply with fluoride.31
Role of water fluoridation in caries prevention :
Systemic vs topical effect of fluoride
For many decades the presumption has been that fluoride benefits
occur before teeth emerge by incorporating into hydroxyapatite
crystals and leading to the formation of fluorapatite, a less soluble
enamel apatite.12 Twenty years of research later we have a new
understanding.6,12,15,23
A number of studies showed that the differences in fluoride
concentration in surface enamel between permanent teeth from low-fluoride and
fluoridated areas were minimal, whereas an inverse relationship between fluoride
levels in enamel surface and caries experience was not found.12,15 Several
laboratory investigations have clearly demonstrated that the presence of low
levels of fluoride (0.03 ppm or higher) in saliva and plaque fluid
reduces the rates of enamel demineralization during the caries process and
promotes the remineralization of early caries lesions.11-12,15 On
the other hand, the level of fluoride incorporated into enamel by systematic
ingestion was proved to have no significant effect in preventing / reversing
caries.11 Moreover, the reexamination of clinical /
epidemiological data fro early and recent community water fluoridation studies
supported the current view that the cariostatic effect of fluoride is almost
exclusively posteruptive and the mechanism of action is topical.12,15,23 A
person living in a fluoridated community in fact may increase this level to
about 0.04 ppm several times during the day.23 In addition, it
has been found that fluoride may also affect oral plaque bacteria by the
interference with acid production.3,6,11 The implications of
these concepts are that frequent exposure to low concentration of fluoride in
the oral cavity is the most important factor in preventing / controlling
caries; on the other hand, the anticaries effects of systemic fluoride are
recognized to be minimal.6,11,23,38
The impact of fluoride-containing products
In the decades past, a number of authors focused their attention
on the caries trend within the communities without fluoridation in comparison
to communities that ceased water fluoridation in comparison to communities
without water fluoridation.1,5,15,19,21,23 In these communities
during the years of water fluoridation, a caries reduction had been observed,
but after the cessation, caries prevalence either did not rise, remained almost
the same or even decreased further.15,21,23 These findings
demonstrate that the cessation of fluoridating community water had no adverse
effects on caries prevalence.
Several epidemiologic studies have supported the evidence
that the degree of caries reductions directly attributable to water
fluoridation have fallen in recent decades. By 1985, within the United States
caries levels in the permanent dentition of children living in community
fluoridated areas was only 18% lower compared to children living in
non-fluoridated areas.5 Among adolescents during this same time
period the caries reduction attributable to community fluoridated water was
8-37% (mean: 26.5%).5 Within the past decade, the gap between
caries rates between fluoridated and non-fluoridated communities has been
significantly lesser than decades prior.6,9,19,23,26 Within the
European nations that never initiated community water fluoridation
programs, a significant reduction in caries rates has been demonstrated.26
The body of literature attributes differing reasons as to
the cause for this decline in caries rates. Many studies attribute the
introduction of fluorinated toothpaste in the early 1970’s.6,9,11,26,29 The
shrinking health advantage from community fluoridated water has been
attributed to the robust expansion of fluoride-containing
products found in the market. New mouth rinses, bottled water,
dietary supplements, and dentist applied or prescribed gels, foams, or varnishes.6,26 The
utilization of these newer topical fluorides have generated caries reduction
rates greater than the rates generated by community fluoridated water.36 Utilizing
these new topical fluoride products the fluoride may be for up to 6 hours mix
with the saliva and plaque in the oral cavity at concentrations that generate
therapeutic effects on enamel demineralization / remineralization.11,23-24 Currently
community fluoridated water programs are reducing caries rates by 15%.32,36 Fluoride
toothpaste in conjunction with mouth rinse reduces caries by 24-26%. The
gels and foams reduced caries at a rate of about 26-28% whereby fluoride
varnish reduced caries by about 46%.6,36
Water fluoridation and socioeconomic dental health inequalities
Despite significant public health strides in the prevention
of caries within the economies classified as developed, caries prevention rates
