@Copyright 1991 by The Humana Press, Inc. All fights of any nature, whatsoever, reserved. 0163-4984/91/2903--0229 $02.00

Zinc in Teeth from Children With and Without Cystic Fibrosis FLORENCE T. CUA Radiation Science Program, Rutgers, the State University, New Brunswick, NJ 08903 Received July 3, 1990; Accepted August 26, 1990

ABSTRACT This study analyzes Zn concentration levels in teeth from children with and without cystic fibrosis with respect to different variables, namely: gender, age, type of teeth, area, fluoridation of water supply, term of pregnancy, maternal smoking habit, and maternal drinking habit. The method of analysis is proton-induced X-ray emission on crown samples. Atomic absorption spectrometry (AAS) studies on some of these samples show close correlation to the PIXE data. In general, the concentration level of zinc in teeth of children greater than 10 years old is less than the concentration level in teeth of children aged 10 years or younger for children who took nontetracycline antibiotics. Breast feeding-mixed feeding-bottle feeding show no significant difference in the zinc concentration in teeth. Index Entries: Proton-induced X-ray emission; atomic absorption spectrometry (AAS); tooth crown; Zinc; breast feeding-mixed feeding-bottle feeding.

INTRODUCTION Cystic fibrosis (CF) is a genetic disorder a m o n g Caucasians with an approximate incidence of 1 in 2000 live births (1). Jacob et al. (2) f o u n d zinc status of the CF group as a whole to be low-normal with a s u b g r o u p having marginal to deficient zinc in their plasma and hair. Their data suggest that zinc m a y be a contributing factor in the low plasma vitamin A. Palin et al. (3) found oral zinc supplementation with 100 m g zinc sulfate over an 8-wk period in 36 patients with CF and 17 siblings not to Biological Trace Element Research

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affect the vitamin A transport system, nor did the exogenous zinc appear to stimulate growth or exert clinical benefit to the CF patients. The patients were fairly healthy in regard to clinical status and zinc in blood. According to Chandra (4), mature human milk has 0.14 4 mg Zn/L, whereas infant formulas contain 3.7-12 mg Zn/L. The recommended zinc intakes are 3 mg/d for infants, and the estimated true requirement by World Health Organization (WHO) as of 1973 is 1.1-1.25 rag/d, and according to King and Turnlund (5), it is 1-1.2 mg/d. Since some children with CF, especially those with poor growth, have low zinc levels, and because of the large losses in diarrhea stools, the current recommendation is 15 mg of elemental Zn daily (75 mg of zinc sulfate or 45 mg of zinc acetate) if monitoring is not done (6). As tetracycline antibiotics caused staining in the teeth of the individuals, zinc concentrations in the CF + NT and CF +T groups were compared. This article is intended to show the effects of several variables such as gender, age, type of teeth, area, fluoridation of water supply, term of pregnancy, maternal smoking habit, and maternal drinking habit on the zinc concentration in crown of children who have CF and those who do not. A similar article published in the International Journal of Proton Induced X-ray Emission (IJPIXE) (7) presents the concentration levels of magnesium, phosphorous, and iron as a function of gender and age, calcium and iron as a function of maternal smoking habit, strontium and fluorine as a function of maternal drinking habit, and fluorine as a function of fluoridation of water supply.

MATERIALS AND M E T H O D S In 1985, the author initiated the "tooth fairy program", which up to date includes 9 CF+NT (cystic fibrosis-nontetracycline antibiotics takers), 6 CF+T (cystic fibrosis-tetracycline antibiotics takers), and 11 NCF (noncystic fibrosis) individuals who gave multiple teeth, and 17 CF + NT and 12 NCF individuals who gave single teeth. There is a total of 26 CF + NT, 6 CF + T, and 23 NCF individuals who gave 51, 15, and 48 teeth, respectively. Of that, only 26 CF + NT individuals and 16 NCF children filled out an accompanying questionnaire. The questionnaire included questions on gender, age, type of teeth, type of area (urban or rural), fluoridation of water supply, term of pregnancy, maternal smoking habits, and maternal drinking habits, as well as vitamins, antibiotics, and treatment for CF. A detailed description of the preparation of samples, the methods of proton-induced X-ray emission (PIXE), and proton-induced gamma emission, including description of the accelerators used, irradiation setup, data acquisition system, and spectrum analysis, are found in Cua (8). Biological Trace Element Research

