I did a couple of full mouth extractions in school... there were no more than 10 teeth in each case. One case did involve 20 teeth although they were all periodontally involved. I also saw a patient who was around my age (28) who I treatment planned FME and a complete upper and lower denture. That was probably the first time I've ever unintentionally made a grown man cry, last I heard, he was actually scheduled to follow through with it. So sad.