Cover Letter 2
Edgar Oganessian, Romana Ivancakova, Erika Lencova, Zdenek Broukal: Alimentary Fluoride Intake in
Preschool Children
The second revision
Authors thank honestly for both editor’s and reviewers´ comments for reediting the manuscript.
Following changes and ads were made in the agreement of all authors.
In the resubmitted manuscript these changes and ads are typed red:
Editor's comment:
Authors corrections
Other editorial requirements:
The abstract revision according to the guidelines
Done.
Background
The knowledge of background alimentary
fluoride intake in preschool children is of
utmost importance for introducing optimal and
safe caries preventive measures for both
individuals and communities. The aim of this
study was to assess the daily fluoride intake
analyzing duplicate samples of food and
beverages in a smaller group of individuals. An
attempt was made to calculate the daily intake
of fluoride from food and swallowed
toothpaste.
Methods
Daily alimentary fluoride intake was measured
in a group of 36 children with an average age of
4.75 years and an average weight of 20.69 kg at
baseline, by means of a double plate method.
This was repeated after six months. Parents
recorded their child’s diet over 24 hours and
collected duplicated portions of food and
beverages received by children during this
period. Pooled samples of food and beverages
were weighed and solid food samples were
homogenized. Fluoride was quantitatively
extracted from solid food samples by a
microdiffusion method using
hexadecyldisiloxane and perchloric acid. The
content of fluoride extracted from solid food
samples, as well as fluoride in beverages, was
measured potentiometrically by means of a
fluoride ion selective electrode.
Results
Average daily fluoride intake at baseline was
0.389 (SD 0.054) mg per day. Six months later it
was 0.378 (SD 0.084) mg per day which
represents 0.020 (SD 0.010) and 0.018 (SD
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English copy edition of the paper
0.008) mg of fluoride respectively calculated
per kg bw/day.
When adding the values of unwanted fluoride
intake from the toothpaste shown in the
literature (0.17-1.21 mg per day) the estimate
of the total daily intake of fluoride amounted to
0.554-1.594 mg/day and recalculated to the
child’s body weight to 0.027-0.077 mg/kg
bw/day.
Conclusions
In the children studied, observed daily fluoride
intake reached the threshold for safe fluoride
intake. When adding the potential fluoride
intake from swallowed toothpaste, alimentary
intake reached the optimum range for daily
fluoride intake. These results showed that in
preschool children, when trying to maximize
the benefit of fluoride in caries prevention and
to minimize its risk, caution should be exercised
when giving advice on the fluoride containing
components of child´s diet or prescribing
fluoride supplements.
English of revised manuscript was “polished” by
Prof. Kenneth Eaton from UCL (UK).
In case English is still poor I will contact Edanz.
Reviewer's report (1): Juliano Pessan
1. Page 7, paragraph 1, line 1: Why was TISAB III used
in proportion 1:1 (v:v)?
This buffer is usually added at a 1:10 ratio. A
reference is needed.
2. Page 7, paragraph 1, lines 6-7: The authors stated
that quantitative extraction of fluoride was done "by
a micro diffusion method using hexadecyldisiloxane
and perchloric acid". The same information appears
in the abstract. However, on the following paragraph
(line 2), it appears that perchloric acid was saturated
with "hexamethyldisiloxane". This needs to be
clarified.
Page 4, paragraph 1, line 5: Please insert "by which"
after "The reason"
Sorry for overlooking missing number zero
(1:10).
Corrected:
In samples of liquid components TISAB III
solution (1:10; v:v) was added for the pH
adjustment. Fluoride content was measured
directly by potentiometric method using
fluoride ion selective electrodes described
below.
Corrected:
Aliquot samples of solid and semi-solid food
components with an added known volume of
deionised water were also homogenized and
processed by the quantitative extraction of
fluoride by a micro diffusion method according
to Taves (1978) [28] as modified by Van Winkle
et al. (2005) [29].
A one ml sample of solid food was put in a 10
cm plastic dish followed by 2 ml of 5M
perchloric acid saturated with
hexadecyldisiloxane.
Corrected:
The reason why pre-school age children have
been selected for the study of fluoride intake is
that at this age an early secretory stage of
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Page 4, paragraph 1, lines 7-10: The sentence is
confusing. As a suggestion, the authors could
consider: "Fluoride intake has usually been indirectly
calculated, based on the records of daily diets and
measured fluoride content in the most frequently
consumed types of food and beverages [16, 17, 18,
31]."
