Your ulcer should heal once the sharp teeth are smoothened in 2 weeks. Use the oral ulcer gel given by your dentist to help it heal and a becozinc supplement everyday.
Rounded teeth hitting the ulcer is fine
Do not disturb the ulcer.If sharp teeth keep poking for a long time creating ulceration, yes it may be dangerous
Health Tips
Meanwhile avoid very hot, spicy , hard and acidic foods for 2 weeks. if not healed in 2 weeks, kindly visit your dentist again so they would change the medication