Morphological studies of the altered pulps of the New Zealand white rabbit after resection of the inferior alveolar nerve and-or the superior cervical ganglion.

This study was carried out to determine the effects of dener-vation of the pulp organs of teeth, particularly on the odontoblasts and their processes. Therefore, resection of the inferior alveolar, cervical sympathetic, or a combination of both types of nerves supplying the mandibular incisor teeth of New Zealand white rabbits was performed and the results compared to adjacent , unaltered teeth. Neural stains were used to evaluate the presence or absence of nerve elements, while histochemical and titrametric methods were employed to determine the presence, location and concentration of cholinesterase enzymes in these teeth. Dilation of blood vessels was noted after cervical sympathetic resection and larger nerve trunks as well as peripherally located fine fibers were absent in the pulps following inferior alveolar nerve resection. Further, irregular dentin formation and associated small openings in the tips of the teeth were observed after nerve resection. Titrametric analysis indicated a significant decrease in the concentration of cholinesterase in the pulp organ of incisors 15-19 days after resection of either the inferior alveolar nerve or both inferior alveolar and cervical sympathetic nerves. Only a slight decrease in the concentration of cholinesterase was noted after removal of the cervical sympathetic nerve alone. Histochemical results confirmed a decrease in cholinesterase after resection of the inferior alveolar, cervical Sympathetic or both nerves. The concentration of the oxidative enzyme, succinic dehydrogenase, however, increased after all three types of nerve resection. This increase was apparent particularly in the odontoblastic cells underlying the predentin. A number of investigators have reported the effects of denervation on the growth patterns of teeth. King ('37) sectioned the cervical sympathetic nerves in rabbits and noted a temporary acceleration of the growth of incisors. He attributed this acceleration to an increase in blood supply which occurred after sectioning. Taylor and Butcher ('51) found a 20-30% increase in the rate of eruption of rat incisors following inferior alveolar nerve resection. They concluded that the loss of sensation which resulted caused a fracture of the continuously erupting teeth. The lack of occlusion may have contributed to the increased rate of eruption. Edwards and Kitchen ('37) noted that resection of sympathetic nerves caused a 2-15% accelerated tooth growth in kittens, while resec-tion of the inferior alveolar nerve produced no definite effect. Bishop and Dorman ('63) reported that stimulation of the superior cervical ganglion caused vasoconstriction of the mandibular artery. Severing of the mandibular nerve resulted in an …