Surface modifications of Ti implants can be used to optimize the properties of the material with respect to tissue integration. From our and other´s previous experiments, there is evidence that modifications in hydrophilicity, which allow rapid wetting of microstructured implant surfaces, will influence initial reactions such as protein adsorption and the overall formation of conditioning macromolecular films which in turn modulate the cellular and host tissue reactions, finally resulting in an accelerated osseointegration.
Different areas of the dental implant surface require a variety of differing properties according to the respective biological needs. Therefore, beneath the ongoing investigation of interactions at the subgingival SLA implant surface, our studies focus on modifications of the Ti surface at the transgingival area. There, it is a challenge for the future to modify the implant surface in a way that prevents bacterial adhesion and biofilm formation but simultaneously prevents bacterial infiltration by establishment of a tight epithelial seal. Of special interest now is the influence of thermodynamic properties, such as dynamic hydrophilicity and surface free energy, on conditioning film formation and subsequent cellular and bacterial behavior. Therefore, our continuing studies aim on the following current scientific questions and focus on the following issues:
Titanium surfaces will be subjected to different modifications to achieve e.g. a range of defined hydrophilicity. The chemical composition and the thermodynamics of these surfaces will be thoroughly analyzed, including surface free energy components, such as polar and dispersive or acidic and basic polar components. This enables to investigate the influence of the surface chemistry and of contaminants on the thermodynamic surface state which is the basis for correlation studies and for modeling of the observed and quantified biological interactions.
The role of conditioning films is a main issue in our research. These films are decisive in all areas of the dental implant since they are formed during initial blood contact as well as by saliva contact. The chemically modified substrates will therefore be tested for blood serum interactions and pellicle formation by a quartz crystal microbalance with dissipation (QCM-D), which enables time-resolved quantification of adsorbed mass and viscoelastic changes at the interface. Based on this knowledge of surface dependent conditioning processes, bacterial interactions will be investigated in a comparing study both with this online-method and by adhesion tests with different bacterial cultures followed by fluorescence microscopic analysis.
Finally, cellular responses are investigated by keratinocyte adhesion, proliferation and spreading on the surface of titanium modifications with and without conditioning films. The results of these investigations will be correlated to the physicochemical surface characteristics.
The clinical relevance is based on the hypothesis, that modification of the initial surface conditioning processes at the timepoint of surgical implantation will finally positively influence and accelerate the process of soft tissue integration as well as the process of osseointegration.