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A root canal only removes the nerve from the tooth and fills the empty space with an inert filler. The cracks on your tooth allowed bacteria to percolate into the nerve space, infecting it and was the reason you needed the root canal. A root canal does nothing to repair a crack. If you are still having pain from biting after a root canal is completed, especially to soft foods, this is not a good sign. There is a good chance that the cracks are so deep that they essentially have separated the remaining tooth into distinct pieces. If your vertical fracture is through and through, as I described, you will lose the tooth. If it is a partial "green stick" fracture, a crown will possibly save the tooth. However, cracks are difficult to diagnose with respect to their severity and extent as most can not be seen.
The only way to know if a crown will rectify the situation is to have you dentist place a temporary crown on the tooth and hold off making the permanent tooth until you are pain free. If you can not get comfortable with a temporary crown, then the permanent one will be no better. Better to take this intermediate step and cross your fingers than to pay for an expensive permanent crown only later to have the tooth removed. I hope this helps.