Hi..
Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concern...
As per your complain and presentation of symptoms if she wears complete dentures then there is a possibility that there is an
abscess which is caused due to any remaining root piece which might have left accidentally in the jaw and as the gums healed over it so it could not be seen and stayed dormant.
It might have re-activated now causing infection and pus formation leading to abscess and swelling..
You should consult an oral physician and get evaluated and get a full mouth
x ray done known as
ORTHOPANTOMOGRAM [OPG] to rule out the exact cause of the swelling..
In case if it is due to over retained root piece then extraction of the same followed by antibiotics can help..
In case if it is not to it he/she will evaluate her for conditions like
Cellulitis or Facial Space Infections and treatment will be planned accordingly..
For a more detailed explanation you can send images of your wife's face and also scans of x-rays by visiting my profile and clicking on "Ask me a question" so that I can guide you better towards treatment..
Hope this information helps..
Thanks and regards..
Dr.Honey Nandwani Arora..