Image distortion in stationary intraoral tomosynthesis from different high-density materials

To evaluate the shape distortion of five high-density dental materials across buccal slices (BS), central slices (CS), and lingual slices (LS) reconstructed by the Portray 3D stationary intraoral tomosynthesis (sIOT) device and compare with those observed in periapical radiography (PA).

Cylindrical specimens (5.5 × 5.5 mm) of amalgam, cobalt-chromium alloy, gutta-percha, titanium, and zirconia were fabricated and positioned in a standardized phantom, with their long axis perpendicular to the image receptor. Images were acquired using the sIOT device, producing BS, CS, and LS; PA images were also obtained. Eight equally distributed radii of each cylinder were measured using ImageJ software. Shape distortion was assessed by comparing measured radii across imaging modalities and to actual dimensions. Two one-way repeated-measures ANOVAs with Sidak post-hoc tests (α = 0.05) were used to analyze (1) differences among imaging modalities, and (2) variations among sIOT slices.

sIOT showed significant distortion compared to PA across all materials. CS most closely approximated actual dimensions, while BS and LS consistently underestimated radii. PA preserved cylindrical shape, whereas sIOT reconstructions displayed radial nonuniform distortion patterns.

sIOT slices consistently produced lower mean radius values than PA, indicating a tendency to minify rather than magnify images. Distortion was most pronounced in peripheral slices, reflecting a nonuniform shrinkage effect. These findings underscore sIOT's limitations in preserving the shape of high-density objects.