Space Maintainers: a complete clinical guide

Introduction

In pediatric dentistry, managing the space in a child’s mouth following the premature loss of a primary tooth is critical for ensuring proper dental development. Space maintainers are specialized dental appliances used to prevent adjacent teeth from shifting into the gap left by a missing tooth, which can lead to malocclusion and other orthodontic problems. This article will delve into the types, indications, and clinical considerations associated with space maintainers, providing valuable insights for dentists.

Importance of Space Maintenance

Premature loss of primary teeth, whether due to trauma, caries, or extraction, can disrupt the normal eruption sequence of permanent teeth. The adjacent teeth may drift into the space, leading to crowding, misalignment, and improper occlusion. These issues can complicate future orthodontic treatment and potentially impact the child's oral health and function. Space maintainers play a pivotal role in preserving the arch length and preventing these adverse effects.

Types of Space Maintainers

The types of space maintainers can be broadly categorized into fixed, removable, and functional types.

1. Fixed Space Maintainers

Fixed space maintainers are cemented onto the teeth and remain in place until the permanent tooth erupts. They are generally more reliable because they don't require patient compliance for effectiveness.

Band and Loop Space Maintainer:
- Design: This is one of the most commonly used fixed space maintainers. It consists of a stainless steel band that is cemented onto an adjacent tooth, with a loop of wire or metal extending across the space to maintain it.
- Indications: Ideal for maintaining space when a single primary tooth is lost, especially in the posterior region.
Distal Shoe Space Maintainer:
- Design: This device includes a metal extension that is inserted subgingivally, following the path of the unerupted first permanent molar.
- Indications: Used when the primary second molar is lost before the eruption of the first permanent molar. It guides the eruption of the permanent molar into the proper position.
Lingual Holding Arch:
- Design: This appliance is used in the mandibular arch and consists of a metal bar that runs along the lingual side of the lower teeth, connecting to bands on the molars.
- Indications: Suitable for maintaining space when multiple primary teeth are missing in the lower arch. It prevents the molars from shifting forward.
Transpalatal Arch (TPA):
- Design: Similar to the lingual holding arch but used in the maxillary arch, this appliance has a metal bar that runs across the palate, connecting the upper molars.
- Indications: Maintains the width of the maxillary arch and prevents the molars from moving mesially.
Nance Appliance:
Nance Appliance
- Design: This appliance uses an acrylic button that rests on the palate, connected to the molars with metal bands and wires.
- Indications: Used in the maxillary arch to prevent the molars from drifting forward after the premature loss of multiple teeth.

2. Removable Space Maintainers

Removable space maintainers are not permanently fixed in the mouth and can be taken out by the patient, which can be beneficial for cleaning. However, they require patient compliance to be effective.

Acrylic Partial Denture:
- Design: Resembling a traditional denture, this appliance consists of acrylic material with clasps that hold onto the remaining teeth.
- Indications: Used to maintain space and replace missing primary teeth, particularly in older children with mixed dentition.
Hawley Retainer:
- Design: A versatile orthodontic appliance that can be modified to include a space-maintaining function, with an acrylic baseplate and wire clasps.
- Indications: Suitable for maintaining space in both the maxillary and mandibular arches, often used when several teeth are missing or after orthodontic treatment.

3. Functional Space Maintainers

Functional space maintainers not only preserve space but also guide the eruption of permanent teeth or modify jaw growth.

Frankel Functional Regulator (FR):
- Design: A bulky appliance that not only maintains space but also encourages proper jaw development and alignment by guiding the eruption of teeth.
- Indications: Used in cases where space maintenance is needed along with functional orthopedic correction, often in the early mixed dentition phase.

Indications for Space Maintainers

Dentists should consider space maintainers in the following scenarios:

1. Premature Loss of Primary Teeth

Primary Molars: The premature loss of primary molars is one of the most common indications for space maintainers. These teeth play a critical role in maintaining the integrity of the dental arch and guiding the eruption of permanent teeth. Without a space maintainer, adjacent teeth may drift into the space, leading to crowding or misalignment of the permanent teeth.
Primary Incisors: While less critical than molars, the loss of primary incisors can also warrant the use of a space maintainer, especially in cases where esthetics or speech development is a concern.

2. Prevention of Malocclusion

Crowding: If a primary tooth is lost prematurely and the space is not maintained, the adjacent teeth can drift into the gap, reducing the available space for the permanent tooth to erupt. This can lead to crowding, which might necessitate future orthodontic treatment.
Crossbite or Open Bite: The loss of primary teeth can also contribute to the development of malocclusions like crossbite or open bite, particularly if the loss occurs early in the dental development phase.

