We are told Charlie is a dental assistant. He arrives at work where the patients are already waiting. He joins the tiny second dental assistant in the back room. They have a brief squabble then Charlie goes to the waiting room to clean the floor with a carpet sweeper. He bumps into a patient and a further squabble starts. Then back to the rear room for more squabbling.

The dentist arrives, and his first patient goes in, obviously in pain. The dentist prepares the nitrous oxide anaesthesic (also known commonly as "laughing gas" due to its effects prior to and after unconsciousness). With the man unconscious he pulls his tooth, but then he can't get him to wake up. He calls for Charlie and when he arrives the dentist runs off. Charlie tries to wake him and eventually tries hitting his head with a mallet. The man revives but starts laughing. Charlie knocks him out with the mallet.

The dentist then returns and Charlie is sent to the drug store to get a prescription. After more fighting with the patients he goes from Dr Pain's surgery to the Sunset Pharmacy. He strikes a man standing at a news-stand outside. He looks at a woman (the dentist's wife) and Charlie kicks him in the stomach before chasing the woman himself, and an incident occurs where she loses her skirt and runs off in embarrassment. He continues fighting with the man, who receives a brick in the face, thus becoming another dental patient. A second brick hits a passer-by equally losing him a tooth.

Meanwhile, the dentist gets a phone call from his maid to say his wife has had an "accident" and he goes home. Charlie returns to find the surgery empty. He picks the prettier of the two female patients in the waiting room. The other lady leaves, leaving them alone. Charlie flirts with her and looks very closely into her mouth, stealing kisses. Meanwhile, the two men struck by bricks arrive. The girl leaves. The tall passerby goes in next. Charlie uses a huge pair of pliers to remove another tooth. With all the noise the news-stand victim enters and a final fight ensues.