In the story Night, some details show the reader that the dentist from Czechoslovakia might not be a dentist.
First of all, Eliezer had this appointment with the dentist to extract one of his tooth's gold crown, and, usually, the nazis, in addition to confiscating the money and property of jews, used to steal anything else that was of value, including the gold in dental fillings and dental crowns. This knowledge made Eliezer put off the procedure more than once.
Also, Eliezer later finds out that the dentist has been arrested for profiting from the gold extracted from the prisoners and that he is going to be hanged for it.
All the dentist's work used to be rough and made with pain, this gives us the idea that he was not a professional in this area, but just wanted the gold pieces inside his patients mouths.