engleski

Analysis of bacterial behavior after nickel exposure: adhesions and biofilm formation on orthodontic archwires and susceptibility to antimicrobial agents

Background: Increased adhesion of bacteria to elements of orthodontic appliances could lead to biofilm formation and increased numbers of pathogenic bacteria in the oral cavity. Staphylococcus aureus has been associated with various oral diseases such as cheilitis, parotitis and mucositis. Exposure to nickel could alter bacterial behavior. Materials and Methods: S. aureus was subjected to exposure and adaptation to various subinhibitory concentrations of nickel. Five bacterial strains adapted to nickel at concentrations ranging from 62.5-1000 mg/L were then tested for adhesion and biofilm on nickel- titanium archwires in saliva. Sub-cultivation on the Muller-Hinton agar was performed to measure the number of adhered colony forming units per mL. The disk diffusion method was performed with all bacteria to assess differences in antimicrobial susceptibility. Results: Adhesion, biofilm formation, biofilm biomass and antimicrobial susceptibility significantly differed between bacterial strains (p<0.001). Bacteria adapted to 250 mg/L of nickel ions showed better adherence, higher early biofilm formation, higher biofilm biomass and often higher antimicrobial resistance than other adapted and non-adapted strains. Bacteria adapted to subinhibitory concentrations of nickel, 62.5 – 250 mg/L, were more resistant to some antimicrobial agents. Bacteria that were subjected and adapted to higher doses, 500-1000 mg/L, were more sensitive to antimicrobial agents and displayed reduced adhesion. Conclusion: Corrosion-induced nickel release from orthodontic appliances could alter the behavior of bacteria in the oral cavity depending on the dose of nickel released. Exposure to low nickel concentrations appears to have a low potential to alter bacterial adherence and biofilm formation, but a greater potential to induce bacterial resistance to antimicrobial agents.

bacteria ; nickel ; adhesion ; orthodontic archwire ; antimicrobial resistance

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