Papers by Author: Lucy DiSilvio

Abstract: Steinemann, 1998 [1] reported an observation made several decades earlier in 1951, by Leventhal [2] in which ‘bone reaction was studied by the insertion of up to 80 titanium screws into the femora of rats. At the end of sixteen weeks the screws were so tight that in one specimen the femur was fractured when an attempt was made to remove the screw’. Consequently, the main reasons given for the suitability of titanium for surgical implantation are its strength, its failure to cause tissue reaction, and the fact that bone becomes attached to titanium. Now, we call this attachment osseointegration which is considered to be the direct structural and functional connection between living bone and the surface of a load-bearing artificial implant. However, osseointegration is not considered to be a chemical bond between titanium and bone. Implant materials that actually bond to bone are considered to be bioactive. Materials for clinical use can be classified into three categories: resorbable, bioactive and nearly inert materials. A bioactive material is defined as a material that elicits a specific biological response at the interface of the material, which results in the formation of a bond between the tissue and that material. Whereas specific bioceramics are considered to be bioactive, titanium alloys are not normally considered to be so. However, recent surface modification of titanium alloys provide evidence that titanium alloys can become bioactive after treatment with NaOH and the ensuing development of a titanate gel on the metal surface.

Abstract: The success or failure of a bioactive ceramic implant material in the body depends on a complex interaction between a synthetic foreign body and the host. These interactions occur at many levels from the nano-structural level, where subtle changes in surface physio-chemistry substantially alters the nature of the biomaterial-host tissue interface, to the meso- or macrostructural level where dependence on porosity mediates bioactivity through its effect on nutrient transfer and scaffold mechanics. Thus the factors that control the biological response to implant materials are a complex combination of mechanical, physical and chemical attributes which when combined favorably lead to ‘bioactivity’ in a material, or more correctly a ‘bioactive’ response to the material. This is illustrated in the successful use of porous bioactive ceramic scaffolds as synthetic bone graft substitute materials, where micro and meso-porosity, bulk and surface chemistry are manipulated to provide a framework that is highly conducive to the process of bone regeneration, balancing bone apposition and remodeling. Moreover, we now have the opportunity to developing an understanding of the complex balance of forces at play during bone grafting through investigation of these biological responses.

Abstract: Surface treated titanium implants are increasingly being used in dental and orthopaedic applications. This study examined the biological response of primary human alveolar osteoblast (aHOB) cells to a novel silicon based anodic spark deposition treated titanium surfaces. Three different titanium surfaces were investigated: anodic spark deposition (ASD) with silicon based (ASDSi), BioSpark™ (BS), and chemically etched (BioRough™, BR). Commercially pure titanium (cpTi) was the non-treated control surface. Physiological and biological evaluations were conducted on all test and control surfaces. Surface scanning (SEM, EDS, and AFM) confirmed a nano-topography, which was textured for all surfaces; and similar surface chemical composition (Ca and P), of significant was the Si peak on the ASDSi surface. Cell morphological study (SEM) showed good adhere and spreading over the surface, with metabolically active cells having extended filopodia. Biological response was observed with cell proliferation on all test surfaces for the period studied. Proliferation rate was seen to increase with time. This initial favourable cell response will be of benefit in the long term osseointegration of the implant surfaces.