Physiologic Evaluation of Dental-Pulp Testing Methods

In dental diagnostic procedures such as dental-pulp testing, the results are generally evaluated subjectively. The purpose of this experiment was to evaluate objectively, by physiological measurement, the end-point of a human dentition pulp test independent of the attention and volition of the patient. A pulp or vitality test of a tooth is primarily a test for conduction of stimuli to the sensory receptors of the tooth. Teeth with non-vital pulps generally do not respond to a vitality test. However, diseased or degenerating pulpal tissue (including wet, necrotic tissue) may conduct an electric current to vital receptors remaining deep in the apical portion of the pulp chamber. Vitality procedures or stimuli often utilized for producing sensation are (1) use of an explorer at the cemento-enamel junction, (2) cold air, (3) ice cones, (4) ethyl chloride, (5) heated gutta percha or impression compound, and (6) electrical vitalometers. The clinical response of the patient to a physical, thermal, or chemical stimulus of the dental pulp is one of pain, expressed outwardly to the observer by various patient reactions. As is well known, the pain threshold varies greatly among patients. Pain may produce an emotional response characterized by many physiologic changes. Some changes that may be measured are sweating (galvanic skin response), skin temperature, respiration, heart rate, blood pressure, brain waves, etc. Lindsley' states that sweating (galvanic skin response) can be used as an index of mild emotional responsiveness. Other terms for this effect are "psychologic response," "skin resistance," "skin conductance," "palmar resistance," "skin potential," "electrodermal response," and "palmar sweating index." In this paper, galvanic skin response will be referred to as "GSR." The GSR test is based on the amount of sweating and the resistance of the skin to an electrical impulse. Further, it has been observed by psychologists that the skin resistance decreases as sweating increases. This test is especially sensitive for sensory and ideational stimuli.