Abstract : Objective : The antimicrobial effect of iontophoresis was investigated comparing the uses of sodium fluoride solution (NaF), ammonia silver solution (ASH), iodine-zinc iodine solution (IZI), and diamine silver fluoride solution (DSF), using different methods of applying electric current.
Methods : E. faecalis ATCC 19433 was used as the test strain. After incubation of the test strain, the medium was adjusted to 106 CFU/mL. A lacuna was made at the apex of the apical lesion simulated in each periapical lesion model using a root canal model. Then, 30 μL of sterile saline agar, 30 μL of defibrinated sheep blood agar containing the test microorganism, and 70 μL of sterile saline agar were overlaid in each lacuna in order.
Different agents, i. e. NaF, ASH, IZI, and DSF, were delivered with anodic and cathodic currents of 1 mA applied for a certain length of time.
After iontophoresis was completed, the drugs were removed from the root canal of the models. Subsequently, the agar containing the test microorganism was collected from the lacunae and diluted appropriately to count the number of colonies (log CFU/mL).
Results and conclusion : The antimicrobial effect varied depending on the current application method for iontophoresis and the choice of medication. The cathodic current applied to NaF showed the most pronounced antimicrobial effect, achieving a killing rate of 99.99% in 25 minutes and a level below detection limit in 50 minutes, which was followed by the cathodic current applied to ASH. At 25 minutes and thereafter, the cathodic currents applied to NaF, ASH and IZI showed significant differences compared to the control. The anodic current with neither ASH nor IZI applied exhibited a significant difference compared to the control, showing no antimicrobial activity. While no black discoloration was observed in the models treated with NaF and IZI, the models treated with ASH and DSF showed black discoloration.
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