For some individuals, the malocclusion that was corrected after an orthodontic treatment relapse. This orthodontic relapse occurs when adequate retention is not provided to the teeth after the finish of the treatment. Our tooth tends to move back to their original position after orthodontic treatment. The dentist thus provides teeth retainer, which is to be worn for a stipulated period.

Hawley retainers are removable retainers with a thin metal wire visible on the front surface of the tooth. Another type of removable teeth retainer is Essix retainers, which are clear transparent trays usually covering your entire teeth.

Fixed retainers are bonded directly to the tooth lingually, in the back surface. Let us understand in detail why teeth move after completion of orthodontic treatment and what can be done to prevent it.

Why do teeth move after braces?

During orthodontic treatment, the teeth are held in position by braces.  On removal of braces, the stretched elastic fibers in the gum start pulling the teeth back to their original position.

This condition is called orthodontic relapse. These fibers require remodeling to stop exerting pressure on the teeth. Delayed growth of the jaws after completion of orthodontic treatment also causes the treatment to relapse.

To avoid orthodontic relapse patients are given retainers, which hold the teeth in their new position. Over time, the teeth stabilize in the new position. In some cases, retainers may be required lifelong.

Numerous factors are responsible for relapse. No single element can be said to be the sole cause of relapse. In most cases, relapse occurs due to a combination of reasons-

  • Whenever teeth are moved orthodontically, the periodontal and gingival fibers encircling the tooth are stretched. These fibers can cause the teeth to come back to their original untreated position (1).
  • Patients with skeletal problems may exhibit relapse due to the continuation of the abnormal growth pattern after orthodontic therapy. Hence prolonged retention is indicated until active growth is completed (2).
  • Bone is the primary support to the tooth. Lightly calcified bone surrounds teeth that have been moved recently. Thus the teeth are not adequately stabilized and tend to move to their original position (3).
  • The primary cause of the malocclusion should be determined at the time of diagnosis, and adequate treatment steps should be planned to eliminate them. Failure to remove the etiology can result in relapse.
  • The third molars erupt late in the development of dentition. They erupt between the ages of 18-25 years. The pressure exerted by the erupting third molars is believed to cause the late anterior crowding causing a relapse (4).
  • Proper intercuspation of upper and lower teeth is an essential factor in maintaining the stability of treated cases. Presence of certain habits such as clenching, grinding, nail biting, lip biting is imperative causes of relapse (5).

Why is retention needed?

  • Corrected teeth conduce to return to their original position.
  • Relapse is likely to occur if corrections are carried out during periods of growth.
  • Overcorrection is recommended in malocclusion
  • Relapse is likely to occur if the original cause of malocclusion is not eliminated.
  • Obtaining proper occlusion is an essential factor in maintaining corrected positions.
  • The farther the teeth have been moved, the lesser is the risk of relapse.
  • Bone and adjacent tissues must be allowed time to reorganize around newly positioned teeth.
  • Arch form, especially in the mandibular arch, cannot be permanently altered by appliance therapy (6).
  • Many treated malocclusions require permanent retaining devices (7).

Retainers and its types

Retainers are mostly recommended to be worn for six months initially, and they are to be worn only at night for six months and gradually withdrawing them.

Treatment with fixed orthodontic appliances in case of rotated teeth should follow at least 12 months of retention, 3-4 months full time and 8-9 months part-time.

The retention phase in growing patients should continue until growth declines. To prevent relapse with slow growth lower teeth alignment, indefinite retention is required (8).

Retention in cases of periodontally weak teeth, diastema closure, and arch alignment require permanent retention.

Removable Retainers

Hawley retainers

The best-known removable teeth retainer is the Hawley retainer, which consists of a metal wire that typically surrounds the six anterior teeth and keeps them in place (9).

The metal wire is anchored in an acrylic base plate that adapts to the palate of the mouth. An aesthetic version of the Hawley retainer has the front metal wire replaced with clear wire.

Advantage
  • Metal wires can be adapted to finish treatment
  • Minor movement of the anterior teeth can be done
Disadvantage
  • Inferior aesthetics
  • Interference with speech
  • Risk of fracture

Essix retainer

They are vacuum formed retainer (VFR). They are clear or transparent retainer that covers the entire arch of teeth (10). This teeth retainer is virtually invisible and clear when worn. Hence, it can provide aesthetic value to the patient. It is advisable to wear VFR only at night.

Advantages
  • Less expensive
  • Less visible
  • More comfortable to wear than Hawley retainers
Disadvantages
  • Prone to rapid breakage and deterioration
  • PVC material

Fixed retainers

These consist of a thin stainless steel wire, which is permanently bonded to the front teeth. Fixed retainers are very unobtrusive. The different types of fixed retainers are:

  • Reinforced fibers
  • Fixed canine and canine retainer
  • Multi-strand retainers

The most preferred bonded retainer is the multi-strand stainless steel wire type as it is bonded to every tooth in the labial segment, using composite resin or acid-etch composite bonding.

For fixed canine and canine retainer, it is only bonded to the canine teeth and hence often cause a relapse of the incisors; and for the reinforced fiber retainers, they tend to fracture commonly.

To prevent minor unwanted tooth movement, the fixed retainer must be passive. They consist of a passive wire bonded to the lingual-side of the incisors. The patient cannot remove fixed retainers.

Advantages

  • Not visible
  • Patient compliance not required

Disadvantages

  • Can lead to tartar build-up or gingivitis
  • Difficulty of flossing
  • Irritation of the tongue

Maintenance of retainers

During the first few days with any teeth retainer use, extra salivation is natural. This occurs due to stimulation of the salivary glands. Initially, it may be difficult to speak after getting a retainer, but this speech difficulty goes away over time.

While eating always remove your retainers to allow natural chewing of the food. This will also avoid the crushing of the retainers. Do not drink a carbonated drink with retainers.

The teeth retainer can act as a reservoir, especially the Essix retainer. It can coat the surface of the tooth with the carbonated drink, leading to decalcification of teeth.

Store the removable retainers in the retainer case for protection, when not in use. Clean the retainer case and retainer with a disinfectant solution regularly.

Do not grind your teeth hard, as it can cause wear or even breakage of the retainers.

Final words on teeth retainer

People who skip wearing retainers have an orthodontic relapse. Wearing retainers is of utmost importance post orthodontic treatment.

If you had spaces between your teeth or had rotated teeth, consult your dentist for fixed retainers option. Such cases, depending on the severity can also require permanent retention.

Maintain adequate retainer hygiene. If you have fixed retainers, go for regular scaling.

Orthodontic relapse occurs when adequate retention is not provided to the teeth after the finish of the treatment. Our tooth tends to move back to their original position after orthodontic treatment. The dentist thus provides teeth retainer, which is to be worn for a stipulated period.