Retention in Orthodontics. Retention Appliances: Fixed and Removable Retainers

Retention is an essential phase in orthodontic treatment, defined as the preservation of the optimal aesthetic and functional position of the teeth after the active phase of orthodontic treatment has been completed. The reorganization of periodontal tissues requires time, typically at least one year, according to various sources. Given the inherent mobility of teeth following treatment, stabilization is essential until the periodontal ligament adapts to the new alignment.

Retainers are devices used for stabilization and are designed to maintain the achieved treatment outcomes until complete morphological and functional adaptation occurs, preventing orthodontic relapse. Their necessity arises from the fact that the histological remodeling of bone tissue progresses much more slowly than the functional and morphological adaptations achieved during active orthodontic treatment.

To be effective, retention appliances must stabilize teeth or jaws in their corrected positions, minimize interference with oral functions, and offer high aesthetic appeal while exerting no additional force on the dentoalveolar system.

In the long term, patient satisfaction is more closely linked to the stability of orthodontic results, irrespective of the initial or final condition of the bite. Changes in the dental system following orthodontic treatment for crowded teeth should be viewed as a process of forming an adaptive-compensatory balance. An important factor that increases the relevance of optimizing orthodontic treatment is the high risk of relapse after orthodontic correction. Therefore, defining prognostic criteria for the stability of orthodontic results is one of the key objectives.

Early intervention in orthodontics is the key to shorter treatment duration, reduced retention needs, and long-term stability. Through myofunctional therapy and functional appliances, we can guide natural jaw development, eliminate harmful oral habits, and reduce the likelihood of relapse – sometimes making long-term retention unnecessary. We invite you to join the First Online Congress on Myofunctional Orthodontics and Functional Jaw Orthopedics! This groundbreaking course brings together top specialists in pediatric orthodontics, functional dentistry, and otorhinolaryngology to share evidence-based approaches for diagnosing and treating malocclusion, jaw growth anomalies, airway dysfunction, posture disorders, sleep apnea, and TMJ dysfunctions.

Classification of Retention Appliances

Retention appliances play a crucial role in maintaining the results of orthodontic treatment until full morphological and functional adaptation occurs, effectively preventing relapse. 

With a wide variety of retention devices available, orthodontists must carefully select the most suitable type for each patient. 

Retention appliances are categorized based on their fixation type and placement location:

✔ By fixation type:

• Removable retainers
• Fixed retainers

✔ By placement location:

• Single-arch retainers
• Dual-arch retainers

Types of Retention Appliances

1. Removable Retainers – Common options include acrylic baseplates with labial bows wires extending beyond molars – Hawley retainers and their modifications. These can be customized with incorporating springs for enhanced stability. Functional appliances such as activators, bionators, stamped splints, trainers, and OSAMU retainers also serve as effective retention tools, but patient compliance is essential.

Among aesthetic removable retainers, the vacuum framed retainers (e.g. OSAMU retainer) stand out, functioning similarly to a positioner but covering only one dental arch. They consist of two layers: a soft, elastic inner layer that securely stabilizes teeth while ensuring ease of placement and removal.

          2. Fixed Retainers – Preferred for their reliability, these are thick wires bonded to the lingual or palatal teeth surfaces using composite material. Fiber-reinforced splints like Fiber Splint or Ribbond can also be used for added stability. While fixed retainers offer superior retention, they may complicate oral hygiene due to difficulty in flossing and an increased risk of periodontal complications.

Removable retainers allow patients to maintain proper oral hygiene more easily and are usually worn only at night. A fixed retainer, sometimes combined with a removable one, is used when it is necessary to minimize the risk of relapse.

Selecting the Optimal Retention Method

Retention strategies should be planned from the outset of orthodontic treatment to ensure long-term stability. A combination of removable and fixed retainers is often preferred, allowing removable retainers to be worn primarily at night while keeping a fixed retainer as a backup in case of breakage.

Fixed retainers remain the most widely used retention method. Indications for fixed retainers include:

• Stabilization of lower incisors in growing patients
• Space maintenance for future prosthetics
• Periodontal patients requiring splinting
• Prevention of diastema reopening
• Post-treatment stabilization after crowding correction

Various materials, including stainless steel wires or braided ligatures, allow customization of fixed retainers for enhanced clinical efficiency. Standard pre-made retainers such as lingual retainers, twisted wires, and preformed splints offer time-saving solutions but require precise adaptation for patient comfort.

Retention Bonding Techniques

Fixed retainers can be bonded directly or indirectly using a model-based fabrication approach. Proper surface preparation, including plaque removal, enamel etching, and adhesive application, ensures durable bonding. Silicone transfer keys aid in accurate placement, securing the wire without distortion. As the adhesive, a flowable composite resin is usually used.

