If post-extraction bone loss is high, bone augmentation is a must, because without it the teeth neighboring the edentulous will suffer and their implantation will steadily decrease. Also, only short and thin dental implants can be placed in a resorbed bone, which cannot withstand masticatory forces for a long time.
If the bone loss is small and the dental implant is inserted in the first 3-6 months post-extraction, bone addition is optional.