Help docs! i'm trying to find out what causes a root canal to crack?

Brittle tooth: Teeth that have undergone root canal therapy become brittle and are more prone to fracture. Teeth treated with root canal therapy usually have a post and crown placed to avoid such fractures.

Root canal: Once a tooth has a root cabal it looses the internal blod supply and will become more brittle and has a chance of fracturing. For most root canal teeth, especially the back teeth a core build up and a crown is the best and most long lasting way to restore them.

Cracked tooth: Any tooth can fracture. If enough pressure is placed on it, it chips or fractures.I once had a patient who cracked anything we did for him, even crowns. Finally we discovered he chewed on ice cubes all day long. Teeth that have had rct are weaker for two reasons.First they are more brittle since their blood supply is gone (same as a dead tree). Secondly, they are heavily restored, making them weak.

Root canal crack up: When a tooth has had a root canal it becomes more brittle than a vital tooth as it has lost its blood supply. Treating these teeth by placing a crown over them somewhat decreases the likelihood of fracture but doesn't eliminate it. We as patients can break anything, we can be very destructive, sometimes without even knowing it.