Investigation
of thepossible
associations
between
fluorosis,fluorideexposure,
andchildhood
behaviorproblems
LindaMorgan,
DMD
Elizabeth
AIIred,MS,Mary
Tavares,
DMD,
MPH
David
Bellinger,PhD
Howard
Needleman,
DMD
Abstract
Purpose:This studyinvestigatedthe potentialassociation
betweenfluoride exposureand behaviorproblemsin chiMren,
as wellasthe prevalence
of andrisk factorsfor fluorosis.
Methods:Childrenbetweenthe ages of 7 and 11 years
(N = 197) were included in the study and were examined
for dental fluorosis usingthe ModifiedDean’sIndex. Parents of subjectscompletedandreturnedthree questionnaires
whichinvestigated
their children’shistoryof exposures
to fluoride, social and medicalbackgrounds,and behaviorusing
the Child BehaviorChecklist (CBCL).
Results:Sixty-ninepercentof the studyparticipantsdemonstratedfluorosis with very mild fluorosis beingthe most
common(39%), while 13%demonstrated moderate
severe fluorosis. Usinga summation
of the ModifiedDean’s
index (Sum of 8), we divided the children into high
fluorosis (HF)and [owfluorosis (LF)groups.Thesegroups
werecompared
to eachother with respectto fluoride exposures andbehavior.
Conclusion:Althoughthere wasno association between
the fluoride exposuresin aggregateandfluorosis, there was
a significant associationbetweensupplementalfluoride
exposurej~omages O-3years andfluorosis. Therewasno associationbetweenbehaviorproblemsanddental fluorosis in
this population. (Pediatr Dent 20:244-52,1998)
or five decades, fluoride has been added to
public water supplies to reduce the incidence of
dental caries. Deanand others determined1 ppm
to be the optimallevel of fluoridation for caries reduction1 while minimizinglevels of dental fluorosis. 2 Since
then however,sourcesof fluoride haveincreased, resulting in a commensurateincrease in the prevalence and
severity of dental fluorosis.3-12 Theseadditional sources
of fluoride include toothpaste, professional topical applications, dietary supplementation, mouthrinses,
processedfood and beverages,and pesticides?" ]2-18 Investigators have attempted to elucidate whichof these
exposuresare primarily responsible for the increase in
dentalfluorosis, withvariedresults.7’ 8.11.14,18, 19-25In
F
244 AmericanAcademyof Pediatric Dentistry
1994, Pendryset al. 26 reported a case-control study in
whichinfant formula, frequent brushing, and inappropriate fluoride supplementation were strongly
associated with dental fluorosis. Similarly, Lalumandier
and Rozier27 reported dental fluorosis to be associated
with dietary fluoride supplementationand the child’s
age whenbrushing was initiated. Skotowski28 also
showedfluoride toothpaste to be associated with fluorosis. Dueto this rise in fluoride exposureand dental
fluorosis, the AmericanDental Association (ADA)and
American Academyof Pediatric Dentistry (AAPD)
changed the fluoride supplementation guidelines to
reduce fluoride exposure in 1994.29 The American
Academyof Pediatrics (AAP)endorsed the new dos30
age schedule in May1995.
Since the institution of fluoridation as a public
health measure, humanand animal studies on the effect of fluoride on teeth havecontinued. Histological,
biochemical, and molecularstudies have better defined
the fluorotic lesion and have helped to differentiate
34-4°
dental fluorosis from other enamel lesions.
Additionly, they have led to a better understandingof
the mechanismby which fluoride acts on the developing tooth to producefluorosis.12’ 15.31-33
Fluoride has beenstudied extensively for its effects
on skeletal, reproductive, genitourinary, gastrointestinal, and respiratory systems, as well as for possible
genotoxic and carcinogenic effects. A reviewconducted
in 1991 by the Ad hoc Subcommitteeon Fluoride of
the Committeeto Coordinate Environmental Health
and Related Programs15 found no conclusive evidence
of the adverse effects of fluoride other than on teeth
(dental fluorosis), bones (skeletal fluorosis), and
gastrointestinal tract (chronic gastritis) with chronic
high exposure.
