Retainer (orthodontics)
Once a phase of orthodontic treatment has been completed to straighten teeth, there remains a lifelong risk of relapse (a tendency for teeth to return to their original position) due to a number of factors: recoil of periodontal fibres, pressure from surrounding soft tissues, the occlusion and patient’s continued growth and development.
[1] The advantage of this type of retainer is that the metal wires can be adjusted to finish treatment and continue minor movement of the anterior teeth as needed.
[4] Hawley retainers also affect speech, especially the d, s, t, and i sounds, however as they are often only worn at night time, this concern may not be so prevalent.
[6] However, if the patient has concerns with regards to the visible metal wire, a clear polyethylene bow can be used to enhance aesthetics.
[1] The process of making an acrylic retainer was featured on the How It's Made TV show on the Science Channel on Season 23, Episode 16.
[8] Some orthodontists feel that it is important for the top and bottom chewing surfaces to meet to allow for "favourable settling" to occur, thus the need for wearing the retainer only intermittently.
[8] However, for patients with disorders such as bruxism, VFRs can be prone to rapid breakage and deterioration due to grinding of the VFR against the opposing teeth.
[10] The original appliance extended only to the canines, however due to the risk of swallowing or aspiration, a modification which includes cribs on the first molars has been described.
[14] They commonly consist of a wire bonded with acid etch and composite to the lingual/palatal surface of the anterior teeth.
In fixed retainers, composite is usually placed to bond and to cover the wire, whilst ensuring no interference in the interdental space.
Fixed retainers are used in situations where instability is more likely, such as severe rotations, periodontal disease and median diastemas.
The orthodontist may advise wearing the retainer for a set period of time or indefinitely after orthodontic treatment.
Recent innovations of a Smart Retainer Case that utilizes: IoT, motion sensors, and a mobile application to track, remind, and reward patients, might be the most effective way of keeping post-orthodontic patients engaged with their final retention and continued wear of their removable retainer.
[13] If not cleaned properly, retainers can act as a food reservoir and lead to caries and gingival inflammation.
Cleaning options for removable retainers include retainer/denture tablets, the use of a toothbrush and fragrance-free soap or non-abrasive toothpaste.
