Oct 125 min read

Navigating the Challenges of Centric Relation in Clear Aligner Therapy

Clear aligner therapy has revolutionised the field of orthodontics, offering patients a discreet and comfortable alternative to traditional braces. However, like any innovative technology, it comes with its own set of challenges. One of the most significant hurdles that orthodontists face is managing Centric Relation (CR) within the constraints of clear aligner therapy.

Dental models mounted in a KaVo articulator

At AlignerService, we understand the critical importance of functional occlusion and Centric Relation (CR) in achieving successful orthodontic outcomes. While clear aligner therapy presents unique challenges, particularly in managing CR, our approach has always been rooted in a deep understanding of these complex principles. This commitment ensures that the treatment plans we help develop are not only effective but also tailored to the intricate needs of each patient.

Understanding Centric Relation and its challenges in clear aligner treatments

Centric Relation (CR) refers to the position of the mandible when the condyles are in their most anterior-superior position in the glenoid fossa, fully seated and braced against the posterior slopes of the articular eminences. This position is crucial in ensuring a harmonious and functional bite, particularly in adult patients whose skeletal growth has ceased.

Unfortunately, current clear aligner software and production processes struggle to accurately accommodate CR. The primary reason is that most clear aligner systems lack the capability to integrate with a virtual articulator—a digital tool that simulates the movement of the jaws. Even if such integration were possible, correctly positioning the maxilla would require a digital facebow transfer, involving specific software and hardware that are not typically available in most general- as well as orthodontic practices.

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The "Bite Jump" Phenomenon

When clear aligner software attempts to simulate changes in a patient’s bite, it often employs a method known as a "bite jump." This term accurately describes what happens: the software repositions the mandible to fit the maxillary teeth in a way that seems reasonably correct in the digital model. However, this approach is far from realistic, especially when treating adults. In children with growing jaws, orthodontists might get away with such adjustments, but adults require a more precise and tailored approach.

Workarounds for Managing Centric Relation

Despite the limitations, there are a few strategies that can be employed to work around the challenges of CR in clear aligner therapy:

Pre-Mounting Models in an Articulator
- One option is to mount your models in a physical articulator before beginning digital aligner treatment planning. By registering the difference between Maximum Intercuspation Position (MIP) and CR, you can perform minor equilibration until a reasonable occlusion is achieved, ideally on at least two molars and the second premolar bilaterally. Transferring your registrations on the models to the mouth of the patient, allows you to position the bite in CR within the aligner software, providing a relatively stable starting point for treatment.
- However, this approach is not without its drawbacks. Very few patients are suitable for initial enamel reduction, particularly since final occlusion adjustments typically occur six months into the retention phase. If enamel has already been removed at the beginning, it leaves little room for further corrections.
Visualizing and Adjusting the End Result
- Another approach involves identifying the patient’s CR, photographing it, analysing it in an articulator and comparing it with MIP. With this information, you can visualise the desired end result and start moving the teeth towards this outcome within the aligner software.
- It’s important to recognise that this method requires ongoing adjustments as the orthodontic treatment progresses. The initial virtual treatment plan is often just an educated guess, and revisions are necessary to adapt to the reality of the patient’s oral condition over time.

The Road Ahead: Challenges and Future Solutions

The frustration of dealing with these limitations is shared by many in the clear aligner community. There are two main reasons why managing CR in clear aligner therapy remains such a challenge:

Traditional Orthodontic Practices
- Historically, orthodontists have not prioritised the muscles and joints when treating patients. Although many claim to consider these factors, the use of a "wristilator" instead of an articulator suggests otherwise. Most dental practices, including the orthodontic practices, have an articulator collecting dust somehere. This oversight contributes to the ongoing struggle to incorporate functional occlusion principles into aligner therapy.
Complexity and Limited Demand
- The number of dentists with the expertise and interest in functional occlusion is small combined with clear aligner competence even smaller. Consequently, there is limited demand for these advanced features in aligner software. Developing solutions that accurately integrate CR into clear aligner treatment is highly complex and, given the niche market, may take years to become a reality.

Integrating Functional Occlusion and Centric Relation

At AlignerService, we have always prioritised the integration of functional occlusion and Centric Relation (CR) into our treatment planning process. Understanding that a successful orthodontic outcome depends not just on the alignment of teeth, but on a harmonious and stable bite, we bring our extensive knowledge of these principles to every case we assist with.

When we help doctors around the world optimise their clear aligner treatments, we go beyond the limitations of standard aligner software by incorporating advanced techniques that address CR. This is to establish a stable starting point or continuously recalibrating the treatment plan as the patient's condition evolves, our approach ensures that each plan is tailored to the unique functional needs of the patient and the vision of the treating doctor.

By seamlessly integrating CR and functional occlusion into clear aligner therapy, AlignerService helps practitioners achieve not only aesthetic success but also long-term stability and patient satisfaction.

Conclusion

Clear aligner therapy offers many benefits, but managing Centric Relation remains one of its biggest challenges. While there are workarounds, they are far from perfect, and the search for a robust solution continues. As the field evolves, we hope to see advancements that better integrate CR into aligner therapy, ultimately providing patients with more precise and effective treatments. Until then, GP's and orthodontists must navigate these challenges with creativity and adaptability, always striving to deliver the best possible care within the current limitations.

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