This study evaluates the efficacy of digital radiography and ultrasound (USG) for the distinction between periapical cysts and granulomas, determines the nature and extent of the periapical lesion, visualizes the lumen of the lesion, assesses its size, content, and vascularity. Material and MethodsThirty patients, ages 18 to 40, with well-defined periapical radiolucencies on maxillary or mandibular teeth, indicated for the extraction or periapical surgery, underwent digital radiography examination using the paralleling technique, followed by USG examination. A sonologist evaluated the lesions' size, echogenicity, and vascular content. The diagnosis was compared to histopathological examinations of tissues obtained through extraction or periapical surgery. ResultsThe diagnostic value of USG compared to the histopathological diagnosis of the periapical cyst was greater than that of the radiographic diagnosis, with an ultrasonographic diagnostic sensitivity (SN) value of 60% and a radiographic diagnostic SN value of 40%, respectively. The diagnostic value of USG imaging against the histopathological diagnosis of periapical granuloma was slightly lower than that of digital radiography, with an SN value of 72.2% for USG and 83.33% for digital radiography. However, the specificity (SP) value and precision of USG imaging were superior to those of digital radiographic diagnosis. USG imaging and radiographic diagnosis had 58.33% and 50% SP values, respectively. In cases of periapical abscess, the diagnostic values of USG against histopathological diagnosis were lower than those of radiographic diagnosis, which had an SN value of 100%. ConclusionUSG with color doppler is a more effective tool than digital radiography for diagnosing periapical lesions. The echo structure of the lesions and the presence of vascularity on USG with color doppler correlated with histopathology better than the radiological diagnosis.