The virtual articulator in aligner orthodontics
Authors: Dr. Werner Schupp, Dr. Julia Haubrich, Dr. Julia Steinmaier (née Funke)
Introduction
Digital movement analysis is playing an increasingly important role in orthodontic diagnostics and treatment. In aligner orthodontics, the assignment of the lower jaw to the upper jaw in virtual treatment planning was previously limited exclusively to the central occlusion (CO). Here, the position of the lower jaw was determined by a "best-fit" adaptation, which, however, did not correspond to the real opening and closing movement of the jaw. This could lead to deviations between the planned and actual occlusion at the end of treatment.
Real motion capture and virtual articulator
By digitally recording individual jaw movements, tooth movements can now be adjusted in the virtual treatment planning (VTS). This enables more precise correction of the occlusion by assigning the lower jaw to a physiological condylar position. The data is captured by a combination of intraoral scans and digital joint registration using a digital motion decoder (DMD). The movement is then transferred to the virtual simulation software OnyxCeph V.T.O.3D to enable patient-specific articulation.
Occlusal changes due to different centers of rotation
The occlusion varies depending on the position of the rotation axis of the lower jaw. If the mandibular movement is only adjusted according to a rigid "best-fit" procedure, non-physiological condylar displacements may occur. This can cause the condyles to shift posteriorly into the bilaminar zone, which in the long term can lead to craniomandibular dysfunction (TMD) in the long term.
Technical procedure for digital joint registration
- Scanning the rows of teeth
- Digital joint registration using DMD
- Determination of the first occlusal contact in physiological condylar position
- Comparison of the DMD data with the intraoral scans in OnyxCeph
- Simulation of tooth movements in the virtual articulator
- Fabrication of the aligners based on the customized simulation
Treatment example: Patient with TMD and anterior abrading
A 39-year-old female patient with TMD and abrasion of the anterior teeth was treated with digital joint registration. Initially, an asymmetrical occlusion with a lack of posterior support was observed. After registering the individual joint movements, the occlusion was optimized in the virtual treatment planning. Treatment with aligners lasted 16 weeks and resulted in complete elimination of the symptoms and a harmonized occlusion.
Conclusion
The use of a virtual articulator in digital treatment planning represents a decisive improvement for aligner orthodontics. The integration of real jaw movements enables more precise predictability of the occlusion and reduces the risk of malocclusion after treatment. This increases treatment efficiency and ensures a stable occlusion in the long term.
Source:
Schupp, W., Haubrich, J., & Funke, J. (2023). The virtual articulator in aligner orthodontics. Journal of Aligner Orthodontics, 7(4), 267-283.