Effectiveness of Microwave Sterilization on Soft Lining Material

Abstract

Aims: The aim of this study was to evaluate the effectiveness of microwave irradiation sterilization on Molloplast-B soft denture liner. Materials and Methods: Sixty specimens of Molloplast-B soft denture liner were fabricated in a standardize procedure and autoclaved. The total 60 specimens were divided into 4 groups. Each group has 15 specimens inculated with Brain Heart Infusion Broth (BHI) media containing one of the tested microorganisms (Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeroginosa and Candida albicans). Then the 15 specimens in each group was further divided into 3 subgroups: group C (positive control); 5 none irradiated specimens, group D (dry microwave treatment); 5 specimens placed in a dry beaker and microwave irradiated at 540W for 6 minutes, group W (wet microwave treatment; 5 specimens immersed in distalled water and irradiated in the same manner as group D. After incubation of all specimens for 24 hours at 37°C, the specimens were got vortex and then the replicated specimens (100μL) of suspensions were plated on 4 selective media appropriate for each organism. All plates were incubated at 37°C for 48 hours. After incubation, colonies were counted. Further 7 days incubation for microwaved specimens was done to verify the effectiveness of dry and wet microwave sterilization. Results: Significant reduction in cfu/ml of all microorganisms was observed at 48 hours. No growth of C. albicans was recorded at 48 hours and after 7 days incubation. Conclusions: Microwave irradiation at 540W for 6 min in dry and wet conditions was proved to be effective in the disinfection of soft lining material specimens contaminated with Staph. aureus, Ps. aeruginosa and B. subtilis. Wet treatment was more effective than dry one. Dry and wet microwave treatment sterilized specimens contaminated with C. albicans.

Effect of Microwave Disinfection on Hardness of Acrylic Base Denture Lining Material

“…The specimens divided as following:-ten specimens, five for each curing method as a control groups. Another ten specimens, five for each curing method for microwave disinfection, specimens were immersed in 200 ml of distilled water (16) and irradiated with 540 Watt per 3 minute (19) three times weekly for one month (20) started form the first time of microwave irradiation (microwave disinfection) to twelve times, the specimens left on bench cooling then tested for hardness by using Shore -Ahardness durometer, The specimens stored in water at 37°C between exposure after each irradiation by microwave. The measurement was based on the penetration of an indentor into a specimen.…”

“…(6) Microwave irradiation has been suggested as a method to disinfect denture bases, (14) Placing contaminated denture materials in water during microwave exposure is required to kill rather than inhibit yeast growth. (13,15,16)…”