New methods of pain measurement and their application to pain control.

Recent pain research advances show promise in their application to the relief of acute and chronic clinical dental pain. Regional electroanalgesia, or transcutaneous electrical stimulation, has been used successfully in the treatment of pain associated with peripheral nerve injuries. Electrical stimulation of teeth also may prove useful as a pain control technique during operative dentistry procedures. Another exciting research finding is the discovery of endogenous or natural pain-suppressing pathways in the brain. There are recent demonstrations that natural-occurring opiate-like compounds and receptors exist in the brain. The elucidation of stimuli and behavioral responses which will activate these specific descending pain control pathways may lead to exciting new methods of pain relief. Thus, both regional electroanalgesia and the discovery of endogenous pain-suppressing pathways offer the possibility of the future expanded use of non-pharmacological pain control techniques. The proper evaluation of new pain control techniques requires the development of better methods of measuring and assessing the multidimensional aspects of the pain experience. Category scales which scale the suprathreshold range of pain from threshold to tolerance levels can be used with both experimental and clinical pain. Sensory Decision Theory has been applied to the analysis of categorical pain responses. This method distinguishes between sensitivity to stimulus intensity and response bias, or the patient's willingness to report a given intensity as painful. Another promising method for scaling pain is the use of ratio-scaling methods with verbal pain descriptors. Verbal descriptors of pain may provide the best method of scaling different dimensions of the pain experience. Reliable and objective descriptor scales have been developed which separate pain along two dimensions: sensory intensity and affect, or unpleasantness. By using cross-modality matching procedures, specific numerical values can be calculated for each verbal descriptor. These scales have been used to measure the intensity and unpleasantness associated with tooth pulp evoked experimental and clinical pain, and should be extremely useful in the evaluation of acute and chronic dental pain. They will be important experimental and clinical adjuncts in determining the efficacy of non-pharmacological pain control methods such as regional electroanalgesia, biofeedback, relaxation-suggestion and hypnosis.