Oral bacterial adhesion on amorphous carbon and titanium films: effect of surface roughness and culture media

Implant infections can cause severe problems from malfunctioning to dangerous sepsis affecting the health of the patient. For many years, titanium has been the most common material used on dental implants due to their mechanical and biocompatibility properties. Recent studies suggest that amorphous carbon (a-C) films can be possible candidates for coating dental implants, improving some important features like biocompatibility and bone formation. In the oral cavity, the risk of an implant infection is high due to multiple species are capable to colonize this site and these biofilm infections can limit the use of these medical devices. The purpose of this study was to evaluate the influence of the surface chemistry, roughness, and culture media in the bacterial colonization process. To achieve this, a-C and Ti films were deposited on rough and smooth surfaces and cultured with different microorganisms belonging to the oral microbiota with mycoplasma medium (MM) or human saliva (HS). Samples were incubated for 24 h, after this, samples were sonicated and the number of attached bacteria was determined by counting the colony-forming units (CFU's) from each sample. The proportion of the species in the biofilms was determined using checkerboard DNA-DNA hybridization. Data were analyzed by Student's t test using Bonferroni's modification of Student's t test and differences on the proportion of the bacterial species attached to each surface were determined using the Mann-Whitney test. Results show an increased number of CFU's on rough surfaces, especially on the a-C surfaces. The incubation media were an important factor on the adhesion of certain taxa, whereas other species were more sensitive to surface chemistry and others to surface roughness.