Small device, big impact: how a simple chairside 3D-printed retractor reshapes dose and patient experience in head and neck radiotherapy

Early and late complications as a result of radiation therapy remain challenging in the radiation treatment of head and neck cancer. Even in the era of intensity-modulated radiotherapy (IMRT) and particle therapy, the tongue, floor of mouth, palate, and buccal mucosa are frequently collateral damage, with pain, dysphagia, trismus, weight loss, unplanned treatment interruptions, and hospitalizations that reverberate far beyond the acute phase. Usually, intraoral devices have focused on enamel shielding and bite opening. These strategies are not trivial, but they are essentially passive. The GUARD randomized trial by Schröter et al. changes the conversation by introducing a simple yet thoughtfully engineered concept: geometry as therapy (1). This is achieved through a semi-individualized, chairside 3D-printed tissue retraction device (TRD) that moves vulnerable soft tissues out of harm’s way in a reproducible and patient-tolerant manner.

Patients receiving IMRT or carbon-ion therapy were randomized to a semi-individualized 3D-printed retractor or to flexible shielding splints. The primary endpoint focused on severe mucositis in regions displaced away from the high-dose target and was assessed by blinded endoscopic review. The topline result is both clinically and mechanistically compelling. The severe mucositis in displaced tissues was essentially reduced in the TRD arm while remaining common with standard shielding. Inside the clinical target volume, where dose was intentionally high, mucositis rates were similar between arms, which reassures that tumor coverage was not compromised. This pattern is exactly what one expects if a device achieves geometric sparing without undermining oncologic intent (1-3).

GUARD builds on a pragmatic fabrication approach that the same group had previously refined and reported. A single pre-printed device design is adapted chairside in roughly one visit using simple impressions and liners (1). The design allows several tongue displacement configurations, including caudal and lateral vectors or a tongue-out option, together with bite opening and dental shielding. In prior feasibility work, the group documented high patient tolerance across a full course of radiotherapy, good positional reproducibility from fraction to fraction, and no meaningful technical failures. In a subsequent randomized clinical study with patient-reported outcomes, the same platform signaled improvements in oral symptoms and function compared with conventional splints. GUARD then adds the hard endpoint that the field cares about most, namely the avoidance of severe mucositis in tissues that can be physically moved out of dose (1).

The dosimetry data provide the missing link between physics and symptoms. When targets were positioned superior to the oral cavity, tongue dose metrics dropped with TRD use. When targets were inferior or posterior to the palate, palatal dose decreased. The TRD provides benefit where anatomy and beam geometry allow meaningful displacement, and the trial reports exactly that. This fidelity to anatomical logic strengthens confidence that the clinical effect is not a chance observation, but the predictable consequence of changing spatial relationships in a controlled and repeatable way (1-3).

From a dental oncology perspective, the implications are immediate. We have long urged early dental involvement to manage caries risk, periodontal inflammation, trismus (4) and prosthetic issues before radiation. The GUARD program suggests that dental expertise can also be harnessed to actively sculpt soft-tissue geometry during treatment. The semi-individualized workflow fits real clinics. It relies on straightforward materials and skills, can be delivered in a single appointment, and integrates with planning CT simulation (1). Many centers already produce bite blocks and positioning aids. Extending that capability to TRDs is an incremental step with potentially outsized clinical gains (1-5).

