BACKGROUND: To evaluate the in vitro antifungal activity of chlorhexidine gluconate (CHX), magnesium oxide (MgO) and cetylpyridinium chloride (CPC) against yeasts of the genus Candida contaminating two tissue-conditioning materials (Visco-gel VG and GC Tissue conditioner). Two disinfection techniques were tested: a) immersion in liquid solution for 10 minutes; b) inclusion of the three tested substances in the mixture of the conditioning material in the form of powder (MgO and CPC) or liquid solution (CHX).METHODS: A contaminating broth was prepared by mixing cultures of three species of Candida (C. albicans ATCC 90029, C. glabrata ATCC 90030, C. tropicalis ATCC 70050) in peptone water up to a turbidity of 5 Mc Farland, corresponding to a total microbial load of 107 CFU/ml. Technique a): 24 specimens of each conditioning material (VG and GC) were prepared according to the instructions of the manufacturers and using a silicone mold for standardizing the dimensions (2 cm in diameter and 0.8 in thickness). All specimens were immersed in 50 ml of contaminating broth for 24 hours at 35°C, then rinsed with sterile water, divided into three test groups and one control group for each material. The specimens of the test groups were immersed for 10 minutes in a disinfectant solution (CHX 0.2 %, MgO 7% or CPC 0.3%). The specimens of the control group were immersed in sterile water for 10 minutes. Then all the specimens were swiped into Candida CHROMagar plates, incubated for 48 hours at 35°C. Technique b): 30 specimens were prepared for this technique and divided into four test groups and one control group. The test specimens were made incorporating the disinfectant agents into the conditioning materials during their mixing in proportions of 0.2% and 1% for CHX, 7% for MgO and 0.3% for CPC; the controls did not contain disinfectants. After contamination for 24 hours in the broth, the specimens were plated. All tests were performed in duplicate.RESULTS: Technique a): Immersion in CHX 0.2% and in CPC 0.3% for 10 minutes almost completely reduced the fungal load of the 3 species of candida of both the conditioning materials (CFU <20 and CFU <10 for CHX 0.2% and for CPC 0.3% respectively), while 7% MgO immersion was not effective (CFU> 330) for any conditioning material. Technique b): In the inclusion technique, no tested disinfectant agent resulted effective in the disinfection of GC and VG (CFU> 330); only 1% CHX incorporated in the GC moderately reduced C. tropicalis (CFU <100).CONCLUSIONS: The immersion of the conditioning materials in CHX 0.2% and in CPC 0.3% proved to be effective against fungal contamination. The inclusion of disinfectants in the material mixture proved to be ineffective, with the exception of 1% CHX which exhibited moderate antifungal activity. In conclusion, the immersion of relined dentures for at least 10 minutes a day in CHX 0.2% or in CPC 0.3% can help to drastically reduce the fungal colonization of the conditioning materials.
|Numero di pagine||1|
|Stato di pubblicazione||Published - 2018|