Oral Bacterial Adhesion and Biocompatibility of Silver-Amorphous Carbon Films: A Surface Modification for Dental Implants

Bacterial adhesion and the subsequent biofilm formation on dental implants is a persistent problem that can cause implant failure. Once biofilm is formed, bacterial cells become highly resistant to antibiotics and host defences (Costerton et al., 1999, Patel, 2005), and clinical experience has shown that biofilms must be removed physically before the infection can be resolved (Costerton, 2005). There is an apparent clinical and microbiological similarity between peri-implantitis and periodontitis (Listgarten and Lai, 1999, Papaioannou et al., 1996). The first indication of the specific role of bacteria in peri-implant infections was originated from microscopic analysis of samples taken from failing implants that shown an abundance of motile rods, fusiform bacteria and spirochetes, whereas samples from successful implants contained only a small number of coccoid cells and very few rods (Mombelli, 2002, Mombelli et al., 1987, Rams and Link, 1983). These findings revealed a site-specific disease process with microorganisms associated in patterns known from chronic periodontitis of natural teeth. The term periimplantitis introduced in the 1980s, describe a destructive inflammatory process affecting the soft and hard tissues around osseointegrated implants, leading to the formation of a peri-implant pocket and loss of supporting bone (Mombelli et al., 1987). Adhesion to a surface is the essential first step in the development of a biofilm and the sequential colonization and formation of the dental plaque is highly orchestrated (Xie et al., 2000). The association of bacteria within mixed biofilms is not random; it has been shown that there are specific associations (complexes) among bacteria in dental biofilms (Socransky and Haffajee, 2005, Socransky et al., 1998, Kolenbrander et al., 2006). In addition, these microbial complexes, can be used to describe the sequential colonization of the subgingival plaque. Some bacterial strains, mainly belonging to the genus Actinomyces (blue complex) and Streptococcus (yellow complex) have been identified as early colonizers of the dental surface, attaching and proliferating at an early stage. A second group of bacteria that functions as bridge between the early and late colonizers are formed by species belonging to the green, purple and orange complexes (i.e. Fusobacterium nucleatum, Capnocytophaga sputigena, Eikenella corrodens). Finally, the third group of species that appears at late stages in