title: Dental amalgam exposure can elevate urinary mercury concentrations in children.
abstract: OBJECTIVE
  Owing to its cost-effectiveness and operative convenience, dental amalgam remains in use as a restorative material for tooth caries in children in many countries. The aim of this study was to evaluate the relationship between dental amalgam exposure and urinary mercury (U-Hg) concentrations in children.
  
  
  METHODS
  In this longitudinal study, 463, 367 and 348 children, 8-11 years of age, were evaluated at baseline, and at the first and second follow-up visits, respectively. The interval between each survey was 6 months. For the oral examination and urine sample, the amalgam-filled tooth surface (TS), and U-Hg and creatinine concentrations of participants were determined, and the cumulative amalgam-filled TS and cumulative creatinine-adjusted U-Hg were calculated. To assess potential covariates, socio-demographic factors, oral health behaviour and dietary factors were surveyed by questionnaire. Data were analysed by the t-test, correlation analysis and mixed-model analysis. The statistical analyses were performed using SPSS 18.0.
  
  
  RESULTS
  Children with more than one amalgam-filled TS exhibited significantly higher creatinine-adjusted U-Hg concentrations than those without, in all three survey periods (P < 0.001). The results for the current and cumulative amalgam-filled TS significantly correlated with those for the current and cumulative creatinine-adjusted U-Hg concentration, respectively, in all surveys (P < 0.001). In the repeated-measures mixed model analysis, current and cumulative amalgam-filled TS was significantly related to current and cumulative creatinine-adjusted U-Hg concentration, respectively (P < 0.001).
  
  
  CONCLUSIONS
  Amalgam-filled TS was significantly correlated with U-Hg concentrations in children. Therefore, dental amalgam exposure can affect the systemic mercury concentration in children.
authors.affiliation: Department of Dental Hygiene, Taegu Science University 47 Yeongsong-ro Buk-gu, Daegu, Korea.
authors.forename: Hye-Jin
authors.initials: HJ
authors.lastname: Baek
authors.affiliation: Department of Dental Hygiene, College of Science & Technology, Kyungpook National University, Daegu, Korea.
authors.forename: Eun-Kyong
authors.initials: EK
authors.lastname: Kim
authors.affiliation: Department of Hospital Management, Graduate School of Public Health, Yonsei University, Seodaemun-gu, Seoul, Korea.
authors.forename: Sang Gyu
authors.initials: SG
authors.lastname: Lee
authors.affiliation: Faculty of Health Science, Daegu Haany University 1 Haanydae-ro, Gyeongsan-si, Gyeongsangbuk-do, Korea.
authors.forename: Seong-Hwa
authors.initials: SH
authors.lastname: Jeong
authors.affiliation: Department of Preventive Medicine and Public Health College of Medicine, Yeungnam University 170 Hyunchung-ro, Nam-gu, Daegu, Korea.
authors.forename: Jun
authors.initials: J
authors.lastname: Sakong
authors.affiliation: Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia, SC, USA.
authors.forename: Anwar T
authors.initials: AT
authors.lastname: Merchant
authors.affiliation: Department of Preventive Dentistry, School of Dentistry, Kyungpook National University, Daegu, Korea.
authors.forename: Sang-Uk
authors.initials: SU
authors.lastname: Im
authors.affiliation: Department of Preventive Dentistry, School of Dentistry, Kyungpook National University, Daegu, Korea.
authors.forename: Keun-Bae
authors.initials: KB
authors.lastname: Song
authors.affiliation: Department of Preventive Dentistry, School of Dentistry, Kyungpook National University, Daegu, Korea.
authors.forename: Youn-Hee
authors.initials: YH
authors.lastname: Choi
mesh_terms: D002648:Child; D003404:Creatinine / Q000652:urine; D003723:Dental Amalgam / Q000737:chemistry* / Q000627:therapeutic use*; D003731:Dental Caries / Q000628:therapy* / Q000652:urine; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008628:Mercury / Q000652:urine*; D009909:Oral Health; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires
chemical_list: D003723:Dental Amalgam; D003404:Creatinine; D008628:Mercury
keywords: Amalgam; children; dental practice
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