I looked puzzled so he explained that each tooth is held in place in the jawbone by the periodontal ligament. The ligament runs around the submerged part of the tooth as well as its roots. It acts as a shock absorber so that the tooth doesn’t rub against the jawbone when pressure is applied. The periodontal ligament also ensures that the tooth remains separate from the jawbone and prohibits additional bone growth in the socket. Wisdom teeth are enclosed in a fluid filled sac as they grow that is used to create the periodontal ligament. Dentists and oral surgeons don’t remove the sac or the periodontal ligament. Their reasoning is that the body breaks it down over time.
However, while the sac and/or ligament deteriorate, the body thinks that the tooth is still there so the jawbone doesn’t heal. New bone won’t fill in the extraction site since the ligament is a biological barrier to such growth. Sometimes when a tooth is extracted a portion of the ligament will come out with the tooth. This is why cavitations come in many shapes and sizes. Since the periodontal ligament doesn’t reach to the top of the socket, a thin boney cap can form over the extraction site, which gives the impression that new bone has formed