Crown and Post Fall Out
Unfortunately, crowns can fall out. Fortunately, there are solutions.
There are some complications when assessing options where a crown has fallen out with regards to the crown actually staying in.
Tooth Structure Below the Crown
The dentist will evaluate if there is enough tooth structure to hold the crown. There is supposed to be 1-2 mm of tooth structure beneath the post to have a good chance of success. On this patient there was no such amount of tooth, which limits the chance of success.
Health of Gum Tissue
The health of the gum tissue and the level of bone is the second point to look at. This patient has severe bone loss and the crown margin was placed deep in the root. That part looked fine, but this means that there was more crown than root. If the ratio of crown height to root height is too high, that is also an unfavorable situation.
Length of Dental Post
A third point to consider is the length of the post. The post needs to have at least half way down the root, but not so thick that it weakens the root, making it prone to fracture. In this case, the post was favorable.
Cementing a Crown
My short term solution was to cement what he had. The last time he had it cemented it lasted only 3 months. The recommendation for him was to go back to his dentist in his country and talk to him about getting an implant for that tooth. Additionally I recommended having a more definitive address of his periodontal disease. Without that he will be having to get his crown re-cemented frequently, and that is without further deterioration of his existing tooth structure.
One other note: when someone loses a tooth, there is a chance to have a dental bridge. However, this patient has enough periodontal disease that the teeth that support this do not have enough bone to support this dental appliance. This means that in a short period of time (a couple of years) the supporting teeth will loosen up. The patient could lose the bridge. So, that is not a recommended solution for this patient.