Old filling came out leaving a hole in back molar, can it be re filled or a crown put on?

Hi there...it just depends on how big the hole is and whether there is a cavity.  Sometimes fillings fall out when a cavity develops underneath the filling.  Your dentist will be able to tell once they can take an xray on the tooth.  Hope this helps.

Hi:
Unfortunately without photo and X-ray it is difficult to give you accurate advice.  Please post photo and X-ray of the affected area.
Best,
Dr. Maddahi

Hello,
It probably won’t need root canal but it has to be evaluated by a doctor to determine whether it will need a crown or it can be refilled with composite and might need to take an X-ray. But by reading what you are saying it probably will only need to remove the brown stains, which may be cavities, and refill with composite.
Dr. Franco
DentArtist Clinic