Antibacterial Effect of Combined Electrolytic and Chemical Decontamination Methods on Dental Implant Surfaces: In Vitro Study

To evaluate the combined effect of direct electrical current and chlorhexidine digluconate (CHX) for decontaminating titanium implant surfaces, using a validated in vitro oral multispecies biofilm model. Contaminated implant surfaces were tested using an electrochemical cell consisting of a three-electrode system immersed in a KI-AL electrolyte, the biofilm-coated implant being the working electrode, a platinum mesh the counter electrode, and an Ag/AgCl electrode the reference. Direct electrical currents (DC) were applied at two voltage levels (-3 V and-0.75 V) for 5 min, followed by a 1-min rinse in 0.12% CHX. The results were compared to 0.12% CHX alone. Untreated contaminated implants served as negative controls. The antibiofilm effect was evaluated by quantitative polymerase chain reaction with propidium monoazide and by scanning electron microscopy in three different implant zones (threads, valleys and transmucosal machined neck). The area of residual bacteria was also calculated by image analysis. The combined treatment significantly reduced the viable total bacterial counts ([-3 V + CHX] = 4.6 and [-0.75 V + CHX] = 4.9 logarithm colony forming units-LogCFU/mL), compared to the negative control group (6.1 LogCFU/mL) and 0.12% CHX alone (6.3 LogCFU/mL). The area of residual bacteria was also significantly reduced, removing over 95% of the biofilm in combined treatment groups, with slightly higher efficiency at -3 V. Electrolytic cleaning was able to reach all implant zones and no significant differences were found between [-3 V + CHX] and [-0.75 V + CHX] for any parameter. The proposed combined treatments were more effective in reducing the vitality of multispecies biofilms on implant surfaces compared to CHX alone.