Until recently, effects on the nervoussystemhavenot
been studied. In 1982, Rotton et al.4! reported subtle
transient attention deficits inducedby the sublingual
application of 0.01 mgof fluoride in healthy human
volunteers. This exposurewassignificantly less than the
fluoride exposure obtained from brushing with fluoridated toothpaste (1 mg)or from a professional topical
PediatricDentistry - 20:4, 1998
fluoride treatment(50 mg).In 1995,Li et alo42 reported that children living in areas with a medium
or high prevalence offluorosis demonstratedlower
intelligence quotientsthan those living in areas with
Score Type
Description
only slight or no fluorosis. Morethan 900 children
betweenthe ages of 8 and 13 years were examined
None
0
Normal
and tested using the China Rui Wen’sScaler for
0.5
Questionable Fewopacities
Rural Areas. Numerous
other studies have reported
an association betweenenameldefects and various
1
Very Mild
< 25%with opacities
neurologic,learning, behavioral, and languagedis2
Mild
25-50%with opacities
orders in children,43-58but nonehavespecifically
Moderate
examinedthe association betweenfluoride-induced
3
> 50%with opacities
enameldefects and behavioral problems.
4
Severe
100%with opacities and pitting
In 1995, Mullinex et al. 59 reported that sysVerySevere
5
Confluentpitting
temic exposureto sodiumfluoride wasneurotoxic
to rats. Behavioraldeficits wereobjectively identified using computer pattern-recognition
questionnaires
technology. Deficits occurred whether exposure was Parent
prenatal, at weaning,or in adulthood. Levels of fluoFollowing enrollment and written informed conride in serumand the brain, specifically the cerebellum sent, a packet of three questionnaires wasgiven to the
parents with written and verbal instructions (fluoride
and hippocampus,correlated with the behavioral alexposurehistory, social/medical history, and CBCL).
terations. The levels of fluoride used are knownto
6°
inducefluorosis in rats, and resulted in serumlevels
Parents were given the option of completingthe questhat were similar to levels found in humanswhoare
tionnaires
at home and returning them in a
61-64
exposed to environmental fluoride of 5-10 ppm
pre-addressed and prestamped envelope, or completandsimilar to levels reported in children followingproing themin the office while waiting for completionof
their child’s dental visit. Parents whodid not complete
fessional topical applications of 1.23%acidulated
65’
phosphatefluoride gel. 66
and return the questionnaires within 2 months were
Althoughthe meanfluoride exposure in the United sent a reminder letter. A second packet of questionStates wouldbe expectedto result in serumlevels well
naires andinstructions wassent out to parents whostill
belowthose reported by Mullinexet al., 59 fluoride is
had not responded within 6 months.
pervasive within our environmentand any behavioral
Fluoride
history
effects, howeversubtle, wouldhave a significant pubThe fluoride history questionnaire consisted of 64
lic health impact.
close-ended
questions. A parent was asked to identify
The purpose of this historical cohort study was to
all
the
towns
in whichtheir child had lived and atinvestigate if an associationexists betweenfluoride extended
school,
methods of infant feeding, use of
posure and behavior problemsin children. In addition,
bottled
or
tap
water,
use of waterfilters, use of supplethe prevalenceoffluorosis and potential risk factors for
mentary
fluoride
and
over-the-counter fluoride
fluorosis wereinvestigated.
products, professional fluoride treatments, initiation
Methods
and frequency oftoothbrushing, adult assistance with
toothbrushing, use of fluoride toothpaste, and
Patients
Patients wererecruited from a pediatric dental prac- amountof toothpaste used.
Most of the questions requested information about
tice in a suburbof Boston.Aletter wassent to parents
the
child’s first 8 years of life becausefluorosis of the
of potential subjects requesting their participation in
permanent
first molars and incisors would have oca study investigating possible associations betweenoral
curred
within
that time.
health and childhood behavior. Parents whosechildren
fulfilled the followingcriteria wereaskedto participate.
