Relative transmitted‐dose reduction of 3D‐printed and elastomeric dental radiotherapy spacers at different thicknesses

Purpose To evaluate the radiation dose reduction of different materials for intraoral radiotherapy prostheses and spacers with different thicknesses. Materials and Methods Three additively manufactured resins—KeySplint Hard (3D‐Hard), Temporary CB Resin (3D‐TCB), and Saremco Print CROWNTEC (3D‐PCB)—and three elastomeric materials—putty‐type polyvinyl siloxane (PVS‐P), light‐body polyvinyl siloxane (PVS‐L), and polyether (PE)—were prepared with two thicknesses (5 and 10 mm, n = 5 per group). Rectangular specimens were fabricated and positioned over an ionization chamber in a solid–water phantom and measured 15 times with a 6 × 8 cm 2 field. The relative transmitted dose reduction was calculated against the bracketed no‐specimen reference values. Statistical analysis was done using two‐way analysis of variance followed by Games–Howell multiple comparisons. Results Material and thickness significantly affected the relative transmitted dose reduction ( p < 0.05), whereas their interaction was not significant ( p > 0.05). PVS‐P had significantly higher transmitted dose reduction than other materials, regardless of material thickness (3.50% ± 0.21% at 5 mm and 5.57% ± 0.43% at 10 mm). Among the additively manufactured resins, 3D‐PCB demonstrated higher transmitted dose reduction, where a significant effect was found at 10 mm thickness. At 5 mm, no significant difference was observed among three additively manufactured resins. However, at 10 mm, 3D‐PCB (3.83% ± 0.98%) produced significantly greater reduction than 3D‐Hard (3.06% ± 1.05%) and 3D‐TCB (3.13% ± 0.98%). For material thickness, the 10‐mm specimens produced greater reduction than the 5‐mm specimens. Conclusions Under the tested phantom and irradiation conditions, material and thickness influenced the relative transmitted‐dose reduction. The highest transmitted dose reduction was observed in PVS‐P. However, the effects were modest and thickness‐ dependent. These setup‐specific effects do not establish intrinsic material attenuation or clinical tissue protection.