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Biomaterial/Biosystem Interfaces in Implantology and Prosthodontics

Aim: This study group focuses on interfacial reactions at biomaterial and implant surfaces that modulate relevant biological responses.

Overview:

Materials in contact to the host environment form an interface that is characterized by a cascade of subsequent reactions with water, ions, proteins, and cells or bacteria. In dental implantology, artificial tooth root implants form interfaces to blood and hard tissue which is important for osseointegration. At transgingival parts of implants or abutments, interfaces to saliva and soft tissue are relevant. Here, a tight epithelial seal is necessary to avoid bacterial infiltration and to reduce the risk of inflammations like peri-implantitis. To improve interfacial reactions, the surfaces of biomaterials and implants are modified to trigger desired and to suppress undesired interfacial reactions.

The project involves material science researchers, technicians and dentists with a focus on surface science and implantology.

The study group wants to better understand the cascade from early interfacial reactions, when conditioning films such as pellicle layers are formed, to fully developed hard or soft tissue integration, or, by bacterial colonization, unwanted biofilms.  Therefore, several recent basic and applied research projects focus on improvements of osseous interfaces as well as and on optimization of transgingival areas of implant as follows.

Development of cell-bacteria model systems for the transgingival area of implants.

This project is currently under consideration for funding

The main aim of this project is to develop transgingival models that are able to simulate and predict soft tissue adhesion to implant surfaces under in vivo conditions, namely in presence of oral bacteria. Two main approaches will be developed and evaluated: (i) Classic static co-cultivation of gingival cells with bacteria on different titanium surfaces and (ii) dynamic online monitoring of adhesion and proliferation of both species using acoustic sensing in a flow system. Both approaches focus on the so far unsolved problem for novel and advanced surface modifications in the transgingival implant region of dental implants, where the so called “race for the surface”, the contest between bacterial adhesion and tissue cell colonization after implantation determines the successful establishment of a gingival epithelial seal that prevents bacterial infiltration and inflammation.

Nanotopographie meets nanowetting – Development of an optimized surface characteristic for the soft tissue response at the transgingival area.

This project is funded by ITI (International Team for Implantology).

Rapid re-establishment and sound anchorage of the gingival seal to the implant or abutment surface is one prerequisite for implant success. Nanotopography of the implant/abutment surface in combination with nanowetting phenomena influences all phases of the healing sequence. Whereas there is considerable knowledge concerning which surface characteristics improve and accelerate the hard tissue integration of implants, requirements for the transgingival implant surface are still unclear. Which micro-and nanoroughness, which nanotopgraphical surface features or which wetting behavior might improve the interface? Titanium surfaces modified by plasma etching with different fluoride gases are investigated here for their potential to form sub-micron structured topographies with hydrophilic wetting characteristic and for their soft tissue and bacterial reactions.

Material-based antibacterial approaches

In this project, different anti-adhesive and antibacterial approaches are investigated to reduce the colonization of bacteria or to attack already adhered bacteria or established biofilms. One approach is by coating of implant surfaces with thin layers of a photocatalytic material such as titanium dioxide. By light irradiation in the UV-A/VIS region, photocalytic anatase coatings are activated and able to decompose or damage organic films such as proteins and bacteria. In course of therapeutic treatment of peri-implantitis, using such implant modifications might ease the removal of biofilms without damaging the implant surface itself.
In another project we study antibacterial effects of totarol, a natural substance extracted from Podocarpus totara, for dental applications. In addition to antibiotics, natural antibacterial agents have potential as prophylactic agents against wound infections, mainly because antibiotic resistance may be avoided. Totarol has already demonstrated antibacterial activity against different bacteria, including Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus (MRSA).

 Clinical observations about risks and treatment of peri-implantitis