The Tooth King only appeared in the episode The Lollistops.
Chowder and Gazpacho came to see him because Chowder lost his teeth. The Tooth King gave him the teeth but then after he said the price was 4 million dollops. When Chowder said he didn't have that much,The Tooth King says he has lost all pity for Chowder so he kicks them out.
The Tooth King is a pair of dentures with wings, a crown, and eyes.