Space MaintainersDental procedure
Space maintainers are recommended when baby (primary) molar teeth are missing or are lost prematurely, for example if the patient has large, unfixable cavities. The goal of space maintainers is to prevent movement of the adjacent permanent first molars (six-year molars), and loss of space for adult (permanent) bicuspids and canines. If the permanent first molars are not held in their proper position, they can drift forward and prevent the bicuspid teeth from being able to move into the mouth on their normal path. The first bicuspids can also move forward and block the normal pathway of movement of the permanent canines into the mouth. It is not necessary to place a space maintainer if any of the front (anterior) six primary teeth in either jaw is lost prematurely.
A congenital disorder known as hypohydrotic ectodermal dysplasia is accompanied by the absence of several teeth, including permanent teeth. Hypodontia is the dental term for congenitally missing teeth. If all the teeth are missing, the term is anodontia.
When one (or more) back teeth of the primary dentition (baby teeth) is lost prematurely or is congenitally missing, there is a risk of the permanent six-year molars drifting forward in the mouth and blocking the eruption pathway of the (permanent) bicuspids. The first bicuspids can also move forward and block the eruption pathway of the permanent canines.
Space maintainers are prescribed to hold the six-year molars in their normal position, as well as to preserve the normal eruption pathway of the bicuspids and permanent canines.
Use of removable partial dentures as space maintainers is less common in children, but may be prescribed if several teeth are missing and the child’s appearance is affected.
Fixed space maintainers are the most common type of space maintainer. The term “fixed” means the device is “cemented” (glued) into place with dental cement and is not meant to be removable by the patient. This makes them more reliable at effectively achieving their goal. It also means they must be removed by the dentist at some point.
Fixed space maintainers include the “band and loop”, the “lingual holding arch”, the “TransPalatal Arch (TPA)”, and the “distal shoe”, the selection of which depends on the number of missing teeth and their position in the dental arch. These different types are described in more detail below.
TransPalatal Arch (TPA) appliance
This is a type of space maintainer used in the upper jaw when primary molar teeth have been lost prematurely on both sides of the dental arch. TPA appliances are formed from two metal bands joined across the palate with a rigid wire, which is soldered to the bands. Making the device involves fitting the metal bands onto the child’s abutment teeth and making an impression (mold). The bands remain in the impression, which is then filled with dental plaster to produce a cast. The TPA device is made in a laboratory, on the casts of the child’s teeth.
When cemented onto the abutment teeth, TPA appliances can be effective at preventing forward movement of those teeth; however they do not always prevent forward tipping of the abutment teeth, and space can still be lost as a result. This is especially true if the child habitually uses their tongue, a finger, or thumb to place pressure on the TPA wire. Sometimes a small button will be attached to the center wire of the TPA appliance, which rests on the child’s palate to prevent tipping of the abutment teeth to which the device is cemented. The device is then called a Nance appliance.
TPA appliances are typically left in place until permanent teeth move in to the spaces created by the missing teeth.
Distal shoe space maintainers
This type of space maintainer is used when the patient is too young for six-year molars to be present in the mouth yet. A distal shoe is placed on a baby molar, and has a projection that extends through the gums to the front (mesial) surface of the un-erupted six-year molar, correctly guiding its eruption pathway into the mouth.
Band and loop space maintainers
This type of device is used when one or more baby molars are lost from only one side of the dental arch, and the six-year molar is present behind them. They feature a metal band around the six-year molar, with a wire arm soldered to it that rests against the back surface of the next remaining tooth forward.
Lingual holding arch
This type of space maintainer is used when one or more baby molars are lost from both sides of the dental arch, and the six-year molars are present behind them. They feature metal bands around the six-year molars, with a wire bent in the shape of the dental arch soldered to the bands and resting on the inside (lingual) surfaces of the patient’s front teeth (Figure 1).
Other types of space maintainers exist and are commonly used, but are generally variations on these basic themes.
- If the primary molar tooth or teeth is/are already missing, and no loss of space has occurred, the dentist will fit stainless steel bands onto the six-year molar(s) that will anchor the space maintainer.
