Is it rare ?

If you're in dire pain or think your infection is spreading call the dental office and say you feel you have an emergency. If that doesn't work, go to the Emergency Room. You may need antibiotics

You have been asking this question for at least two weeks. Why aren't you dead yet ?

it makes you a huge troll as you have been asking the same question for 2 weeks now

Try to get in sooner, or get them to give you a antibiotic.

Yes, the infection can spread.

It is very important to control the infection with antibiotics. 

The infection can cause heart failure. 

Dentists prefer you be on antibiotics before they start doing any repair.  Give your dentist a call. Your dentist can call a prescription in to a pharmacy so that you can start the antibiotics before your appointment, so that when you do see your dentist, something can be done with the tooth, without spreading the infection (bacteria into the blood stream). 

If your dentist doesn't do that, then find a qualified dentist.  It's your life.   

Relax. The trucker had the infection for days.

I don't understand why you're being made to wait 2 weeks.

Call another dentist immediately.

It may not spread into your brain, but it certainly is going to get worse inside of 2 weeks.

You wouldn't let an infection on your hand, or in your eye fester for two weeks... would you?