Cracked Molar treatment options?

Typically, vertically fractured teeth have poor prognosis because the vertical fracture often extends down the roots and split the roots.  If you currently have no symptoms, the dentist can place a temporary crown as a diagnostic tool.  While he is cutting the tooth down for the temporary crown, he can try to eliminate the crack as far as the eye can see without encroaching on the nerve .  You can wear the temporary crown for a period of time, i.e. one to two months. 
After awhile, it becomes a cost analysis.  If the tooth is asymptomatic, you only need to finish the crown, then proceed with that.  If however, the tooth is painful to chew on, and may require further treatment, then it is best to just extract the tooth.  The cost of the temporary crown is part of the diagnostic procedure.