You can't, as it is infection causing the swelling. Try calling your GP and tell them your situation and see if they will give you an script for antibiotics. The dentist won't touch it while it's abcessed, and would put you on antibiotics to clear up the infection before doing anything with the tooth. If you have a regular dentist, I would think they would also write the script, since this will be thier first step anyway.
You could do some warm salt water rinses - to help pull the infection out, use some oil of oregano as well. Mammo's right, you'll need to get a script to fight the infection before a dentist can do anything.
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