Removable Retention Appliances

1. Hawley Retainer

The Hawley retainer, introduced in the 1920s, is one of the most widely used removable retention devices for upper jaw. It consists of Adam’s cribs on molars and an adjustable labial bow extending from canine to canine, ensuring control over incisor positioning and facilitating posterior occlusal settling. Moreover, in cases of overbite, a bite plane can be added, residual spaces can be closed through activation.  However, in cases where first premolars were extracted, modifications are required to prevent the reopening of extraction spaces, as a standard Hawley retainer does not provide adequate retention in such situations. 

2. Positioners “active” retainers

These retainers are elastomeric or rubber, can be pre-formed or custom-made. Positioners are highly effective in restoring normal soft tissue tone and preventing gingival hyperplasia following orthodontic treatment. Their advantages include:
✔ Transparency – Aesthetic and discreet
✔ Durability – Resistant to fractures
✔ Continuous wear effect – Helps stabilize teeth in their final alignment, can provide minor corrections and provide the settling of the occlusion

However, the use of positioners as long-term retainers presents several challenges:
❌  Patient compliance – Due to their bulk, positioners are difficult to wear for 24 hours daily; most patients adapt to using them primarily at night.
❌  Limited control over incisor alignment – They do not fully prevent incisor tipping or rotation.
❌  Potential for deep bite relapse – Positioners may contribute to increased incisal overlap over time.
❌  Muscle-induced tooth mobility – Muscle forces can lead to unintended movements.
❌  Contraindications – Positioners are unsuitable for patients with nasal breathing difficulties.

Despite these limitations, positioners excel in preserving occlusal relationships while simultaneously stabilizing intra-arch tooth positions.

3. Thermoplastic Vacuum-Framed Retainers (VFR)

VFRs are manufactured from polyvinylchloride sheets by heating them and adding vacuum pressure. Such retainers are made for both jaws and usually cover all teeth, with the most posterior teeth at least half covered in order to prevent overeruption.

These retainers are gaining popularity due to their:
✔ Quick and easy fabrication
✔ Comfortable fit
✔ Aesthetic appeal
✔ Better control of incisor alignment than Hawley Retainers

However, they are:
❌  Fragile – Prone to breakage
❌  Short-lived – Require frequent replacement
❌  May lead to occlusal changes with prolonged wear as they do not retain intrusion and extrusion
❌  Without adding thich wires might be less effective in retaining expansion cases

4. OSAMU Retainer

The OSAMU retainer functions similarly to a positioner, but covers only a single arch rather than both. It consists of two layers:
✔ An outer rigid layer
✔ An inner soft elastic layer (Bioplast), which fills interproximal spaces, forming “rubber wedges” that stabilize teeth without affecting placement or removal.

Functional Retainers

Functional appliances play a key role in preserving skeletal corrections during the retention phase, particularly in growing patients. These devices are recommended for patinets who experience relapse of distal occlusion (2–3 mm) after early treatment.

✔ Indications:

• Maintaining occlusal and skeletal changes during ongoing jaw growth
• Preventing posterior and downward rotation of the mandible

Since skeletal stimulation in adults is not possible, functional retainers are effective only in adolescents, as vertical growth potential is essential for maintaining treatment results.

Fixed Retention Appliances

Fixed retainers are used when long-term stabilization is required due to anticipated dental instability. They can be manufactured by bending steel wires directly at the chairside, or made in the laboratory using a model from an impression. During a fixed retainer placement, it should be held passively (without activating the retainer, because it might cause unwanted tooth movement) with dental floss, elastic bands, or an occlusal jig, and fixed with a flowable composite resin.

Fixed Retainers are used in cases for:

✔ Preventing lower incisor crowding due to late mandibular growth

• The primary cause of late incisor crowding in adolescence (16–20 years) is continued mandibular growth, leading to lingual tipping of incisors.
• Recommended appliances:
  • Bonded lingual bar (attached to canines or first premolars)
  • Intercanine bonded retainer

✔ Maintaining closure of diastemas

• Even after frenectomy, upper central incisors have a tendency to separate.
• A flexible bonded wire positioned near the gingival margin prevents diastema relapse while allowing slight independent tooth movement.

✔ Preserving space for prosthetic restorations

• Retainers prevent adjacent teeth from drifting into extraction spaces, which is crucial for future prosthetic work.
• Recommended appliances:
  • Heavy-gauge wire bonded to adjacent teeth
  • Temporary prosthetic retainers (e.g., bonded pontic retainers for anterior spaces)

✔ Controlling post-extraction space closure in adults

• Fixed retainers offer superior reliability in maintaining space closure.
• Bonding the retainer to the buccal surfaces of posterior teeth ensures stability.

Clinical Applications of Retention

Retention planning is categorized based on the type and duration of treatment: limited, moderate, and permanent or semi-permanent retention.