Social/medical
history
1.7-11 years of age
The social and medical questionnaire consisted of
122 open- and close-ended questions. A parent was
2. Presenceof permanentincisors and first molars
asked about their child’s height, weight, birth length
3. No history of pervasive developmentaldisorders
and weight, gestational age at birth, educationalprobor mental retardation
lems, medicaldiagnoses, hospitalizations, and history
4. Nosibling enrolled in the study.
of prescription medicationuse. It also requestedinforThis last criterion insured statistical independence mation about parents, including their heritage, age,
of observations.
marital status, employment
and time spent at job, highPediatric Dentisiry-20:4, 1998
AmericanAcademyof Pediatric Dentistry 245
ScoringIndex
Description
Sumof 12
Thefluorosis scores for all 12 teeth
that were examinedwere summed.
Whenscores were available for
fewer than 12 teeth, a weighted
score wascalculated by dividingthe
sumby the numberof teeth present
and multiplyingby 1 2.
Sumof 8"
Thefluorosis scores for the incisors
(eight teeth) that wereexamined
were summed.
Whenscores were available for
fewerthan eight teeth, a weighted
score wascalculated by dividing the
sumby the numberof teeth present
and multiplyingby eight.
69 expressedfluorosis as the
Dean
highest score assignedto two teeth.
Dean’s*
Thehighest fluorosis score for any
one tooth.
Median
Themedianscore of all 12 teeth
examined.
Mode
The score that occured most
frequently amongall 12 teeth that
were examined.
¯ Sumof 8 used for comparisonbetweenHFand LF groups with
respect to behavior,fluorosis, andfluoride exposure.
* Dean’sused to report prevalence.
est level of educationattained, and history of learning,
neurologic, or psychiatric problems. The same questions were asked about the child’s biologic parents if
the child wasadopted. Parents were also asked to identify whoprovidesafter-school supervisionfor the child
and howoften, and to identify stressful events in the
child’s life such as death, divorce, and abuse.
Behavior
questionnaire
67 is the most widely used measure of beThe CBCL
havior problemsin childhoodpsychiatric epidemiologic
studies.68 It consists of 143 open-andclose-endedquestions. Parents are askedto rate manypossible behaviors
as either never occurring, sometimesoccurring, or often occurring.Parentsare also askedto judgetheir child’s
performancein sports, hobbies, games,clubs and organizations, jobs, and schoolsubjects. Questionsare also
askedabout relationships with friends and siblings. The
CBCLyields a total problem behavior score and two
broad-band summaryscores (internalizing and exter246 American
Academy
of PediatricDentistry
nalizing). Theinternalizing score reflects the prevalence
of behaviorsthat are overcontrolledor inhibited (e.g.,
social withdrawal, depression, anxiety). Theexternalizing score reflects behaviorsthat are undercontrolled
or represent "acting out" (e.g., aggression,hyperactivity, antisocial).
Fluorosis
examination
Oral examinations were performed on each subject
to evaluate the presenceof dental fluorosis. This fluorosis examination was conducted by the principal
investigator (LM)using direct vision with the standard
overheadlight and a dental mirror. ThemodifiedDean’s
index69 (Table1) wasusedboth to quantify fluorosis for
the scoring of individual teeth andto quantify the prevalence of dental fluorosis in this population. This index
was chosen becauseit is the most commonly
used index
in studies evaluating dental fluorosis, thus permitting
comparisonof our findings with those of other prevalence studies. Onlythe labial/buccal surfaces of the
maxillary and mandibularpermanentincisors and first
molars were scored. Enamelopacities were considered
fluorotic in origin if they weresymmetrically
distributed,
were diffuse in nature, followed the perichymata, and
weremorevisible in tangential reflected light. Thesecri35
teria are consistentwith those usedby Moller,36 Russell,
4 Fourteen percent of the subjects were
and Zimmerman?
re-examinedby the principal investigator 6 monthsafter the initial fluorosis examinationto assess intrarater
reliability usingthe kappastatistic (N = 336teeth).7°
assess intrarater reliability, the ModifiedDean’sscores
were collapsed as follows; 0 and 0.5 = 0, 1 and 2 = 1,
and3 or greater = 2. Intrarater reliability analysisyielded
kappascores of 0.58 to 0.89 for the lowerincisors, 0.53
and 0.57 for the right molars, and 0.15 to 0.46 for the
upperincisors andleft molars.Withexceptionof the lower
incisors, kappascores for eachright tooth werehigherthan
those for the contralateral tooth.
