Тіс қалыпқа келтіргіш құрылғылар

Device to hold teeth in position

Orthodontic retainers are custom made devices, usually made of wires or clear plastic, that hold teeth in position after surgery or any method of realigning teeth. 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. By using retainers to hold the teeth in their new position for a length of time, the surrounding periodontal fibres adapt to changes in the bone which can help minimize any changes to the final tooth position after the completion of orthodontic treatment. Retainers may also be used to treat overjets.

Removable retainers include Hawley, Vacuum formed, Begg and Barrer. They provide orthodontic retention when worn and they can be taken in and out of the mouth. They can be worn part time or full time if required or as advised by the orthodontist. In comparison to fixed retainers, removable retainers are easier to clean. Named for its inventor, Dr. Charles A. Hawley, the labial wire, or Hawley bow, incorporates 2 omega loops for adjustment. It is anchored in an acrylic baseplate that sits in the palate (roof of the mouth). They are made from metal wire running along the outside of the teeth. There are many adaptations possible with Hawley retainers. It also benefits from being robust and rigid, easy to construct and allows prosthetic tooth/teeth to be added onto with metal stops placed mesial and distal to the prosthetic teeth to prevent any relapse. To help fix rotations; acrylic facing can be added to the labial bow and a bite plane added to maintain the result of deep overbite correction. Also, to control the position of the canine, reverse U loop can be employed. Additionally, to avoid occlusal interferences, the labial bow can be soldered to the cribs. 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. Research shows that participants that wear Hawley retainers report being more embarrassed about the appliance than wearing vacuum formed retainers and they found Hawley retainers more difficult to wear. However, if the patient has concerns with regards to the visible metal wire, a clear polyethylene bow can be used to enhance aesthetics. This clear or transparent retainer normally fits over the entire arch of teeth, however some designs fit only from canine to canine (clip on retainer). The retainer is clear and so virtually invisible when worn. Hence, it can offer an aesthetic advantage relative to other retainers. VFRs, if worn 24 hours per day, do not allow the upper and lower teeth to touch, as the retainers cover the occlusal (biting) surfaces of the teeth. 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. retention was achieved with fixed retainers. They allow occlusal settling, as no wire work crosses the occlusion. Begg retainers are robust enough to be worn during eating, however they are less retentive than Hawley retainers and the labial bow is more prone to distortion.

The Barrer retainers (aka Spring retainers) carry acrylic bows both labially and lingually.

Fixed retainers are often used to provide orthodontic retention and avoid relapse. 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. Occasionally the patient will require a removable retainer as well. Fixed bonded retainers can be designed with a smooth wire or flexible spiral wire which is also known as multi strand wire. The most commonly used are multi strand wire bonded to all six anterior teeth or a round stainless steel wire bonded to the canines only. Although fixed retainers depend less on the patient’s cooperation for regular wearing, they are more difficult to clean and therefore need more attention from the patient to prevent plaque accumulation and subsequent gingival inflammation.