• IINCLUSION CRITERIA

Dental outpatients undergoing elective removal of impacted third molars based on a preoperative diagnosis of the type and number of teeth to be extracted. The difficulty of extraction will be classified based on clinical exam and a panoramic radiograph as simple extraction (1), soft tissue impaction (2), partial boney impaction (3), or full boney impaction (4). Both lower teeth to be extracted should be similarly boney impacted, and the score for each of the two lower teeth should be 3 to 4. Uppers are usually in soft tissue. The diagnosis for each tooth will be confirmed by the oral surgeon after the procedure based on the surgical procedure actually performed.

CRPS patients are referred with a diagnosis of CRPS-I or CRPS-II in one limb only, based on pain (1) that is post-traumatic and spread beyond the region of the injury; (2) has persisted for more than 2 weeks; and (3) is associated with swelling, altered skin color or skin temperature, altered sweating, allodynia or hyperesthesia or limitation of active movement. Atrophic changes in skin, hair loss or nail changes, or disuse atrophy of skeletal muscle may be present.

Both sexes are to be studied.

Children can participate, if they can provide adequate self-ratings.

All ethnic and racial groups can participate.

Patients must be willing to return to NIH for follow-up evaluation under this protocol.

EXCLUSION CRITERIA

Dental outpatients must not be taking any medications chronically (with the exception of oral contraceptive agents).

Pregnant and lactating women are excluded.

Based on the oral surgeon's postoperative diagnosis, any extraction which is classified as producing unusual surgical trauma will result in exclusion from the remainder of the study.

Dental subjects will also be excluded if they are not adequately sedated by midazolam alone and require intraoperative administration of an opioid drug such as fentanyl, administration of greater than 14.4 ml of local anesthetic (2% lidocaine with 1:100,000 epinephrine), or postoperative administration of a steroid for possible injury to the inferior alveolar nerve.

Patients referred with CRPS-I or CRPS II who have abnormal screening test results or who have non-traumatic disorders to which pain may be attributed (gout, malignancy, arthritis, etc.) will be excluded.

Any patients who have had ablative procedures for treatment of their neuropathic pain disorder will not be eligible for inclusion in this study.

Subjects with impaired mental capacity that precludes informed consent and children who cannot provide adequate self-ratings are excluded.

Patients who have a positive HIV result will be excluded.

Subjects with obviously impaired mental capacity that precludes informed consent and ability to provide adequate self-ratings are to be excluded.

Patients who have a positive HIV result will be excluded.