3. Delayed Eruption of Permanent Teeth

Prolonged Space Maintenance: In cases where the eruption of permanent teeth is delayed (due to genetic factors, local pathology, or trauma), maintaining the space with a space maintainer is crucial. This ensures that the permanent teeth have sufficient room to erupt properly once they are ready.
Ectopic Eruption: When a permanent tooth is erupting out of its normal position, the adjacent teeth may shift, compromising space. Space maintainers help to guide the erupting tooth into the correct position.

4. Bilateral Loss of Primary Teeth

Multiple Teeth in the Same Arch: When multiple primary teeth are lost prematurely, particularly in the same arch, there is a significant risk of the dental arch collapsing, leading to severe crowding or spacing issues. Space maintainers are often indicated in these cases to preserve the arch length and width.

5. Maintenance of Arch Integrity

Arch Length and Width: The loss of primary teeth can lead to a reduction in arch length or width, which can have long-term implications for occlusion and jaw development. Space maintainers help in preserving the natural dimensions of the dental arch, ensuring proper alignment and occlusion of the permanent teeth.

6. Guiding the Eruption of Permanent Teeth

Distal Shoe Appliance: Specifically indicated when a primary second molar is lost before the eruption of the first permanent molar, a distal shoe appliance guides the eruption of the permanent molar, ensuring it erupts in the correct position.
Functional Guidance: Some space maintainers also serve a dual function by guiding not just the eruption but also the alignment of the erupting permanent teeth, thereby reducing the need for more complex orthodontic treatments later.

7. Management of Congenital Absence of Teeth

Agenesis of Permanent Teeth: In cases where a permanent tooth is congenitally missing, space maintainers can be used to hold the space until a decision is made about a more permanent solution, such as dental implants or bridges.

8. Post-Extraction in Pediatric Patients

Following Extraction Due to Caries or Trauma: When a primary tooth is extracted due to severe caries or trauma, the adjacent teeth are at risk of shifting into the extraction space. A space maintainer can prevent this unwanted movement, preserving space for the future eruption of the permanent tooth.

How Space Maintainers Are Made?

Creating a space maintainer involves a precise process that ensures the appliance fits well and functions effectively to maintain the space for the developing permanent teeth. Here’s a step-by-step guide on how space maintainers are made:

1. Initial Assessment and Diagnosis

Patient Evaluation: The process begins with a thorough clinical examination of the patient. The dentist assesses the number of missing teeth, the condition of the adjacent teeth, and the overall oral health of the patient. Radiographs are often taken to evaluate the underlying permanent teeth and their stage of development.
Treatment Planning: Based on the evaluation, the dentist determines the type of space maintainer needed (e.g., band and loop, lingual holding arch, distal shoe). The decision considers factors like the patient’s age, oral hygiene, and the expected eruption timeline of the permanent teeth.

2. Impression Taking

Dental Impressions: An accurate impression of the patient’s dental arch is taken using dental impression material (usually alginate). This impression captures the details of the teeth and gums, which is essential for fabricating a well-fitting appliance.
Bite Registration: In some cases, a bite registration may be taken to capture the patient’s occlusion (how the upper and lower teeth come together). This helps in ensuring the space maintainer does not interfere with the patient’s bite.

3. Model Creation

Pouring the Model: The impression is used to create a plaster or stone model of the patient’s teeth. This model serves as a replica of the patient’s dental arch and is used to fabricate the space maintainer.
Trimming the Model: Once the plaster or stone has set, the model is trimmed and refined to remove any excess material and to ensure accuracy in the details.

4. Appliance Fabrication

Design and Planning: The dentist or a dental technician designs the space maintainer on the model. The design depends on the type of space maintainer. For example, a band and loop space maintainer involves creating a metal band that fits around the tooth and a loop that spans the missing tooth's space.
Band Fitting: For fixed appliances like the band and loop or lingual holding arch, a stainless steel band is selected and fitted around the abutment tooth (the tooth adjacent to the space). The band is carefully shaped and adjusted to ensure a snug fit.
Wire Bending and Soldering: The loop or arch wire is bent from stainless steel wire to the appropriate shape and length. It is then soldered to the band in the case of a band and loop maintainer. For more complex appliances like the Nance appliance or lingual holding arch, additional components like acrylic buttons or palatal bars are fabricated and attached.
Acrylic Work: In cases where the space maintainer includes acrylic components (e.g., Nance appliance), the acrylic is carefully molded and cured to ensure durability and comfort.

5. Fitting and Adjustment

Initial Fitting: The fabricated space maintainer is then tried in the patient’s mouth. The dentist checks for proper fit, making sure that the appliance is secure and does not cause discomfort or interfere with the bite.
Adjustments: Minor adjustments may be made to ensure the appliance fits perfectly. This might involve reshaping the bands, trimming any excess acrylic, or adjusting the wires for optimal comfort and function.

