Inadvertent tooth movement with fixed lingual retainers

•Passive and securely bonded fixed anterior retainers are an effective way to prevent posttreatment relapse but require regular supervision.•Small-diameter flexible spiral wires bonded to each tooth pose the greatest risk for creating significant inadvertent tooth movement and resulting complications.•Early detection of bonding failures, wire breakage, and tooth movement created by the retainer is critical in preventing major problems.•A patient with a fixed retainer should be seen regularly by the general dentist if not by the orthodontist, and the orthodontist should accept responsibility for dealing with problems if they arise.•Interaction with a periodontist using bone induction procedures is needed for retreatment of patients with severely displaced teeth.

Fixed retainers are effective in maintaining the alignment of the anterior teeth more than 90% of the time, but they can produce inadvertent tooth movement that in the most severe instances requires orthodontic retreatment managed with a periodontist. This is different from relapse into crowding when a fixed retainer is lost. These problems arise when the retainer breaks but remains bonded to some or all teeth, or when an intact retainer is distorted by function or was not passive when bonded. In both instances, torque of the affected teeth is the predominant outcome. A fixed retainer made with dead soft wire is the least likely to create torque problems but is the most likely to break. Highly flexible twist wires bonded to all the teeth appear to be the most likely to produce inadvertent tooth movement, but this also can occur with stiffer wires bonded only to the canines. Orthodontists, general dentists, and patients should be aware of possible problems with fixed retainers, especially those with all teeth bonded, because the patient might not notice partial debonding. Regular observations of patients wearing fixed retainers by orthodontists in the short term and family dentists in the long term are needed.