Ssceptibilidad a la corrosión localizada y biocompatibilidad

GRAU J. CASTROGIOVANNI. PARISI J. REIGOSA M

Congreso; Congreso de metalurgia y materiales SAM. CONAMET; 2014

A B S T R A C T Corrosion resistance and biocompatibility are some of the most important properties to be satisfied by the alloys used to elaborate surgical implants. In the present work, the susceptibility to localized corrosion and cytotoxicity of ASTM F745 austenitic and ASTM A890 Type 5A duplex stainless steels were analyzed. ASTM F745 is used for cast implant, while ASTM A890 Type 5A has also been invetigated for orthodontic bracket fabrication. Susceptibility to localized corrosion was evaluated by means of cyclic polarization tests using aqueous solution of 0.9 wt % NaCl at 37 ºC and pH between 4 and 9. On the other hand, citotoxicity was analyzed by neutral red (NR), methyl tetrazolium (MTT) and collagen type I assays, according to ISO 10995-5 Standard, using the rat osteoblastic cell line UMR-106 (ATCC, CRL-1661). Complamenting the biological studies, the  technique of direct contact was performed, by which the UMR-106 cells were cultivated on the alloys surfaces, previously sterilized, to evaluate the biocompatibility. Cyclic polarization tests revealed that ASTM A890 Type 5A duplex stainless steel has a lower susceptibility to pitting corrosion and a greater repassivation capacity than ASTM F745 austenitic stainless steel. The better anti-corrosion behavior of the duplex stainless steel can be ascribed to its higher Cr and N content, that increase the Pitting Resistance Equivalent Number (PREN) in media containing Cl- ions. From the biological perspective, RN, MTT and collagen type I assays, show the absence of cytotoxic compounds released to the environment from both stainless steels. At the same time, the direct contact technique showed that UMR-106 cells adhere to smooth surfaces of the alloys. According to the methodology of analysis used, it can be concluded that both stainless steels have a high biocompatibility.