Which is Better: Stainless Steel or Titanium Alloy?

AIM: To investigate immunologic reactions after implantation of stainless steel (SS) alloy and titanium (Ti) alloy in a rat model. Macrophage and cytokine responses have been reported after in vivo and in vitro application of different biomaterials. MATERIAL and METHODS: Wistar albino rats were used. After an exploration of the thoracolumbar paravertebral muscle tissue of the subjects, Group I underwent sham surgery, and Groups II and III underwent implantation of Ti alloy and SS alloy rods respectively. The CD4, CD8, CD25 (IL-2R) (lymphocyte and CD4 gate), CD4+CD8+ and CD4+CD25+Foxp3+ (Tregs), IL-4, IL-10, IL-6, IL-17A, TGF-beta,TNF-alpha in the blood were analyzed. RESULTS: CD4, CD25 (IL-2R), CD4+CD8+ and Tregs levels were lower in Group III compared to Group I (sham) and Group II. IL-6, IL-17A, TGF-beta and TNF-alpha levels in Group III showed a significant increase on all days in comparison with Group I and Group II. IL-4 and IL-10 levels were lower in Group III than those in Group II; and a significant decrease was observed in the IL-10 level. There was a reduction in IL-6 and IL-17A levels in Group II as opposed to Group I. CONCLUSION: As opposed to SS alloy, Ti alloy suppresses the development of inflammation by inhibiting the pro-inflammatory response; strengthens the humoral immune system by intensifying the antibody-dependent immune response; triggers the development of immune tolerance by regulating the immune response; and activates the mechanism that prevents immune response-related damage from occurring.