Statistical
analysis
Initially, six methods were used to combinethe
scores for individual teeth in order to determine an
overall fluorosis score for each patient (Table 2).
these six summationindices, the sumof the fluorosis
scores for the eight incisor teeth (Sumof 8) wasmost
highly correlated with the fluoride exposuresreported
by parents. Therefore, the Sumof 8 was used as the
fluorosis index in the remainderof the analyses.
Becausefew children did not have any fluorosis and
becausethe fluorosis scores were not normallydistributed, subjects were categorized as either LF or HF.
Thosewith a score of 12 or less (76%)were classified
as LF, while those with a score greater than 12 were
classified as HF(24%).
Data were entered into a database using dBaseIII
Plus (Ashton-Tate, Torrance, CA)on an IBMpersonal
computer. Data analyses were conducted using SAS
PediatricDentistry-20.’4, 1998
and 197 participants returned completed questionnaires yielding a
response rate of 81%(197/244).
Exposure
%
In general, the study participants
were
healthy, Caucasian (97%) chilLived in a fluoridated community
any time betweenbirth and 6 yr 86
dren living in intact families (95%).
Lived in a fluoridated community
any time betweenbirth and 3 yr 80 The majority of mothers were emUsedfluoridated toothpaste before secondbirthday
74 ployed (65%) and nearly 90%of both
ReceivedF supplementationany time from birth to 6 yr
53 parentsheld at least a collegedegree.
and
fluoride
exposure
ReceivedF supplementationany time from birth to 3 yr
52 Fluorosis
Fig 1 showsthat the distribution of
Receivedany formof topical fluoride treatment frombirth to 3 yr
30
Sumof 8 fluorosis scores wasnot norReceivedconcentrated formula mixedwith fluoridated water
25 mal because very few children had high
Usedfluoridated toothpaste before first birthday
19 fluorosis scores while manyhad low
; fluorosis scores.
Fig 2 showsthat the distribution
(SASInstitute, Cary NC)and Stata (Stata Corporation, of fluorosis scores using Dean’s Index was morenorCollege Station, TX).
mal, with a central tendency corresponding to very
Wilcoxon’srank-sumtest was used to assess associamild fluorosis. Theprevalenceof fluorosis in this poputions betweenfluorosis, fluoride exposures,and behavior lation using this index was 69%, with very mild
as measuredby the CBCL
total, externalizing, and influorosis being the most common(39%) and 13%
ternalizing scores. Relationshipsbetweenfluorosis and demonstratingmoderateto severe fluorosis.
fluoride exposures were examinedusing Fisher’s exact
Table 3 presents the most common
reported sources
test. Fisher’s exact and Wilcoxon’srank-sumtests were of exposureto fluoride. Mostof the children lived in a
usedto assess the associationsbetweenchildren’s social/
fluoridated community(86%) and used fluoridated
medicalhistory and their fluorosis scores and fluoride
toothpaste early in life (74%). In addition, morethan
exposure. The measure of fluoride exposure used was half of the subjects received fluoride supplementation.
reported use of supplementalfluoride.
Comparisonbetween the HFand LF groups revealed
Canonical correlation analyses were conducted to
only the use of supplementalfluoride prior to age 3 to
assess the association betweenaspects of a child’s fluobe significantly higher in the HFgroup(P = 0.049). The
ride exposurehistory and the severity of fluorosis (Sum
of 8 score) and betweenaspects of a child’s fluoride
exposuresand CBCL
scores (total, internalizing, externalizing). In these analyses, the following factors
constitutedthe set of fluoride history variables;residence
in a townwith fluoridated water during various time
=o
lo
~b
intervals, use of concentratedformula, whetherformula
wasreconstituted using tap water, whetherthe tap water wasthe primarysourceof water, the numberof years
that the tap wasthe primary source of water, whether
supplementalfluoride was given during different time
intervals, whethertopical fluoride wasapplied, the frequencyand amountof fluoridated toothpaste used, and Fig1.Distribution
offluorosis
score
(Sum
of8)instudy
population
the age at whichfluoridated toothpaste wasfirst used.
