Effect of Simulated Soft-Tissue Edema on Ultrasonographic Detection of Nondisplaced Dentoalveolar Fractures: An Ex Vivo Animal Model Study

Objectives: This single-blinded ex vivo diagnostic accuracy study evaluated high-frequency ultrasonography for detecting nondisplaced dentoalveolar fractures and assessed the effect of simulated post-traumatic soft-tissue edema. Methods: Eighteen fresh sheep heads provided 108 anatomically distinct sites (54 fractured and 54 non-fractured controls). Two blinded oral and maxillofacial radiologists independently assessed each site, yielding 216 observer-level evaluations. Cone-beam tomography (CBCT) served as the reference standard. Edema was simulated by submucosal injection of 0.5, 1.0, or 1.5 mL sterile saline. Results: Simulated edema was associated with significantly lower odds of correct ultrasonographic classification in the GEE analysis accounting for within-site clustering (OR = 0.217; 95% CI, 0.096–0.491; p < 0.001). Accuracy decreased from 87.0% to 59.3%, sensitivity from 96.3% to 77.8%, and specificity from 77.8% to 40.7%. False-negative and false-positive rates increased from 3.7% to 22.2% and from 22.2% to 59.3%, respectively. Observer confidence also decreased significantly (3.53 ± 0.90 vs. 2.61 ± 0.86; p < 0.001). No statistically significant differences in diagnostic accuracy were detected among the three edema-volume groups. Conclusions: Simulated soft-tissue edema substantially impairs ultrasonographic detection of nondisplaced dentoalveolar fractures. These experimental findings suggest that negative ultrasonographic findings obtained in the presence of soft-tissue swelling should be interpreted cautiously, with complementary imaging considered when clinically indicated.