Figure 16.

Because two-dimensional imaging suffers from superimposition of anatomic structures, determination of the extent and pathogenesis of periradicular lesions can present diagnostic challenges. This is particularly true of the maxillary posterior region, where the roots of teeth overlap and anatomic structures form complex patterns. A patient presented with discomfort in the maxillary right that extended from the nose to the ear. On clinical examination buccal swelling and induration were present—all teeth tested vital except the maxillary right first molar. A periapical radiograph (a) demonstrated areas of low density at the apices of the maxillary right first and second molars. CBCT images ((b) 10 mm curved planar, (c) axial, (d) sagittal, (e) cross-sectional) however demonstrated a much more extensive (21.4 mm maximum length) unilocular lesion, centered on the palatal root of the maxillary first molar, and extending anteriorly to the second bicuspid and posteriorly to the second molar. Also note the large internal resorptive lesion at the mid-palatal root of the maxillary first molar, not visible on the periapical radiograph. Biopsy confirmed the lesion to be a periapical granuloma with abscess formation.