Characterization and Evaluation of Surface Modified Titanium Alloy by Pulse Nd:YAG Laser for Orthopaedic Applications: an Invivo Study

Abstract

The overall reaction of the living system body to a foreign material implant is governed by a number of factors that determine whether the implant is accepted or rejected. Biocompatibility and biosafety are considered to imply that the clinical application of a biomaterial should neither cause any adverse reaction nor endanger the life of a patient. Generally, parameters determining the biocompatibility are: itissue as a host and iiimplant as a guest. Animal testing is an inherent component of biocompatibility testing. The use of in vitro methods can reduce the extend of animal testing and significantly reduce time and cost of testing. Knowledge of basic mechanisms of cell–material interaction and better understanding of ongoing processes at the cellular level during interaction of anchorage dependent cells can aid in the development of new biomaterials. Factors affecting the tissue–implant interface from biocompatibility point of view include: general health, immunity factors, roughness, surface porosity, chemical reactions, corrosion and cytotoxicity. Thus, the surface characterization of biomaterials is particularly important if the biocompatibility of implants is to be understood. Possible mechanisms through which a biomaterial can interact with a metallic implant is illustrated in Fig. 1. A variety of surface properties are believed to be responsible for the favorable performance of titanium implants, in particular the presence of a chemically very stable oxide film protecting the underlying metal from corrosion, the moderate charge of he surface under biological conditions, the very low concentration of charged species within the dissolution products and a dielectric constant e for titanium oxide close to that of water (e =78). The result is that the titanium surface does not lead to excessively strong interaction (and denaturation) with proteins in the extra cellular matrix; rather the surface is in some way water like, interacting gently with the hydrophilic outer surface of the protein molecules. Nature of interaction between osteoblast cells and their substrate can influence the ability of these cells to produce an osteoid matrix around an implant which in turn will determine the fate of the implant. Attachment of anchorage dependent cells is the first step in the process of cell surface interactions which in turn can affect subsequent cellular and tissue responses.