Endotoxin contamination in the dental surgery

1 Department of Microbiology, B514 West Fee Hall, Michigan State University, East Lansing, MI 48824, USA 2 Department of Pathology, B514 West Fee Hall, Michigan State University, East Lansing, MI 48824, USA Correspondence M. K. Huntington mark.huntington{at}usd.edu Received 14 February 2007 Accepted 24 May 2007 Dental waterlines contain large numbers of Gram-negative bacteria. Endotoxin, a component of such organisms, has significant health implications. Paired samples of dental unit water and the aerosols generated during dental procedures were collected, and assayed for bacteria and endotoxin levels, using heterotrophic plate counts and the Limulus amoebocyte lysate test. Consistent with published studies, the extent of bacterial contamination in the dental waters sampled for this investigation surpassed the levels associated with potable water, with counts in excess of 2.0 x 10 6 c.f.u. ml –1 in some samples. Correspondingly high concentrations of endotoxin [up to 15 000 endotoxin units (EU) ml –1 ] were present in the water. A statistically significant Spearman correlation coefficient of =0.94 between endotoxin (EU ml –1 ) and bacterial load (c.f.u. ml –1 ) was demonstrated. All of the aerosol samples contained detectable endotoxin. Further studies of the consequences of dental endotoxin exposure, and evaluation of means to prevent exposure, are warranted. Abbreviations: CDC, Centers for Disease Control and Protection; EU, endotoxin unit; LAL, Limulus amoebocyte lysate. Present address: Center for Family Medicine, 1115 East Twentieth Street, Sioux Falls, SD 57105, USA. Present address: Vanson HaloSource, Inc., 14716 NE 87th Street, Redmond, WA 98052, USA.