FIXED RETAINERS

used in situations where intra-arch instability is anticipated and

prolonged retention is planned.

major indications

1. Maintenance of lower incisor position during late growth.2. Diastema maintenance.3. Maintenance of pontic or implant space.4. Keeping extraction spaces closed in adults

1. Maintenance of lower incisor position during late growth.Major cause of lower incisor crowding in the late teen years: late growth of the mandible in the normal growth pattern.Relapse into crowding is almost always accompanied by lingual tipping of the central and lateral incisors in response to the pattern of growth.

Fixed lingual bar, attached only to the canines (or to canines and first premolars) and resting passively against the flat lingual surface of the lower incisors above the cingulum.This prevents the incisors from moving lingually and is also reasonably effective in maintaining correction of rotations in the incisor segment.

A bonded canine-to-canine retainer is preferred for two reasons:(1) unless bands were used during the active

treatment, band space can be a problem(2) the labial part of a band tends to trap plaque

against the cervical part of the labial surface, predisposing this area to decalcification, and is also unsightly.

Fixed canine-to-canine retainers must be made from a wire heavy enough to resist distortion over the rather long span between these teeth. Usually 30 mil steel is used for this purpose with the end of the wire sandblasted to improve retention when it is bonded to the canines.

It is also possible to bond a fixed lingual retainer to one or more of the incisor teeth.major indication for this variation is a tooth that had been severely rotated teeth but it should not be held rigidly during retention that’s why a more flexible wire should be used.

A good choice for a fixed retainer with adjacent teeth bonded is a braided steel archwire of 17.5 mil diameter

2. Diastema maintenanceIndication: teeth must be permanently or semipermanently bonded together to maintain the closure of a space between them.The best retainer for this purpose is a bonded section of flexible wire.The object of the retainer is to hold the teeth together while allowing them some ability to move independently during function, hence the importance of a flexible wire.

3. Maintenance of pontic or implant space.Using a fixed retainer for a few months reduces mobility of the teeth and often makes it easier to place the fixed bridge that will serve, among other functions, as a permanent orthodontic retainer.Implants should be placed as soon as possible after the orthodontics is completed, so that integration of the implant can occur simultaneously with the initial stages of retention.

The preferred orthodontic retainer for maintaining space for posterior restorations is a heavy intra-coronal wire, bonded in shallow preparations in the future abut ment teeth

Anterior spacesfixed retainer in the form of a simple acid-etch bridge, such as a replacement tooth held by twist wires bonded to adjacent teeth which decreases the chance of soft tissue inflammation and provides better stability.

4. Keeping extraction spaces closed in adultsThe major objection to any fixed retainer is that it makes interproximal hygiene procedures more difficult.

ACTIVE RETAINERSUsed when relapse or growth changes after orthodontic treatment will lead to a need for some tooth movement during retention.accomplished with a removable appliance that continues as a retainer after it has repositioned the teeth, hence the name.Specifications:• realignment of irregular incisors.• functional appliances to manage Class II or

Class III relapse tendencies.

• Realignment of Irregular Incisors: Spring RetainersIf late crowding has developed, must reduce the interproximal width of lower incisors before realigning them, so that the crowns do not tip labially into an obviously unstable position.Cause:late mandibular growth.Stripping:• reduce the mesiodistal width of the incisors• Decrease the amount of space required for their alignment• flattens the contact areas• increases the inherent stability of the arch in this region.

As with any procedure involving the modification of teeth, however, stripping must be done cautiously and judiciously. It is not indicated as a routine procedure.

Interproximal enamel can be removed with either:• abrasive strips • thin discs in a handpiece.

width of each lower incisor can be reduced up to 0.5 mm on each side without going through the interproximal enamel.

If irregularity is modest and if the teeth are to be realigned without moving facially, a canine-to-canine clipon is usually the active retainer used to realign crowded incisors. steps:(1) reduce the interproximal width of the incisors and apply topical fluoride to the newly exposed enamel surfaces(2) prepare a laboratory model, on which the teeth can be reset into alignment(3) fabricate a canine-to-canine clip-on appliance

modest degree of relapse: fixed appliance for comprehensive retreatment must be considered. With bonded brackets on the lower arch from premolar to premolar, superelastic NiTi wires can be used to bring the incisors back into alignment quite. If the incisors are advanced toward the lip when this is done, a bonded lingual retainer should be placed before the brackets are removed. Permanent retention obviously will be required after the realignment.

Correction of Occlusal Discrepancies: Modified Functional Appliances as Active Retainersconsists of maxillary and mandibular retainers joined by an interocclusal bite block. the description does illustrate the potential of an activator to simultaneously maintain the position of teeth within the arches while altering, at least minimally, the occlusal relationships.

Pure retainer =object is to control growth, and tooth movement is largely an undesirable side effectactivator as an active retainer = move teeth and no significant skeletal change is expected.If more than 3 mm of occlusal correction is sought, and over this distance, tooth movement as a means of correction is a possibility. The correction is achieved by restraining the eruption of maxillary teeth posteriorly and directing the erupting mandibular teeth anteriorly.

Any of the family of modified activators designed to produce tooth movement is most useful in this active retention mode, not in early mixed dentition treatment where tooth movement for the most part is undesirable. On the other hand, the more flexible a removable appliance becomes, the less suited it is for the retention part of active retention and the more likely it would be to require replacement with another type of retainer when the occlusal relationship had been reestablished. An activator or bionator with an acrylic framework that contacts most teeth therefore is usually the best compromise when this type of active retention is needed. The appliance is made like any other functional appliance, with a slight advancement of the mandible into the correct occlusal relationship. In contrast to a functional appliance that would be placed as a retainer immediately upon completion of active treatment, some freedom of eruption for posterior teeth normally would be provided.