Pain Measurement in Healthy Volunteers

This study will attempt to develop and validate improved subjective measures of pain sensation and use these measures to evaluate pain sensitivity in patients. Normal healthy volunteers and dental patients undergoing third molar extraction may be eligible for this study. Participants will undergo the following procedures: Volunteers: Volunteers will participate in two 90-minute sessions in which they will receive and rate four heat stimuli per minute applied to the skin for a maximum of 36 minutes. The heat stimuli range from 37° (Degree)C to 51° (Degree)C (99° (Degree) F to 124° (Degree) F) and last 2 to 3 seconds. A drug commonly used in dental treatments may be administered during the second session. This will be either a maximum of 0.15 mg fentanyl, a short-acting narcotic pain killer, or a maximum of 5 mg saline, an inactive substance (placebo). Dental patients: Dental patients will participate in two 60-minute sessions. The first session will be on the day before the third molar extraction, and the second session will be immediately before the dental procedure. The heat stimulus procedure will be identical to that described above for normal healthy volunteers.