A loose tooth in an adult: what causes it, and when it can be kept

Often, the reason is gum disease. Periodontitis, which many people still call pyorrhoea or simply gum disease, slowly breaks down the fibres and bone that hold a tooth, and as the support shrinks, the tooth starts to move. The 2018 classification counts that movement among the signs that a case is more complex to manage.^[1] How much bone has gone, and whether it is still going, is explained on bone loss around teeth, and how it is treated on gum disease treatment.

An infection can loosen a tooth too. When the nerve inside a tooth dies and becomes infected, the infection can reach the gum and bone around the root; the 2017 world workshop classifies these as endodontic-periodontal lesions, and their signs bear directly on the prognosis and the treatment. An abscess in a gum pocket can also destroy tissue quickly.^[4] Here the treatment is aimed at the infection, often root canal treatment, and the movement is reassessed once it has settled.

A crack running down a root is another cause, and it is looked for on the X-rays and in how the tooth responds to tests. Teeth also loosen a little while braces or aligners are moving them, which is expected and settles again during retention.^[5] These causes often overlap, a tooth with reduced bone and a heavy bite for example, which is why they are separated at the assessment before anything is treated.

A heavy bite does not start gum disease. The 2017 world workshop review concluded that excessive biting forces do not initiate periodontitis or attachment loss, and that the evidence they speed up existing disease is weak. The same review supports treating the bite as part of gum treatment, to reduce mobility and make chewing more comfortable, and notes that reducing mobility may help the gum treatment work.^[6]

Grinding matters over the long term. In the review of periodontally treated molars, grinding (bruxism) was one of the risk factors for losing a molar during maintenance, alongside smoking, diabetes and missed visits.^[2] A systematic review also found that adjusting the bite on teeth with mobility or premature contacts may improve their attachment, on limited evidence.^[7] So where grinding is part of the picture, a night guard is usually part of the plan, and selective adjustment of the contacts that overload a tooth is described on occlusal therapy.

At the assessment, the bite is checked tooth by tooth, and grinding is looked for in the wear of the teeth and in anything you, or someone who sleeps nearby, have noticed at night.

The evidence is encouraging. In the review of 41 studies, periodontally treated molars were kept in 82% of cases over a mean of 14.7 years of maintenance, with fewer than one molar per patient lost per decade, and the authors concluded that long-term retention of these teeth can be achieved.^[2]

The same review lists what raised the risk: older age, smoking, grinding, diabetes, missed maintenance, upper molars, deep pockets, involvement of the area between the roots, higher mobility, and a tooth whose nerve had died.^[2] Several of those can be changed, and mobility is one of them. That matters because, in a study that followed 82 patients for eight years after gum treatment, the pockets of mobile teeth responded less well than those of firm teeth with the same severity of disease.^[3]

A tooth cannot always be kept, and when that is the case it is said plainly, with the options laid out. But the first aim is to keep it, and the plan is built on what the evidence ties to keeping teeth: treating the gum disease, steadying the bite, and supportive care at an interval of 3 to 12 months set from your own risk.^[8]