It's a bit of a crap shoot really. I lost the very last molar (lower left) ten years ago, and was warned that there was the possibility that the tooth directly above it, [since it no longer had anything to "hit" while biting down or chewing], might slowly erupt and loosen. And that the teeth adjacent to the lost molar would shift. (Whenever there is a gap in the mouth the remaining teeth tend to want to "move" to fill it!)
An implant was suggested but this was ten years ago and the process was not nearly as sophisticated as it is today.
I opted to take my chances, said "no" to bridge and/or implant and was very fortunate not to have any problems with teeth shifting or that upper molar erupting downwards.
However, recently, the molar directly in front of the missing one (this molar had been root-canaled and crowned) just fractured under the crown and couldn't be saved. So THAT was pulled. So now I have BOTH molars missing on that side and can't HAVE a bridge. So now I need implant(s). TWO molars missing on same side will definitely cause a major shift in my mouth, not to mention not being able to really chew properly. Not yet sure if I will get one or two. The $$$$ makes me swoon.
Did your dentist tell you he saw the beginnings of a problem? or have your remaining teeth remained stable?
And I know the "idea" of a titanium screw makes you queasy but I hear the hardest part is the orig. extraction! And I heard there is nothing more stable and secure than a good implant.