Abstract It is important, considering the wide range of orthodontic devices currently available on the market, to select the most biocompatible orthodontic implant available on the market. Current science data have shown that in vitro measurements of the toxicity of residual particles produced by various orthodontic apparatuses with oral cell lines provide accurate data. In this relation, three commercially available implants, i.e., stainless steel and titanium implants have been tested for in vitro biocompatibility. Methods: Human gingival fibroblasts (HGFs) have been used as the in vitro model to determine cellular morphology, viability of the cells, and cytotoxicity via a 24-hour and 72-hour test for celular implant exposure with 3-(4,5-dimethythiazol-2-yl)-, 2-5,5-diphenyltetrazolium bromide (MT) and LDH test. Results: The results compare implant surface structure and topography with biological, laboratory assessments related to the direct cells (genetic fibroblasts) and blood vessel toxicology (HET-CAM) trial. A relative cytototoxicity of HGF cells occurs for the stainless steel implant, while the other two tests did not produce substantial alteration in HGF cells. Conclusion: The stainless steel implant caused mild cytotoxic effects among the three orthodontic implants samples. This calls for improved alertness in their clinic usage, especially in patients with a strong sensitivity to nicke 1,2 .