Orthodontic retention — When, Why, and How

Dr Geoffrey Hall — Specialist Orthodontist, OrthoED Institute

Orthodontic retention is often described as the “last phase” of treatment. In reality, retention is a continuation of orthodontic therapy, and in many ways the most important determinant of long-term success. Teeth have a strong biological tendency to relapse toward their pretreatment positions, driven by periodontal fibre memory, occlusal forces, muscular pressures, and ongoing growth and ageing. No appliance—fixed braces or aligners—can eliminate these forces.

For general dentists providing orthodontic care, understanding when retention is required, why relapse occurs, and how to design an appropriate retention strategy is essential for predictable outcomes and ethical patient consent.

Why retention is necessary

Relapse is not a failure of orthodontics; it is a biological reality. Classic and contemporary studies have consistently demonstrated that untreated dentitions continue to change throughout life. Even ideal, untreated occlusions show late crowding and arch-length reduction with age.

Key biological drivers of relapse include:

• Periodontal fibre memory, particularly supracrestal fibres that recoil after rotational correction
• Occlusal forces and function, which favour interdigitation patterns established early
• Soft tissue pressures from lips, cheeks, and tongue
• Continued craniofacial growth and ageing, especially mandibular growth into adulthood

The orthodontic literature is unequivocal: without retention, most orthodontic corrections relapse to some degree. This is particularly true for rotations, spacing closure, mandibular incisor alignment, and transverse expansion.

When is retention required?

The short answer is: always.

However, the duration and type of retention should be tailored to the movements performed and the patient’s risk profile.

High-risk situations (require long-term or permanent retention)

• Rotational correction (especially canines and incisors)
• Mandibular incisor alignment
• Spacing closure (including diastema closure)
• Expansion beyond original arch form
• Adult orthodontic treatment
• Periodontally compromised patients

Multiple long-term follow-up studies show that mandibular anterior alignment is particularly prone to relapse, even decades after treatment. Consequently, indefinite retention in the lower anterior region is commonly recommended.

Lower-risk situations (still require retention)

• Minor alignment in growing patients
• Treatment that preserves original arch form
• Minimal incisor repositioning

Even in these cases, short-term retention alone is rarely sufficient.

Why “short-term retention” is a myth

A persistent misconception is that teeth “stabilise” after a fixed period (e.g. 6–12 months). The evidence does not support this.

Long-term studies by Little and others demonstrated clinically significant relapse 5, 10, and even 20 years post-treatment, despite apparently stable early results. Age-related changes—often called “late mandibular crowding”—occur regardless of whether orthodontic treatment was performed.

Therefore, retention must be viewed as long-term risk management, not a temporary precaution.

How to choose the right retention method

Retention strategies broadly fall into two categories:

1. Removable retainers
2. Fixed (bonded) retainers

Each has advantages and limitations.

Removable retainers

Advantages

• Allow good oral hygiene
• Can be adjusted or replaced
• Control transverse and sagittal relapse effectively when worn

Limitations

• Entirely compliance-dependent
• High risk of reduced wear over time

Clear thermoplastic retainers (often aligner-style) are popular because of comfort and aesthetics. However, evidence suggests that compliance decreases significantly after the first year, even with good initial motivation.

Removable retainers are best used:

• In the maxillary arch
• In combination with fixed lower retention
• With clear, written wear protocols

Fixed (bonded) retainers

Advantages

• Compliance-free
• Highly effective for rotational and spacing relapse
• Particularly valuable in the mandibular anterior region

Limitations

• Technique-sensitive bonding
• Risk of plaque accumulation if poorly maintained
• Can fail unnoticed by patients

Bonded retainers have strong evidence supporting their effectiveness in maintaining lower incisor alignment. However, patients must be educated about hygiene and the need for regular monitoring.

A common and defensible approach is:

• Bonded lower canine-to-canine retainer
• Removable upper retainer at night

Duration of retention: what should we tell patients?

Ethically and medico-legally, patients should be informed that:

Retention is long term and often indefinite.

The orthodontic literature increasingly supports lifelong nighttime wear of removable retainers and long-term maintenance of bonded retainers, particularly in adults.

Importantly, this should be framed as:

• A normal part of orthodontic care
• Comparable to wearing glasses to maintain visual correction
• A shared responsibility between clinician and patient

Clear expectation setting reduces dissatisfaction and complaints.

Retention in the aligner era

The aligner era has not reduced the need for retention—if anything, it has increased its importance.

Aligner treatments frequently involve:

• Arch expansion
• Incisor proclination
• Non-extraction alignment

These movements are inherently less stable and place greater reliance on retention. Aligners as retainers are effective, but only if worn consistently.

A practical OrthoED retention framework

At OrthoED, we teach a simple hierarchy:

1. Plan retention at the start of treatment, not the end
2. Match the retainer to the movement risk
3. Combine fixed and removable retention when indicated
4. Educate patients clearly and repeatedly
5. Review retainers long term

Retention failure is rarely a surprise when planning is adequate—it is usually predictable.

Conclusion

Orthodontic retention is not an optional extra or an afterthought. It is a fundamental component of orthodontic treatment, underpinned by decades of biological and clinical evidence.

For general dentists, the key message is clear:

If you move teeth, you must plan to hold them.

Successful orthodontics is measured not at debond, but years later—when alignment, function, and periodontal health are still intact. Thoughtful, long-term retention is what turns short-term success into lasting outcomes.

Bibliography (peer-reviewed)

1. Little, R. M., Wallen, T. R., & Riedel, R. A. (1981). Stability and relapse of mandibular anterior alignment. American Journal of Orthodontics, 80(4), 349–365.
2. Little, R. M. (1999). Stability and relapse of dental arch alignment. British Journal of Orthodontics, 26(4), 245–251.
3. Sinclair, P. M., & Little, R. M. (1983). Maturation of untreated normal occlusions. American Journal of Orthodontics, 83(2), 114–123.
4. Proffit, W. R., Fields, H. W., & Sarver, D. M. (2019). Contemporary Orthodontics (6th ed.). Elsevier.
5. Renkema, A. M., et al. (2008). Long-term effectiveness of bonded retainers. American Journal of Orthodontics and Dentofacial Orthopedics, 133(4), 496–502.
6. Vagdouti, N., et al. (2015). Compliance with removable retainers. European Journal of Orthodontics, 37(5), 489–495.
7. Papageorgiou, S. N., et al. (2017). Stability of orthodontic treatment outcomes: A systematic review. Angle Orthodontist, 87(6), 891–903.