Si-Based Amorphous Thin Films for the Performance Improvement of Dental Prostheses and Implants

It is well known that determining the physico-chemical surface properties of both dental and intrabony prostheses is a powerful means that may help elucidating some fundamental features of the interface between the recipient tissues and the prosthesis itself. When dealing with dental prostheses (total dentures, fixed dental prostheses, partial removable dental prostheses), a continuous contact with different tissues and body fluids is required for their different parts. Indeed roughness, porosity and surface energy, as well as surface elemental composition, will strongly influence the response of the tissues, eventually contributing to the success or fail of the prosthesis. This is even more true for the implant-supported fixed dental prostheses, where an intra-bony part, i.e. the dental implant, is connected through a transmucous structure, i.e. the implant abutment, to the intraoral part, i.e. the fixed prosthesis. Thus the same titanium material is supposed to enhance both bone and epithelial healing, whilst the intraoral framework and artificial teeth –which may be made by several different materials- are to avoid bacterial adhesion as much as possible. Several surface modification processes are currently used in order to improve the prostheses performances, but many of them are still not completely satisfactory, and a continuous research effort is still required to improve their effectiveness. In this chapter, we describe the use of silicon-based amorphous thin film alloys to improve the performances of dental prostheses and implants. Indeed, hydrogenated amorphous silicon-based alloys, such as amorphous hydrogenated silicon-oxygen (a-SiOx:H) alloys possess interesting properties, which can be exploited for the surface modification of dental prostheses and implants. They are inert and largely biocompatible materials and do not embed dangerous metallic elements, such as Ni, Al, Cr, or Mo, which could be released into the body during the long term contact within living tissues. Moreover, the hydrogen incorporation, which is typical of amorphous material grown by plasma-assisted CVD techniques, has already been proven helpful in enhancing the biocompatibility of silicon and silicon-based materials. We studied the effects of amorphous silicon-based alloys for the performance improvement of several bulk materials used for the fabrication of prostheses and implants, including ceramics, resins, titanium and cobalt-chromium alloys. The films showed interesting properties as for the bacterial adhesion reduction, the biocompatibility improvement and the corrosion protection of bulk materials under study.