retreatment

i had a root canal done for 45th and 46th tooth in 2004 and 2006 respectively. now my dentist found the 45th has an infection or crack in its root, but i feel no pain now; and the 46th has some metal left in its root which caused infection and pain. the 46th gave me pain when i touch it with my finger and chewing.

i have consulted 2 dentists. one told me redo root canal for 46th and leave 45th as it is now because it does not give pain yet.

another one told me to extract half tooth which has metal for 46th and redo root canal for other half and 45th, than do a bridge and crowns for 45th and the half tooth of 46th.

i like to have your advice.  thanks