I have a lot of metal porcelain teeth, can they set off the airport security metal detector? would that cause alarm?

Your restorations would most likely not trigger any alarms. I only have one patient who ever had such an experience: he had a large bite guard fabricated out of metal. Even if the metal detector alarm triggers, an inspection of your mouth would reveal no weapons.

Today many people have implants which contain more metal than porcelain crowns. Not enough metal to set off alarm as in a hip or knee replacement.

Will not react with a magnetometer. You're ok to go through a magnetometer