The Departments of Physics, Dental Prosthodontics and Biomaterials, and Department of Oral and Maxillofacial Surgery at UAB propose an interdisciplinary program to evaluate nanocrystalline coatings for dental implants. We propose to test the hypothesis that the wear and bone fixation characteristics of TMJ (temporomandibular joint) implant devices can be significantly improved by manipulation of the nanostructure of diamond coatings (adhesion and wear) and hydroxyapatite coatings (fixation). Nanocrystalline diamond coatings with surface roughness of only 5-10 nm will be produced by microwave plasma chemical vapor deposition process with methane/hydrogen/nitrogen species. Our preliminary adhesion and toughness studies have shown no shear failure/loosening of diamond particles up to 150 kg indentation load. Nanocrystalline calcium phosphate (primarily hydroxyapatite) coatings will be deposited by pulsed laser deposition techniques onto the screws and device surfaces in contact with bone. Precise control of chemistry and structure of the thin coating should result in a more optimum surface for fixation with bone. Novel design strategies will be implemented for uniform coating over curved surfaces by rotation and translation of the implant in the activated plasma. Nanostructured -diamond and -hydroxyapatite can be interfaced on the same implant, provided diamond deposition at high temperature is done first followed by a low temperature deposition of hydroxyapatite using pulsed lasers. Nanoindentation studies will be carried out to measure the modulus and hardness of coatings as well as wear testing under simulated dental conditions. In vivo biocompatibility testing of nanostructured diamond and calcium phosphate ceramics will be carried out using standardized model systems, including injection of particulate debris, plus soft and hard tissue evaluations of particulates and implants. The in vivo part will be carried out in collaboration with an oral and maxillofacial clinician/surgeon at UAB, who actively participates in the area of TMJ surgical reconstruction.
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