Hello there ,
Thanks for writing your query,
According to your clinical history i suspect the dark shadow seen in the x ray
is nothing but indicative of periapical infection in relation to lower front teeth.
It is nothing but bacterial infection that spreads to the deeper structures of the tooth and involves the tooth nerve
tissue leading to pulpitis
We can save such infected and fractured tooth by root canal
procedure, provided the periodontal status of the tooth is good. That is, if the tooth is not mobile.
Root canal procedure disinfects the tooth by removing the infected nerve tissue and the root canals are cleaned,shaped and filled with permanent restorative material.
Once the treatment is completed , the tooth can be restored with a prosthetic crown coverage.
i hope this helps ,