remain stratified along socioeconomic levels. And caries prevention
continues to this day to be a significant public health problem for
the majority of the world population residing in what are classified as
developing nations.9,17,20,26 Studies conducted within and
external to the United States have suggested community water fluoridation may
reduce these oral health inequalities that exist between social classes.4,18,33 Other
studies suggest an absence of evidence supporting this suggestion.27 As
previously noted, confounding the debate are the studies that suggest advances
in children oral health is attributable to a greater degree to fluoride-containing
toothpaste as opposed to community fluoridated water systems.6,9,11,26,29 Variables
such as socioeconomic status, lifestyle and dietary habits all
affect the prevalence of caries making predictions more confounding.10,34
Irregardless of these trends, National and International agencies
joined by dental associations continue to call for community water fluoridation
programs targeting “underprivileged” communities.6,17,29,31-32 The
World Health Organization’s World Oral Report 2003 in what appears to be more
in line with the trends identified in the body of literature advances the
pursuit of developing affordable toothpaste for utilization in communities
identified underprivileged.32 In their report, the World Health
Organization cited the economics of implementation of community water
fluoridation programs versus the utilization of fluoride toothpastes.
Fluorosis: an emerging problem in fluoridated communities
Long term utilization of fluoride prior to the developmental
emergence of our teeth may result in Fluorosis. Fluorosis is
classified as a hypomineralization of bone enamel whereby the bone surface and
subsurface become pourous. This pourousness of the bone causes the bone enamel
to appear opace, pitted and or stained.3,6,31 Community fluoridated
water supplies with a fluoride level of 1 ppm , may manifest a community
fluorosis prevalence of 51%. This has not become the significant public health
concern it may well deserve due to the fact that the fluorosis tends to be
denatured enough as to not be visible to the public. The aesthetics have yet to
be influenced.3,16 Of concern however, is the body of
literature illucidates a trend favoring an increase in the prevalence of
fluorosis within communities forging ahead with community fluoridated water
programs. One systematic review concluded that fluorosis to the degree to be of
an aesthetic concern to the public affected 12.5% of the population residing in
fluoridated communities in the United Kingdom.28 The public
health concern is manifested by the fact that fluorosis, irregardless of
aesthetic degree is an early indication of excessive intake of
fluoride during the development of enamel formation.
As discussed earlier, the promotion of fluoride toothpaste versus
the economics of community water fluoridation programs has been advocated. Of
concern made manifest by the body of literature is the knowledge regarding
young children’s inability to adequately and sufficiently expectorate the
fluoride toothpaste enough to illiminate the risk of fluorosis.2-3,6,14 Risk
of fluorosis is further manifest by the consumption of powdered infant formula
that has been prepared with fluoridated water.3,22,25,35 Contributing
to the risk of fluorosis are the consumption of food and beverages manufactured
or processed in regions of community fluoridated water. Some of the bottled
waters currently found in the market contain significant fluoride
concentrations.3,22,25,35 The advancing utilization of dietary
fluoride supplements during the early years of life advances further the risk
for fluorosis.2-3,6-7,31,35
In an attempt to mitigate these advancing dietary fluorides, based
upon the body of literature recommendations have come forth to limit dietary
fluorides, especially within those communities supplied with community
fluoridated water.2,6,25,29,31,38 With this aim, public health
organizations and dental associations have advocating improved fluoride
delivery systems.6,23,31,38 In response to the body of
literature, the Forum on Fluoridation 2002 advocated reducing the fluoride
content within community fluoridated water supplies to between 0.6 to 0.8 ppm
which is believed would reduce the fluorosis risk while not abatting the caries
prevention advantages.3
Fluoride level in drinking water and osteosarcoma
There exists a biological pathway whereby fluoride may potentially
contribute to the incidence rate of osteosarcoma. And this pathway would be at
its most significant during periods of bone growth, especially in males. 99% of
the aggregate of fluoride within the human body is located in the skeleton.
