So what happened here?
The tooth was originally crowned due to fractures/cracking that started because of a large silver filling, which we’ve examined in other posts like this one. The cracks may have continued, slowly, inside the tooth (similar to a crack in a car’s windshield).
When they got to the nerve, the tooth became symptomatic and needed the root canal. But the cracks kept going, and the tooth completely fracture off inside the crown.
