If a single molar is extracted and some type of bridge (rather than an implant) is placed, will serious bone loss still occur?

I understand that, when teeth are lost, bone loss occurs (causing changes in the appearance of the face/jaw) -- and that adjacent or opposing teeth may shift position. Do dramatic changes in the look of the face occur when it's just one missing tooth (e.g., a lower molar)? If an implant is not an option, will a bridge at least stop teeth from shifting? I may not be a good candidate for an implant for various reasons, but I'm scared of how a missing molar may change the way my face looks. Thank you