Roughly 50% of daily ingested fluoride becomes deposited into
calcified tissue, either bone or teeth. Fluoride triggers cells to
commence cell division, thus fluoride advances the proliferation of
osteoblasts exacerbated during periods of bone growth. Within our youth
population, bone structure actually permits greater adherence for the fluoride
to exchange. The metaphyseal regions of long bones, where long bone
growth occurs, is a preferred location for the genesis of Osteosarcoma within
our youth. Since the amount of fluoride in bone is dependent on the amount of
fluoride ingested, and the quantity of intake is on average greater for males,
males are at a higher risk.
This relationship between fluoride and osteosarcoma has been
examined in a relatively limited number of animal and human studies with
confounding and conflicting results.
Blakely in an ecological analysis designed to cover the entire
nation of Great Britain found no association between fluoride in drinking water
and osteosarcoma or ES. Bassin in a relatively small ( 103 cases aged
under 20 years) case-control study reports an increased osteosarcoma risk
with fluoride in the drinking water for males and no significant risk for females.
However, another case-control study utilizing the same dataset found no
association. Two ecological studies from the United States and Ireland
concluded no association between fluoridated drinking water and osteosarcoma.
Both of these studies had weaknesses in their reporting of fluoride exposure.
Summary & Recommendations
Fluoridation of drinking
water was instituted as a major public health initiative to reduce dental
caries in children and adults in the United States. The CDC has recognized
water fluoridation as one of the ten greatest public health achievements of the
twentieth century (CDC,1999). Despite this, arguments against water
fluoridation began shortly after the introduction of fluoride into the public
water supply. These arguments arose from concerns of safety and control
(Harding & O’Mullane, 2013).
After the initiation of water
fluoridation, early studies estimated a 50-70% reduction in dental caries due
to fluoridation. This number eventually plateaued as access to bottled water
and use of fluoride toothpaste became widespread (CDC, 1999).
This research review on water
fluoridation was of interest given the controversial nature of the current
recommendations and findings within the literature. The research conducted does
exhibit trends of high incidences of dental fluorosis from higher levels of
fluoride exposure through drinking water. It appears that research regarding
dental fluorosis due to fluoride is more prevalent when compared to
osteosarcomas, skeletal fluorosis, and fluoride. Perhaps this is because
fluorosis is visible to the eye and therefore the link between fluoride and
dental fluorosis was made earlier than the link between fluoride, skeletal
fluorosis, and osteosarcomas. In 2006 the National Research Council (NRC)
was asked to reevaluate the maximum contaminant level goal (MCLG) of fluoride
in drinking water set forth by Environmental Protection Agency in 1986. The
MCLG refers to the maximum contaminant level in naturally occurring
fluoridation and is not the recommendation for artificially fluoridated water.
The MCLG has been 4mg/L since 1986. After the NRC reviewed collective
evidence, comprised of studies from the early 1990s until 2006, the committee
collectively determined that the MCLG of 4 mg/L of fluoride should be lowered
as such exposure puts children at risk for severe dental fluorosis.
Future Research
Future research should focus
on a number of areas regarding fluoridation of water in order to draw accurate
conclusions about the safety of fluoride in drinking water. First, research
should focus on longitudinal studies in fluoridated and non-fluoridated
communities and compare bone metabolism measurements and bone complications
between the two. Calcitonin was reported by Chen et al. (2013) to be the most
sensitive of bone metabolism indicators and may be of use in further research
(Chen et al., 2013). Secondly, research should focus on exact levels of
fluoridation that produce adverse effects such as dental fluorosis.
According to the CDC, studies done in the United States from 1979-1989
looking at the effectiveness of water fluoridation in caries reduction had
tapered off to 8-37% (CDC, 1999). As noted above, the NRC’s research
suggested that the MCLG of 4mg/L be lowered. Perhaps this is an argument to
reduce the amount of fluoride artificially added to drinking supplies as to
further reduce the risk for dental fluorosis (National Research Council, 2006).
