Does a tooth with 90% bone loss need extraction?

A tooth has lost nearly 90% of its bone support. It's mobile. The patient has swelling and says his teeth are loose. Does that mean the tooth needs to be extracted? In this case, I walk through the full-mouth X-rays, CT scan, periodontal charting, bacterial testing and—most importantly—the patient's occlusion. Despite the severe bone loss, extraction was not our first choice. We treated the factors contributing to the disease: bacterial load, root surface calculus and occlusal trauma. At reevaluation, the patient's response was simple: *“My teeth are tighter.”* This case illustrates a principle that has guided much of my periodontal treatment planning: don't make the treatment decision based only on how much bone has already been lost. Look at what remains, determine why the disease is active, and decide whether those factors can be controlled. For dentists, hygienists and dental students interested in periodontal diagnosis, occlusion, periodontal endoscopy and complex treatment planning. Have you treated—or been told to extract—a tooth with this much bone loss? I'd be interested in your thoughts. 0:00 His teeth are loose — can we save them? 0:42 The occlusal problem 2:14 What the X-rays reveal 4:45 Bacterial testing and treatment 10:52 “My teeth are tighter” — what happened?