I heard it was most convenient to begin the implant process at the time
of extraction and inquired with the oral surgeon .

He said it would not be appropriate to implant immediately because of
bone loss due to  previous infection. He said implant would be a good
option for me once the bone has regenerated.

It's interesting that bone can regenerate but cracked teeth cannot
heal.

    You may find that if your wisdom tooth (#17) is present it may tip
forward into the space left by #18.  You may also get some drifting down
of the upper molars into the space.  However, this movement is not
predictable.
    If you're in good health, there are no major health risks other than
normal risks attending surgery in the mouth (infection, etc.), or
failure of the implant fixture to integrate.  If you are diabetic the
chances for failure are higher.  Ditto heavy smoker.  Some patients with
metabolic bone disease are probably poor surgical risks, as are patients
receiving bis-phosphonate drugs (esp. intravenously)--you'd know it if
you were.  Otherwise implants have a very good track record, and for
most people an acceptable risk level.

Steve