Bacterial inactivation/sterilization by argon plasma treatment on contaminated titanium implant surfaces: In vitro study

Background: Surface treatment by argon plasma is widely used as the last step of the manufacturing process of titanium implant fixtures before their sterilization by gamma rays. The possibility of using such a technology in the daily clinical practice is particularly fascinating. The aim of the present study was to assess the effects of the argon plasma treatment on different titanium implant surfaces previously exposed in vitro to bacterial contamination. Material and Methods: Sterile c.p. titanium implant discs with turned (T, Sa: 0.8 mu m), sandblasted/acid-etched (SAE, Sa: 1.3 mu m) and titanium plasma sprayed (TPS, Sa: 3.0 mu m) surface were used in this study. A strain of Ag-gregatibacter actinomycetemcomitans ATCC3718 was grown at 37 degrees C under anaerobic conditions for 24 h and then transferred on six discs for each of the three surface types. After 24 hours, a half of the contaminated discs (control group) were directly used to evaluate the colony forming units (CFUs). The other half of the contaminated discs (test group) were treated in an argon plasma chamber for 12 minutes at room temperature prior to be analyzed for CFU counting. All assays were performed using triplicate samples of each material in 3 different experiments. Results: When the CFU counting was carried out on control discs, a total of 1.50x10(6)+/- 1.4x10(5), 1.55x10(6)+/- 7.07x10(4) and 3.15x10(6)+/- 2.12x10(5) CFU was respectively assessed for T, SAE and TPS discs, without statistically significant differences among the three surfaces. On the contrary, any trace of bacterial contamination was assessed for titanium discs treated in the argon plasma chamber prior to be analyzed, irrespectively to the implant surface tested. Conclusions: Within the limit of this study, reported data suggested that the argon plasma technology could be efficiently used to decontaminate/sterilize previously infected titanium implant surfaces.