A cast and post are usually done in a general practitioners office. These are not uncommon and are done when there is not enough tooth structure left to secure a crown. Rarely is this procedure referred out to a specialist. A dental implant is an entirely different procedure and is done afer the tooth and remaining root has been extracted.
Before a cast and post is done, a good root canal must be done in the tooth. The post extends down into the canal. This requires removal of some of the root canal filling. It is possible that your dentist wants to refer out your case because of problems with the root canal. After retreatments, there may be some problem that your general dentist feels are beyond her expertise. A tooth that has been retreated twice for a root canal does not have a good prognosis. If your insurance does not cover a prosthdontist, but does cover an endodontist (root canal specialist), perhaps you could see the root canal specialist to have the post space prepared and readied for a crown, and then the general dentist could finish the job. I would not pressure a general dentist to do a job that they prefer to send out to a specialist. It means that they do not feel that they can do a good job, considering the complications. You should see an endodontist for an opinion on if the tooth is a good candidate for a post an crown. It may be better to have it extracted, if it is in such poor condition, and have a bridge made. This would also most likely be covered by your insurance.
I hope this helps.
Sincerely, Jewel Simpson
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