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The Association between Caries and Childhood Lead Exposure.



Epidemiologic studies suggest an association between lead exposure and caries caries
 or tooth decay

Localized disease that causes decay and cavities in teeth. It begins at the tooth's surface and may penetrate the dentin and the pulp cavity.
. Our objective was to establish whether children with a higher lead exposure as toddlers had more caries at school age than children with a lower lead exposure. We used a retrospective cohort design. A sample of children who attended second and fifth grades in the Rochester, New York This article is about the city of Rochester in Monroe County. For the town in Ulster County, see Rochester, Ulster County, New York.
Rochester, once known as The Flour City, and more recently as The Flower City or
, public schools during the 1995-1996 and 1996-1997 school years were examined for caries through a dental screening program. For each child we assessed the number of decayed, missing, or filled surfaces on permanent teeth (DMFS DMFS Decayed/Missing/Filled Surface (dentistry) ), and the number of decayed or filled surfaces on deciduous teeth
See also Deciduous. "Baby teeth" redirects here. For the band of that name, see Baby Teeth (band).


Deciduous teeth, otherwise known as milk teeth, baby teeth, temporary teeth or primary teeth
 (dfs); the number of surfaces at risk (SAR (Segmentation And Reassembly) The protocol that converts data to cells for transmission over an ATM network. It is the lower part of the ATM Adaption Layer (AAL), which is responsible for the entire operation. See AAL.

SAR - segmentation and reassembly
) was also recorded. Lead exposure was defined as the mean of all blood lead levels collected between 18 and 37 months of age by fingerstick [provided the blood lead level was [is less than or equal to] 0.48 [Micro]mol/L ([is less than or equal to] 10 [micro]g/dL)] or venipuncture venipuncture /veni·punc·ture/ (ven?i-pungk´chur) surgical puncture of a vein.

ve·ni·punc·ture or ve·ne·punc·ture
n.
. A total of 248 children (197 second graders and 51 fifth graders) were examined for caries and had a record of blood lead levels to define lead exposure. The mean dfs was 3.4 (range 0-29); the mean DMFS was 0.5 (range 0-8). Logistic regression In statistics, logistic regression is a regression model for binomially distributed response/dependent variables. It is useful for modeling the probability of an event occurring as a function of other factors.  was used to examine the association between the proportion of children with DMFS [is greater than or equal to] 1, and the proportion with dfs [is greater than or equal to] 1, and lead exposure [[is less than] 0.48 [micro]mol/L vs. [is greater than or equal to] 0.48 [micro]mol/L ([is less than] 10 [micro]g/dL vs. [is greater than or equal to] 10 [micro]g/dL)] while controlling for SAR, age at examination, and grade in school. For DMFS, the adjusted odds ratio was 0.95 [95% confidence interval confidence interval,
n a statistical device used to determine the range within which an acceptable datum would fall. Confidence intervals are usually expressed in percentages, typically 95% or 99%.
 (CI), 0.43-2.09; p = 0.89); for dfs, the odds ratio was 1.77 (95% CI, 0.97-3.24; p = 0.07). This study did not demonstrate that lead exposure [is greater than] 10 [micro]g/dL as a toddler was a strong predictor of caries among school-age children. However, the results should be interpreted cautiously because of limitations in the assessment of lead exposure and limited statistical power. Key words: blood lead, children, dental caries, dentistry, lead poisoning lead poisoning or plumbism (plŭm`bĭz'əm), intoxication of the system by organic compounds containing lead. , teeth. Environ Health Perspect 108:1099-1102 (2000). [Online 26 October 2000]

http://ehpnet1.niehs.nih.gov/docs/2000/108p1099-1102campbell /abstract.html

Despite declines in recent years, the Years, The

the seven decades of Eleanor Pargiter’s life. [Br. Lit.: Benét, 1109]

See : Time
 prevalence of elevated blood lead levels remains a concern in the United States United States, officially United States of America, republic (2005 est. pop. 295,734,000), 3,539,227 sq mi (9,166,598 sq km), North America. The United States is the world's third largest country in population and the fourth largest country in area. . The second part of the Third National Health and Nutrition Examination Survey (NHANES III NHANES III Third National Health & Nutrition Examination Survey Public health A population-based survey conducted by the National Center for Health Statistics, designed to assess the health and nutritional status of the noninstitutionalized Americans ), conducted from 1991 to 1994, estimated that 4.4% of children 1-5 years of age have blood lead levels [is greater than or equal to] 0.48 [micro]mol/L ([is greater than or equal to] 10 [micro]g/dL) (1). Thus, approximately 890,000 children in the United States (2) have blood lead levels exceeding the threshold defined by the Centers for Disease Control and Prevention Centers for Disease Control and Prevention (CDC), agency of the U.S. Public Health Service since 1973, with headquarters in Atlanta; it was established in 1946 as the Communicable Disease Center.  (CDC See Control Data, century date change and Back Orifice.

