Antimicrobial activity of disinfectants used in prosthetic dentistry depending on the degree of dilution (an experimental in vitro study)

Relevance. Determining the antimicrobial activity of disinfectants and their impact on conditionally pathogenic microbiota (CPM), as well as justifying the selection of agents for treating dental impressions and prostheses, remains an unresolved issue requiring thorough research. The effects of quaternary ammonium compounds (QAC) on various microorganisms, particularly regarding their effective dilution in dental practice, are not well-studied despite their widespread use. Objective. To compare the antimicrobial activity of alkaline combined disinfectants, QAC derivatives, and polyhydric alcohols at various dilutions against CPM strains in vitro. Materials and methods. Dilutions of domestic disinfectants—"Megadez Ortho" (VladMiva), "Vendelin" (Bozon), and "Trilox" (Biotorg)—were prepared in sterile heart-brain broth (Himedia Labs, India) ranging from 1:200 to 1:200,000. Microbial growth curves were assessed using a bioreactor RS (Biosan, Latvia). The study involved three test strains of CPM: Staphylococcus aureus , Escherichia coli , and Bacillus cereus . Results. The in vitro experiment results indicate that working solutions of the disinfectants at dilutions of 1:200 and 1:20 exhibit bactericidal activity against all test strains: S. aureus , E. coli , and B. cereus . The antimicrobial activity against B. cereus was observed at slightly higher concentrations compared to S . aureus and E. coli . Conclusion. Based on the decrease in disinfectant activity, the preparations can be ranked in the following order of decreasing efficacy: "Trilox" → "Vendelin" → "Megadez Ortho." A notable advantage of "Trilox" is its statistically significant higher activity against spore-forming bacilli B. cereus .