Microbial contamination of denture polishing equipment

INTRODUCTION: Lathes and pumice slurry are commonly used without change or disinfection for polishing both new and old, repaired dentures PURPOSE: To identify and quantify any microorganisms harboured in these components in the laboratories of an academic teaching institution where the machines are in constant daily use. MATERIAL AND METHODS: Two machines were identified and labelled in each laboratory, one for exclusive use for new dentures and the other for dentures which had been exposed to any form of patient oral contact. Users were so informed. Samples were collected twice daily on alternate days over a period of one week and tested for the presence and type of microorganisms, and whether the levels of contamination increased with usage. RESULTS: Pumice throughout was contaminated with a variety of bacteria, yeasts and moulds. notably Aspergillus, which will hover in the abundant aerosol during polishing. Cross-contamination can thus occur between dentures, posing danger to patients. Consultation between the dental staff and the Department of Medical Microbiology established a standardised disinfection protocol for the polishing wheels, machinery and pumice slurry. CONCLUSION: Prevention of cross contamination is crucial to avoid inadvertent but nevertheless culpable infection of denture-wearing patients, as well as for personal protection.