PMC5514811_01
(a and b) Clinical photograph and intraoral periapical radiograph. (c) Cone-beam computed tomography scan axial slices, i - At the level of the pulpal floor showing five distinct canal orifices, ii - At the cementoenamel junction showing Y-shaped canal anatomy, iii - 1.2 mm apical to the cementoenamel junction showing J-shaped canal anatomy, iv - 4 mm apical to the cementoenamel junction showing three separate canals, v - 6.5 mm apical to the cementoenamel junction showing four separate canals, vi - Apical portion of the root showing three portals of exit. (d-i-vi) Diagrammatic representation of the complex root canal anatomy at different axial levels corresponding to the cone-beam computed tomography scan slices
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F1
In addition, the crown morphology was found to be abnormal [Figure 1a]. Intraoral periapical radiograph revealed a periapical radiolucency of about 4 mm with localized bone loss along the distal aspect of the tooth [Figure 1b]. At the beginning of the floor of the pulp chamber, five separate canal orifices were seen; three round orifices of the mesiobuccal, mesiolingual, and distolingual canals, one oval-shaped orifice of the mesial paramolar tubercle canal, and a teardrop-shaped orifice formed by the fusion of the distal paramolar tubercle and the distobuccal canals [Figure 1c-i]. At the cementoenamel junction (CEJ), a "Y-" shaped root canal anatomy was observed [Figure 1c-ii]. The curved portion of the J-shaped canal was formed by the communication between the mesiobuccal, mesiolingual, and distolingual canals, and the straight arm of the "J" was formed by the fusion of the mesial tubercle, distal tubercle, and the distobuccal canals [Figure 1c-iii]. Beyond this, the canal anatomy changed into three separate canals (mesiobuccal, mesiolingual, and a ribbon-shaped outline formed by the fusion between the mesial tubercle canal, distal tubercle canal, and the distobuccal canal) [Figure 1c-iv]. The canal anatomy further changed into four canals, 6.5 mm from the CEJ [Figure 1c-v]. Finally, at the apex, three portals of exits were seen; two from the main tooth and one from the tubercle [Figure 1c-vi]. Diagrammatic representation of the canal pattern is shown in Figure 1d-i-d-vi.