I havbe been told I need an upper 8 tooth permanent bridge including replacing the two front teeth. After filing down the teeth the dentist took x-rays and said I should have root canals on the 6 remainibg teeth even though the teeth never had cavities. I believe he said the canals are large, whatever that means, and it is better to have the root canals done now, so as not to have problems in the future, and require the bridge to have to be redone.
Does this make sense to you? How long should I expect the bridge to last with and without the root canals?

Thanks for your help.