Otic ganglion parasympathetic neurons innervate the pulp of the mandibular incisor of the guinea pig.

Neurons innervating the pulp of the lower incisor of the guinea pig have been traced using the fluorochrome Fast blue. Besides those located in the ipsilateral Gasser's ganglion, a small number of parasympathetic cells in the ipsilateral otic ganglion were also found to innervate the pulp (chiefly the deepest region) via the inferior alveolar nerve. This is the first anatomical evidence of the presence of parasympathetic fibers in the teeth of mammals. It is suggested that these parasympathetic neurons stimulate the vasodilation of the arterioles supplying the tooth pulp.