title: Analysis of the cause of failure in nonsurgical endodontic treatment by microscopic inspection during endodontic microsurgery.
abstract: BACKGROUND
  This study examined the clinical causes of failure and the limitation of a previous endodontic treatment by an inspection of the root apex and resected root surface at 26× magnification during endodontic microsurgery.
  
  
  METHODS
  The data were collected from patients in the Department of Conservative Dentistry at the Dental College, Yonsei University in Seoul, Korea between March 2001 and January 2011. All root-filled cases with symptomatic or asymptomatic apical periodontitis were enrolled in this study. All surgical procedures were performed by using an operating microscope. The surface of the apical root to be resected or the resected root surface after methylene blue staining was examined during the surgical procedure and recorded carefully with 26× magnification to determine the state of the previous endodontic treatment by using an operating microscope.
  
  
  RESULTS
  Among the 557 cases with periapical surgery, 493 teeth were included in this study. With the exclusion of unknown cases, the most common possible cause of failure was perceived leakage around the canal filling material (30.4%), followed by a missing canal (19.7%), underfilling (14.2%), anatomical complexity (8.7%), overfilling (3.0%), iatrogenic problems (2.8%), apical calculus (1.8%), and cracks (1.2%). The frequency of possible failure causes differed according to the tooth position (P < .001).
  
  
  CONCLUSIONS
  An appreciation of the root canal anatomy by using an operating microscope in nonsurgical endodontic treatment can make the prognosis more predictable and favorable.
authors: Microscope Center, Department of Conservative Dentistry, College of Dentistry, Yonsei University, Seoul, Korea.
authors: Minju
authors: M
authors: Song
authors: Hyeon-Cheol
authors: HC
authors: Kim
authors: Woocheol
authors: W
authors: Lee
authors: Euiseong
authors: E
authors: Kim
mesh_terms: D001424:Bacterial Infections / Q000601:surgery; D003748:Dental Equipment; D003763:Dental Leakage / Q000209:etiology / Q000601:surgery; D003786:Dental Pulp Cavity / Q000033:anatomy & histology; D019232:Dental Restoration Failure / Q000706:statistics & numerical data*; D005549:Foreign-Body Reaction / Q000601:surgery; D006801:Humans; D007049:Iatrogenic Disease; D008853:Microscopy; D008866:Microsurgery / Q000379:methods; D010485:Periapical Periodontitis / Q000601:surgery; D011842:Radicular Cyst / Q000601:surgery; D012390:Root Canal Therapy / Q000009:adverse effects*; D019227:Tooth Apex / Q000473:pathology* / Q000601:surgery