1. Limited Retention
   • Crossbites: Anterior when overbite is adequate; posterior when axial inclinations are reasonable after treatment.
   • Serial Extractions: Satisfaction rates vary depending on the extent of the treatment.
   • Canine Extractions & Other Tooth Extractions: Often require retention to prevent space opening, such as with Class II relations.
   • Growth Retardation Corrections: Retention needed after maxillary growth is slowed.
   • Teeth Separation: When maxillary or mandibular teeth are separated for eruption.
2. Moderate Retention
   • Class I Non-Extraction: Retention needed until normal lip and tongue function are restored.
   • Class I/II Extraction Cases: Require retention until functional balance is achieved.
   • Corrected Deep Overbites: Retention is needed for vertical stability, especially in cases of mandibular rotation or overbite correction.
   • Rotated Teeth: Early corrections may require fixed retention to maintain alignment.
   • Ectopic Eruption or Supernumerary Teeth: Prolonged retention may be needed, often with bonded lingual retainers.
3. Permanent or Semi-Permanent Retention
   • Expansion Treatment: Especially in the mandibular arch, to maintain alignment.
   • Spacing Issues: Significant spacing between teeth may require ongoing retention.
   • Severe Rotations or Malpositions: Often need permanent retainers to prevent relapse.
   • Class II, Division 2 Malocclusion: Retention may be extended for muscle adaptation.

Duration of Retention Period in Orthodontics

Retention duration varies widely, with some treatments requiring only a short period, while others may need lifelong maintenance. A "healing phase" follows active treatment, stabilizing teeth, while a "maintenance phase" guards against future relapse. Patients should be fully informed about the retention process before starting orthodontic treatment.

Neglecting the retention phase is one of the most common yet overlooked mistakes in orthodontics leading to relapse and patient dissatisfaction. But retention is just one of many critical errors that can occur during treatment. The "Orthodontic Treatment Mistakes: Camouflage and Retreatment Protocols for Compromised Cases" course will teach you how to identify and correct iatrogenic complications, manage space closure mistakes, and apply camouflage protocols for Class 2 and Class 3 malocclusions. Master the biomechanics of retreatment, learn to handle ectopic canines, and ensure long-term stability for your patients. Don’t let small errors turn into big problems – elevate your expertise and refine your clinical approach!

Several factors contribute to relapse, including the role of facial muscles, the persistence of harmful habits such as tongue thrusting or lip biting, individual characteristics of the bone tissue, morphological changes in the periodontal ligaments, continued jaw growth, occlusal interference, and differences in the size of the upper and lower teeth.

To ensure a stable result, certain conditions must be met:

1. First molars and canines must be in Class I occlusion.
2. The width of the dental arch at the canine region should remain unchanged.
3. The interincisal angle should be close to normal, with normal torque on the upper and lower incisors.
4. Overbite and overjet should be within normal limits, with no sagittal open bite.
5. All spaces should be closed, and all rotations eliminated.
6. The roots of the teeth should be parallel.
7. Occlusal contacts should be stable.

The specifics of the retention period can vary depending on the type of malocclusion being corrected. For example, after treating a Class II, relapse may occur due to shifts in the dental arches, differences in the growth of the jawbones, or backward movement of the lower jaw. In these cases, using a facebow on the upper molars at night and a traditional retainer during the day can help prevent relapse.

Correcting a deep bite is a nearly essential component of orthodontic treatment, and many patients require control of incisal overlap during retention. In late adolescence, continued vertical growth of the alveolar processes can pose a potential problem. For these patients, removable retainers with an occlusal platform are often used for several years after treatment.

After treating a Class III, a chin cup cannot prevent genetically determined growth of the lower jaw. Instead, it may cause the jaw to rotate downward and backward, increasing the lower third of the face and shifting the chin backward. Functional appliances for treating mesial occlusion have similar effects. For pronounced skeletal forms of mesial occlusion, it is better not to carry out tooth-alveolar compensation until skeletal growth is complete. However, for moderate skeletal problems, functional appliances or positioners are recommended to maintain occlusal relationships during growth after treatment.

In cases of open bite, harmful habits such as thumb-sucking can lead to relapse. Control of the eruption of upper molars is essential for retention in these cases. A high-traction facebow or appliances with occlusal blocks in the posterior regions are used to manage the vertical growth of the alveolar processes.

For crossbite treatment, the use of removable retention plates at night is recommended to maintain the results.

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In conclusion, the success of the retention phase relies heavily on the careful restoration of occlusal relationships and the thoughtful use of a combination of retention devices. Fixed retainers are most convenient for patients with poor compliance, while removable devices are better suited for patients with good hygiene practices. The use of removable appliances is generally preferred for maintaining retention when hygiene is a concern.