Last Exit to Springfield (S04E17)

Lisa goes to the dentist and learns that she needs braces. At the same time, Mr. Burns tries to remove the dental plan from the plant employees' benefits, and an upset Homer becomes a union leader, taking the workers out on a strike. Burns tries to run the plant with robots, but cannot dent the workers' resolve, and agrees to restore the dental plan if Homer will resign as union leader. (Prime Video)