Panel 1: As I alluded to yesterday, Mrs Divot is a difficult patient. Her reaction to having John try to examine her is to holler in terror and explain that she can't stand anything in her mouth and gags easily.
Panel 2: She then tells her son The Ome.....Trevor to stop playing with John's equipment and to play in the waiting room so he won't get mad like the last dentist did. John is staggered and asks "'Last' one?" in confusion.
Panel 3: She gets all kinds of casual about missing a few appointments and having her cheques bounce once or twice before stating that a Dr Nedwitt (Nitwit) referred her to John.
Panel 4: As he tries to remember what he did to piss Nedwitt off, John's expression sours as he says that he must remember to thank him.
Summary: This, of course, will be done by palming off his own Patient From Hell. In other words, Mike has a new dentist and doesn't know it yet. Also, this was probably meant to disrupt Rod's ability to deal with other dentists on a professional and personal level as they might have assumed that what Lynn drew is what they were getting.