Effectiveness of Sterilization by Microwave Irradiation on Polyvinyl Siloxane Contaminated with Candida Albicans: An Invitro Study

Aims: This in-vitro study aimed to evaluate the effect of microwave irradiation on polyvinyl siloxane impression material contaminated with candida Albicans. Materials and methods: 30 samples were fabricated from the acrylic mold with disk shape 5*2 (diameter*thickness). Samples incubated with Brain Heart Infusion Broth (BHI) media containing Candida albicans. Then were divided into 30 samples into 6 groups: C (positive control); 5 non-irradiated specimens, 3MWD ( samples irradiated for 3minute in dry condition), 6MWD (samples irradiated for 6minute in dry condition), 3MWW (samples irradiated for 3minute in wet condition), 6MWW (samples irradiated for 6minute in wet condition), CHX (samples immersed in 0.5% chlorhexidine) After incubation of all samples for 24 hours at 37°C, the samples were got vortex and then serial dilution carried out of suspensions then cultured on Sabouraude Dextrose Agar after incubation for 24 hours at 37°C bacteria were counted. A further 7 days of incubation for microwaved samples was done to verify the effectiveness of both dry and wet microwave sterilization for two periods of time. Results: There was a significant reduction in cfu /ml of candida albicans at 24 hours of incubation. No growth of C. albicans was recorded after 7 days of incubation. Conclusions: Microwave irradiation at 640W for both wet and dry conditions for 3 and 6 min was proved to be effective in the disinfection of polyvinyl siloxane specimens contaminated with. Candida. albicans

Effectiveness of Microwave Sterilization on Surface Roughness of Polyvinyl Siloxane Impression Material

Aims: The study aimed to investigate the effect of sterilization by microwave irradiation at 640W on the surface roughness of polyvinyl siloxane. Materials and methods: 30 samples of addition silicone impression material with a thickness of 20mm and 3mm as diameter. The acrylic mold was used for the samples' fabrication. The samples were divided into six groups each group had five specimens (C) control (3MWD) Samples irradiated for 3minute in dry conditions, (6MWD) samples irradiated for 6minute in dry conditions, (3MWW) samples irradiated for 3minute in wet condition, (6MWW) samples irradiated for 6minute in wet condition and (CHX) samples immersed in chlorhexidine with 0.5% concentration for one hour. A profilometer (Talysurf 10, R.P.I. LTD, Metrology Division) is used for measuring surface roughness by taking the means of three points with the aid of a stylus. Results: There were statistical differences between the control group and the tested groups. Mann-Whitney showed that only 3MWD had no statistical differences from the control group. Conclusions: Disinfection of polyvinyl siloxane using the microwave at 640W for 3 minutes is safe or recommended regarding its least effect on the surface roughness