CDC - Control Data Corporation
) (3). Many of these children are urban, minority children (1,3,4). This same population of children also has the highest rates of dental caries in the United States (5,6). This disproportional dis·pro·por·tion·al  
adj.
Disproportionate.



dispro·por
 burden of caries and lead exposure in urban, minority populations suggests a potential association.

Results of animal-model studies report an association between lead exposure and caries (7,8). In a recent study, pregnant rats were randomized ran·dom·ize  
tr.v. ran·dom·ized, ran·dom·iz·ing, ran·dom·iz·es
To make random in arrangement, especially in order to control the variables in an experiment.
 to receive either lead-contaminated water or lead-free water; the exposure was continued until the rat pups were weaned wean  
tr.v. weaned, wean·ing, weans
1. To accustom (the young of a mammal) to take nourishment other than by suckling.

2.
 (9). The mean smooth surface and sulcal surface caries scores were higher among the lead-exposed rat pups than the nonexposed rat pups.

Human epidemiologic studies also report an association between lead exposure and caries. Studies report a positive association between lead level in teeth and caries (10,11). Gil et al. (12) reported that a high tooth lead level is significantly associated with levels of plaque and Lactobaccilli (odds ratio 2.79 and 2.52, respectively), both known risk factors for caries. However, this study was cross-sectional, and thus could not establish the sequence of exposure and disease.

We conducted a study to examine the temporal association between lead exposure and caries. In contrast to the study of Gil et al. (12), our study used blood lead measurements made when the subjects were toddlers, a critical time period in permanent-tooth development. Our objective was to determine whether children with higher lead exposure as toddlers had more caries at school age than children with lower lead exposure.

Materials and Methods

Identification of Subjects

We used a retrospective cohort design. Children who attend second and fifth grades in the public schools in the city of Rochester, New York, are examined for caries through a program conducted by the Eastman Dental Center The Eastman Dental Center, founded in 1915, along with the Eastman Department of Dentistry, is a unit of the University of Rochester School of Medicine and Dentistry, serving as the University of Rochester's primary dental care and education facility. . The caries measures of all children examined are maintained on a computerized database. All subjects in this study were identified from the 1995-1996 and 1996-1997 academic school years of this database.

We linked the children in the caries database to a database of blood lead levels maintained by the local county health department. The blood lead level database is a record of all blood lead levels obtained on children who resided in Monroe County Monroe County is the name of seventeen counties in the United States, named after President James Monroe:
  • Monroe County, Alabama
  • Monroe County, Arkansas
  • Monroe County, Florida
  • Monroe County, Georgia
  • Monroe County, Illinois
  • Monroe County, Indiana
, which includes Rochester, New York, since 1986. We excluded entries for children born before March 1984 and after September 1990 to restrict the database to children who could have been second or fifth graders during the 1995-1996 and 1996-1997 academic school years. We also excluded blood lead levels obtained on children less than 18 months of age or greater than 37 months of age, and all fingerstick blood lead levels [is greater than or equal to] 0.48 [micro]mol/L ([is greater than or equal to] 10 [micro]g/dL). The names (first and last), health department identification number, and date of birth of the remaining children were compiled onto a roster; blood lead levels were not included on this roster. One investigator (J.C.) searched the roster for each child examined for caries by the caries screening program. Individuals on the roster and on the caries database were compared by first name, last name, month of birth, day of birth, and year of birth; at least four of these identifiers had to match to allow enrollment into the study. Children who were enrolled constituted the primary sample of the study.

The Institutional Review Board of the Eastman Dental Center and Strong Memorial Hospital approved this study.