Other research should focus
on the cost of artificial fluoridation and the actual benefit. As mentioned
above, the availability of bottled water and fluoride toothpaste has aided in
the decrease of dental caries among populations. The research does argue
however, that lower-income populations may have limited access to these
resources and water fluoridation is a means of providing the benefits of
fluoridation to these populations (CDC, 1999). Research of the risks and
benefits of water fluoridation in a diverse group of communities should be
undertaken. This will provide information about the reliance of lower-income communities
on fluoridated water for dental protection.
The link between fluoride and
osteosarcomas remains to be seen in the literature. Levy and Leclerc (2012)
found that there was no definitive link between fluoride and osteosarcomas and
similarly, Blakey et al. (2014) found there was no evidence of a relationship
between fluoride in drinking water and osteosarcoma or Ewing sarcoma.
Contradicting these findings was the study done by Bassin et al. (2006), that
links increased fluoride intake with increased incidences of osteosarcomas in
males. As mentioned by Blakey et al. (2014) the research done by Bassin
et al. (2006) had a small sample size. Thus far, it seems that lack of
participants has been a barrier to further research on this topic, but given
the concerns for safety, it is imperative to continue researching the effects
of fluoride on bone health and health in general.
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007-0437-6
Wondwossen, F., Astrom, A.N., Bjorvatn, K., & Bardsen, A.
(2004). The relationship between dental
caries and dental fluorosis in areas with moderate and high-fluoride drinking
water in ethiopia. Community Dentistry and Oral Epidemiology, 32,
337-344.
Appendix A
Evidence Table
Note: No Observational or Qualitative Studies were included in this
analysis.
|
Clinical question/topic
(generic PICO format): What are the effects of fluoride on dental and bone
health?
P: Does fluoride improve or deteriorate bone
dental and bone health?
I: Addition of fluoride in that drinking water.
C: Analyze data comparing the effects of
fluoride on dental and bone health
O: Fluoride weakens teeth and bones
|
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Inclusion/Exclusion criteria: Within the last 14
years, topics pertain to bone and dental health and/or caries and fluoride
consumption. Exclusion criteria: Other health related problems related to
fluoride consumption; other sources of fluoride other than water supply.
|
|
Keywords/search terms: Fluoride, dental
caries, bone, health, fluoridated water
|
|
Databases Searched: CINAHL, ProQuest,
EBSCO, PubMed
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Experimental Studies
|
First Author/
year
|
Study Question
|
Study design/
intervention
|
Sample/Size Sampling
method
|
Analysis
|
Significant findings
|
|
Kakumanu, (2013)
|
|
|
|
|
Serum fluoride of 0.43mg/L can lead to skeletal
fluorosis.
|
|
|
|
|
|
|
|
Quantitative Studies
|
First Author/
year
|
Study Question
|
Study design
(domain/tradition)
|
Sample/Size Sampling
method/Setting
|
Analysis/
themes
|
Significant findings
|
|
Bassin, E. (2006)
|
What is the relationship between the level of
fluoride in drinking water and the incidence of osteosarcoma?
|
case-control design
|
103 cases under the age of 20 and 215 matched
controls
|
exploratory analysis
|
an association between fluoride exposure in drinking
water during childhood and the incidence of osteosarcoma among males but not
consistently among females
|
|
Chachra, D. (2010)
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The long-term effects of water fluoridation on the
human skeleton.
|
Quantitative Longitudinal
|
92 femoral heads; 53 from patients in Toronto and 39
from Montreal Canada from SEP 1996-AUG 2000 who were undergoing total hip
arthroplasty. Median age of donors was 66 Y from Toronto and 70 Y from
Montreal.
|
Epidemiological studies have failed to observe an
effect of municipal fluoridated drinking water on bone.
|
1) The lack of a strong relationship between fluoride exposure
and bone fluoride content.
2) Wide variables in properties makes it difficult to pinpoint
fluoride-related effects.
