If implants can be placed, this will help to retain what bone you have.
 I'm not a surgeon, so I don't know how much bone can be reasonably
grafted, nor how much is needed in your case.
    My recommendation is to see an oral/maxillofacial surgeon.  Sometimes a
routine panoramic x-ray is enough to see what's going on.  Sometimes a
CAT scan is required.

Steve

Teeth 18 and 19 both had root canals and crowns about 10 years ago.
Last year, 19 cracked below the gum line and had to be extracted (that
was fun).  Last month, 18 abcessed (even more fun) and was pulled as
well.  What to do now?
I've been told I have bone loss in that same area.  If bone is grafted,
do I have a pretty good chance of gaining enough strength to hold
implants?  If I leave the space empty, is 17 next?  My preference would
be to make the best choice, in terms of the long run, even if it means
greater expense.