Modifikacija svojstava stomatoprotetskih akrilata biocidnim agensima na bazi srebra

Abstract

The research was based on the assumption that the modification of commercially available hot and cold polymerizing PMMA materials by adding silver-based biocidal agents (silver nanoparticles - AgNPs; silver chloride - AgCl) results in their antimicrobial potential against microorganisms that cause denture stomatitis, without potentially toxic effects on oral tissues. The goal of the research was to modify and test the properties of hot and cold polymerizing PMMA (examination of the chemical structure, amount and distribution of the silver-based biocidal agent; surface characteristics of the modified materials; the effect of the modification on the degree of polymerization, i.e. the amount of residual monomer; potential release of silver from the modified materials; biocompatibility testing in in vitro conditions on cell cultures and testing the antimicrobial potential of the modified materials against microorganisms isolated from patients with prosthetic stomatitis as well as commercially available strains of C. albicans and S. aureus). The material was modified by incorporating different concentrations of AgNPs and AgCl (2%, 5% and 10% AgNPs, as well as 10% AgCl). The analysis of the composition of the oral flora of patients wearing mobile dental prostheses was performed by taking swabs from the basal surface of the dental prostheses and the mucous membrane of the denture support on a sample of 15 patients with clinically diagnosed prosthetic stomatitis and an analogous control group without clinical manifestations of this disease. The results of the analysis of the composition of the oral flora of the denture supporting tissue in patients with denture stomatitis indicate the presence of C. albicans on the basal surfaces of mobile dentures as well as on the surrounding oral tissue. The results of testing the chemical structure of modified PMMA materials indicate the incorporation of biocidal agents (AgNPs/AgCl) into the polymer chain with a better distribution of smaller sized biocidal agents (AgNPs). The color stability of the modified PMMA indicates a decrease in reflection, i.e. a significant darkening of the modified materials (AgCl-PMMA CP is 90% darker than control, while AgNPs-PMMA CP is 130% darker than unmodified PMMA CP; that is, AgCl-PMMA HP is 100% darker than control, while AgNPs-PMMA HP is 200% darker than unmodified PMMA HP), so further work should be done to improve this property. The results of testing the degree of polymerization of modified PMMA materials indicate a decrease in the amount of residual monomer in hot polymerizing PMMA, while modifying cold polymerizing PMMA resulted in a decrease (10% AgNPs-PMMA) but also an increase in the amount of residual monomer (10% AgCl- PMMA). The release of silver from the modified materials did not occur, so the antimicrobial effect can be explained by direct contact with the tested microorganisms. The results indicate antimicrobial activity against commercial strains of C. albicans and S. aureus as well as C. albicans isolates. Regarding the investigation of the effect of modified hot and cold polymerizing AgNPs-PMMA and AgCl- PMMA on the viability and proliferation of L929 cells in cell culture, the results indicate their unchanged and optimal biocompatibility compared to the control and unmodified PMMA materials. The research resulted in chemically and antimicrobial effective modification of commercially available PMMA with biocidal agents, without affecting the viability and proliferation of cell culture. This created a good basis for further testing of modified materials in in vivo and clinical conditions, which would result in improved acrylate materials for the production and readaptation of dental prostheses. Improving the properties of the materials available on the market would solve the problem of the prevalence of prosthetic stomatitis and enable its successful prevention and therapy, which would solve a significant health and socioeconomic challenge.