Background: Incorporation of natural antimicrobial agents into tissue conditioners might inhibit microbial colonization and prevent complications such as denture stomatitis.
Aim of the study: The present study compared antimicrobial properties of tissue conditioner (TC) incorporated with two (5% and 10%) concentrations of pumpkin (PK), rosemary (Rm), or propolis (Pp) extract powders at different storage times (3 and 7 days) against Candida albicans (C. albicans) and Streptococcus mutans (S. mutans).
Materials and Methods: Pilot study was performed to determine minimum inhibitory concentration (MIC) of Pk and Rm against C. albicans and S. mutans using broth-microdilution method. TC disc-shaped samples (n=3/group) mixed with (5% and 10%) concentrations of either Pk, Rm or Pp powders, positive and negative control groups were prepared. Agar-diffusion test was performed and zones of inhibition were measured in millimeters after 3 and 7-days. Data were statistically analyzed.

Results: Maximum inhibition zone against C. albicans was seen in 5% and 10% Pp after 3 & 7 days, which was greater than effect of +ve control group at same periods. For S. mutans, maximum inhibition zones were seen with +ve control group at both time intervals, followed by 10 Rm and 10 Pk extracts after only 3 days. Propolis extract produced larger inhibition zones than Rm and Pk after 7 days at both tested concentrations.
Conclusion: Propolis extract powder incorporated into TC exhibited considerable antimicrobial efficiency against both C. albicans and S. mutans. Incorporation of natural antimicrobial agents in TC can be used as effective alternative to topical synthetic agents.