FIXED OR REMOVABLE APPLIANCE?
Many tooth movements can be treated with either. To help you decide which approach is best suited for your patient, SML has created the following criteria checklists:
Fixed when…
- Bodily movement of teeth is required.
- Anterior bands, brackets, and wires are acceptable to the patient.
- The teeth to be banded have the clinical crown fully exposed.
- The patient has excellent oral hygiene, minimizing the possibility of decay.
- Likelihood of patient wearing a removable appliance is doubtful.
Removable when…
- Bodily movement of teeth is not required. Removable appliances mainly provide a tipping action.
- Esthetics are important. The patient needs an inconspicuous appliance.
- Enough teeth are present and sufficiently erupted for appliance anchorage.
- The patient requires an appliance that does not interfere with proper oral hygiene.
- The patient is cooperative and responsible, i.e. they will wear an appliance as prescribed and will guard against loss or breakage.
- There are economic considerations. Removable appliances require less chair time.
Featured Appliances
Adams Clasp
The Adams Clasp can be used on both molars and bicuspids for removable orthodontic dental appliances.
It gains its retention by engaging the mesial and distal undercuts of these teeth. Therefore, it is essential that the tooth being clasped be sufficiently erupted so that the mesial and distal undercuts are fully exposed.
Ideal for any removable orthodontic appliances – Hawley’s, Schwarz’s, Sagittal’s, Twin Blocks,
Another consideration when using this clasp is to place it only where it will not create an occlusal interference. An occlusal interference can cause a functional shift of the patient’s mandible.
Posterior Occlusal Coverage
Posterior occlusal bite planes are mainly used to open the vertical dimension on orthodontic dental appliances sufficiently to correct crossbites.
When jumping an anterior crossbite, posterior coverage will prevent the eruption of the posterior segments controlling the development of an open bite.
During the correction of a posterior crossbite, posterior coverage will allow the upper arch to be developed without dragging the lower arch along with it. By intercuspating one side, an anchorage unit can be set up that facilitates a unilateral crossbite correction.
Recurved Springs
Recurved springs are designed to move an individual tooth in a labial or buccal direction.
However, by altering the length and direction of the open end, it can also be used to help rotate the tooth. These springs can be made with or without helical coils. Note – To prevent the activated spring from riding up the cingulum, a composite ledge is commonly placed on the lingual aspect of the tooth.
Springs are ideal for single or multiple tooth rotations in the anterior segment – and cross bites.
Rapid Palatal Expander
Rapid Palatal Expander (RPE) screws were designed to be used for rapid expansion and separation of the mid-palatal suture, for early orthodontic treatment. To be effective, they must always be used in a fixed approach, either banded or bonded.
These screws are available in a variety of sizes and configurations, offering a large range in the amount of lateral expansion that can be accomplished. Although designed for rapid palatal expansion, these screws are frequently used as part of a fixed bracket Straight wire technique that applies gentle forces for slow development.
Standard Hawley Labial
The most common arch wire design is shown here. The labial bow will generally embrace the six anterior teeth and join the acrylic between the canine and the first premolar.
However, the labial portion may be restricted to any part of the anterior region, or extended as far distally as the first molar.
“C” Clasp
“C” Clasps are most commonly used where the use of another type of clasp would create a significant occlusal interference. Eliminating an unwanted occlusal interference is important for two reasons.
In children, an occlusal interference can cause them to abnormally shift their mandible. In adults, these interferences usually lead to poor compliance as biting on the clasps is very uncomfortable.
To make this clasp more retentive, it is usually used in conjunction with a composite buccal button. This composite undercut will allow the clasp to snap into position.
Delta Clasp
The Delta Clasp is a derivation of the Adams Clasp. Its name comes from the shape of its retentive portion.
It is commonly used with the Clark Twin-Block because, with this appliance, occlusal interferences are not an issue and an extremely retentive clasp is needed.
Like the Adams Clasp, the tooth to be clasped must be erupted enough to expose the buccal undercuts.
Ball Clasp
Ball clasps are typically used as auxiliary retention in conjunction with other clasps. They are usually placed tightly into the interproximal embrasure between two posterior teeth.
This is usually sufficient to create the retention needed, however it can also be adjusted mesially or distally to engage the undercut of either tooth. This is particularly useful during the exfoliation stage of the mixed dentition. When one primary molar is lost, a simple adjustment will allow you to regain the retention needed to continue on with treatment.
Finger Clasp
Finger clasps are typically used as auxiliary retention in conjunction with other clasps in the primary and mixed dentition when 6-year molars are not sufficiently erupted to be clasped.
The clasps are usually placed tightly between two posterior teeth and locked into the mesial or distal buccal undercut of one of them. Because the end of the wire is left sharp to increase retention, some patients complain that the clasp causes their tissue to become irritated.
