Reinnervation of teeth, mucous membrane and skin following section of the inferior alveolar nerve in the cat.

The reinnervation of teeth, mucous membrane and skin has been investigated in the cat following section of the inferior alveolar nerve. Evidence for regeneration of sectioned fibres and for sprouting of unsectioned nerves supplying adjacent tissues (collateral sprouting) was sought. In some experiments the cut nerve ends were reapposed whilst in others the central stump was either covered with an acrylic cap or sealed inside a nylon tube. The jaw opening reflex evoked by electrical stimulation of canine tooth pulp was abolished by inferior alveolar nerve section but returned within 3-9 weeks with a raised threshold and increased latency. After re-apposition or acrylic capping, some sectioned nerves regenerated but, compared with normal, they had decreased conduction velocities, greater variation in their mechanoreceptor fields and produced smaller compound action potentials in the teeth. There was little evidence of collateral sprouting. The nylon tube completely blocked regeneration but the denervated tissues were reinnervated by collateral sprouting. Fibres supplying tooth pulp were present in the ipsilateral mylohyoid, the ipsilateral and contralateral lingual nerves and the contralateral inferior alveolar nerve. Except for the ipsilateral lingual nerve, these nerves do not normally include pulpal fibres. Partial reinnervation of skin and mucous membrane occurred and this was derived from the ipsilateral mylohyoid, lingual and buccal nerves and the contralateral inferior alveolar nerve.