Perspectives on orthodontic retention

Dr. Dustin S. Burleson discusses the importance of following up on orthodontic treatment

Introduction

Orthodontic retention bridges the gap between the active phase of orthodontic treatment and the long-term stability of achieved results. There is a 35.22% overall failure rate¹ for bonded retainers, with an escalating trend observed in prolonged follow-up durations. This highlights the critical role retention plays in preserving orthodontic corrections and perhaps why so many orthodontists prescribe thermoformed retainers following orthodontic treatment.

The retention phase of orthodontic care aims to preserve the orthodontic correction achieved during active treatment. Its primary objective is to stabilize the dentition in its corrected position, facilitate occlusal settling, and mitigate the risk of relapse — a phenomenon in which teeth gradually revert to their pre-treatment alignment. Retention procedures are critical for both orthodontists and general practitioners (GPs) involved in post-treatment care.

Orthodontists rely on effective retention strategies to safeguard the time, effort, and resource investments made during active treatment. On the other hand, GPs contribute to the long- term success of orthodontic results by reinforcing the importance of compliance with retention protocols and promptly addressing any issues that might arise.

This article focuses on orthodontic retention, equipping orthodontists and GPs with essential knowledge and tools to optimize patient care and maintain a healthy and stable occlusion for each patient.

The science of retention

While the concept of orthodontic retention may seem straightforward, its efficacy depends on a thorough understanding of the underlying scientific principles that influence tooth movement and stability. Central to retention is the principle of tissue remodeling. This process involves the periodontal ligament and surrounding bone adapting to new tooth positions. This process is inherently influenced by biological factors such as:

• Bone density
• Gingival architecture
• Individual patient variability

The stability of tooth position after treatment is determined by the principal fibers of the periodontal ligament and the supra-alveolar gingival fiber network. These fibers help maintain a balanced relationship between the teeth and the surrounding soft tissue.

Orthodontic treatment disrupts the periodontal ligament and the gingival fiber network, requiring these fibers to reorganize after removing the appliances.

The gingival fiber network consists of collagenous and elastic-like oxytalan fibers. While the collagenous fibers typically remodel in 4 to 6 months, the oxytalan fibers can take up to 6 years to fully reorganize.² The slow remodeling of these supra-alveolar fibers, especially in initially rotated teeth, contributes to the risk of relapse after orthodontic treatment.

This extended timeline is why long-term, routine retainer use is critical. The retainers help maintain the new positions while the periodontal ligament and surrounding structures fully adjust and stabilize. Orthodontists typically recommend wearing retainers full-time for the first 3 to 6 months, followed by night-time wear as advised, to ensure the teeth do not relapse into their original positions.

Moreover, the mechanical aspects of retention cannot be overlooked. Retainers serve as external forces counteracting teeth’s natural tendency to relapse into their original positions (Figures 1-4). Various retainer designs, ranging from traditional Hawley retainers to bonded lingual and thermoformed retainers, exert different degrees of force and control on the teeth and periodontium. The significance of orthodontic retention cannot be overstated.

Retainer types

Hawley retainers are ideal for slight adjustments, as they exert gentle, passive forces to maintain the position of the teeth. An orthodontist can adjust the metal wire by applying light pressure if minor corrections are needed.

Bonded lingual retainers, also known as permanent retainers, provide constant contact to keep the teeth in place, preventing movement. This is especially important for maintaining the alignment of severe rotations or space closure, but without aftercare maintenance, relapse can occur due to the aforementioned risk of bond failure.

Thermoformed or clear plastic retainers offer full coverage of the teeth, maintaining their alignment with gentle, even pressure. They are especially good for preventing relapse and are often used as an ideal solution to retain tooth alignment and arch form.

Retention duration varies based on factors like the severity of the malocclusion and treatment method. Generally, orthodontists oversee retention for 12 to 24 months post-treatment.³ After this, they may expect GPs to monitor retention and subsequent dental changes. Clear communication between orthodontists and GPs is essential to ensure a smooth transition in retention responsibility and proper ongoing care.

Impact on patient health

Maintaining orthodontic results relies heavily on orthodontic retainers. However, their presence within the oral cavity can induce significant alterations in the oral ecosystem, potentially escalating the risk of various oral diseases.⁴ Fixed orthodontic appliances, including lingual bonded retainers, pose a unique challenge to oral hygiene. Their presence hinders the efficient removal of food particles and plaque, creating an environment conducive to bacterial growth and biofilm formation.

Bacterial colonization has many implications for oral health, including:

• Periodontal disease: Accumulation of bacterial biofilms on retainer surfaces can contribute to gingivitis and periodontitis, leading to gum inflammation and tissue
• Halitosis: Bacterial growth in the oral cavity, including on retainer surfaces, can produce malodorous compounds, which contribute to halitosis or bad breath.
• Caries lesions: The presence of biofilms on retainers increases the risk of enamel demineralization and the formation of caries lesions, particularly in areas prone to plaque accumulation.

Clinical observations also confirm the presence of gingivitis and enamel decalcification around fixed appliances, manifesting as visible signs of inflammation and demineralization.⁵ Moreover, poor oral hygiene habits and past periodontal conditions contribute to the susceptibility to periodontal complications associated with orthodontic retainers. Therefore, orthodontic retention must go beyond a “set it and forget it” approach. It’s a continuous commitment, not just a one-time recommendation.

Care of retainers

Patients must be educated about the risk of orthodontic retainers serving as substrates for bacterial growth.⁶ The presence of irregularities on retainer surfaces (grooves and ridges) increases the likelihood of plaque biofilms forming. Additionally, microcracks and abrasions on thermoformed retainers, despite their promising results in controlling plaque index and gingival health, give bacteria a chance to grow. Patients in orthodontic retention should be educated on proper cleaning techniques and understand the significance of hygiene protocols to prevent the growth of bacterial biofilms.

