Hybrid Fabrication of Patient-Specific Intraoral Stents for Head and Neck Radiotherapy: A Retrospective Case Series with Exploratory Dosimetry
This retrospective case series demonstrates that a hybrid fabrication workflow combining functional molding and 3D printing can successfully produce patient-specific intraoral stents for diverse head and neck radiotherapy cases, achieving selective reductions in mean oral-cavity dose without compromising target coverage while maintaining clinical usability.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Radiation therapy for cancers in the head and neck is a delicate balancing act. Doctors must deliver a powerful dose of energy to destroy a tumor while sparing the healthy tissues that surround it. The challenge is that the mouth, tongue, lips, and salivary glands sit very close to these targets. When a patient lies still for treatment, these soft tissues naturally settle in a way that often puts them directly in the path of the radiation beam. To solve this, medical teams sometimes use custom-made devices called intraoral stents. These are essentially mouthguards designed to gently push the tongue down or pull the lips and cheeks back, creating a physical gap between the healthy tissue and the tumor. By moving the healthy tissue out of the way, doctors hope to reduce the amount of radiation it receives, which can lower the risk of long-term side effects like dry mouth or difficulty swallowing.
A team of researchers in Ukraine recently explored a new way to make these life-saving devices. Instead of relying on traditional dental labs or complex scans of the patient's teeth, they developed a hybrid method that combines hands-on clinical work with modern digital tools. They created custom stents for sixteen adults with head and neck tumors, using a workflow that started with a soft silicone mold taken directly inside the patient's mouth. This mold captured the exact shape of the patient's teeth, gums, or even the smooth ridges left after surgery. The team then scanned this soft mold outside the mouth to create a digital blueprint, which was used to print a hard, custom-fit device using a 3D printer. This approach allowed them to tailor the devices to patients who had lost all their teeth or had significant changes to their mouth structure after surgery, conditions that often make standard devices difficult to use.
The researchers tested how well these custom stents worked by looking at two main things: how comfortable and reliable they were for the patients, and how they changed the radiation dose calculations. In terms of comfort, the devices performed well. Eleven of the sixteen patients were able to complete their full course of radiation treatment while wearing the stent. No one reported that the device broke or caused intolerable pain, and only one patient needed a small adjustment to the device before treatment began to make it more comfortable. The team also checked the devices during treatment using special X-ray images taken at different times. These images showed that the patients' jaws and tongues stayed in the same, intended positions throughout the treatment, proving that the devices held their shape and position reliably.
When the team analyzed the radiation dose, they found that the stents did indeed change the distribution of energy in the mouth, but the results were specific rather than universal. In seven pairs of detailed comparisons, the average radiation dose to the entire mouth was lower when the stent was used. On average, the dose dropped from 44.11 Gy to 42.94 Gy, a small but measurable reduction. In one specific patient, the reduction was much more significant, with the average dose to the mouth dropping by 5.2 Gy. The researchers also looked at whether the stent helped the radiation hit the tumor as intended. They found that the coverage of the tumor remained exactly the same with or without the device, meaning the stent did not interfere with the primary goal of treating the cancer. However, the study also noted that while some healthy areas received less radiation, other nearby structures, such as specific salivary glands or the jawbone, sometimes received slightly higher doses. This indicates that the benefit of moving tissue is a trade-off that depends heavily on the individual's anatomy and the specific location of the tumor.
The study concludes that this hybrid method of making stents is a practical and effective way to customize treatment for a wide range of patients, including those with no teeth. The devices successfully held tissues in place and reduced the average radiation dose to the mouth in most cases examined. However, the researchers are careful to state that these findings do not yet prove that the stents will definitely reduce long-term side effects or that they are superior to other planning methods. The results are based on calculations and a small number of patients, so the team suggests that larger, future studies are needed to confirm whether these dosimetric improvements translate into real-world health benefits for patients. For now, the work demonstrates that it is possible to quickly and accurately create personalized tools that help doctors navigate the complex geography of the human mouth during cancer treatment.
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