Creating customized oral stents for head and neck radiotherapy using 3D scanning and printing

Abstract

Background To evaluate and establish a digital workflow for the custom designing and 3D printing of mouth opening tongue-depressing (MOTD) stents for patients receiving radiotherapy for head and neck cancer. Methods We retrospectively identified 3 patients who received radiation therapy (RT) for primary head and neck cancers with MOTD stents. We compared two methods for obtaining the digital impressions of patients’ teeth. The first method involved segmentation from computed tomography (CT) scans, as previously established by our group, and the second method used 3D scanning of the patients’ articulated stone models that were made during the conventional stent fabrication process. Three independent observers repeated the process to obtain digital impressions which provided data to design customized MOTD stents. For each method, we evaluated the time efficiency, dice similarity coefficient (DSC) for reproducibility, and the 3D printed stents’ accuracy. For the 3D scanning method, we evaluated the registration process using manual and automatic approaches. Results For all patients, the 3D scanning method demonstrated a significant advantage over the CT scanning method in terms of time efficiency with over 60% reduction in time consumed ( p < 0.0001) and reproducibility with significantly higher DSC ( p < 0.001). The printed stents were tested over the articulated dental stone models, and the trueness of fit and accuracy of dental anatomy was found to be significantly better for MOTD stents made using the 3D scanning method. The automated registration showed higher accuracy with errors < 0.001 mm compared to manual registration. Conclusions We developed an efficient workflow for custom designing and 3D-printing MOTD radiation stents. This workflow represents a considerable improvement over the CT-derived segmentation method. The application of this rapid and efficient digital workflow into radiation oncology practices can expand the use of these toxicity sparing devices to practices that do not currently have the support to make them. Electronic supplementary material The online version of this article (10.1186/s13014-019-1357-2) contains supplementary material, which is available to authorized users.

Individualized 3D-Printed Tissue Retraction Devices for Head and Neck Radiotherapy

“…For the TRD design presented here, the concept of customizing pre-fabricated structures was selected over producing fully individual appliances for each patient. This decision was based on a study which compared fabrication time and accuracy of fit of two fully individual TRD types based on i) segmented CT scans and ii) optical stone models scans ( 13 ). Regarding fabrication time, CT segmentation alone required, on average, 40 min, while optical scanning and model registration required a minimum of approximately 20 min.…”

“…The clinical application of novel CAD/CAM-based TRDs was assessed in an individual approach in 10 patients undergoing radiotherapy of head and neck tumors. These devices are not limited to either tongue depression ( 11 , 13 ) or tongue lateralization ( 10 ), but they allow—in only a single printing design—caudal or bi-lateral tongue displacement, and stabilization of a tongue-out position. In this study, tongue retraction was quantified using volumetric analysis of the irradiation plans.…”

Three-Dimensional Printed Silicone Bite Blocks for Radiotherapy of Head and Neck Cancer—A Preliminary Study

“…According to different origins of HNC, depressors or elevators were used to reduce incidental exposure of the tongue and healthy structures during RT [20]. These kinds of 3D printed bite blocks were manufactured recently, and their clinical use is still being investigated and evaluated [21][22][23].…”

The impact of tongue-deviating and tongue-depressing oral stents on long-term radiation-associated symptoms in oropharyngeal cancer survivors

“…While patient-specific custom oral stents, fabricated by our dental oncologists, are commonly used at our center for the treatment of OPC based on the aforementioned rationale and the demonstrated dosimetric advantages [8][9][10][11][12][13][14], the use of custom oral stents may not be routinely used in many radiation oncology practices owing to availability of dental expertise/resources or lack of studies demonstrating clinical benefit in terms of late toxicity reduction. In recent years, pre-fabricated commercial stent products became available and stent fabrication became easier and less time consuming with the innovation of 3D printers [15][16][17]. However, 3D printers in hospitals are still not common devices.…”