Measures

Lead exposure. For each child, lead exposure was defined as the mean of all blood lead levels which met the following criteria: a) collected between ages 18 and 37 months and b) collected via venipuncture phlebotomy Phlebotomy Definition

Phlebotomy is the act of drawing or removing blood from the circulatory system through a cut (incision) or puncture in order to obtain a sample for analysis and diagnosis.
 or via fingerstick phlebotomy, provided the blood lead level was [is less than or equal to] 0.48 [micro]mol/L ([is less than or equal to] 10 [micro]g/dL). The first criterion defines the age period during which blood lead levels tend to peak in children (13); selecting blood lead levels from this age period thus maximizes the variance of the lead exposure measure. The second criterion was necessary because blood collected by fingerstick phlebotomy may be contaminated contaminated,
v 1. made radioactive by the addition of small quantities of radioactive material.
2. made contaminated by adding infective or radiographic materials.
3. an infective surface or object.
 by lead-containing dirt on the skin (3).

Laboratories in Monroe County are accredited accredited

recognition by an appropriate authority that the performance of a particular institution has satisfied a prestated set of criteria.


accredited herds
cattle herds which have achieved a low level of reactors to, e.g.
 to assay blood for lead by the New York New York, state, United States
New York, Middle Atlantic state of the United States. It is bordered by Vermont, Massachusetts, Connecticut, and the Atlantic Ocean (E), New Jersey and Pennsylvania (S), Lakes Erie and Ontario and the Canadian province of
 State Department of Health and are required to participate in a proficiency-testing program (14). They are required to report demographic information, phlebotomy method (fingerstick or venous), and the blood lead level of all children under 6 years of age to the local county health department.

Blood lead levels were measured by graphite furnace atomic absorption Graphite furnace atomic absorption spectrometry (GFAAS) (also known as Electrothermal Atomic Absorption Spectrometry (ETAAS)) is a type of spectrometry that uses a graphite-coated furnace to vaporize the sample.  spectrometry (15). Blood samples were assayed twice and the mean was reported.

Lead exposure is ideally based on multiple blood lead levels obtained over a period of time (16), or on bone or tooth lead level measured by X-ray fluorescence X-ray fluorescence (XRF) is the emission of characteristic "secondary" (or fluorescent) X-rays from a material that has been excited by bombarding with high-energy X-rays or gamma rays.  (17). Nevertheless, studies demonstrate that a single blood lead level at age 24 months is correlated with a cumulative lead exposure measure at early school age, the age period during which the caries assessment was conducted in our study. Rabinowitz et al. (18) reported a moderate correlation (r = 0.48) between blood lead level at age 24 months and dentine dentine,
n See dentin.


dentine

one of the hard tissues of the teeth which constitutes most of its bulk. Lies between the pulp cavity and the enamel, and where it is not covered by enamel is covered by cementum, the third hard substance
 lead level in deciduous teeth at age 7 years. Dietrich reported a high correlation (r = 0.86) between the blood lead level at age 24 months and the mean lifetime blood lead level (defined as the mean of 20 quarterly blood lead levels from age 3 months to 5 years) (19).

Dental caries. For each child we defined caries as the number of decayed or filled surfaces on deciduous teeth (dfs), and the number of decayed, missing, or filled surfaces on permanent teeth (DMFS). The data for these measures were obtained from an examination conducted through a caries screening program, described above. The caries screening examination was done by licensed hygienists who were unaware of the child's lead exposure status. The visual-tactile criteria of Radike was used for determining caries (20); no radiographs were used. Caries were scored with the aid of a fiber-optic light source, a plane mirror, and a no. 23 piano wire explorer. At the time of the caries assessment, the hygienist also obtained a plaque score and recorded whether each tooth surface was sealed.

Measurement of covariates. After identifying the primary sample, we obtained measures of covariates via a telephone interview. The interviewers were blinded to the child's caries and lead exposure status. The interviewers called homes based on telephone numbers obtained from three urban pediatric pediatric /pe·di·at·ric/ (pe?de-at´rik) pertaining to the health of children.

pe·di·at·ric
adj.
Of or relating to pediatrics.
 clinics in Rochester and from the Rochester City School District The Rochester City School District is a public school district in New York State that serves approximately 33,000 students in the city of Rochester in Monroe County, with over 6,000 employees and an operating budget of $484 million (~$14,854 per student). . The interviewers called on multiple occasions during the day, evening, and weekends. If no contact was made after at least five attempts, the interviewers mailed a letter to the parents asking them to call.

