Mar 06, · There are actually two answers as to will a loose tooth tighten back up. It really depends on what caused the loose adult tooth in the first place. If it was due to a trauma of some kind, the tooth is very likely to tighten up once bone and gum tissue are completely healed. Dec 03, · First of all, let's discuss the causes of loose teeth in adults. There is no shortage of causes when it comes to a loose tooth. It may be because a buildup of plaque and tartar has gotten so severe that it's reached up and underneath the gums.