The patients often ask about the replacement of the older restorations. They are always curious whether the fillings are permanent or should they only be replaced if there is any problem regarding the restoration or the related tooth?
The answer to above is here. No restoration is permanent. Especially the old fillings are more prone for wear and breakage. The fillings might not be bothering in the present time but the old fillings are supposed to cause problems later in the near future.
However the recommendations to replace the old restorations do not depend upon the age of the patient. If your dentist is asking you to replace the existing restoration, ask him the reason. You can also ask for the X-ray proof of the present problem. If you are still in doubt regarding the opinion, you are always free to take second opinion.