6. Cementation (for Fixed Appliances)

Cementation: Once the fit is confirmed, the fixed space maintainer is cemented in place using dental cement. The cement is carefully applied to the band, and the appliance is seated onto the tooth. The dentist ensures that the appliance is stable and securely bonded to the tooth.
Final Checks: After cementation, the dentist checks for any residual cement around the bands and removes it. The patient is asked to bite down to confirm that the appliance does not interfere with their occlusion.

7. Patient Education and Follow-Up

Oral Hygiene Instructions: The patient and their caregivers are educated on how to care for the space maintainer, including maintaining good oral hygiene around the appliance to prevent plaque buildup and caries.
Follow-Up Schedule: Regular follow-up appointments are scheduled to monitor the space maintainer, check for any issues, and ensure that the underlying permanent tooth is erupting properly.

Clinical Considerations for Space Maintainers

When deciding to use a space maintainer, several clinical considerations must be taken into account to ensure the appliance’s effectiveness and the patient’s comfort. Proper planning, placement, and follow-up are crucial to achieving the desired outcomes and preventing complications. Here are the key clinical considerations for space maintainers:

1. Timing of Placement

Early Intervention: The timing of space maintainer placement is critical. Ideally, the space maintainer should be placed as soon as possible after the loss of a primary tooth to prevent adjacent teeth from drifting into the space. Delaying placement can lead to space loss, complicating future treatment.
Eruption Timing: The dentist should consider the timing of the eruption of the permanent tooth. In some cases, it may be appropriate to cancel placement if the permanent tooth is expected to erupt soon and is unlikely to be compromised by the temporary loss of space.

2. Type of Space Maintainer

Fixed vs. Removable: The choice between fixed and removable space maintainers depends on the specific case, including the number of missing teeth, the patient’s age, and their ability to comply with oral hygiene instructions. Fixed maintainers are generally preferred for younger children or when long-term maintenance is required, as they do not rely on patient compliance.
Single vs. Multiple Teeth Loss: The type of space maintainer should be selected based on whether one or multiple teeth are missing. For example, a band and loop appliance might be suitable for a single missing tooth, whereas a lingual holding arch may be needed for multiple missing teeth.

3. Patient Compliance and Oral Hygiene

Oral Hygiene Maintenance: Patients and caregivers must be educated about the importance of maintaining oral hygiene with a space maintainer in place. Poor oral hygiene can lead to plaque accumulation, caries, and periodontal issues around the appliance, especially with fixed space maintainers.
Patient Education: Educating the patient and caregivers on the purpose of the space maintainer, how to care for it, and the importance of follow-up appointments is essential for successful outcomes.

4. Fit and Comfort

Customization and Fit: The space maintainer must be custom-fitted to the patient’s mouth to ensure comfort and effectiveness. A poorly fitted space maintainer can cause discomfort, irritation, or even damage to the surrounding tissues.
Adjustability: The dentist should consider the need for adjustments as the patient’s mouth grows and changes. Removable space maintainers offer more flexibility for adjustments, while fixed space maintainers may require professional intervention for modifications.

5. Monitoring and Follow-Up

Regular Check-Ups: Ongoing monitoring is critical to ensure the space maintainer is functioning correctly and to check for any potential complications, such as shifting teeth, appliance loosening, or tissue irritation.
Assessment of Eruption: The eruption of the permanent tooth should be regularly assessed to determine when the space maintainer can be removed. Over-retention of a space maintainer can interfere with the eruption of the permanent tooth.

6. Potential Complications

Appliance Dislodgement: Fixed space maintainers may become loose or dislodged, which can lead to swallowing or aspiration risks. Regular follow-ups help detect and address this issue promptly.
Tissue Irritation or Overgrowth: The space maintainer, particularly fixed types, can irritate the surrounding gum tissue. In some cases, the gum tissue may grow over the appliance, leading to discomfort and the potential need for surgical intervention.
Caries Development: The bands or wires of fixed space maintainers can trap food particles and plaque, increasing the risk of caries. Meticulous oral hygiene and regular dental cleanings are essential to mitigate this risk.

7. Long-Term Impact

Impact on Permanent Teeth: The long-term impact of the space maintainer on the eruption and alignment of the permanent teeth should be considered. The appliance should be designed to not only maintain space but also facilitate the correct positioning of the incoming permanent teeth.
Consideration of Future Orthodontic Treatment: If future orthodontic treatment is anticipated, the type and design of the space maintainer should be selected with this in mind, as certain appliances can influence the development of the dental arch and jaw structure.