3) Decades of studies have shown minimal evidence of
effects of fluoride on bone and that fluoridated water affects adults with
healthy bone.
|
|
Levy, S.M.
(2014)
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Effects of life-long fluoride intake on bone
measures of adolescents: A prospective cohort study
|
Longitudinal prospective cohort study
|
1382 cohort members from Iowa. Newborn to 15 yrs.
630 members received 1 or more bone density
assessments,415 bone scans to age 15, and 358 completed accelerometry data.
Overall, 358 members were included in the analysis.
|
Exploratory analysis
|
1) Variance in mineral density of bone was very low.
2) None of the weak associations with fluoride intakes was
statistically significant.
3)The associations between fluoride intake and bone outcome
measures remain weak.
4)
|
|
Jones, G. (2008)
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1. Is water fluoridation associated with altered
fracture risk (particularly of the hip) at a population level. 2. Are the
differences between studies consistent with confounding or chance variations
between studies.
|
Quantitative Meta-analysis
|
26 epidemiological studies collected from May
1996-November 1997 using Medline database. 5 excluded r/t no extractable
data. 18 extractable data r/t fx; 10 r/t bone mass (7 had both). 10
Ecological; 11 cross-sectional; 3 cohort. Sample: 21 Studies
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Fleiss Method; standard chi-squares (homogenecity)
and random effects (heterogenicity); multi/univariate analysis
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1. Water fluoridation has no evident effect on fracture risk.
2. Studies were of poor quality which authors
identified; more rigorous studies needed to further evaluate effect of
fluoride on health.
|
|
Phipps, K. (2000)
|
Does fluoridation influence bone mineral density and
fractures in older women.
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Multi-Centered Prospective Study
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9704 white women >65 years old. Selected from 4
different areas in the U.S. by reviewing jury selection, registry of voters,
motor vehicle records, membership records of health plans.
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Chi Square tests, proportional hazard, logistical
regression models; variance/covariance; multivariable models.
|
Continuous fluoride exposure 31% less hip fractures;
27% less vertebral fractures; increased wrist fractures/ decreased bone
mineral density (not stat. significant)
|
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Levy, M. (2012)
|
Is fluoride in the drinking water associated with
the presence of osteosarcoma’s in children and adolescents?
|
Ecological study
|
Gathered from CDC Wonder Database of 5-19 year olds
from 1999-2006 categorized by age group, state and sex.
|
Gamma distribution method, Poisson regression
models, SAS statistical software, SEER statistical software
|
Fluoridated drinking water is not associated with an
increased presence of osteosarcomas in children and adolescents
|
|
Blakey, K. (2014)
|
Is fluoride a risk factor for bone cancer?
|
Quantitative ecological study
|
2566 persons with osteosarcoma; 1650 Ewing’s sarcoma
aged 0-49 gathered from 1980-2005; Data gathered from 10 regional cancer
registries from Great Britain.
|
Negative binomial regression with STATA
version 12. Likelihood ration tests, 2-sided P values, sensitivity analyses;
positive threshold effect, Akaike Information Criterion
|
No evidence to link levels of fluoride (artificial
or natural) in the drinking water to osteosarcoma/Ewing’s sarcoma in
Great Britain
|
|
Li, Y. (2001)
|
Is there a link between levels of fluoridated water
and overall/hip fractures in 6 Chinese communities
|
Randomized Clinical Trial
|
8266 males and females split into 6 groups of > or equal to
50 years old.
Random recruitment in communities with
fluoride water levels from 0.25-7.97 who have lived in the same area for 25
years.
