From “Correcting” a Tooth to “Rehearsing” the Entire World

Lu Han

Postdoctoral Fellow, International Simulation Technology Science and Innovation Center, International Innovation Research Institute, Beihang University, Hangzhou

I have undergone two orthodontic treatments, and the vastly different experiences have given me a genuine appreciation for the impact of simulation technology innovation. My first treatment was in 2008, when I opted for the traditional metal bracket solution, which was the mainstream choice at the time. During that period, I had to visit the hospital almost every week for follow-up appointments: each time, an experienced physician would first carefully examine the progress of the tooth alignment, confirm the direction of subsequent adjustments, and then a younger doctor would manually turn the wires on the brackets to adjust the position and force of the applied pressure. I later learned that this method of treatment relies heavily on the clinician’s operational experience—if the wire tension is too light, the treatment process is delayed; if it is too heavy, it may cause irreversible damage to the teeth and gums. Although the doctors at that time were sufficiently conscientious and responsible, the first treatment still left some minor oral issues, which also set the stage for regret regarding the upper limit of the effectiveness of the second treatment.

Years later, I began my second orthodontic treatment, this time opting for the Invisalign solution. The changes brought about by the technology were truly transformative. At the start of the treatment, the doctor used only a scanner to scan every surface of each tooth in my mouth one by one, while the equipment beside it simultaneously generated a high-precision three-dimensional model of the oral cavity (as shown in Figure 1). The entire scanning process took no more than ten minutes, and it was both efficient and comfortable. Subsequently, I also had a lateral cephalometric X-ray taken to provide more comprehensive skeletal and dental data to support the treatment plan design.

Figure 1 Example of a high-precision three-dimensional oral model generated by real-time scanning

After obtaining the three-dimensional model and X-ray data, the manufacturer, in conjunction with the orthodontic goals set by the doctor, conducts digital simulation prediction through biomechanical analysis: it precisely plans the treatment progress for the next one to two years, detailing the direction and distance of movement for each tooth on a weekly basis; it predicts whether there is a risk of root damage due to excessively rapid movement, or how to optimize the plan to reduce the problem of tooth relapse in the later stages of treatment.

Ultimately, the shape of the aligners to be worn each week, the expected changes in the teeth at different stages, and even the final outcome at the end of the orthodontic treatment are all clearly presented in a visual format (as shown in Figure 2). If I am dissatisfied with the details of tooth movement at a certain stage, the doctor can promptly adjust the parameters and regenerate a new simulation plan. Once the plan is finalized, dozens of custom-made aligners are produced all at once, and I only need to replace them every one to two weeks as required. In this way, the orthodontic process no longer relies heavily on the doctor’s personal technique and experience, nor does it require frequent visits to the hospital. Remote follow-up appointments can be completed simply by taking oral photos with a smartphone, and the desired orthodontic results can still be reliably achieved.

Figure 2 Visual simulation analysis and generation of the orthodontic treatment plan

Having personally experienced these two completely different orthodontic methods, I have gained the most direct appreciation for the convenience and peace of mind brought by modeling and simulation technology. Every few weeks, I can compare the actual changes in my teeth against the simulated projections and clearly see whether they align with the planned path—at the very beginning of the treatment, I could already intuitively “see” the final orthodontic outcome, unlike the first time, when I could only passively rely on the doctor’s judgment throughout the process and wait in uncertainty.

This leads me to imagine: in the future, perhaps only a single smart aligner would be needed to complete the entire orthodontic process. Its built-in sensors could scan the oral cavity in real time, synchronizing the data to a digital model of the mouth. Even if issues such as improper wear or sudden changes in oral conditions arise midway, the system could promptly detect deviations between the actual situation and the simulated predictions through reliable assessment, automatically correct the model, re-run simulation-based prediction, and adjust the force application plan—thereby ensuring, to the greatest extent, that the orthodontic outcome does not go off track.

Is this not a vivid application of “digital twin” technology? Based on the oral digital model generated from the initial scan, the model is dynamically updated through real-time data collection, the simulation plan is continuously optimized, and adjustments are automatically fed back and executed according to reliability assessments—forming a complete closed loop of “sensing, simulation, decision-making, and execution.” This allows the orthodontic process to autonomously and reliably guide itself toward the preset goal.

The journey of correcting a single tooth is, in essence, a precise deduction of the microscopic world. It reveals to us that when dealing with complex systems, those “black-box” operations that once relied on personal experience, whose processes were difficult to trace, and whose outcomes were fraught with uncertainty, can be completely surpassed by “white-box” simulations based on highly reliable digital models, with transparent and traceable processes. When the entire complex process becomes visible, calculable, and optimizable, human wisdom and energy can be liberated from tedious repetitive operations and anxiety over the unknown, allowing us to focus on more core goal-setting and value judgments. Every step of a tooth’s movement is precisely predicted by the model and verified in real time, granting us an unprecedented sense of control and peace of mind—we can finally “see” the power of time and be confident that it is steadily progressing toward the desired destination.

From the treatment of a single tooth to the design of a home; from the optimization of a transportation route to the intelligent governance of a city—whether it is medical treatment concerning individual health or public affairs concerning societal operations, these complex processes are expected to achieve long-term and stable intelligent management with the help of trustworthy modeling and simulation technology. When we take enhancing people’s sense of well-being as our core goal and establish sufficiently reliable digital twin models for all things, we can simulate optimal solutions for countless “what-if” scenarios in advance, steadily moving toward a better reality that has been verified through simulation. By then, “everything can be simulated” will no longer be just a slogan; simulation technology will truly illuminate our future, ensuring that every expectation is precisely fulfilled.