A prospective parallel design study testing non-inferiority of customized oral stents made using 3D printing or manually fabricated methods

Background and purpose: Customized mouth-opening-tongue-depressing-stents (MOTDs) may reduce toxicity in patients with head and neck cancers (HNC) receiving radiotherapy (RT). However, making MOTDs requires substantial resources, which limits their utilization. Previously, we described a workflow for fabricating customized 3D-printed MOTDs. This study reports the results of a prospective trial testing the non-inferiority of 3D-printed to standard and commercially-available (TruGuard) MOTDs as measured by patient reported outcomes (PROs). Materials and methods: PROs were collected at 3 time points: (t1) simulation, (t2) prior to RT, (t3) between fractions 15-25 of RT. Study participants received a 3D-printed MOTDs (t1, t2, t3), a wax-pattern (t1), an acrylic-MOTDs (t2, t3) and an optional TruGuard (t1, t2, t3). Patients inserted the stents for 5-10 min and completed a PRO-questionnaire covering ease-of-insertion and removal, gagging, jaw-pain, roughness and stability. Inter-incisal opening and tongue-displacement were recorded. With 39 patients, we estimated 90% power to detect a non-inferiority margin of 2 at a significance level of 0.025. Matched pairs and t-test were used for statistics. Results: 41 patients were evaluable. The 3D-printed MOTDs achieved a significantly better overall PRO score compared to the wax-stent (p = 0.0007) and standard-stent (p = 0.0002), but was not significantly different from the TruGuard (p = 0.41). There was no difference between 3D-printed and standard MOTDs in terms of inter-incisal opening (p = 0.4) and position reproducibility (p = 0.98). The average 3D-printed MOTDs turnaround time was 8 vs 48 h for the standard-stent. Conclusions: 3D-printed stents demonstrated non-inferior PROs compared to TruGuard and standard-stents. Our 3D-printing process may expand utilization of MOTDs.