Methods: Forty-seven prostheses ready for dispatch (prior to packaging) from a commercial dental laboratory were sampled for microbial contamination. A moistened swab was rubbed across all surfaces of each prosthesis, then placed in reduced transport fluid. The resultant suspension was plated onto nutrient agar and R2A agar. Preliminary identification was made for representative isolates.
Results: Thirty-nine of the prostheses swabbed yielded microbial growth. Of 54 representative isolates, 42.5% were coagulase negative staphylococci, 25.9% Gram negative rods, 9.2% Bacillus spp. and 5.5% streptococci. The amount of contamination could be related to individual technicians, with some consistently generating more contamination than others.
Conclusions: Prior to dispatch, completed prostheses may be contaminated, primarily by isolates of environmental origin. The different results indicated for individual personnel indicate a need for hygiene awareness, and CPD. However, it would be expected that the clinician would disinfect the prosthesis before placing in the patient's mouth, thus the overall risk to the patient should be negligible.