Subgingival titanium wire implantation induces weak inflammatory responses but does not promote substantial T cell activation

Titanium is a biocompatible material commonly used for dental treatments. However, the detailed mechanism underlying the weak biological activity of titanium has not been elucidated. We investigated both the inflammatory responses and T cell activation induced by solid titanium in the gingiva in mice. Both titanium and nickel wire implantation promoted neutrophil infiltration into the gingiva on day 2. Nickel, but not titanium, wire implantation enhanced proinflammatory cytokine expression and dendritic cell activity in gingival tissue by day 2. Nickel wire implantation enhanced the activity of T cells in draining lymph nodes on day 5. Moreover, T cell and neutrophil infiltration and elevated proinflammatory cytokine expression in the gingival tissue were still observed on day 5. However, no such augmented biological responses were observed after titanium wire implantation. These findings suggest that, unlike nickel, solid titanium does not induce sufficient inflammatory responses leading to T cell activation in gingival tissue.