Vascular and Nerve Supply to the Molar Teeth of Guinea Pigs

¹ Department of Anatomy, School of Medicine, University of Southern California, Los Angeles, California

Guinea pigs of varying ages were used in a study to interrelate the morphology and the function of the molar teeth with their vascular and nerve supply. The blood vessels were demonstrated by the saline solution-India ink-gelatin perfusion method, (Fig. 23) whereas the nerves were demonstrated by the Pearson's silver gelatin method.

The reaction of the pulp to the oral environment resulted in the deposition of bone-like material, or osteodentin, which finally obliterated the pulp.

The terminal relationship of the blood vessels in the pulp depended on the region studied. At the apical third of the tooth, the pulpal capillaries were located at the predentin border; at the middle third of the tooth, there was a gradual "withdrawal" of the terminal capillary plexuses from the odontoblastic zone so that, at the occlusal third, the vascular terminals were restricted in location to the pulp.

In the region of the enamel organ, blood vessels penetrated the enamel organ to lie directly adjacent to the ameloblasts, and this intimate relationship persisted to the epithelial attachment.

The vascular supply to the periodontal ligament arose mainly from the intraalveolar vessels that perforate the bone to pass gingivally alongside the bone. In their gingival course, branches were given off that passed across the ligament to supply the enamel epithelial layers.

Nerve supply to the pulp consisted of nonmedullated nerves that always were intimately associated with blood vessels throughout their course. This direct association with blood vessels leads to the assumption that the nerves in the pulp of the molar tooth are autonomic in nature.

Two types of nerve endings were found in the periodontal ligament: nonmedullated nerve fibers that may terminate as "free nerve endings" and nerve fibers that may terminate as encapsulated, spindle-like structures.