(N= 197).
The power of our hypothesis tests was calculated
assuminga Student’s t test comparisonof CBCL
scores
(SD = 10) for HF(N = 50) and LF (N = 150) children
(alpha = 0.05; two-tailed, beta = 0.20). A sampleof 200
children would provide 80%powerto detect an effect
size of 4.6 points, or approximatelyone-half of a standard deviation on the summaryCBCLscales.
Results
Sample
Twohundred and forty-six children were examined
and met the study criteria. Twoparticipants withdrew
PediatricDentistry-20.’4, 1998
Fig2. Prevalence
offluorosis
(Modi[Jed
Dean’s
Index)
instudy
population
(N= 197).
AmericanAcademyof Pediatric Dentistry 247
Discussion
The purpose of this study was to investigate if an
association exists betweenfluoride exposureand behavCBCLScore HF (N = 47) LF (N = 150) P value
ior problems in children. Fluoride exposure was
measuredby the clinical presence of enamelfluorosis
Total
0.22
41 (26-65)
44 (24-76)
on the permanentincisors and by history of fluoride
Externalizing 40 (30-60)
44 (30-73)
0.07
exposure as reported by parents. Epidemiologicstud7. and animalstudies72-74 have
ies by Deanand coworkers
Internalizing 46 (33-71)
46 (31-77)
0.96
showna linear dose-responserelationship betweenfluoride exposureandseverity of fluorosis. Fluoridehistories
havebeen used by manyto confirmthe diagnosis offluocanonical correlation analyses indicated that the fluorosis and to identify which sources have been most
ride history variables, in aggregate, were not signif5’ 8,14, 26-28In addition,we
influential in its development.
icantly associated with clinical assessmentsoffluorosis
also examinedthe prevalenceof fluorosis and risk fac(likelihood ratio statistic = 0.78; df= 41,155;P=0.41).
tors for fluorosis by comparingfluorosis scores with
Behavior,
fluorosis,
and
fluoride
exposure
reported fluoride histories and social/medicalhistories.
Table 4 showsthat there were no significant assoThe prevalence offluorosis in this study was 69%,
ciations betweenthe three CBCL
scores (total, exterwhich is muchhigher than early prevalence studies
nalizing, and internalizing) and fluorosis group, where conducted when communitywater was the predomihigher CBCL
scores indicate more behavior problems. nant sourceof systemicfluoride exposure.7~’ 75, 76 The
Onlyone of the fluoride exposurevariables was sighigher prevalence is undoubtedly due to an increase
nificantly associated with a high CBCL
score. Children in the numberof systemic sources of fluoride exposure.3-12~8, 26-28Similarly,the prevalenceof 69%is also
whoboth used topical fluoride betweenthe ages of 3
and 6 years and fluoridated toothpaste betweenthe ages higher than the prevalences reported in more recent
of 1 and 2 years were morelikely to have more behav- studies, whichrange between22 and 36%.5, 6, 8 Howior problems (P = 0.05). The canonical correlation
ever, two of the most recent studies 27’ 28 did report
analyses indicated that the fluoride exposurevariables,
fluorosis prevalences of 78 and 72%,which are more
in aggregate, were not significantly associated with
similar to our findings. Lalumandierand Rozier27 dechildren’s CBCL
scores; total score (likelihood ratio starived their population from a private dental practice
tistic = 0.87; dr= 41,155; P=0.98), externalizing score
in North Carolinawhereonly half of the subjects lived
(likelihood ratio statistic = 0.88; df= 41,155; P=0.99),
in a fluoridatedarea. Fluorosisin subjects living in fluoandinternalizing score (likelihoodratio statistic = 0.82;
ride-deficient areas wasassociated with dietary fluoride
df= 41,155; P = 0.77).
supplementationand age at initiation oftoothbrushing.
