title: Effect of surface roughness of biomaterials on Staphylococcus epidermidis adhesion.
abstract: BACKGROUND
  Implant-related infections are caused by adhesion of bacteria to the surface of biomaterials. In this in vitro research, we evaluated the ability of Staphylococcus epidermidis (ATCC35984) to adhere to the surface of solid biomaterials at different levels of roughness below 30 nm Ra and investigated the minimum level of roughness required to promote bacterial adhesion on five kinds of biomaterials: oxidized zirconium-niobium alloy (Oxinium), cobalt-chromium-molybdenum alloy (Co-Cr-Mo), titanium alloy (Ti-6Al-4 V), commercially pure titanium (Cp-Ti) and stainless steel (SUS316L), samples of which were categorized into a fine group and a coarse group according to surface roughness. The test specimens were physically analyzed and the viable bacterial density of the adhered bacteria was quantitatively determined (n = 20).
  
  
  RESULTS
  The amount of bacteria that adhered to the biomaterials in the coarse group was higher than those in the fine group. Oxinium, Ti-6Al-4 V and SUS316L in particular demonstrated statistically significant differences between the two groups (P < 0.05). Of the materials, the Co-Cr-Mo specimens exhibited significantly lower amounts of adhered bacteria than the Ti-6Al-4 V, Cp-Ti and SUS316L specimens in the fine group. Similarly, the Co-Cr-Mo specimens in the coarse group exhibited significantly lower values than the other four materials.
  
  
  CONCLUSIONS
  These results suggest that minimum level of roughness affecting initial bacterial adherence activity differs according to the type of biomaterial used, and that even a surface roughness of below 30 nm Ra in Oxinium, Ti-6Al-4 V and SUS316L can promote bacterial adhesion. Relative hydrophobic Co-Cr-Mo surfaces were less susceptible to bacterial adherence.
authors.forename: Itaru
authors.initials: I
authors.lastname: Yoda
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1, Sakamoto, Nagasaki 852-8501, Japan. koseki@nagasaki-u.ac.jp.
authors.forename: Hironobu
authors.initials: H
authors.lastname: Koseki
authors.forename: Masato
authors.initials: M
authors.lastname: Tomita
authors.forename: Takayuki
authors.initials: T
authors.lastname: Shida
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Horiuchi
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Sakoda
authors.forename: Makoto
authors.initials: M
authors.lastname: Osaki
mesh_terms: D001422:Bacterial Adhesion; D001672:Biocompatible Materials; D015169:Colony Count, Microbial; D006801:Humans; D050296:Microbial Viability; D008855:Microscopy, Electron, Scanning; D013212:Staphylococcus epidermidis / Q000502:physiology*; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials