Tooth feels numb, if I go to the dentist what are the chances it’ll be taken out?

Hi, I’m 18 and recently my tooth has been feeling numb. I’m going to make an appointment to the dentist about it, however I’m scared if I do, they’ll take it out which I really don’t want as it is right at the front of my mouth. This all started when I got a ulcer about 4 days ago and the ulcer was rubbing right up against the tooth that now feels numb. Does anyone have any idea why my tooth is numb? And what news I should prepare for at the dentist?