ABSTRACT
In orthodontic therapy, different materials are used and subjected to a damp oral environment, which can modify their properties. The purpose of this study was to evaluate the biocompatibility of eight metallic and non metallic orthodontic materials in human oral fibroblast culture. The specimens consisted of eight clinically used materials, including two coil springs, two glass ionomer cements, two O-rings and two orthodontic acrylic resins. Teflon was used as a negative control. After a release period of each material in the culture medium for 20 days, the viability of oral cultivated fibroblasts was compared to the negative control by MTT assay. Biocompatibility was also assessed using the direct method in which cell viability was evaluated by an invert phase contrast microscope, after direct exposure to the tested materials. MTT assay showed stainless steel [P.V=0.665] and Bayer acrylic resin [P.V=0.l79] to be biocompatible with gingival fibroblasts. Significant differences were observed between the biocompatibility of all study groups [Nickel titanium [PV=0.037], Acropars acrylic resin [PV=0.014] and both studied O-rings [PV=0.001], [PV=0.016]] and the control group. According to the direct method, stainless steel and Nickel titanium showed grade 1, glass ionomer cements grade 4 and other materials revealed grade 0 cytotoxicity. The two studied glass ionomer cements were highly cytotoxic. Bayer acrylic resin was more biocompatible than Acropars acrylic resin