*Article* **The E**ff**ect of In Vitro Electrolytic Cleaning on Biofilm-Contaminated Implant Surfaces**

**Christoph Ratka 1,**†**, Paul Weigl 1,**†**, Dirk Henrich 2, Felix Koch 3, Markus Schlee <sup>3</sup> and Holger Zipprich 1,\***


Received: 15 August 2019; Accepted: 3 September 2019; Published: 6 September 2019

**Abstract:** Purpose: Bacterial biofilms are a major problem in the treatment of infected dental and orthopedic implants. The purpose of this study is to investigate the cleaning effect of an electrolytic approach (EC) compared to a powder-spray system (PSS) on titanium surfaces. Materials and Methods: The tested implants (different surfaces and alloys) were collated into six groups and treated ether with EC or PSS. After a mature biofilm was established, the implants were treated, immersed in a nutritional solution, and streaked on Columbia agar. Colony-forming units (CFUs) were counted after breeding and testing (EC), and control (PSS) groups were compared using a paired sample *t*-test. Results: No bacterial growth was observed in the EC groups. After thinning to 1:1,000,000, 258.1 ± 19.9 (group 2), 264.4 ± 36.5 (group 4), and 245.3 ± 40.7 (group 6) CFUs could be counted in the PSS groups. The difference between the electrolytic approach (test groups 1, 3, and 5) and PSS (control groups 2, 4, and 6) was statistically extremely significant (*p*-value <sup>&</sup>lt; 2.2 <sup>×</sup> <sup>10</sup><sup>−</sup>16). Conclusion: Only EC inactivated the bacterial biofilm, and PSS left reproducible bacteria behind. Within the limits of this in vitro test, clinical relevance could be demonstrated.

**Keywords:** dental implant; biofilm; infection; perio-prosthetic joint infection; periimplantitis; electrolytic cleaning
