Bone Loss to the Third Thread

Dr. Marcus asks us:

One of my patients has had 5 maxillary 3i dental implant fixtures placed by a periodontist. On checking for the seat of the dental implant abutments, I noted that the 3 anterior fixtures have bone loss, already down to the third thread.

They have never been loaded, just submerged beneath the transitional upper, so I guess there could have been some lateral force on them, but enough to cause this much loss in less than 6 months? Any thoughts? What should I be looking to do? What can happen here? Thanks.