The current semi-individualized approach was intentionally designed to be accessible and fast. As intraoral scanning becomes ubiquitous and 3D printers more capable, fully digital TRDs that eliminate impressions, shorten chair time, and encode patient-specific retraction vectors can be compared head to head with the semi-custom devices used in GUARD (1). Standardized reporting of tongue and palate substructures within dose-volume histograms will allow comparisons across centers and trials. Daily image guidance already used in head and neck radiotherapy can be leveraged to document inter-fraction tongue and palate positions, closing the loop between planned geometry and delivered geometry (4). Challenges with resin types for the manufacture of semi-customized TRDs remain, as there is a need for studies on the effects of material hardness after radiation exposure and non-interference with computed tomography planning for radiotherapy, which requires the resin material to have a Hounsfield density close to that of water (5). The technique is not complex. First, identify the anatomical scenarios where the displacement can meaningfully move the tongue or palate out of the high-dose region. Second, integrate a semi-individualized TRD into the pre-radiation dental workflow for those cases, with clear communication between dentistry, radiation oncology, and physics regarding intended displacement, verification, and tolerances (1-3). Third, measure what matters. Capture patient-reported pain, diet level, and swallowing in a routine and standardized way, and track unplanned care and treatment interruptions (1). Even outside of a formal trial, this information will build an institutional learning system and support continuous improvement.

The larger lesson of GUARD, reinforced by the group’s prior feasibility and randomized work, is that a small device can have large clinical consequences. A device that can be designed once, adapted in minutes, and reproduced reliably across weeks of treatment has the right ingredients for impact. Moving from passive shielding to active, semi-individualized displacement is a shift that aligns with how we already think about target coverage and organ protection. It treats the oral cavity not as a bystander to be padded, but as a dynamic space that can be shaped to protect the patient without sacrificing cancer control (1).

The GUARD study’s main limitations are as follows: the study’s analysis of the density (Hounsfield Unit) of the silicone device and its verification of the interference that this material may have on CT analysis and radiotherapy planning; the study’s heterogeneous group of anatomical regions, which differ significantly in terms of the primary radiation area and, consequently, the analyses of effects on oral mucositis; the study’s small sample size, which means that statistical significance is not yet relevant; and, lastly, the effect of TRD on the late effects of radiotherapy. These constraints call for more and larger research on the subject.

Despite other scientific publications by our research group on the subject of intraoral devices for use during radiotherapy and their impact on reducing adverse effects, the opinion expressed at this time is unbiased and transparent, and we clearly maintain an independent critical perspective and in the search for information in the scientific literature that contributes effectively at the present time and in the near future to improvements in the quality of life of individuals undergoing antineoplastic therapy in the head and neck region.

Acknowledgments

None.

Footnote

Provenance and Peer Review: This article was commissioned by the editorial office, Translational Cancer Research. The article has undergone external peer review.

Peer Review File: Available at https://tcr.amegroups.com/article/view/10.21037/tcr-2026-1-0077/prf

Funding: None.

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://tcr.amegroups.com/article/view/10.21037/tcr-2026-1-0077/coif). The authors have no conflicts of interest to declare.

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References

1. Schröter P, Christ LV, Dvornikovich K, et al. Randomized controlled trial of semi-individualized 3D-printed tissue retraction devices vs. standard shielding splints in head and neck cancer treated with intensity-modulated and particle radiotherapy (GUARD). Oral Oncol 2025;169:107604. [Crossref] [PubMed]
2. Herpel C, Held T, Labis C, et al. Oral Sequelae after Head and Neck Radiotherapy: RCT Comparing 3D-Printed Tissue Retraction Devices with Conventional Dental Splints. J Clin Med 2023;12:2789. [Crossref] [PubMed]
3. Herpel C, Schwindling FS, Held T, et al. Individualized 3D-Printed Tissue Retraction Devices for Head and Neck Radiotherapy. Front Oncol 2021;11:628743. [Crossref] [PubMed]
4. Carneiro MC, Chicrala GM, Freitas VM, et al. Assessment of mouth opening before and after head and neck radiotherapy in patients with intraoral stents. Rep Pract Oncol Radiother 2023;28:352-60. [Crossref] [PubMed]
5. Martins LJO, Borges AFS, Ferreira GZ, et al. Material Selection for Constructing an Intraoral Stent Used in Radiotherapy: Analysis of Density and Structure. J Adv Med Med Res 2016;16:1-6.