- An impression of the dental arch will be made with the band(s) in place on the tooth.
- The band(s) will be removed from the teeth and placed in the impression, and a stone cast of the teeth will be poured into the impression.
- When the stone cast hardens, a wire or wires will be positioned onto the casts in such a way that they can prevent the molar(s) from moving. Once in place, the wires will be soldered to the bands.
- The solder joint(s) will be smoothed and polished.
- The space maintainer is carefully removed from the stone cast and disinfected.
- The patient will return to the dentist for cementation of the space maintainer onto the anchoring tooth or teeth. Generally, the material used to glue the bands is a permanent crown cement (luting agent) made of resin, glass ionomer, resin-ionomer, carboxylate, or other dental materials. These generally don’t taste very good. Dental glue is very tough, does not dissolve in mouth moisture, and is generally considered safe for human use.
Advantages and benefits of space maintainers
Some advantages and benefits of space maintainers include:
- Space maintainers prevent undesirable movement of the permanent molar and bicuspid teeth.
- Space maintainers preserve space in the dental arch for the bicuspid and permanent canine teeth to move into.
- Space maintainers preserve the shape of the arc along which the teeth are positioned in the jaw (dental arch).
Disadvantages and risks of space maintainers
Some disadvantages and risks of space maintainers include:
- May be difficult to clean around
- If the patient’s oral hygiene is not good, the gums may become inflamed around the space maintainer. In some cases, the gums may grow around the space maintainer, requiring surgical removal (usually a minor procedure).
- Patients can develop tooth decay (caries) if plaque is not effectively removed from around the device.
- Generally need to be removed by a dentist at a later date
- May loosen or break
- Young patients may have difficulty cooperating with the impressions and cementation procedures necessary to correctly place a space maintainer.
- Sedation may be recommended if the patient is especially young, or has special needs. Sedation of children has its own risks which should be fully understood and carefully considered before undergoing treatment. It may be that “crooked teeth”, poor dental arch form, malocclusion, or any other complications that may result from the premature loss of primary molar teeth can more safely be addressed when the patient becomes older.
- Frequent monitoring and adjustment of certain types of space maintainers (e.g. distal shoe) may be recommended to be sure the device itself is not preventing normal movement of the permanent six-year molar(s) into the mouth.
Other care that may be needed
Space maintainers are placed following the premature loss, or removal (extraction) of a tooth. Tooth removal, if necessary, is generally billed separately, one procedure per each tooth that is removed.
Other treatment options
Removable dentures can be an option if the patient is missing multiple teeth. These may not be recommended for young children, or children with special needs, who may be incapable of understanding the purpose of, limitations of, and care of the dentures.
Traditional fixed bridges may be an option for space maintenance in children whose growth and development is complete, and who are congenitally missing permanent teeth. Resin bonded fixed bridges that don’t significant removal of tooth structure can be an option for space maintenance in mixed-dentition (some permanent and some primary teeth are present) patients, although traditional stainless steel space maintainers like those described on this page are generally more economical.
Dental implants restored with crowns are an option only for patients whose growth and development is complete. For boys, growth and development is generally complete by age 18 to 20. For girls, growth and development may be complete as early as age 16 to 18.
Special implants known as temporary anchorage devices (TADs) are now being used by orthodontists at certain positions in the mouth to direct orthodontic tooth/jaw movement forces, even in patients whose growth and development may not be complete. These are generally not used to replace teeth, however and they are normally removed following orthodontic treatment.
Orthodontic treatment can be successful at regaining lost space, realigning the dental arches, and correcting improper alignment of the upper and lower teeth (malocclusion), whether or not these conditions were caused by premature loss of primary teeth. However, preventing or simplifying the need for orthodontics is one of the goals of space maintainers.
What if I do nothing?
If space is lost for the permanent teeth, orthodontic treatment may become necessary that might otherwise have been avoided. Even in patients who would normally require orthodontic treatment, space maintainers can simplify the orthodontic treatment plan.
Author: Thomas J. Greany, D.D.S.
Editor: Ken Lambrecht
This page was reviewed by members of our review board.
This page was last updated on June 3, 2016.
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