8. Cost and Durability

Material Choice: The material used for the space maintainer should balance durability with comfort. Stainless steel is commonly used for its strength and resistance to corrosion, but acrylic components might be added for comfort in removable appliances.
Cost Considerations: While cost should not compromise care, the choice of space maintainer should consider the financial implications for the patient’s family, including potential replacement costs if the appliance is lost or damaged.

Potential Complications

While space maintainers are effective tools for preserving dental arch space and preventing malocclusion following the premature loss of primary teeth, they are not without potential complications. Understanding these complications helps in preventing them and managing issues promptly if they arise. Here are some of the most common complications associated with space maintainers:

1. Discomfort and Soft Tissue Irritation

Gingival Irritation: Ill-fitting space maintainers, particularly fixed ones, can cause irritation or ulceration of the gingival tissues. The metal bands or wires may rub against the soft tissues, leading to discomfort, pain, or inflammation.
Tissue Overgrowth: In some cases, the gum tissue may overgrow around the appliance, particularly in cases where the space maintainer is left in place for an extended period. This can complicate removal and may require surgical intervention to correct.

2. Caries Development

Plaque Accumulation: Fixed space maintainers, especially those with metal bands, can create areas that are difficult to clean. Plaque accumulation around the bands or wires can increase the risk of caries, particularly on the abutment teeth. This is a common complication if oral hygiene is not meticulously maintained.
Decalcification: The areas around the bands can also be prone to decalcification, leading to white spot lesions, which are early signs of enamel demineralization and caries.

3. Appliance Dislodgement or Loss

Loose Appliances: Space maintainers can become loose due to poor bonding, failure of the cement, or gradual loosening over time. A loose space maintainer can become a choking hazard if it dislodges completely, especially in young children. It may also fail to maintain the necessary space effectively.
Swallowing or Aspiration: In rare cases, a dislodged space maintainer can be swallowed or aspirated, leading to more serious complications requiring immediate medical attention.

4. Unintended Tooth Movement

Uncontrolled Tooth Drift: If a space maintainer is improperly designed or placed, it may not prevent unwanted tooth movement effectively. Adjacent teeth might still drift into the space, leading to crowding, midline shifts, or other alignment issues.
Altered Eruption Path: In some cases, space maintainers, particularly distal shoe appliances, can inadvertently alter the eruption path of the underlying permanent tooth if not properly positioned, leading to an impacted or misaligned tooth.

5. Interference with Permanent Tooth Eruption

Delayed or Blocked Eruption: If a space maintainer is left in place for too long, it can impede the eruption of the underlying permanent tooth. This can result in delayed eruption or the tooth erupting in an incorrect position.
Impacted Teeth: Poorly positioned appliances can also cause impaction of the permanent teeth, particularly if the appliance interferes with the normal eruption pathway.

6. Allergic Reactions

Metal Sensitivity: Some children may have an allergic reaction to the materials used in space maintainers, particularly the nickel present in stainless steel. Symptoms may include redness, swelling, and itching in the areas where the metal is in contact with the tissue.

7. Breakage of the Appliance

Fracture of Components: Removable space maintainers, particularly those made with acrylic, can fracture if dropped or subjected to excessive force. Similarly, wires or bands in fixed appliances can break, rendering the space maintainer ineffective.
Replacement Costs: Frequent breakage of removable appliances can lead to increased costs for replacement, which can be a concern for patients and caregivers.

8. Oral Hygiene Challenges

Difficulty Cleaning: Fixed space maintainers can create challenges for maintaining good oral hygiene. Food particles and plaque can easily accumulate around the appliance, particularly around the bands and wires, leading to gingival inflammation and decay.
Compliance Issues: Removable space maintainers require patient compliance, and younger children may not consistently wear the appliance or may remove it during meals, leading to inconsistent space maintenance and increased risk of complications.

9. Psychosocial Impact

Aesthetic Concerns: Some children may be self-conscious about wearing a space maintainer, particularly if it is visible when they smile or speak. This can lead to reluctance to wear the appliance, especially with removable space maintainers.
Speech and Eating Difficulties: Initially, space maintainers can cause difficulties with speech or eating, which can be distressing for the child. While most children adapt over time, these issues can contribute to non-compliance with removable appliances.

Conclusion

Space maintainers are a vital tool in pediatric dentistry, playing a significant role in preventing malocclusion and ensuring the proper development of a child's dentition. By understanding the types, indications, and clinical considerations, dentists can effectively use these appliances to safeguard their young patients' oral health. Regular monitoring and patient education are key to the successful long-term use of space maintainers, ensuring optimal outcomes for developing smiles.

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