Optimized silicon reinforcement of carbon coatings by pulsed laser technique for superior functional biomedical surfaces fabrication.

We report on the fabrication of silicon-reinforced carbon (C:Si) structures by combinatorial pulsed laser deposition to search for the best design for a new generation of multi-functional coated implants. The synthesized films were characterized from the morphological, structural, compositional, mechanical and microbiological points of view. Scanning electron microscopy revealed the presence, on top of the deposited layers, of spheroid particulates with sizes in the micron range. No micro-cracks or delaminations were observed. Energy dispersive x-ray spectroscopy and grazing incidence x-ray diffraction pointed to the existence of a C to Si compositional gradient from one end of the film to the other. Raman investigation revealed a relatively high sp3 hybridization of up to 80% at 40-48 mm apart from the edge with higher C content. Si addition was demonstrated to significantly increase C:Si film bonding to the substrate, with values above the ISO threshold for coatings to be used in high-loading biomedical applications. Surface energy studies pointed to an increase in the hydrophilic character of the deposited structures along with Si content up to 52 mN m-1. In certain cases, the Si-reinforced C coatings elicited an antimicrobial biofilm action. The presence of Si was proven to be benign to HEp-2 cells of human origin, without interfering with their cellular cycle. On this basis, reliable C:Si structures with good adherence to the substrate and high efficiency against microbial biofilms can be developed for implant coatings and other advanced medical devices.

Retrieval analysis on dental implants biointegration phases.

This study was developed for evaluating the possible causes of losing primary stability of dental implants and to find possible associations between implant designs or implant surface treatment and the quality of surrounding bone tissue. There have been evaluated five CP (Commercial Products) titanium dental implants having different shapes and surface morphology. All the implants have been extracted between three and six month from insertion time due to the loosening of primary stability. The lost during three to six months of the primary stability for the dental implants evaluated at the interface was attributed to blood supply deficiency of the surrounding bone in case of the implants inserted in the anterior-lateral and lateral mandible bone, on implant surrounding bone with consecutive necrosis without leaving the possibility of normal healing both for the maxilla and the mandible, or to prosthetic load deficiency by applying forces out of the implant axis.