Analysis of Cause of Endodontic Failure of C-Shaped Root Canals

Figure 4

Representative photos of various causes of endodontic failure of C-shaped root canals. (a1) Calcified canal: preoperative periapical radiography. (a2) Root-resected surface of calcified C-shaped root canals. (b1) File separation: preoperative periapical radiography. (b2) Postoperative periapical radiography. (c1) Leaky canal. (c2) Retrograde filling with MTA. (d1) Isthmus connecting mesial and distal canals. (d2) Retrograde filling with MTA. (e1, e2) Overfilling: overextended gutta-percha. (f) Missing canal: only the mesiolingual canal is filled with gutta-percha in the mandibular left second molar. (g) Missing canal: only the palatal canal is filled with gutta-percha in the maxillary right first molar.