For subjects drinking fluoridated water, fluorosis was
Social
and
medical
variables
also associated with age of initiation of brushing.
Weexaminedsocial and medical variables to see if
Skotowskiet al.28 derived their populationfrom a denthey confoundedthe relationship between’the fluorotal clinic in IowaCity, Iowa,which,like ours, washighly
sis score and the CBCLscore or the relationship
educated. Amountof toothpaste use and greater expobetween fluoride exposure and the CBCLscore. We
sure to fluoridated waterwerejudgedto be risk factors.
found no significant relationships.
The distribution of fluorosis in this study was inTable 5 compares the HF and LF groups with reteresting. Althoughmost children exhibited very mild
spect to social, demographic, and medical characfluorosis (39%), we also found a significant number
teristics. Therewereno significant differences between
of patients with moderateto severe fluorosis (13%).
these two groups, with the exception of those in the
This is similar to the distribution reported by
LFgroup with a history of moreremedial help in readLalumandier and Rozier27 whonoted 19%of patients
ing (P = 0.02). Theages of the participants weresimilar
to have moderateor moresevere fluorosis. This, howin both groups.
ever, is in contrast to mostother recent studies, which
A positive history for fluoride supplementationbein the prevalence but not the
tween ages 0 and 6 years was more frequent among havereported an increase
3’ ~2,28,77
severityof fluorosis.
children with a college graduate mother(P = 0.08) or
The finding ofa fluorosis prevalence of 69%in our
an unmarriedfather (P = 0.05). A negative history of
study is muchhigher than the national average of
fluoride supplementation was associated with having
6 but reflective of the population. Eighty-six per22%,
a history of allergy (P = 0.05), a nonbiologic mother cent of the population lived in a fluoridated
or father (P = 0.02, 0.05), a motherwith a history of
community,yet 53%also received fluoride supplemenpsychiatric problems(P = 0.05), or a sibling with
tation. In addition, 74%had early exposure to
learning disability (P = 0.05).
toothpaste and 30%had early exposureto topical fluo248 AmericanAcademyof Pediatric Dentistry
PediatricDentistry- 20.’4, 1998
giene practices and are morelikely to use fluoridated toothpaste and topical and systemic
fluorides. Theyare also morelikely to maketheir
child’s first dental appointments
early in the child’s
Characteristic
HF
LF
life, whichmayresult in morefluoride exposure.
(N = 47) (N = 150) P value
Comparisonbetween fluoride exposure variSex
ables and the Sumof 8 scores for fluorosis
Male
55
49
0.27
revealed supplemental fluoride given before the
Race
age of 3 years to be more frequent in the high
Caucasian
98
97
0.66
fluorosis group, whichis consistent with findings
in otherstudies.819,21, 22,26,27, 78It is alsoconsisEducation
tent with the most critical time for the
Motherwith college or
developmentoffluorosis in upper anterior teeth,
graduate degree
87
87
0.57
22-26 months of age. 79 Our analyses failed to
Father with college or
demonstrateany significant associations between
graduate degree
0.43
87
85
the fluoride history variables in aggregateandthe
clinical assessmentsof fluorosis. ManyinvestigaMaternal Employment
tors have reported sources of fluoride other than
Full time
47
45
0.95
supplementationto be risk factors for the develPart time
19
21
opmentof fluorosis, including use of fluoridated
Nonemployed
34
33
toothpaste, use of infant formula, and higher soChild’s SchoolHistory
cioeconomic
status. 512, 14, 22, 26, 27 Althoughour
History of a school problem 6
13
0.17
fluoride questionnaireinvestigated all these expoRepeateda grade
2
sures, presumablywe wouldneed a larger study
5
0.32
sampleto demonstratestatistically significant asRemedialhelp in reading
11
25
0.02"
sociations with fluorosis. In addition, if wehad
Remedialhelp in math
9
7
0.50
beenable to extract twogroupswith distinctly difChild’s MedicalHistory
ferent fluorosis scores fromthis population, more
Hospitalization
10
9
0.51
exposurerisk factors mayhavebeenidentified. FurHistoryof ear infection
87
77
0.10
thermore, the elucidation of dental fluorosis risk
Historyof allergy
26
29
0.38
factors is a difficult task giventhe ubiquitousnaHistory of asthma
9
10
0.51
ture of fluoride, the difficulty in obtainingaccurate
History of ADHD
6
4
0.37
and completefluoride exposurehistories, and the
History of LD
6
0.44
9
difficulty in accuratelymeasuring
dental fluorosis.
