Shot Peening Reduces Bacteria Function on Titanium

Mishawaka, IN—October 19—Dr. Thomas Webster, Associate Professor of Engineering with Brown University, presented his research paper titled "Decreased Bacteria Functions on Shot Peened Titanium" at the Eleventh International Conference on Shot Peening this September.

The study's objective was to use shot peening to modify the surface of implanted titanium and implement nanoscale surface features that reduce bacterial function without the aid of pharmaceutical agents. The testing was conducted on S. aureas , P. aeruginosa and S. epidermis—commonly found bacterias in prosthetic infections. "Results demonstrated significantly lower functions of all bacteria of interest to the present study on shot-peened titanium. In this manner, aside from the well-documented mechanical properties of shot peening, this study provided evidence that infection can be reduced on shot-peened titanium and thus should be further explored for orthopedic applications," cited the paper's authors.

The experimental methods compared the bacteria cultured on three sets of five Titanium 6Al-4V samples. The titanium samples were differentiated by five types of peening media and were peened with conventional shot peening processes. The bacteria was seeded onto the titanium samples and cultured for up to seven days. The study was conducted without antibiotics. Results of the in-vitro study demonstrated significantly less of each bacteria type on shot-peened titanium compared to titanium controls; in particular, titanium peened with micro-bead media. The researchers speculate that due to the unique nanometer surface features created by shot peening, the new surface energy altered initial protein interactions and inhibited bacterial attachment. 

The study was funded by Electronics Inc. Electronics Inc. manufactures products that improve the quality and control of the shot peening process including the MagnaValve media valve, controllers, Almen gages and Almen test strips. 

Shot peening is a cold-working process in which a metal surface is peened to induce compressive stresses and thereby improve fatigue life. Shot peening is used in aerospace, automotive, energy, medical and other industries that need to improve the fatigue properties of metal components. For more information on shot peening, watch the video "What is Shot Peening."