Local anesthetics used by dentists may also contain adrenaline. This may interact with harmala alkaloids.
I would be most concerned about receiving the anesthetics while still MAO inhibited. After the effects of the anesthetics have worn off, it is probably safe to ingest harmalas.
When smoking the harmala alkaloids, the dose is very much smaller than when ingesting orally, so the risks of interactions are also much lower. Typically, 15 to 25 mg is sufficient when smoked, whereas an oral dose starts at 150 mg.
Unfortunately, not much is known about the interactions of smoked harmalas. In case of doubt, it is better to wait a day.