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Table 1 Quality Assurance Results for Zinc in Crown NAME

PIXE I

AAS 2

ratio

MIP3I

84

139

ST20

84

80

I 05

I06E

119

46

2 59

N28R

108

83

I 30

~,4B

154

142

I 08

KI2C

109

49

2 22

MCRP

126

176

0.72

KND

109

141

0.77

N5P

77

139

0.55

302

415

0.73

MIP2S

0 604

1.16~0.69

l.~roton-induced x-ray emission ~at~nic absorption

spe2trcc.etry

Quality Control~Quality Assurance At least two Zn standards were used for the PIXE runs. Repeat spectrum analysis was used to insure reproducibility. Agreement was within 5%. For quality assurance purposes, 10 teeth analyzed by the PIXE method were analyzed by Perkin-Elmer Model NO. 603 flame/acetylene atomic absorption spectrometer (AAS) located at the Environmental Science Department. A linear plot of absorbance vs concentration shows a linear correlation. The results from the quality assurance study for Zn is reported in Table 1. The range of the ratio of PIXE/AAS is 0.55-2.22 and the mean is 1.16 -+ 0.69, with a correlation of 0.87. This agrees well with Clayton et al. (9), who compared PIXE/AAS zinc results in hair samples and found a ratio of 1.19 ___ 0.15.

Statistical Analysis The following statistical analysis programs were performed on the AS-9000 mainframe computer at the Center for Computer and Information Services, Rutgers, the State University. Biological Trace EAement Research

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P r o c e d u r e General Linear Models (PROC GLM) (10) was u s e d to give a contrast a m o n g the m e a n s of the elemental concentration of the individuals in the p o p u l a t i o n g r o u p s , CF + T , CF + NT, a n d NCF, w h e n the s a m p l e sizes of the p o p u l a t i o n g r o u p s were not the same. There w e r e 14 individuals i n c l u d e d w h o s u p p l i e d teeth ranging from 2-10 in n u m b e r . The possibility that bias, a s k e w i n g of the data toward the variable category that the individual belongs to, exists o w i n g to i m p r o p e r w e i g h t i n g of the multiple teeth from individuals. A t-test was d o n e c o m p a r i n g the m e a n of the m e a n s of the teeth for each individual from m u l t i p l e teeth category with the a b o v e - m e n t i o n e d m e a n s , a n d nonsignificant difference was f o u n d . T-test a s s u m e s a n o r m a l distribution for b o t h cases. PROC GLM w a s previously d o n e on the m e a n s of the individual Zn concentration a n d no significant difference a m o n g C F + NT, CF + T , a n d NCF was f o u n d . T-test is a statistical analysis m e t h o d (11) u s e d to d e t e r m i n e w h e t h e r the m e a n s of two p o p u l a t i o n s are the same. A normal distribution was a s s u m e d for the t-test. It is r e c o m m e n d e d that 30 samples be available for each category (12). Since this is a pilot study, s o m e of the p o p u l a t i o n g r o u p s h a d less than 30 samples. The values for the concentration were taken for teeth individually rather than based on individual contribution. PROC M E A N S was used to obtain the m e a n s and s t a n d a r d deviation of the zinc concentration levels for the teeth in the 3 p o p u l a t i o n g r o u p s of CF + NT, CF + T, a n d NCF.

RESULTS AND DISCUSSION Using PROC MEANS, the m e a n of the zinc concentration values in the teeth c r o w n s of children with CF w h o took tetracycline antibiotics (CF +T) w a s f o u n d to be 140 • 39 [15], in the teeth c r o w n s of children with CF w h o took nontetracycline antibiotics ( C F + N T ) was 131 +- 52 [51], a n d in the teeth c r o w n s of n o n C F (NCF) children, 130 -+ 56 [48], respectively. The p o p u l a t i o n g r o u p s in Tables 2-9 i n c l u d e d teeth from CF a n d NCF c h i l d r e n w h o filled out the questionnaires. The results in Tables 2-9 are those of the m e a n of the teeth taken individually. The zinc concentration values are constant as a function of birth year (8), a n d since the c r o w n of all types of teeth is f o r m e d by the first year of life (13), theoretically, all types of teeth c r o w n s can be c o n s i d e r e d as similar in e l e m e n t concentratio.n. Table 4 s h o w s zinc in incisors n o t to be significantly different to nonincisors (see ref. 8 for erratum). O n e of the individuals with six teeth w a s m i s t a k e n to have CF a n d the zinc data analyzed as such. O n recategorization as b e l o n g i n g to the n o n C F g r o u p , the zinc concentration for central incisors for C F + N T w a s f o u n d n o t significantly different to that for NCF. Biological Trace Element Research