One of the most efficient cleaning techniques is the daily use of a soft-bristled toothbrush combined with non-abrasive toothpaste. It’s important for patients to brush their retainers gently but thoroughly, ensuring all surfaces are cleaned, including the crevices where bacteria are likely to accumulate. In addition to manual brushing, soaking retainers in a non-alcoholic, antimicrobial solution can significantly reduce bacterial load. Solutions containing ingredients like chlorhexidine dissolve biofilms and kill bacteria more effectively than water alone.⁷ Soaking retainers daily or at least a few times a week in these solutions helps maintain a hygienic environment and prevents the build-up of odor-causing bacteria.

Challenges with fixed retainers

Fixed orthodontic retainers, while effective in maintaining tooth alignment, present unique challenges in terms of oral hygiene maintenance and bacterial adhesion. Unlike removable thermoformed retainers, fixed retainers cannot be easily removed for eating, drinking, or oral hygiene routines. This lack of accessibility creates an environment conducive to bacterial biofilm formation, posing several potential drawbacks.

The adhesion and growth of bacterial biofilms on fixed retainers can lead to various undesirable consequences like unpleasant odors, gingival inflammation, recession,⁸ and unplanned tooth movement. These can not only impact patient satisfaction but may also compromise compliance with retention protocols.

Moreover, bacterial biofilms on the retainer surface have broader implications for oral health. They can disrupt the existing oral microbiota and expose individuals to the conditions we’ve mentioned, further escalated by inconsistent oral hygiene practices and unhealthy diets.⁹ Fixed retainers may also interfere with oral hygiene practices and have the potential to for plaque and calculus. These complications highlight the importance of implementing preventive programs to minimize the adverse effects of orthodontic treatment.

Patient education on proper cleaning techniques, such as floss threaders and interdental brushes, is crucial for maintaining periodontal health. We advocate for a patient-centered approach that tailors treatment to individual needs. It’s essential to educate patients about the potential drawbacks associated with fixed lingual retainers.

Benefits of routine retainer replacement

Much like changing a toothbrush every 3 months to maintain oral hygiene, replacing removable or thermoformed retainers periodically is necessary because they endure significant wear. As they age, retainers may also become loose and prone to harboring bacteria, posing risks to oral health and compromising the effectiveness of orthodontic treatment.

Retainers should be replaced regularly for several reasons:

• Improved retention performance: A fresh retainer ensures optimal fit and function.
• Enhanced oral hygiene: Minimizes bacterial buildup on retainers, reducing the risk of oral diseases.
• Preservation of orthodontic investment: Protects treatment results by minimizing the potential for relapse and maintaining tooth alignment (Figures 5-10).
• Increased patient comfort: New retainers offer a better fit and feel, improving patient comfort, compliance, outcomes, and satisfaction.

Innovative retainer programs, such as Retainer Club, boost patient compliance and satisfaction. By partnering with orthodontists and GPs, Retainer Club offers a seamless solution for regular retainer replacement, providing patients with convenient access to online ordering and fast home delivery services. This approach not only streamlines the retainer replacement process but also empowers patients to prioritize their oral health while maximizing the value of their orthodontic investment.

Clinical recommendations

Orthodontists and GPs can benefit from practical guidelines for retainer selection and maintenance to optimize patient outcomes.

When choosing a retainer, consider:

• Patient compliance
• Treatment goals
• Individual anatomical factors

Removable retainers, such as thermoformed retainers, offer convenience and ease of use, particularly for patients with good compliance and mild retention needs. Alternatively, fixed retainers, including bonded lingual retainers or prefabricated retainers, may be more suitable for patients requiring greater retention or those prone to non-compliance.

Once a retainer is selected, proper maintenance is essential to ensure its effectiveness and longevity. Patients should be instructed on regular cleaning routines, including brushing the retainer with a soft toothbrush and mild soap or using specialized retainer cleaning solutions.

Also, patients should also be advised to avoid exposing the retainer to extreme temperatures or excessive force. This can lead to damage or distortion of the appliance. For optimal results, educate patients about retainer retention and replacement. Highlighting the importance of retention boosts patient compliance; discussing neglect consequences, like bacterial buildup or retainer deterioration, reinforces protocol adherence.

Promoting evidence-based practice will require orthodontists and GPs to stay up-to-date on the latest research findings and clinical guidelines regarding orthodontic retention. With this, practitioners can make informed decisions that prioritize patient safety and maximize treatment outcomes. Regular monitoring of fixed lingual retainers by orthodontists or general practitioners is crucial to ensure optimal dental health. Teeth can shift over time, retainers may break or become compromised, emphasizing the necessity for timely intervention to maintain the integrity of orthodontic treatment outcomes.

Conclusion

Orthodontic retention is a crucial part of orthodontic treatment, preserving the results obtained during active treatment. To mitigate the risks associated with retainer wear, clinicians must adopt proactive management strategies. This includes regular monitoring, timely replacement, and diligent maintenance to safeguard against potential complications such as bacterial buildup, retainer deterioration, gingival inflammation, periodontal recession, unplanned tooth movement, and relapse.

Patient education and engagement are central to successful orthodontic retention. Clinicians who inform patients about the benefits and potential consequences of regular maintenance are more likely to motivate and encourage patients to remain compliant. Encouraging patients to prioritize their oral health and follow recommended protocols is essential to promoting long-term orthodontic stability and oral health outcomes.