Proportion of unmyelinated axons in the rat inferior alveolar nerve and mandibular molar pulps after neonatal administration of capsaicin.

Neonatal rats were given capsaicin subcutaneously. Controls received vehicle only. Six months later the nerve fiber populations in the dorsal root L4, in the inferior alveolar nerve and in mandibular molar pulps were examined by electron microscopy. The proportion of unmyelinated axons was found to be markedly decreased in root and nerve specimens from capsaicin-treated rats. However, the pulpal nerves in tooth specimens from these rats showed no obvious alterations.