We can't know for sure. After all these were fictional characters in a story.

I suppose one possibility is he was a gambler, particularly a regular loser with all the other refernces to his debts and failed deals.

I should think his money would be welcomed anywhere. His offices had pictures of many movie stars. Whether he was a good dentist or not, he was plugged into high society and high rollers.

Never saw it.

Well I have to admit this was not one of my favorite episodes. Wesley Corman is a snake, that's for sure and it's obvious that his father-in-law is the real dentist. But I have to wonder if digitalis would really be soaked up through a crown in a tooth. I'm seeing my own dentist next week and I"m going to ask him that very same thing. You know there is something funny about this episode though. Just like in A Stitch In Crime where columbo has the stomach ache and the doctor writes him a prescription;' well in this case Dr. Corman asks Columnbo "Do you always chew on one side of your mouth Lieutenant? " I seem to recall Columbo having a tooth problem in this episode. I'm sure there are other episodes with similar issues. Just can't think of any right now.