Part 2 - Etanercept: Patients will be randomly assigned to receive either 1) etanercept injected under the skin or 2) saline (an inactive placebo) injected under the skin. Patients in this group will also undergo two aspirations of fluid from the jaw joint - once before treatment begins and again 6 weeks later. For this procedure, the joint is numbed with an anesthetic and then a needle is inserted into the jaw space to withdraw fluid, which will be analyzed for inflammatory processes in the joint.