The questionnaire used in the telephone interview had five sections that asked about demographics, fluoride exposure, diet, oral hygiene Oral Hygiene Definition

Oral hygiene is the practice of keeping the mouth clean and healthy by brushing and flossing to prevent tooth decay and gum disease.
, and medical history (Table 1). Regarding demographics, we collected the head of household's occupation and highest grade attained in school in order to calculate socioeconomic status socioeconomic status,
n the position of an individual on a socio-economic scale that measures such factors as education, income, type of occupation, place of residence, and in some populations, ethnicity and religion.
 as defined by the Hollingshead scale (21). The child's date of birth, sex, and ethnicity were obtained from the caries database.
Table 1. Makeup of questionnaire.

Demographics
 Head of household's occupation
 Head of household's highest grade attained in school
Fluoride exposure
 Name of communities the child has ever lived in
 Age began, frequency, and type of toothpaste use
 Age began, frequency, and type of mouthwash use
 Age began, frequency, and type of fluoride
  supplement use
Diet
 Whether consumed each of seven specified
  carbohydrates the previous day
 Number of snacks per day
Oral hygiene
 Time since last dental visit
 Frequency of tooth brushing
 Whether child flosses
Medical history
 Presence of conditions that predispose to caries
 Current medications


In addition to collecting data on tooth brushing and flossing flossing,
n the mechanical cleansing of interproximal tooth surfaces with stringlike, waxed or unwaxed dental floss or tape.

flossing aids,
n.
, oral hygiene was also assessed by the hygienist as part of the dental examination. Hygiene was ranked as "good" if there was no plaque and "poor" if the degree of plaque buildup required a referral for cleaning; all other degrees of hygiene were ranked as "fair." The hygienist also assessed each tooth surface to determine whether it was sealed and therefore not at-risk for caries. We defined surfaces at risk as the number of tooth surfaces present minus the number of tooth surfaces that were sealed.

Analysis

We analyzed caries experience separately for permanent teeth (DMFS) and deciduous teeth (dfs). For the analysis of DMFS, children with no permanent teeth were excluded, and for analysis of dfs, children with no deciduous teeth were excluded.

The distribution of caries was highly skewed skewed

curve of a usually unimodal distribution with one tail drawn out more than the other and the median will lie above or below the mean.

skewed Epidemiology adjective Referring to an asymmetrical distribution of a population or of data
, with at least half of the subjects having DMFS or dfs = 0 (see "Results"). Therefore, logistic regression was used for analysis, with the presence or absence of caries as the response. Explanatory variables included the number of surfaces at risk, age at exam, grade in school (2 or 5), and lead exposure. Lead exposure was dichotomized at a mean blood lead level of 0.48 [micro]mol/L (10 [micro]g/dL), using the cutoff defined by the Centers for Disease Control and Prevention (3).

To assess the influence of potential confounding variables on the results, we reestimated regression models with the following covariates added as explanatory variables: sex, ethnicity, socioeconomic status, whether the child had lived in a community with fluoridated water, use of toothpaste, age at which child began using toothpaste, brushing frequency, use of mouth rinse, use of fluoride supplement, use of floss (Free, Libre and Open Source Software) See free software and open source. , time since last dental examination, dental hygiene dental hygiene
n.
The practice of keeping the mouth, teeth, and gums clean and healthy to prevent disease. Also called oral hygiene.
 rating, carbohydrate consumption, number of snacks per day, whether the child had been breast fed, and use of medications that cause dry mouth.

Caries on particular subsets of tooth surfaces were also analyzed, using the same methods. The subsets were chosen based on hypothetical mechanisms by which lead exposure may cause caries:

* A decrease in salivary flow salivary flow,
n the amount of saliva naturally produced by the salivary glands. Saliva production is increased by the presence of food or irritating substances, such as vomit, in the oral cavity.
 impairs the buffering function of saliva in protecting the tooth against bacterial acids and leads to an increase in the prevalence of caries (22). A rat study reported that lead exposure is associated with a concurrent decrement To subtract a number from another number. Decrementing a counter means to subtract 1 or some other number from its current value.  in salivary flow (23). Because lead ingestion ingestion /in·ges·tion/ (-chun) the taking of food, drugs, etc., into the body by mouth.

in·ges·tion
n.
1. The act of taking food and drink into the body by the mouth.

2.
 typically occurs at 1-3 years of age (13), we reasoned that this mechanism would more likely affect deciduous teeth rather than permanent teeth. Similarly, since lingual lingual /lin·gual/ (ling´gwal)
1. pertaining to or near the tongue.

2. in dental anatomy, facing the tongue or oral cavity.


lin·gual
adj.
1.
 surfaces (surface of tooth facing the tongue) are in more contact with saliva than buccal buc·cal
adj.
1. Of, relating to, adjacent to, or in the direction of the cheek.