Behavior
problems
were
evaluated
by having
Residence
parents
complete
the
CBCL.
Comparison
of the
Live with both
three
summary
behavior
scores
for
the
HF
and LF
biological parents
89
95
0.13
groupsdid not showanysignificant association to
Marital Status
exist betweenfluorosis and childhood behavior
Divorcedparents
4
6
0.49
problems.Similarly, fluoride exposurevariables in
aggregate were not significantly associated with
Numberof Siblings
behavior problemsin children. Of the 369 indiOnly child
9
5
0.63
vidual
comparisons made, only one association
Three or more
6
9
was significant at the 0.05 level (children who
History of TraumaticEvent 64
61
0.45
both used topical fluoride between3 and 6 years
of age and fluoridated toothpaste between1 and
Age(medianyears)
10.0
9.8
0.45
2 years of age). However,this finding maybe due
...................
.... "~
I__~21,211ZI77;Z?Z~II777
to chanceas it is expectedthat 18 significant as¯ P < 0.05.
sociations wouldexist by chancealone at the 0.05
confidencelevel.
ride treatment. Theseexcessive fluoride exposuresmost
An association between fluoride exposure and belikely contributed to the high prevalence of fluorosis
havior problems however, cannot be definitively
in this study group. The children were predominantly excludedby this study. This population was generally
fromfamilies of high socioeconomic
status as reflected
from the same geographic area, the same socioecoby the high percentage of parents with college degrees nomicstatus, and had similar fluoride exposures. In
(90%).Thesefamilies wouldtend to havebetter oral hy- fact, most of the children in this population had sigPediatric Dentistry -20:4, 1998
AmericanAcademyof Pediatric Dentistry 249
nificant fluoride histories, i.e., 86%lived in a fluoridated community, 54%used fluoride supplements,
and 73%used a fluoridated toothpaste early in life. The
similarities of the groups we comparedmayhave made
it difficult to find differences in behavior that might
be related to exposure.It wouldhavebeenideal to compare children with high exposureto those without any
exposure, e.g., comparingchildren from a community
werethe water has the legal upperlimit of fluoride concentration at 4 ppm with children living in a
demographically similar communityin which the water contains less than 0.3 ppmof fluoride.
Second,the measureof fluorosis is not an objective
measurement,but subjective and difficult to reproduce.
This wasreflected in the intrarater reliability scores,
which were not high for most comparisons. Additionally, there existed a general difference in the scores of
teeth on the patient’s right and left sides. The higher
kappascores for the right side can be attributed to better visibility by the examiner,whowas positioned to
the right of patients during the examination. Smaller
differences were found betweenthe scores of the lower
incisors on the right andleft sides becauseless variability existed in the scores of these teeth, and they had
fewer fluorotic lesions than the other teeth examined.
Themorenormalthe tooth’s appearance(i.e., less fluorosis), the higher the agreementrate will be, because
agreementregarding normality is usually greater than
agreement regarding abnormality.8~ Conversely, the
upper incisors, with lower kappa scores, had greater
variability in fluorosis. Thus,the morediagnostic cat81
egoriesthere are to consider,the lowerthe reliability.
In addition, it is difficult to reproducea score when
the index is the estimationof the percentageof surface
affected rather than a more discrete measure. The reproducibility of fluorosis scores mayhave been more
reliable if broadercategories wereused, for example,if
a tooth were simply scored as demonstratingfluorosis
or no fluorosis. This wasnot feasible in this study because of the small numberof subjects without fluorosis.
