Effects of the penetration of a root canal filling material into the mandibular canal. 2. Changes in the alveolar nerve tissue.

The root canal filling material "Vitapex" (Neo Dental Chemical Products Co., Tokyo), made of calcium hydroxide and iodoform with the addition of silicone oil, was experimentally injected into the mandibular canals of dogs, and its effect on the alveolar nerve tissue was examined by light and electron microscopy. No change was observed as long as the injected paste did not come into direct contact with the nerve, but tissue damage was found at sites of direct contact. After removal of degenerated nerve debris by macrophages and Schwann cells, the persisting external membranes or "Schwann tubes" appeared to provide a scaffolding for axonal regeneration and Schwann cell proliferation.