2. Of or relating to the mouth cavity.


buccal
 surfaces (surface of tooth facing the buccal and labial labial /la·bi·al/ (la´be-al)
1. pertaining to a lip or labium.

2. in dental anatomy, pertaining to the tooth surface that faces the lip.


la·bi·al
adj.
 mucosa) (24,25), this hypothesis also predicts that the lingual surfaces would be less affected by reduced salivary flow. Therefore, in addition to dfs and DMFS, we analyzed caries on deciduous deciduous /de·cid·u·ous/ (de-sid´u-us) falling off or shed at maturity, as the teeth of the first dentition.

de·cid·u·ous
adj.
1.
 lingual surfaces and deciduous buccal surfaces.

* It has been proposed that lead may bind with salivary sal·i·var·y
adj.
1. Of, relating to, or producing saliva.

2. Of or relating to a salivary gland.



salivary

pertaining to the saliva.
 fluoride and thus diminish its protective effect on enamel demineralization demineralization /de·min·er·al·iza·tion/ (de-min?er-al-i-za´shun) excessive elimination of mineral or organic salts from tissues of the body.

de·min·er·al·i·za·tion
n.
 (26). Because fluoride is most effective in preventing caries on smooth surfaces (the sides of the teeth), and least on occlusal occlusal /oc·clu·sal/ (o-kloo´z'l)
1. pertaining to the masticating surfaces of the premolar and molar teeth.

2. occlusive.


oc·clu·sal
adj.
1.
 surfaces (the chewing surfaces) (27), we analyzed caries on smooth surfaces and occlusal surfaces separately. Again, because lead ingestion typically occurs at 1-3 years of age (13), we expected that this mechanism would affect deciduous teeth rather than permanent teeth and therefore conducted the analysis on deciduous teeth.

* Another proposed mechanism is that lead, incorporated into enamel during calcification calcification /cal·ci·fi·ca·tion/ (kal?si-fi-ka´shun) the deposit of calcium salts in a tissue.

dystrophic calcification
, may render the enamel more susceptible to caries (28). Permanent teeth calcify cal·ci·fy
v.
To make or become stony or chalky by deposition of calcium salts.



calcify

to mineralize by the deposition of calcium salts.
 between birth and 16 years of age (29). This age period includes the time during which blood lead levels tend to peak in children (13). We thus reasoned that permanent teeth would be more affected than deciduous teeth. However, several of the permanent teeth calcify outside the age range when children tend to ingest in·gest  
tr.v. in·gest·ed, in·gest·ing, in·gests
1. To take into the body by the mouth for digestion or absorption. See Synonyms at eat.

2.
 lead. Because the first permanent molars calcify between birth and age 36 months (29), an age period much more likely to overlap the age during which children tend to ingest lead, we analyzed caries on the first permanent molars.

Results

A total of 1,660 children were examined for caries at their elementary schools during the 1995-1996 and 1996-1997 academic years. Of these children, 248 had 1 or more appropriate blood lead measurements. These children composed the primary sample for analysis. Table 2 lists the demographics, lead measures, and dental measures of this sample. Parents of 154 children (62%) completed a telephone interview, 8 (3%) parents declined the interview, and 86 (35%) could not be contacted. The demographics, lead measures, and dental measures of the 154 children whose parents completed the telephone interview are presented in Table 2; these measures were comparable to those for the entire primary sample of children.
Table 2. Comparison of variables between the
primary sample and interviewed sample.

                                           Primary    Interviewed
Variable                                   sample       sample

Sample size                                  248          154
Demographics
  Sex (% male)                               50%          49%
  Ethnic distribution
    African American                         68%          69%
    White                                    10%          10%
    Hispanic                                 20%          18%
    Asian                                     2%           3%
Lead measures
  Mean lead exposure ([micro]g/dL)(a)       10.7         11.5
  Lead exposure range                       0-45         2-45
  Mean age at blood                         27.3         27.5
    collection (months)(b)
  Lead level range                        18.0-36.8    18.0-36.7
Mean age at dental                           8.4          8.4
  examination (years)
Age range                                 6.9-12.0     6.9-12.0
Grade at examination
  Second                                     79%          79%
  Fifth                                      21%          21%
Hygiene score
  Good                                        3%           3%
  Fair                                       90%          88%
  Poor                                        7%           9%
Mean dfs(c)                                3.4(d)       4.2(e)
dfs range                                   0-29         0-29
Mean deciduous SAR(f)                      54.4(d)      53.8(e)
Deciduous SAR range                         4-88         4-80
Mean DMFS(g)                               0.5(h)        0.50
DMFS range                                   0-8          0-8
Mean permanent SAR(i)                      52.9(h)       53.60
Permanent SAR range                         8-128        8-128

