To determine if impression compounds should be reused based on microbial tests and if it can be a source of cross-infection.
Methods:
10 complete denture patients participated in the study which was approved by the School of Oral Health Research Committee in Suva, Fiji. Microbiological tests were conducted on impression compound to detect the presence of bacteria.
Swabs of impression compounds were taken at different stages to identify the critical stages at which bacteria may contaminate the compound.
The swabs were inoculated on Chocolate, MacConkey agar, and Cooked Meat Medium.
For plates showing growth, colonies were observed and identified using Gram stain, Microbact ™ identification kits and other biochemical tests.
Simple descriptive statistics were used to summarize findings.
Results:
Transfers of viable organisms from patients' mouths were found on the compound.
60% of unused compound had bacterial presence. 80% of disinfected trays showed bacterial presence while 40% of hot water baths had bacteria. 90% of the compound samples following rinsing under tap water displayed oral and hospital bacterial presence.
80% of swabbed casts revealed that bacteria remaining on the impression compound are transferred onto casts, as 80% of the sample showed bacterial presence.
Storage of the impression compound showed that keeping the compound in the hospital setting acts as a colonizing medium for hospital pathogens, as all the samples (100%) showed presence of hospital pathogens.
These pathogens still survived on all (100%) of the impression compound samples after their immersion in hot water baths and prior to reuse in other patients.
Conclusion:
Our microbial evidence illustrates that impression compounds should not be reused. Impression trays and poured casts were found to be potential sources of contamination. Proper disinfection and sterilization procedures should be followed to decrease the chances of cross-contamination particularly in immuno-compromised patients and laboratory staff.