Nitinol as a Biomedical Material

Applications of superelastic Nitinol (SE NiTi) wires in orthodontics is due to its good characteristics such as low stiffness, high spring back, high stored energy, biocompatibility, superelasticity, and shape memory effect. The mechanical properties of these wires are paid special attention. Nitinol produces continuous optimal forces and eventually causing rapid tooth movement without any damage. Nitinol is distinguished from other materials by demonstrating thermoelastic martensitic deformation behavior whose origin lies in a reversible crystallographically driven structural change, and produces the large recovery strains (6%). The most important characteristics of the behavior of SE NiTi to the clinician are the generation of near-constant forces for a very large deflection which may be controlled over a wide range by affecting its composition, thermomechanical treatment, and manufacturing process. This provides a basis for what we have termed ‘variable transformation orthodontic.’ The clinician should know the biomechanical behavior of the bone as well as the diameters, heights, and connection of each dental implants, to plan the proper treatment according to the biological and anatomical conditions of individual patients. SE NiTi is used in stents, clippers and staples, and rods. Owing to the permeable porous structure of Nitinol, living tissues grow directly into the body of implant, thereby transforming it into a new composite material. If it is applied in knee treatment it reduces knee implant aseptic loosening. Porous NiTi alloy, therefore, presents better osteoconductivity and osteointegration than bulk NiTi alloy.