There have been also attempts check details to employ drugs such as bisphosphonate and simvastatin, which induce osteogenesis more efficiently.
CaP implants, including hydroxyapatite (HAp), are well known for good osteoconductivity (the early stage of osteogenesis) as well as for direct binding to bone tissue in vivo. Alkaline phosphatase expression and parathyroid hormone response were higher in cultures grown in HAp than in cultures grown in titanium [6], and the in vitro formation of extracellular matrices was greater on CaP coatings than on titanium. Several mechanisms of the principal factors involved in osteogenesis on CaP ceramics have been considered. First, implanted CaP (HAp) acts as a nucleation site and exhibits crystallographic properties in an AT13387 solubility dmso epitaxial process of the newly developed structure. The calcium ions dissolve from the CaP surface, resulting in the deposition of a mineralized layer. This stimulates the bone cells to continue extracellular matrix (bonding zone) synthesis and calcification [7]. CaP ceramics adsorb many osteo-conductive and/or osteo-inductive proteins, which have an important role in the mineralization of bone tissues. In spite of their rapid and strong bonds to living bone tissues and favorable osteogenic ability, CaP ceramics alone cannot be used for implants because of their
lack of strength. Accordingly, CaP coatings on Ti implants produced by the plasma spraying have frequently been used [8]. These CaP coated implants, however, often develop fractures in their coatings as well as at the titanium interface after implantation. The reason for this is thought to originate in
the comparatively thick, porous, non-uniform (crystalline surrounded by an amorphous mass), and poorly adherent CaP layer produced by plasma spraying (Fig. 5). These fragments of a certain size cause phagocytosis by macrophages, leading to inflammation. It is therefore desirable for the materials to be rapidly and completely absorbed in the host tissues and to be entirely replaced with bone tissue. When osteogenesis occurs at the site where old bones are absorbed (remodeling of bones), the CaP coatings should Methamphetamine be no thicker than necessary. Attempts have recently been made to solve problems in the plasma spraying technique using a cold-plasma surface modification as above-mentioned [9]. In the cold plasma, ion-plating [10] and the ion sputtering [11], which are a kind of physical vapor deposition (PVD), are used to produce implant materials consisting of a thin, homogeneous, and adherent CaP coating. Ion beam dynamic mixing (IBDM) was also introduced as a suitable technique for fabricating a thin and adherent ceramic layer [12].