Do you need a crown if you have a root canal on a lower left molar performed over a bridge?

If you have a root canal done, most likely you'll need a crown. But if it was done through a bridge, there is already a crown on that tooth. A bride is just three or more crowns fused into one piece to replace a missing tooth. It is possible that doing a root canal through the brige will damage the bridge and the whole until may need to be replaced if that happens. But that's not common.