Degeneration and regeneration of motor and sensory nerves: a stereological study of crush lesions in rat facial and mental nerves.

The aim of this study was to evaluate the degeneration and regeneration of a sensory nerve and a motor nerve at the histological level after a crush injury. Twenty-five female Wistar rats had their mental nerve and the buccal branch of their facial nerve compressed unilaterally against a glass rod for 30s. Specimens of the compressed nerves and the corresponding control nerves were dissected at 3, 7, and 19 days after surgery. Nerve cross-sections were stained with osmium tetroxide and toluidine blue and analysed using two-dimensional stereology. We found differences between the two nerves both in the normal anatomy and in the regenerative pattern. The mental nerve had a larger cross-sectional area including all tissue components. The mental nerve had a larger volume fraction of myelinated axons and a correspondingly smaller volume fraction of endoneurium. No differences were observed in the degenerative pattern; however, at day 19 the buccal branch had regenerated to the normal number of axons, whereas the mental nerve had only regained 50% of the normal number of axons. We conclude that the regenerative process is faster and/or more complete in the facial nerve (motor function) than it is in the mental nerve (somatosensory function).

Neurosensory disturbance after sagittal split and intraoral vertical ramus osteotomy: as reported in questionnaires and patients' records.

This retrospective study aimed at evaluating the long-term incidence of neurosensory disturbance (NSD) after sagittal split osteotomy (SSO) and intraoral vertical ramus osteotomy (IVRO). Furthermore, a comparison was made between the results obtained by questionnaires and information in the patient records in the evaluation of nerve function. Finally, the degree of discomfort caused by the NSD was evaluated. One hundred and twenty-nine patients, who underwent IVRO (79 patients) and SSO (50 patients), were included. Questionnaires were mailed to the patients at least one year after the operation. The records of all patients, who returned the questionnaires, were reviewed. The results of NSD obtained by questionnaires and records differed indicating a disagreement between the judgement of the surgeon and the patient's opinion. Long lasting NSD was underestimated by the surgeon as compared to the patient's subjective symptom. Long lasting NSD was reported in 7.5% (questionnaire), 3.8% (record) after IVRO and in 11.6% (questionnaire) and 8.1% (record) after SSO.