(a) To convert to [micro]mol/L, multiply by 0.0483. (b) Mean age at
blood collection for blood lead level. (c) The number of
decayed or filled surfaces in deciduous teeth. (d) Twenty
children had no deciduous teeth and were excluded from
the computation. (e) Fourteen children had no deciduous
teeth and were excluded from the computation.
(f) Deciduous surfaces at risk (equal to the total number of
deciduous surfaces minus number of sealed deciduous
surfaces). (g) The number of decayed, missing, or filled
surfaces in permanent teeth. (h) One child had no permanent
teeth and was excluded from the computation.(i) Permanent
surfaces at risk (equal to the total number of permanent
surfaces minus number of sealed permanent surfaces).


Among the primary sample of children (n = 248), the mean lead exposure was 0.52 [micro]mol/L (10.7 [micro]g/dL) and ranged from 0 to 2.17 [micro]mol/L (0-45 [micro]g/dL; Table 2). One hundred sixty-four (66%) children had a lead exposure [is less than] 0.48 [micro]mol/L ([is less than] 10 [micro]g/dL), and 84 (34%) had a lead exposure [is greater than or equal to] 0.48 [micro]mol/L ([is greater than or equal to] 10 [micro]g/dL). Twenty children had no deciduous teeth, 114 (50%) had a dfs = 0, and 114 (50%) had a dfs [is greater than or equal to] 1; the mean dfs was 3.4 and ranged from 0 to 29 (Table 2). One child had no permanent teeth, 199 (81%) had a DMFS = 0, and 48 (19%) had a DMFS [is greater than or equal to] 1; the mean DMFS was 0.5 and ranged from 0 to 8 (Table 2). These proportions of caries are comparable to national prevalence studies (5, 6).

The proportions of children with caries in permanent teeth (DMFS [is greater than or equal to] 1) as a function of lead exposure [[is less than] 0.48 [micro]mol/L vs. [is greater than or equal to] 0.48 [micro]mol/L ([is less than] 10 [micro]g/dL vs. [is greater than or equal to] 10 [micro]g/dL)] were 15% and 27%, respectively. The proportions of children with caries in deciduous teeth (dfs [is greater than or equal to] 1) as a function of lead exposure were 46% and 59%, respectively. However, children with lower lead exposure [[is less than] 0.48 [micro]mol/L ([is less than] 10 [micro]g/dL] were younger on average than those with higher lead exposure (8.1 years vs. 9.1 years, respectively; p [is less than] 0.001), more likely to be in second grade (90% vs. 60%, respectively; p [is less than] 0.001) and had fewer permanent surfaces at risk (means 47.0 vs. 64.3, respectively; p [is less than] 0.001). Therefore, we included age at exam, grade in school, and surfaces at risk as covariates in all the logistic regression analysis relating caries to lead exposure.

Table 3 reports the adjusted odds ratios for the probability of caries in children with high versus low lead exposure. For the DMFS measure, the odds ratio was 0.95 [95% confidence interval (CI), 0.43-2.09; p = 0.89). For the dfs caries measure, the odds ratio was 1.77 (95% CI, 0.97-3.24; p = 0.07). The only statistically significant association was for caries on the deciduous lingual surfaces, for which the odds ratio was 2.31 (95% CI, 1.18-4.51; p = 0.01). Adding the patient characteristics listed in the previous section to the regressions did not strengthen the estimated associations between lead exposure and caries.
Table 3. Adjusted odds ratios for association of
caries with lead exposure [< 0.48 [micro]mol/L vs.
[is greater than or equal to] 0.48 [micro]mol/L
(<10 [micro]g/dL vs. [is greater than or equal to]
10 [micro]g/dL)].(a)

Caries measure        OR     95% CI

Permanent teeth
  DMFS(b)             0.95   0.43-2.09
  First molar         1.12   0.52-2.39
Deciduous teeth
  dfs(c)              1.77   0.97-3.24(*)
  0cclusal surfaces   1.43   0.78-2.60
  Smooth surfaces     1.44   0.80-2.62
  Lingual surfaces    2.31   1.18-4.51(**)
  Buccal surfaces     1.51   0.72-3.15

(a) Adjusted for age at examination, grade in school, and
the number of surfaces at risk. (b) The number of decayed,
missing, or filled surfaces in permanent teeth. (c) The number of
decayed or filled surfaces in deciduous teeth. (*) p =
0.07. (**) p = 0.01.


