Dentine circumpulpal

Shapiro, I.M., Dobkin, B., Tuncay, O.C. and Needleman, H.L (1973). Lead levels in dentin and circumpulpal dentin of deciduous teeth of normal and lead poisoned children, Clin. Chim. Acta 46, 119-123... 

The toxicokinetic relationships between tooth Pb and PbB have been evaluated. Levels of lead in various tooth components as measured and reported were related to available data on PbB by Rabinowitz (1995). Dentine, whole-shed teeth or crowns, but not circumpulpal dentine, were included. Mean tooth Pb values varied from 2.8 to 12.7 ppm and PbB levels from 6.5 to 17 n-g/dl. A good fit was found in plots of tooth versus PbB... 

Denmark Aarhus children, first grade (156) Urban community Pb exposures circumpulpal dentine Pb mean 10.7 pg/g high Pb > 18.7 pg/g, low Pb s 5 pg/g PbB mean = 5.1 pg/dl Significant association of Pb-dentine with Bender, Full-Scale Wise and verbal WISC Hansen et al. (1989)... 

Danish schoolchildren (Aarhus, first grade, N= 156) having urban community Pb exposures were tested using circumpulpal dentine Pb levels as exposure marker and various psychometric measures (Hansen et al., 1989). The Bender, WISC-R Full Scale, and Verbal Test IQ decrements were significantly associated with the dentine Pb levels. Urban community Pb exposures in Dunedin, New Zealand, children (age 11, V=579) were evaluated by... 

Cleveland, OH low SES children [providing shed incisor teeth] (154) WPPSI test full-scale, verbal, and performance IQs at 4 years, 10 months Pb measured as circumpulpal dentine Pb Significant inverse association of dentine Pb with verbal IQ marginal association with full-scale IQ Greene and Ernhart (1993)... 

A subset of this cohort (N = 242) was tested at 4.8 years of age using the Fid Scale, Verbal, and Performance Scales of the WPPSI IQ Test as the outcome and maternal, cord, and early postnatal PbB values as exposure indicators (Emhart et al., 1989). No statistically significant associations were reported. A further subset (N = 164) of this cohort was similarly tested at the same age using a cumulative Pb exposure measure, circumpulpal dentine Pb measured from shed incisors (Greene and Emhart, 1993). They reported significant inverse statistical associations of Verbal IQ and marginal association of Full Scale IQ with the Pb-T measurements. 

It is likely that differences in lead levels in different types of teeth found in whole-tooth analysis, are in part due to the relative proportions of enamel, primary and secondary dentine in different teeth, but this does not explain why there should be a difference in samples of circumpulpal dentine from incisors in different jaws. 

Any detailed assessment of lead in dentition as a useful indicator is confounded by the fact that the various relevant studies have not employed a standard sampling protocol. Some researchers have employed whole tooth or crowns (Pinchin et al, 1978 Steenhout and Pourtois, 1981 Delves et al, 1982 Ewers et al, 1982 Smith et al, 1983), while others have employed lead levels in regions of teeth, generally secondary (circumpulpal) dentine (Shapiro et al, 1973, 1975 Needleman et al, 1979 Grandjean et al, 1984). In most cases, lead levels in whole or dissected teeth have been used as such, but reporting of lead burden as a function of age has also been done. 

Saenger, P., Rosen, J.F. and Markowitz, M.E. (1982) Diagnostic significance of edetate disodium calcium testing in children with increased lead absorption. Am. J. Dis. Child., 136, 312-315 Schroeder, S.R., Hawk, B., Otto, D.A., Mushak, P. and Hicks, R.E. (1985) Separating the effects of lead and social factors on IQ. Environ. Res., 38, 144-154 Shapiro, I.M., Needleman, H.L. and Tuncay, O.C. (1972) The lead content of human deciduous and permanent teeth. Environ. Res., 5, 467-470 Shapiro, I.M., Dobkin, B., Tuncay, O.C. and Needleman, H.L. (1973) Lead levels in dentine and circumpulpal dentine of deciduous teeth of normal and lead poisoned children. Clin. 

The lead level was determined according to procedures described in detail elsewhere (Grandjean ei al, 1984, 1986). In short, each tooth is split into two halves. The exposed pulp chamber is then thoroughly cleaned, and about 0.5-1 mg of the soft circumpulpal dentine from one of the two tooth segments is removed by a wolfram-carbide rosette burr. The powder is weighed and dissolved in 100/il concentrated HNO3 which is subsequently diluted by 400 fl redistilled water in a sample cup. The detection of lead takes place by electrothermal atomic absorption spectrometry. This method has shown excellent reproducibility. 

Grandjean, P., Nielsen, O.V. and Shapiro, I.M. (1979) Lead retention in ancient Nubian and contemporary populations. ]. Environ. Pathol. Toxicol, 2, 781-787 Grandjean, P., Hansen, O.N. and Lyngbye, K. (1984) Analysis of lead in circumpulpal dentin of deciduous teeth. Ann. Clin. Lab. Sci., 14, 270-275 Grandjean, P., Lyngbye, T. and Hansen, O.N. (1986) Lead concentration in deciduous teeth variation related to tooth type and analytical technique. ]. Toxicol Environ. Health, 19, 437-445... 

The importance of consensus in terminology was highlighted by a misunderstanding of the analytical procedures employed, because of a differential use of the labels, primary, secondary and circumpulpal dentine, by different research groups. This indicated one area where improvements in inter-study communication could be made with ease. Exchange of personnel between study groups to observe analytical procedures, or a video-recording to demonstrate the process, would resolve such differences. The latter procedure would also provide a record which could be kept for reference purposes. 

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