Experimental Investigation of the Referred Pain of Aerodontalgia'

Dental pain caused by changes in barometric pressure was shown by Reynolds, Hutchins, Werner and Philbrook (1946) to be, at least in the great majority of cases, a result of referred pain from an occluded paranasal (usually maxillary) sinus. A neural mechanism was proposed which explained not only all of the phenomena observed in their study but also the widely variant observations of previous investigators. In summary, this hypothesis was as follows: The afferent nerve from a tooth, after once being painfully stimulated, as by a blow, deep cavitation, cavity preparation, over-filling resulting in occlusal trauma, pulp exposure, infection, or extraction, continues to react by means of a constant series of excitation waves for a considerable period of time (even years). After the original external stimulus has disappeared, however, this excitation subsides to a subliminal level. Thus no pain is experienced in the tooth until stimulation of an associated structure (innervated from the same segment) produces a facilitation of the excitation existing in the afferent nerve from the tooth sufficient to carry this excitation to the central nervous system where the subjective sensation of pain arises. This concept is schematically presented in the accompanying diagram (fig. 1). Many modifications of such a mechanism are possible, as discussed in the previous paper. Inasmuch as this hypothesis arose only from a statistical study of data collected without experimentation, it was thought desirable to test it by experimental procedures.