how long does it take for a nerve to die in a tooth?

I have no dental insurance and can't afford to see a dentist. My wisdom tooth on the top is rotting out but its doing it from the top down and the exposed nerve is causing pain. Please help
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Get help ASAP or find some way to get yourself to a dentist, free clinic, ANYTHING. This is a response posted by a dentist on a forum I frequent when someone posted claiming to have the same thing you have, except when he posted this the nerve had died but started aching again... "In case you're considering skipping treatment to save some money - don't. You suffered from pulpitis, an inflammation of the pulp of the tooth caused by micro-organisms accompanying the cavity. The nerve is now dead, most likely gangrened. Because you did not get endodontic therapy it has now turned into apical periodontitis, which means it has spread to the tissues surrounding the tip of the root. So if you were fearing the infection would reach the root canal - well, it has and it's now moved on; it is currently making it's way through the bone around the tooth, slowly digging and growing - this is why the pain has returned, the infection is creating pressure in the tissues. Further postponement will result in the tooth abscess completely perforating the bone. You may get lucky and the pus could drain through the gums. You don't want to know what happens if you get unlucky and the infection spreads to other regions of your body (example - brain)."
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