title: Immune function effects of dental amalgam in children: a randomized clinical trial.
abstract: BACKGROUND
  Dental amalgam is a widely used restorative material containing 50 percent elemental mercury that emits mercury vapor. No randomized clinical trials have determined whether there are adverse immunological effects associated with this low-level mercury exposure in children. The objective of this study was to evaluate a subpopulation of the participants in the New England Children's Amalgam Trial for in vitro manifestations of immunotoxic effects of dental amalgam.
  
  
  METHODS
  The authors conducted a randomized clinical trial in which children requiring dental restorative treatment were randomly assigned to receive either amalgam for posterior restorations or resin-based composite restorations. They assessed 66 children, aged 6 to 10 years, for total white blood cell counts, specific lymphocyte (T-cell and B-cell) counts and lymphocyte, neutrophil and monocyte responsiveness across a five-year period. Because of the small number of participants, the authors acknowledge that the study is exploratory in nature and has limited statistical power.
  
  
  RESULTS
  The mean number of tooth surfaces restored during the five-year period was 7.8 for the amalgam group and 10.1 for the composite group. In the amalgam group, there was a slight, but not statistically significant, decline in responsiveness of T cells and monocytes at five to seven days after treatment; the authors consistently observed no differences at six, 12 or 60 months.
  
  
  CONCLUSIONS
  The findings of this study confirm that treatment of children with amalgam restorations leads to increased, albeit low-level, exposure to mercury. In this exploratory analysis of immune function, amalgam exposure did not cause overt immune deficits, although small transient effects were observed five to seven days after restoration placement.
  
  
  CONCLUSIONS
  These findings suggest that immunotoxic effects of amalgam restorations are minimal and transient in children and most likely do not need to be of concern to practitioners considering the use of this restorative dental material.
authors.affiliation: Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. shenker@upenn.edu
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Shenker
authors.forename: Nancy N
authors.initials: NN
authors.lastname: Maserejian
authors.forename: Annie
authors.initials: A
authors.lastname: Zhang
authors.forename: Sonja
authors.initials: S
authors.lastname: McKinlay
mesh_terms: D000704:Analysis of Variance; D001402:B-Lymphocytes / Q000187:drug effects / Q000378:metabolism; D002648:Child; D003188:Composite Resins / Q000627:therapeutic use; D003723:Dental Amalgam / Q000378:metabolism / Q000494:pharmacology*; D003793:Dental Restoration, Permanent / Q000379:methods; D005260:Female; D006801:Humans; D007107:Immune System / Q000187:drug effects* / Q000378:metabolism; D007962:Leukocytes / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008628:Mercury / Q000494:pharmacology / Q000652:urine*; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors
chemical_list: D003188:Composite Resins; D003723:Dental Amalgam; D008628:Mercury