Volume 204 Issue 12, 28 June 2008
Coloured scanning electron micrograph of the surface of a human tooth (yellow), showing a carpet of spherical bacteria (blue) and red blood cells (red). More than 300 species of bacteria inhabit the human mouth. They feed on the organic film of saliva and food debris that coats the teeth. They produce the enzyme lactate dehydrogenase, which converts sugars into lactic acid. This has a demineralising effect on the tooth enamel, causing tooth caries. The red blood cells may have arisen from bleeding gums, an early sign of gingivitis. COVER IMAGE copyright THIERRY BERROD, MONA LISA PRODUCTION/SCIENCE PHOTO LIBRARY
Editorial
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