Page 5, paragraph 1, line 4: Quotation marks of
"water for infants" are not necessary.
Results (page 9, paragraph 1, lines 5-6): Please
change "1 kg child's weight and 1 day" by "kg child's
weight per day".
Results (page 9, paragraph 4, line 1): Please replace
"child´weight" by "child's weight".
Page 10, paragraphs 2 and 3 should be combined
into a single paragraph.
Page 11, paragraph 2, line 2. Please insert
"However," before "the estimate of alimentary..."
Table 3 should be presented in the Results section of
the manuscript. No
caption for tables should appear in the Discussion.
development of the permanent anterior teeth
enamel takes place and is very sensitive to
increased fluoride intake [2, 13].
Corrected:
Fluoride intake has usually been calculated
indirectly, based on the records of food and
drinks consumed each day and to the known
fluoride content ofn the most frequently
consumed types of food and beverages [16, 17,
18, 31].
Corrected:
Bottled water for infants is very popular, even
in families of preschoolers, for its low content
of nitrates, nitrites and sulphates.
Corrected:
The total fluoride intake of liquid and solid food
components was then calculated per 1 kg
child's weight per day.
Corrected:
The difference in the daily intake of fluoride
calculated per child’s weight and day between
baseline and after six months of study was not
statistically significant (p<0.190).
Corrected:
The double plate approach therefore provides
better evidence for alimentary fluoride intake
than the “basket” approach. Even so, the
results of this study should be interpreted with
caution as they depended on how thoroughly
and accurately the parents duplicated the food
and drinks that their child actually received.
Another limitation of this study is that the
duplicate plate method was conducted for only
24 hours, both at baseline and after six months.
Recent studies have suggested that it should be
done at least for two consecutive days [11, 24,
27] in order to provide more accurate
estimates. An attempt was made to reduce that
limitation of the daily fluoride intake estimates
by collecting food samples on days when their
parents were off work and at home.
Corrected:
However the estimate of alimentary fluoride
intake from toothpaste in preschool children
must be treated with caution as it is highly
variable among children [1, 19] due to the
amount of toothpaste used, its flavour [15] and
other factors.
Added to the Results section:
« Table 3 near here »
Using the values of unwanted fluoride intake
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from the toothpaste shown in the literature [6,
7, 9, 10, 16] (0.17-1.21 mg per day) it was
possible to estimate how the similar intake
from fluoride toothpaste in the summation with
the results of this study contributed to the total
daily intake and in the calculation of the intake
of fluoride per 1 kg bw/day. The estimate of the
total daily intake of fluoride amounted to
0.554-1.594 mg/day and recalculated to the
child´s body weight to 0.027-0.077 mg/kg
bw/day (Table 3).
Changed in the Discussion section:
When adding the values of unwanted fluoride
intake from the toothpaste shown in the agematched children in the literature [6, 7, 9, 10,
16] (0.17-1.21 mg per day) it is possible to
estimate that fluoride intake on average would
reach the lower limit of the safe range (0.05 to
0.07 mg/kg bw/day). This range is supported by
previous studies [16, 17, 18]. However, for
some children this range could be exceeded.
Reviewer's report (2): Michael McGrady
... to expand the discussion to include the effect of
stomach contents, pH and presence of ions such as
calcium on the absorption of fluoride systemically as
this has a major impact upon the relative risk of
developing fluorosis.
... a discussion relating to the risk benefit of
fluoride and caries in Discussion and Conclusion
sections
Added to the Discussion section:
The dynamics of fluoride absorption, whether
coming from food or swallowed toothpaste
depends on the stomach contents, pH and
some ions such as calcium and can have a major
impact upon the relative risk of developing
fluorosis. The enamel maturation can be
endangered both by the long-lasting overintake of fluoride or, to some extent, by the
steep peaks of plasma fluoride due to its quick
absorption from empty stomach [2, 22].
Added to the Discussion section:
Irrespective of the generally accepted major
impact of topical fluoride in caries prevention
its systemic intake in preschool children can
contribute both to its benefit and to the risk of
developing fluorosis. One of the main issues of
dental public health is to minimize the risk of
fluoride overdose by the fluoride and diet
counselling both in individual and community
levels.
Added to the Conclusions section:
These results showed that in preschool
children, when trying to maximize the benefit
of fluoride in caries prevention and to minimize
its risk, caution should be exercised when giving
advice on the fluoride containing components
of child´s diet or prescribing fluoride
supplements.
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September 8, 2011
Zdenek Broukal (corresponding author)
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