Cross-infection hazards associated with the use of pumice in dental laboratories.

The bacteriological contamination of pumice slurry in polishing units in a dental clinical area (high risk), a production laboratory (medium risk), and a non-clinical teaching laboratory (low risk), was investigated. Slurry samples taken from all three areas were found to be heavily contaminated with pathogenic organisms. The investigations were repeated following the addition of a disinfectant with both bacteriocidal and virucidal properties to the pumice. Lower bacterial counts were obtained indicating that routine disinfection of pumice slurries is desirable.