Orthodontic Retention Appliances: Removable and Fixed Retainers
1. No Retainers
2. Removable Retainers
3. Fixed Retainers
In some cases the occlusion provides retention and helps prevent relapse. The best known example of this is the correction of a labial crossbite so long as adequate overbite is present
There are 3 main types all consisting of a combination of acrylic baseplate and wire framework
• Hawley Retainer
• Begg Retainer
• Barrer Retainer
This is the most commonly used removable retainer by Orthodontists as it has proved to be robust and effective. It can be used in the upper and lower arches and consists of Adams cribs on the permanent 1st molars and a labial bow with U loops at their distal end. There are some variables in the design such as a flat anterior bite plane to open up the bite allowing over-eruption of the posterior teeth thus reducing an overbite. Another example is an acrylated labial bow aiding control of rotations.
Begg Retainer (‘Wrap around’ retainer)
This retainer differs from the Hawley in that it has no clasps thus reducing the amount of wire crossing between contact points and maximising the potential for the occlusion to settle during the retention period. The main problem comes when you use it for the lower arch as the length of the wire is considerable and more likely to deform
Barrer Retainer (‘Spring’ retainer)
This retainer type is good at not only providing retention but additionally can restore alignment of the lower labial segment if it has already begun to relapse and so has an ‘active’ component. Normally the appliance consists of S/S wire contoured around the labial and lingual tooth surfaces with vertical loops lying distal to the canines. Acrylic flanges help to improve retention of the appliance. If it is being use to aid correction of a relapsing lower labial segment, interproximal stripping is necessary to achieve correct alignment.
Other removable retainer types include-
• Vacuum Formed Retainers (VFR’s)
This form of retention is used when the occlusion is considered to be unstable and extremely likely to relapse following active orthodontic treatment. They may also be used to prevent ‘late lower incisor crowding.
The most obvious advantage of fixed over removable is the elimination of patient compliance. They are mainly used for the lower arch with a removable retainer still the preferred option for the upper arch. Flexible multistrand wire is bonded to the lingual/palatal surfaces of teeth with composite. They still allow teeth to move independently to each other in response to occlusal force whilst still maintaining correct alignment. They are produced either directly (at chair side) or indirectly (in the lab) and then positioned with a locating device.
The main disadvantage of this appliance is that it can be difficult to clean around and they prevent flossing so if the patient has poor oral hygiene, caries and periodontal disease can ensue.
The main indications for choosing this appliance over removable are
- Severe rotations
- Maintain lower incisor proclination
- To combine periodontal and orthodontic treatment (i.e. splinting)
- Diastemas, generalised spacing, adult space closure
- Severely displaced palatal canines following realignment
- Non-surgically treated anterior open bit cases