Microbicidal Power of Silver Nano Particles and Its Benefit in Soft Liner Obturator Prosthesis

Abstract

Background : Indeed growth of some microorganisms, such as Candida and bacteria like Staphylococcus, Streptococcus, and Klebsiella on the soft liner obturator prosthesis has been demonstrated. Microbial colonisation on acrylic appliances represents a challenge for the scientific community to develop new bioactive compounds. Objectives: To achieve this aim, one solution is application of silver nano particles (SNPs) and detects its antimicrobial activity. Silver release from acrylic resins containing silver nano particles is more effective than using silver in micrometer dimensions. Methodology : Purification of bacterial culture and preparation of inoculums (10 5 cfu/ml) for seven clinical human isolates: E. coli, K. pneumoniae, Staphylococcus aureus, strptococcus pyogenes, strptococcus mutans, Enterococcus fecalis and finally candida albicans. Solutions of SNPs and five antimicrobials ( penicillin G, Tetracyclin, Cefoperazone, Ofloxacin and amphotricin B) were prepared in eleven different ppms concentrations as the following; 30 ppm, 15 ppm, 10 ppm, 7.5 ppm, 5 ppm, 3.75 ppm, 2.5 ppm, 1.875 ppm, 1.25 ppm, 0.625 and 0.313. The MICs and the MBCs were detected for all the antimicrobials and compared with those of SNPs. Also antimicrobial susceptibility testing was performed by the disk diffusion method using impregnated disks with 10ppm of SNPs solution which were placed on inoculated agar with E. coli and S. aureus and the inhibition zones were measured and reported. Antimicrobial effect of silver inside the soft relining acrylic was tested by preparing acrostone soft relining acrylic with silver (12ppm) and another silver free preparation was used as a control. Results : The MIC and MBC of the silver were less than those of most antibiotics except those for Ofloxacin which showed less MIC and MBC for both gram positive and gram negative. Gram positive organisms were more resistant to silver than gram negative. The growth inhibition zones by the disk diffusion method were 8 and 6 mm for S. aureus and E. coli, respectively. The free silver preparation showed microbial growth after 24 hours of incubation unlike the silver preparation. The silver protected the soft relining acrylic from bacterial and fungal growths tell the 10th week and produced a safety zone of inhibition around it. Conclusions : SNPs showed a respectable antimicrobial effect with low MIC and MBC and it seems that using SNPs in acrylic resins protects the preparation from bacterial and fungal growth inside, adhesion to its surface, and made a safety zone around it and If we put in consider the mechanical hygiene of the mouth we expect a better results.