One hundred seventeen patients with posterior teeth requiring endodontic treatment were studied. Specific clinical findings were recorded, including pulp, vitality, preoperative pain, sensitivity to percussion, and the presence of a periradicular radiolucency. Excluded from the study were teeth with restorations to be maintained, greater than class I mobility, pocket depths > 5 mm, endodontic retreatments, and patients taking pain altering medications. Teeth were randomly assigned to 1 of 3 groups: (i) total occlusal reduction, (ii) simulated occlusal reduction (nonfunctional cusp reduction), or (iii) control (occlusion untouched). After canal instrumentation, a questionnaire was used by patients to record pain responses over a 48-h post-operative period. Responses were tabulated using a chi(2) test (p = < 0.05), and a statistically valid profile of patients most likely to benefit from occlusal reduction was developed. Occlusal reduction should prevent postoperative pain in those patients whose teeth initially exhibit pulp vitality, percussion sensitivity, preoperative pain, and/or the absence of a periradicular radiolucency.
