Evaluation of foreign bodies in the maxillofacial region with cone beam computed tomography and ultrasonography: an ex vivo study.

BACKGROUND: When foreign bodies in the human body are not diagnosed (detected), it can cause various inflammatory reactions. Therefore, they should be detected and removed immediately. Taking a detailed patient history, performing a clinical examination, and selecting the appropriate imaging method are important for detection. The location, structure, and size of the foreign body affect the choice of radiography technique. This study aims to compare the detectability, measurement accuracy, and acoustic behaviors of various foreign bodies in the maxillofacial region using Cone Beam Computed Tomography (CBCT) and Ultrasonography (US) under ex vivo conditions. METHODS: Foreign bodies (wood, amalgam, glass, tooth, graphite, composite, plastic, and stone) and orthodontic materials (Elgiloy wire, TMA wire, stainless steel wire, stainless steel bracket, and ceramic bracket) with different sizes were placed on the mandibular cortical bone and in the tongue of a sheep's head. Foreign bodies' visibility and diameter measurements were made with CBCT and US. Data were statistically analyzed using the Wilcoxon rank-order test, the Friedman test, and the Pearson correlation coefficient. RESULTS: CBCT demonstrated superior inter- and intra-observer agreement, while the US exhibited higher sensitivity (95.4%) in detecting foreign bodies. CBCT failed to visualize plastic and wood, whereas the US successfully detected all materials. Larger foreign bodies could be detected more easily with both imaging methods. There was no statistically significant difference between the diameters of the foreign bodies measured on CBCT and US and their actual diameters (p > 0.05). Posterior acoustic enhancement was detected in glass, amalgam, stainless steel wire, and stainless steel brackets, while posterior acoustic shadowing was observed in teeth, composite, plastic, and stone. CONCLUSIONS: CBCT is optimal for radiopaque foreign body detection, whereas the US excels in identifying radiolucent materials. All foreign bodies could be visualized with US, wood and plastic could not be observed with CBCT. As the size of the foreign body increased, it could be observed more clearly on both CBCT and US. The foreign body sensitivity of the US was higher than that of the CBCT. These findings suggest that CBCT is preferable for identifying metalic and dense radiopaque foreign bodies, while the US may be beneficial in detecting radiolucent materials such as wood and plastic.