That depends on what teeth are missing. If it is as limited as one tooth, then treatment is focused on that gap. However, if many teeth are missing, and if they have been missing for a long time, not only are teeth gone but the bone that used to hold onto them is gone. This can lead to the collapse of a person’s lower face with sunken-in lips and premature old age lines. The good news is that restoration of a more youthful facial appearance and smile are quite predictable.