Options to Save Cracked Teeth?

It sounds from your description that the tooth is not restorable and needs to be extracted.  I would see a dentist ASAP and get an opinion, the longer you wait the greater the chance that you will have to have the tooth extracted

 

Bicuspid teeth are notorious to crack, especially the lingual cusp (tongue side), when an leaky old silver filling is present. When old metal fillings leak and there is recurrent decay underneath (often hidden by the metal filling making it also difficult to detect on an xray) the old metal filling becomes analogous to a metal wedge "splitting a wood log." The fractured tooth, if the fractured portion is above bone, can often be restored with a crown. However, if the fractured portion extends below the gum, and below the bone along the root surface, the long term prognosis becomes much more guarded and sometimes an extraction and replacement with a dental implant is indicated. The best advice is to get the tooth evaluated as soon as possible (waiting a month is never a good idea) to prevent any further complication and remember my favorite old adage, "Be true to your teeth or they'll be false to you!"

It is hard to dela with the pain, and its very uncomfortable. If the crak is down to the root like you said, you will get an infection and and a root canal treatment will not be the best option because the tooth will re-infect again. The bets lasting restoration is to extracted and have an implant placed, it will look great and you will be very happy. Other options like removable partial "flipper" or a bridge are available too, but they are not the most comfortable option and with a bridge you have to remove tooth structure from the adjacent teeth. If the tooth has a minor crack and no infection you can have a crown done to keep the crack together and hopefully does not go down to the rooth of the tooth. If your dentist can not determined how bad the crack is, a specialist in root canal tretaments uses equipments to check how far the cracks goes. Always consult with your dentist first before making any decisions.