|Book debut||Arthur's Tooth|
|Cartoon debut||"Arthur's Tooth"|
He appears when D.W. decides that she wants to lose a tooth. Jane takes both of them to see him, and Arthur plays with his fake mouth, making fun of the echoing sound it emits whenever you talk into it. Jane asks him to take his hand out of it (even though Arthur only talked into it) to which Dr. Sozio replies, "Oh, that's okay, Mrs. Read. That's what it's for."
He also appeared in a picture in the Arthur's Guide to Children's Hospital Boston website feature as someone working in the cast room. His appearance is almost the same as it is on the show, except he has brown glasses frames instead of gray and is wearing blue and gray under his coat instead of green and white.