Discussion

This study identified some paths for future study, and other avenues that do not look promising. We found that the odds ratio relating caries on deciduous teeth to lead exposure was marginally significant (0.05 [is less than] p [is less than] 0.10); the odds ratio for caries on deciduous lingual surfaces was significant at the 0.05 level (Table 3). None of the remaining comparisons were significant. Despite these significant findings, we did not see patterns of caries consistent with postulated mechanisms. For example, the hypothesis that lead, incorporated into enamel during calcification, renders the enamel more susceptible to caries would suggest a stronger association between lead exposure and caries in permanent teeth (DMFS) than in deciduous teeth (dfs). However, this pattern was not seen. Also, the hypothesis that lead causes a decrease in salivary flow would suggest a stronger association between lead exposure and caries in deciduous teeth than permanent teeth. Although this pattern was seen, the deciduous lingual surfaces were more affected than deciduous buccal surfaces--the opposite of what was expected. Therefore, the most conservative interpretation of the data is that this study failed to demonstrate a strong association between lead exposure and caries.

However, there are three limitations that may have caused an underestimation of any association. First, the lead exposure measure, in many cases based on a single blood lead level, was not a precise measure of cumulative lead exposure. Blood lead levels drawn after age 37 months were not included because studies have shown that most children are exposed to lead before this age (13). However, had lead exposure increased after age 37 months, we would be underestimating the true lead exposure, and such a misclassification bias would underestimate the odds ratios. Second, because the subjects were examined at a young age (the mean age at examination was 8.4 years), the caries experience of the permanent teeth was low (the mean DMFS score was only 0.5).

Therefore, sufficient time may not have elapsed e·lapse  
intr.v. e·lapsed, e·laps·ing, e·laps·es
To slip by; pass: Weeks elapsed before we could start renovating.

n.
 for caries to become manifested on permanent teeth. Moss et. al. (30), in a secondary data analysis of the NHANES III, reported a significant association between lead exposure and caries on permanent teeth of an older cohort of children aged 5-17 years. Finally, the purpose of the school-based caries-screening program was to identify cavitary lesions that required treatment, not to identify noncavitary, precarious lesions. This will underestimate the prevalence of caries (31).

Another limitation of this study was that it lacked statistical power to detect a low yet clinically relevant odds ratio. The secondary data analysis by Moss et al. (30) reports odds ratios of 1.36-1.66 for caries in permanent teeth. Although they appear to be low, such odds ratios imply a sizable burden of disease: an additional 2.7 million children may have caries as a result of lead exposure (30). The odds ratios reported by Moss et al. are consistent with our data, in that they are included in our confidence intervals. However, with a sample size of 248 subjects, we had less than 30% power for detecting an odds ratio of [is less than or equal to] 1.5.

In summary, this study did not demonstrate an association between lead exposure and caries. However, due to the limitations described above, the findings do not exclude 1the possibility that such an association exists.

REFERENCES AND NOTES

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(2.) American Academy of Pediatrics The American Academy of Pediatrics ("AAP") is an organization of pediatricians, physicians trained to deal with the medical care of infants, children, and adolescents. Its motto is: "Dedicated to the Health of All Children.  Committee on Environmental Health. Screening for elevated blood lead levels. Pediatrics 101:1072-1078 (1998).

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schoolchildren school
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(6.) Kaste LM, Selwitz RH, Oldakowski RJ, Brunelle JA, Winn DM, Brown LJ. Coronal cor·o·nal
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1. Of or relating to a corona, especially of the head.

2. Of, relating to, or having the direction of the coronal suture or of the plane dividing the body into front and back portions.
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A group of elements that are present in the human body in very small amounts but are nonetheless important to good health. They include chromium, copper, cobalt, iodine, iron, selenium, and zinc. Trace elements are also called micronutrients.
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(18.) Rabinowitz MB, Leviton A, Bellinger DC. Blood lead-tooth lead relationship among Boston children. Bull Environ Contain Toxicol 43:485-492 (1989).

