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| Author(s): |
Carolina de Souza Guerra
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Piracicaba, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba |
| Defense date: | 2010-12-14 |
| Examining board members: |
Raquel Fernanda Gerlach;
Frederico Barbosa de Sousa;
Márcia Andréia Mesquita da Silva Veiga;
Viviane Elisangela Gomes;
Eduardo Mello De Capitani
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| Advisor: | Raquel Fernanda Gerlach |
| Abstract | |
Objectives: The objectives of this study are: a) to compare the concentrations of lead in different layers of enamel with those found in prenatal and postnatal dentine of primary teeth collected from: 1 - Santo Amaro, Bahia State, 2 - Cubatão, São Paulo State, 3 - Ribeirão Preto, São Paulo State and Mato Leitão, Rio Grande do Sul State b) analyze the spatial distribution of lead in same samples by micro X-Ray Fluorescence with Synchrotron Radiation . Methods: A surface enamel acid-etch microbiopsy was performed in vitro in the enamel surface and five sucessives samples of superficial enamel were removed. Lead was measured by Inductively coupled plasma mass spectrometry, while phosphorus was measured colorimetrically to establish biopsy depth. Pieces of prenatal and postnatal dentine were dissolved in ultrapure nitric acid. Longitudinally cut of some samples of primary teeth were analyzed by micro-XRF. Four anatomical areas were analyzed by bidimensional (x, y) scanning in each tooth section. These anatomical areas were: Superficial enamel (SE), Subsuperficial enamel (SSE), Primary Dentine (PD), and Secondary Dentine (SD). Results: Median superficial enamel lead content of the teeth collected in Santo Amaro were statistically higher than the one from teeth collected in Ribeirão Preto, Cubatão and Mato Leitão (p<0.0001 for these comparisons). The lead concentration in the enamel did not differ when results from Ribeirão Preto and Mato Leitão, or Cubatão and Mato Leitão were compared. Median lead contents found in prenatal and postnatal dentine of Santo Amaro teeth were statistically higher than the ones found in teeth from Ribeirão Preto and Cubatao (p<0.001). No difference was found when prenatal and postnatal dentine values from Ribeirão Preto were compared with those from Cubatao. Spearman's correlation coefficient for lead concentration in dentine versus lead concentration in the enamel surface was significant for Ribeirão Preto (Prenatal dentine versus enamel r=0,3, p=0,003 e r=0,3, p=0,0013 and Posnatal dentine versus enamel r=0,27, p=0,06 e r=0,21 e p=0,15), and Santo Amaro (Prenatal dentine versus enamel r=0,38, p=0,0001 e r=0,18 e p=0,08 and Postnatal r=0,3, p=0,015 e r=0,2, p=0,1) . No correlation significant was found in Cubatão (Prenatal dentine r=0,118, p=0,195, r=0,05, p=0,59; Postnatal dentine r=0,05, p=0,59, r=0,09, p=0,28). The ?-SRXRF confirmed a heterogenous distribution of lead in the primary incisors, with the highest signal found in superficial enamel and inner dentine. The Pb/Ca intensity decreased from surface enamel to secondary dentin in all the samples analyzed. Conclusions: this study shows that there is a weak but significant correlation between the lead levels found in the superficial enamel and the ones found in the pre- and postnatal dentine, but only in the samples from cities that showed higher lead values (in this study Ribeirao Preto and Santo Amaro). The ?-SRXRF confirmed a heterogenous distribution of lead in the primary incisors, with the highest signal found in superficial enamel and inner dentine (AU) | |