Biocompatibility improvement of NiTi orthodontic wire from various coatings

NiTi alloy is one of important materials in orthodontics. Shape memory effect of this material ensures the possibility to deliver highly desireable light forces for thooth movement. Unfortunately, NiTi has problem in the high amount content of Ni that can cause allergy or even risk of poisioning in the human body due to Ni ion released. To overcome this problem, several methods of coatings were performed to prevent the releasing of Ni ion. They were Electropolishing Pretreatment combined with Photo Electrocatalytic Oxidation, TiN Pack Cementite, Advanced Oxidation Process and Biomimetic Hidroxyapatite. The objective of this research was to analyze the effect of various coatings to the biocompatibility of orthodontic wire. Biocompatibility of coated NiTi wire was investigated through MTT assay using BHK-21 fibroblast cell in order to analyze the toxicity of each coating method. In addition, the surface roughness was determined using Atomic Force Microscope (AFM). Furthermore, the attachment and spreading of fibroblast cell were observed by Scanning Electron Microscope (SEM). The result was revealed that biomimetic HA coating has the highest cell viability percentage due to its surface morphology.