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(22.) Bowen WH, Pearson SK, Young DA. The effect of desalivation on coronal and root surface caries in rats. J Dent Res 67:21-23 (1988).

(23.) Craan A, Nadon G, P'an AYS AYS At Your Service
AYS Are You Sure?
AYS Are You Serious?
AYS About Your Sexuality (Unitarian Universalist education publication)
AYS All You See
AYS Andover Youth Services (Andover, MA) 
. Lead flux through kidney and salivary glands salivary glands (săl`əvâr'ē), in humans, three pairs of glands that secrete the alkaline digestive fluid, saliva, into the mouth.  of rats. Am J Physiol 247:F773-F783 (1984).

(24.) Dawes C, Watanabe S, Biglow-Lecomte P, Dibdin GH. Estimation and velocity of the salivary film at some different locations in the mouth. J Dent Res 68(11):1479-1482 (1989).

(25.) Dawes C. The ebb and flow the alternate ebb and flood of the tide; often used figuratively.

See also: Ebb
 of the salivary tide. In: Cariology for the Nineties (Bowen WH, Tabak LA, eds). Rochester, NY:University of Rochester The University of Rochester (UR) is a private, coeducational and nonsectarian research university located in Rochester, New York. The university is one of 62 elected members of the Association of American Universities.  Press, 1993;133-141.

(26.) Rao GS. Dietary intake and bioavailability bioavailability /bio·avail·a·bil·i·ty/ (bi?o-ah-val?ah-bil´i-te) the degree to which a drug or other substance becomes available to the target tissue after administration.

bi·o·a·vail·a·bil·i·ty
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(27.) Klein H. Dental effects of community water accidentally fluoridated for nineteen years. II. Differences in the extent of caries reduction among different types of permanent teeth. Public Health Rep 63:563-573 (1948).

(28.) Brudevold F, Steadman LT. The distribution of lead in human enamel. J Dent Res 35:430-437 (1956).

(29.) Arey LB. Developmental Anatomy developmental anatomy
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The study of the structural changes of an individual from fertilization to adulthood.
: A Textbook and Laboratory Manual of Embryology embryology

Study of the formation and development of an embryo and fetus. Before widespread use of the microscope and the advent of cellular biology in the 19th century, embryology was based on descriptive and comparative studies.
. 7th ed. Philadelphia, PA: W.B. Saunders Co., 1965.

(30.) Moss ME, Lanphear BP, Auinger P. Association of dental caries and blood lead levels. JAMA JAMA
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(31.) Spencer AJ. Skewed distributions--new outcome measures. Community Dent Oral Epidemiol 25:52-59 (1997).

James R. Campbell James Romulus Campbell (May 4, 1853 - August 12, 1924) was a U.S. Representative from Illinois.

Born near McLeansboro, Hamilton County, Illinois, Campbell attended the public schools and the University of Notre Dame, Notre Dame, Indiana. He studied law.
,(1) Mark E. Moss,(2) and Richard F. Raubertas,(3)

(1)Department of Pediatrics, (2)Department of Community and Preventive Medicine preventive medicine, branch of medicine dealing with the prevention of disease and the maintenance of good health practices. Until recently preventive medicine was largely the domain of the U.S. , and (3)Department of Biostatistics, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA

Address correspondence to J. R. Campbell J. R. “Doc” Campbell (b. 1918) is an American attorney in the state of Oregon, United States. He was the 82nd Associate Justice of the Oregon Supreme Court and served on the Oregon Court of Appeals. , Rochester General Hospital, Department of Pediatrics, MOB Suite 300, 1425 Portland Avenue, Rochester, NY 14621-3095 USA. Telephone: (716) 922-4028. Fax: (716) 922-3929. E-mail: James. Campbell@viahealth.org

We thank J. Ettel for her assistance in data collection, W. Bowen for methodological advice, and C. Meyerowitz and G. Watson for reviewing the manuscript.

This work was funded by the National Institute of Environmental Health Sciences The National Institute of Environmental Health Sciences (NIEHS) is one of 27 Institutes and Centers of the National Institutes of Health (NIH),which is a component of the Department of Health and Human Services (DHHS). The Director of the NIEHS is Dr. David A. Schwartz. , National Institutes of Health, grant RO3 ES08610-01.

Received 9 February 2000; accepted 20 June 2000.
COPYRIGHT 2000 National Institute of Environmental Health Sciences
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2000, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

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Author:Raubertas, Richard F.
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Date:Nov 1, 2000
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