Third, our measuresof fluoride exposure, fluorosis,
and fluoride history questionnaires were indirect. Although degree of fluorosis has been shownto correlate
69’ 7~, 80 it is not as
with the amount
of fluoride exposure,
effective a measurewhenthe two groups being compared
havesimilar fluoride exposurehistories. Thefluoride history questionnaire, although extensive, was not able to
accurately documentall exposures to fluoride nor the
extent of exposuresthat did occur. In addition, the fluoride questionnairerelied on the recall of parents. It is
difficult for parentsto provideaccurateaccountsof their
child’s eating, brushing, and drinking habits fromyears
ago. In addition, parents mayhaveover-reportedthe use
of fluoride dueto the setting in whichthe questionnaire
was given. For example,parents maytend to over-report
toothbrushinghabits to the dentist.
250American
Academy
of PediatricDentistry
Similarly, the use of the parent CBCL
rather than
the teacher CBCLmayhave provided judgments that
were not as objective. It wouldhavebeen preferable to
use both the parent and teacher versions of the CBCL
to ensure more comprehensive reporting of the
children’s behavior.
Comparison
of the social/medical history with fluorosis and fluoride exposure(as measuredby history for
fluoride supplementuse) showeda few associations,
someof whichare easily explained, while others are not.
The association betweenremedial help in reading and
low fluorosis mayhavebeen due to chance. The literature has reported medicalproblemsthat are associated
with fluorosis, includingdisorders in acid-base balance,
calciumdeficiency, disruptionsin urinary flow, andkid83’ 84 but these werenot elucidated in our
ney problems,
study. Manyauthors have reported higher socioeconomicstatus to be relatedto fluorosis.9’ 12, 22, 8587 Of the
two social variables associated with increased fluoride
supplementation,only one--motheris a college graduate-follows this trend; however,its association wasnot
a statistically significant finding. Twoof the five social
and medicalvariables associatedwith no fluoride supplementation are logical; children with a mother with a
history of a psychiatric problemand children with a sibling with a history of a learning disability. These
householdsmayhaveless structure and maybe less able
to follow through with a daily regimensuch as fluoride
supplementation.
In summation,it is of concernthat sodiumfluoride
wasrecently found to be neurotoxic in rats. However,
our study failed to find an association betweenfluoride
exposure and behavior problems in children. Yet our
studycannotlay this issueto rest. It is hopedthat it serves
as an impetusfor further investigations on this subject
with two populations with disparate fluoride exposures.
Conclusions
1. Sixty-ninepercent of children fromthis population
of high socioeconomic-status
families living mostly
in fluoridated communities
demonstratedfluorosis,
with mild fluorosis being the most common.
2. The use of supplemental fluoride prior to age 3
wasfoundto be a risk factor for dental fluorosis.
3 No significant association was found between
fluoride history variables in aggregate and the
clinical assessmentof dental fluorosis.
4. Dental fluorosis was not significantly associated
with behavior problemsin this population.
This study was funded by the AAPD
Educational Foundation and
Proctor and Gamble.Wethank the following for their help on
this project: Dr. Phyllis Mullenix, a neurotoxicologist at
Children’s Hospital, whoshared her fluoride neurotoxicologydata
with us and helped to initiate this project, and Chestnut Dental
Associates where data collection took place over the course of
many months.
PediatricDentistry- 20.’4,1998
Dr. Morganis instructor in Pediatric Dentistry, HarvardSchool
of Dental Medicineand Assistant in Dentistry, Children’s Hospital; Ms.Allred is biostatistician, Children’s Hospital and instructor in Biostatistics, Harvard School of Public Health; Dr.
Bellinger is a research associate in Neurology,Children’s Hospital, and associate professor of Neurology, Harvard Medical
School; Dr. Needleman
is clinical professor of Pediatric Dentistry,
Harvard School of Dental Medicine and associate Dentist-inChief, Children’s Hospital; and Dr. Tavares is associate clinical
investigator, Forsyth Dental Center, all in Boston, Massachusetts.
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