Biofilm Formation on Amorphous Carbon and Titanium Films

Objective: Amorphous carbon (a-C) films are a surface modification process that present similar biological properties than titanium and increase osteoblast differentiation. Nowadays, the biofilm formation process on titanium surfaces is not completely understood, and it is well known that bacterial biofilms on dental and orthopedic implants can cause prosthetic infections and lost of the implant. The purpose of this study was to evaluate the initial formation of an oral biofilms on a-C and Ti films. Methods: Amorphous carbon (a-C) and titanium (Ti) films were deposited on 316L stainless steel (SS) substrates using a dc magnetron sputtering. The biofilm model included nine members of the normal oral microbiota; Actinobacillus actinomycetemcomitans serotype b, Actinomyces israelii, Campylobacter rectus, Eikenella corrodens, Fusobacterium nucleatum ss nucleatum, Peptostreptococcus micros, Porphyromonas gingivalis, Prevotella intermedia and Streptococcus sanguinis. Colony forming units (CFUs) were counted and the proportion of the composition of the biofilm in each surface was analyzed using checkerboard DNA-DNA hybridization. Data were analyzed by ANOVA and significant differences determined using Bonferroni's modification of Student's t-test. Results: CFUs were affected by surface chemical composition, higher CFUs were counted on a-C films and stainless steel (SS) surfaces in comparison to Ti films. Biofilm composition was also affected by surface chemistry, A. actinomycetemcomitans, F. nucleatum and E. corrodens showed higher proportions on a-C films while P. intermedia and S. sanguinis were higher on Ti films. SS surfaces showed higher proportions of P. gingivalis and A. israelii. Conclusions: Surface chemistry seems to be an important factor in the early steps of biofilm formation. Bacterial adhesion evaluated from the CFU's seems to be higher on a-C films than in Ti films. The proportion in the biofilm of individual strains was also influenced by surface chemistry. Supported by CONACYT P45833