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The characteristics of bio films in dental implants

To date, there is only little scientific evidence that the molecular processes involved in the formation of biofilms on implant surfaces differs significantly from the phenomena observed in natural teeth. These processes may roughly be classified into pellicle formation and subsequent adhesion and proliferation of microorganisms.

Pellicle formation

Any material inserted in the oral cavity is immediately covered by the salivary pellicle, which is a thin film of salivary constituents that adsorb to the substratum surface. The term salivary pellicle has been introduced by Dawes in 1963. Though significant differences in the composition of the salivary pellicle on different substrata with only slight differences in surface topography or composition have been reported (Milleding et al., 2001; Tanner et al., 2003), the salivary pellicle primarily consists of proteins, but carbohydrates and lipids have also been detected (Slomiany et al., 1986). Protein adsorption to solid surfaces—for blood serum well known as the Vroman effect—is a complex process and heavily impacted by the interactions of the substratum with the adsorbing proteins. Thus, many researchers agree that the substratum surface properties are transferred through a salivary pellicle layer by the selective adsorption of proteins with the highest affinity to the substratum surface. With regard to the salivary pellicle, this phenomenon has frequently been referred to as the so-called “shine through effect”. Thus, it is clear that the impact of the salivary pellicle on subsequent microbial adhesion differs between distinct materials, as microbial adhesion occurs as an interaction between a pellicle-coated bacterium and a pellicle-coated solid surface (Teughels et al., 2006). These considerations underline that the salivary pellicle is not necessarily analogous on dental enamel and materials applied for oral implantology.

With regard to titanium surfaces, several researchers analyzed the constituents of the salivary pellicle, identifying numerous salivary proteins such as albumin, amylase, calgranulin, fatty acid-binding protein, immunoglobulines, and prolactin-inducible protein (Kohavi et al., 1995; Steinberg et al., 1995; Dorkhan et al., 2013). Lima et al. (2008) identified only few differences in the salivary pellicles on titanium and zir- conia, with pellicles including amylase, immunoglobulins, albumin, fibronectin, and fibrinogen. However, it should be borne in mind that the analysis of the salivary pellicle is heavily dependent on the methodology applied, so studies from different groups employing different biochemical approaches are hard to compare.

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