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Zinc in Teeth of Children with CF Table 2 Zinc Concentration Values in Crown of Children Which are Males and Females CF~NT NCF Prob

Gender

Total

Male

124Z47(33)

i15~41(II)

0.5971

122~45(44)

Female

151~60(18)

141~66(16)

0.6699

!46L62(34)

Prob

0.0846

0.2566

Total

133~53(51)

131~58(27)

0.0469 0.8460

Table 3 Zinc Concentration V~ues in Crown of Children Who we G~ater than 10 or L e ~ ~ a n or Equ~ ~ 10 Age

greater I0

CF~NT

than

NCF

Prob

Total

I09Z22(10)

129~62(13)

0.2989

120149(23)

less t h a n or 139Z57(41) equal to i0

127~52(17)

0.4709

136Z55(58)

Prob

0~

Total

133253(51)

0.9477

0.2446

123=55(30)

0.6804

Table 4 Zinc Concentration V~ues in Crown of Children Which are Incisors and Nonincisors Ty~,e

CF*NT

NCF

incisor

130148(30)

126C44(19)

0.7278

128146(4s )

Nomincisor

138~61(21)

133~74(Ii)

0.8425

126~64(32)

Prob

0.6321

0.7271

Total

133Z53(51)

128~56(30)

Area

Prob

Total

0.56s 0.6804

Table 5 Zinc Concentration Values in Crown of Children Living in Urban and Rural Areas CF~NT NCF Prob

Total

urban

2618(23)

32~ii(28)

0.042

29~10(51)

rural

31~I0(29)

30~!2(2)

0.8952

31=10(31)

Prob

0.0668

0.8630

Total

29•

32~ii(30)

Biological Trace Element Research

0.5076 0.1904

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Cua Table 6 Zinc Concentration Values in Crown of Children Who Live in Fluoridated or Nonfluoridated Areas Fluoridation of W a t e r Supply

CF-NT

NCF

Prob

Total

Fluoridated ~ater supply

136~68(26)

130~52(iI)

0.8039

134~85(37)

Nonfluoridated water supply

131~33(25)

127!59(19)

0.8036

129h67(44)

Frob

0.7618

0.9048

Total

133~53(51)

128~56(30)

0.7200 0.6804

Table 7 Zinc Concentration Values in Crown of Children Born Full-term or Pre-term Term

CF~NT

NCF

Prob

Total

Preterm

155~75(6)

126~38(5)

0.4554

142~60(II)

Fuliterm,

131Z50(44)

138~69(17)

0.6372

133~56(61)

Prob

0.3070

0.7042

Total

124~54(50)

136Z63(22)

0.6386 0.8984

Table 8 Zinc Concentration Values in Crown of Children Whose Mothers Smoke and Those Whose Mother Do Not S m o k e Maternal smoking habit

CF~NT

NCF

Prob

Total

Mother smoking

123~63(12)

124Z32(8)

0.9732

124~52(20)

Mother does not smoke

137Z54(31 )

142Z76(14)

0.7805

138Z61(45 )

Prob

0.4890

0.4435

Total

133~56(43)

136!63(22)

Biological Trace Element Research

0.3465 0.8613

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Table 9 Zinc Concentration Values in Crown of Children Whose Mothers Drink and Those Whose Mother Do Not Drink Alcoholic Beverages Maternal drinking habit

CF~NT

NCF

Frob

Total

Mother drinking

129~58(16

!40~80(7)

0.7056

132~64(23)

Mother does not drink

!44~57(26

124~56(15)

0.5S86

140~56(41)

Prcb

0.4120

0.8353

Total

138Z57(42

136~63(22)

0.60~4

0.8814

The only significant difference is for age > 10 and age