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Multiple logistic regression; bivariate analysis,
modified method of Taves, Chi squares, and T-tests.
|
Long-term exposure from drinking fluoridated water
> or equal to 4.32ppm increases overall fracture risk. Levels 1-1.06ppm
decrease overall fracture risk relative to no fluoride in the water, this
finding was not noted however in hip fractures
|
|
Odiyo, J.O. (2012)
|
What are the effects of fluoride concentrations in
groundwater in Siloam Village in African
|
Quantitative
|
150 Households (total 400 peope) and 189 school
learners in a rural African village (Siloam)
|
None specified; Survey/Questionnaire
|
87% households use fluoridated and 85% had mottled
teeth; 50% 11-14 year old school learners had mottled teeth; 52.7% of
households have 1-5 people in their household with mottled teeth. 91% knew of
neighbors with mottled teeth
|
|
Chen, S. (2013)
|
|
Quantitative
|
|
|
Low doses urinary fluoride cause slight
abnormalities of bone mineral density but at higher levels cause significant
bone mineral density
|
|
Vestergaard, P. (2008)
|
1) Does fluoride treatment alone or in combination with
calcium, vitamin D or an antiresorptive drug increase
spine or hip BMD compared with calcium, vitamin D
or an antiresorptive drug?
2) Does fluoride treatment alone or in combination with
calcium, vitamin D or an antiresorptive drug reduce the
risk of vertebral or non-vertebral fractures compared
with calcium, vitamin D or an antiresorptive drug?
3) Were there differences in the effect of fluoride on BMD
or fracture risk that could be attributed to fluoride
formulation, dose or treatment duration?
4) What were the adverse effects of fluoride
treatment?
|
Meta-analysis
|
25 random clinica trials from PubMed (1951-present),
Embase (1974-present), and ISI (1945-present) narrowed from 2028 articles.
Search terms: Fluoride AND bone mineral OR fracture
|
Random effects model, t-tests, Chi squares, odds
ratio, weighted mean difference, funnel plots, forest plots, regression
model, Trim and Fill method, Jadad quality score, review manager 4.2.7.
|
Fluoride treatment increased spine/hip bone mineral denisty
depending on treatment duration. No effects seen in risk of hip/spine
fracture risk. Quality of bone during fluoride treatment is inferior.
Fluoride anabolic effect bone mineral decreases biomechanical
competence of new formed bone
|
|
Wondwossen, F. (2004)
|
What is the relationship between
caries and dental fluorosis in Ethiopian children living in Rift Valley areas
known for endemic fluorosis?
|
Prospective Quantitative Design
|
A census of all children of the
resident study population aged 12–15 years was undertaken. A total of 306
children, 152 girls (mean age 13.5 years) and 154 boys (mean age 13.1 years),
were included in the study. Informed consent was obtained from the children
and their parents, as well as from local authorities.
|
Total of 306 children (12–15 years
old), selected from areas with moderate (0.3–2.2 mg/l), or high (10–14 mg/l)
fluoride concentration in the drinking water were interviewed and examined
for caries and dental fluorosis. Scorings were recorded according to the DMF
system, and the Thylstrup-Fejerskov (TF) Index.
|
A positive relationship between
dental caries and dental fluorosis was observed across various tooth types,
in both areas.
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Literature Reviews
|
First Author/
year
|
Study Question
|
Study design
(domain/tradition)
|
Sample/Size Sampling
method/Setting
|
Analysis/
themes
|
Significant findings
|
|
National Research Council (2006)
|
Evaluating the effects of Fluoride in Drinking Water
regarding teeth/bone health
|
Literature Reviews of studies regarding use of
fluoride and its effects on dental/bone health
|
|
|
|
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Pizzo,G.
(2007)
|
What is the current role of community water fluoridation in
preventing dental caries?
|
Meta-
Analysis
|
Original articles and reviews published in English from 1/2001
to 6/2006. No mention as to how many. Bibliography references 38 articles
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Themes:
a. systemic vs topical effect of fluoride
b. Impact of fluoride containing products
c. water fluoridation and socioeconomic dental health
d. Fluorosis: an emerging problem in fluoridated communities
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Although water fluoridation may still be a relevant public
health measure in poor and disadvantaged populations, the use of topical
fluoride offers an optimal opportunity to prevent caries among people living
in both industrialized and developing countries.
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