This clasp is also particularly useful during the exfoliation stage of the mixed dentition. When one primary molar is lost, a simple adjustment towards the undercut of the remaining tooth will allow you to regain the retention needed to continue on with treatment.
Buccal Bond “C” Clasp
When a buccal undercut needs to be created for retention of a clasp, dental composite can be easily bonded to the tooth.
This composite ledge is usually placed after the appliance is fabricated. However, if you prefer, you can place the appropriate composite ledge(s) prior to taking the impression for appliance fabrication.
Crozat Clasp
Crozat clasps are typically used on first permanent molars as part of a Crozat appliance. They consist of three parts.
The main body of the clasp, called the crib, is formed from one piece of wire and is tightly adapted around the entire tooth. The second wire, called the crescent, provides the retention by engaging the undercuts of the proximal surfaces.
The third part of the clasp is the occlusal rest. It passes through the lingual groove and rests tightly on the occlusal surface.
Round Contoured
A Round Contoured arch wire is bent to closely fit against the labial surface of the anteriors.
It is used to securely hold the teeth in their final position after active treatment is completed.
Acrylic Arch Wires
This design gains superior anterior retention through the use of clear acrylic that tightly conforms to the labial and interproximal surfaces of the incisors. This prevents any movement of these teeth.
It is often used on “wrap-around” labial wires because the intimate contact it creates stabilizes this long wire.
Reverse Hawley
The Reverse Hawley labial wire is fabricated with the adjustment loop running from the mesial to the distal of the cuspid.
This design is chosen when you do not want any wire in the embrasure distal to the cuspids. A typical scenario requiring this design is when positive cuspid control is needed, particularly if the cuspid has been rotated significantly during orthodontic therapy.
Ricketts Arch Wire
The Ricketts Arch, like the Reverse Hawley, crosses the dentition through the embrasures interproximal to the laterals and cuspids.
The “Omega” loops are placed on the laterals and the distal recurved arms are contoured to the cuspids. These distal recurves can be used to affect minor lingual rotation of the cuspids, unilaterally or bilaterally.
Witzig Double Loop
This labial arch wire is a modification of the Ricketts arch wire using a narrow vertical loop.
This design is excellent for final stability of the anterior segment but only allows for very minor adjustments during retention. It is typically used only as part of a removable final retainer when orthodontic therapy is complete.
Wrap-Around
The Wrap-Around labial is excellent for final retention.
It is usually soldered to the buccal bar of the Adams clasp or to “C” clasps. Retention wires are usually placed between the laterals and cuspids to help stabilize the long labial. Wrapping around in this manner eliminates the possibility of occlusal interferences or opening interproximal contacts.
Lap Springs
Lap springs provide a gentle sweeping action against the lingual aspect of the upper and lower anteriors. These springs are most often used in conjunction with lateral developing appliances.
Once there is enough space for the teeth, the lap springs can provide enough force to move them into alignment. A labial bow that has been pre-bent into the ideal arch form is usually used to prevent these springs from moving the anteriors too far labially.
Direct Pressure Springs
Direct Pressure Springs are soldered to the labial arch wire and can provide a direct lingual movement, a rotation force, or an occlusal force depending upon their placement and adjustment.
Three different design modifications are shown here.
Lingual Mushroom Spring
Lingual Mushroom springs are used to upright any single lower posterior tooth with the exception of the distal-most tooth in the arch.
They are often preferred over a micro-screw or mini-screw, because they are less bulky and less likely to irritate the patient’s tongue.
Distal Recurved Spring
A Distal Recurved Spring is used to upright a lingually tipped molar. This spring is easy to adjust and can effectively upright a molar with only a few adjustments.
Placing a rest aids in controlling any super-eruption of the molar as it is being uprighted.
Apron Spring Labial
The Apron Spring is an active labial arch wire that is primarily used to retract severely flared anteriors.
It features two spring coils for light, continuous lingual movement and is easily activated with finger pressure.
Incline Plane
An anterior incline plane is usually added to the acrylic when one wants to actively guide and maintain the mandible in a forward postured position.
It is typically used when a minor skeletal correction is needed or as part of a support phase appliance during Class II treatment.
Anterior Bite Plane
Thickening the lingual acrylic behind the upper anteriors creates an anterior bite plane.
This bite plane can open the vertical dimension by allowing the posterior teeth to erupt, provide clearance to correct teeth in a locked lingual crossbite, take pressure off of the anteriors in severely closed bite cases and clear the occlusion sufficiently to allow for the placement of brackets on the lower anteriors.
Occlusal Rest
Occlusal Rests can be added to stabilize the arch wire when several edentulous areas are present.
The Occlusal Rest can be covered with bonding material, to maximize retention of the entire appliance.