There were a total of 16 implants in very close contact with peripheral nervous tissue in study II. There were no perineural implants in the 2-week group. In the 4-week group, one stainless steel and 2 Ti-6Al-4V implant capsules were found very near to the nerve, but no NiTi capsules were found close to the nerve. In the 8-week group, there was one implant capsule in the stainless steel group, 5 in the NiTi group and one in the Ti-6Al-4V group with very close contact to the nerve. In the 12-week group, 2 stainless steel and 2 NiTi implant capsules were found next to the nerve. In the 26-week group, there were 2 NiTi and 1 stainless steel implant capsules near the nerve.
There were no signs of necrosis, prolonged inflammation or irritation with the NiTi material. Also, no accumulation of specific cell types, cells with phagocytosed material, foreign particles or abnormal fibrous tissue responses were seen in the perineural tissue with any of the tested materials.
There was no edema, neuronal or glial reaction or inflammatory reaction in the nerve itself. Very few giant cells, PMNs, plasma or mast cells could be observed in the area between the nerve and the encapsulating membrane (Figure 5-7, A3-4, B2-4 and C2-3).
The end-stage neural and perineural responses were nearly inert with NiTi and also with the other tested materials.