The Controversy Concerning the Innervation of the Teeth

In studying the literature on the histology of the tooth, one is impressed with the want of unanimity in the views expressed by various writers. One cannot select a single tissue entering into the formation of the tooth, whose function is not, even today, interpreted in several ways. This is especially true in the problem of nerve fibers ending in association with the odontoblasts or penetrating the dentin and terminating in its substance. This is not due to the lack of careful work, but rather to the difficulty which surrounds these investigations. To search for the first allusions to nerves in the teeth is to go back to antiquity. The time when dental pain was not discussed is beyond our knowledge. Galen (Taylor, 1922) in his anatomical researches recognized seven pairs of cranial nerves and classified the trigeminus as the third. Galen also records two sites of pain, one in the tooth and the other in the surrounding tissues (Latham, 1901). Aetius of Amida, 502-575, a celebrated Greek physician and author stated the cause of toothache was known only to God. He taught that the mucous membrane of the mouth tissues is provided with nerves from the 3rd pair of cerebral nerves and that the teeth, too, by a small hole existing at the end of every root, receive tiny ramifications of sensitive nerves, having the same origin (Weinberger, 1926). Leeuwenhoeck (1678) gave the first description of the tubular nature of the dentin from observations made on one of his own teeth. However it was not until some 170 years later that the dentinal tubules were cited as being a possible structural element whose contents entered into the cause of dental pain.