title: The prognosis of root canal therapy: a 10-year retrospective cohort study on 411 patients with 1175 endodontically treated teeth.
abstract: OBJECTIVE
  To evaluate the 10-year prognosis of consecutively endodontically treated or retreated teeth and to investigate some of the prognostic factors which could predict the long-term outcome of endodontic therapy.
  
  
  METHODS
  This retrospective cohort study included any patient who had endodontically treated or retreated teeth from 1986 to 1998 by a single operator in a private practice. Outcome measures were clinical and radiographic success assessed by the operator, radiographic success assessed by an independent outcome assessor and complications evaluated 10 years after treatment. Descriptive statistics, life table, Kaplan-Meier and Cox regression analyses for success were fitted.
  
  
  RESULTS
  A total of 411 patients with 1175 endodontically treated teeth were identified. Ten years after treatment 102 patients (24.8%) with 223 (19.0%) teeth were lost at the follow-up. The number of teeth that were originally treated and retreated were 704 and 471, respectively. Thirty-two teeth (2.7%) had one complication, which was successfully treated. A total of 988 (84.1%) teeth were considered a complete success, 46 (3.9%) a partial success, 52 (4.4%) a partial failure and 68 (5.8%) had to be extracted according to the treating clinician. For 21 teeth (1.8%) there was no follow-up information. The radiographic healing of 1086 teeth was evaluated by an independent assessor: 980 (90.2%) showed complete healing, 52 (4.8%) improvement, and 54 (5.0%) no change or worsening. The life-table analysis showed 93% of teeth surviving at 10 years after endodontic treatment. There were no differences for survival rates between teeth treated for the first time and those that were retreated (Kaplan-Meier). Teeth retreated because of symptoms or for a periapical/lateral radiolucency were more likely to fail.
  
  
  CONCLUSIONS
  Approximately 7% of endodontically treated teeth were extracted 10 years after treatment. Symptoms and radiolucency of teeth needing retreatment may be important predictors for failure.
authors.affiliation: Udine, Italy. federica.fonzar@studiofonzar.it
authors.forename: Federica
authors.initials: F
authors.lastname: Fonzar
authors.forename: Alberto
authors.initials: A
authors.lastname: Fonzar
authors.forename: Piercarlo
authors.initials: P
authors.lastname: Buttolo
authors.forename: Helen V
authors.initials: HV
authors.lastname: Worthington
authors.forename: Marco
authors.initials: M
authors.lastname: Esposito
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D015331:Cohort Studies; D019232:Dental Restoration Failure; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D015993:Life Tables; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010485:Periapical Periodontitis / Q000000981:diagnostic imaging / Q000628:therapy*; D011379:Prognosis; D016016:Proportional Hazards Models; D011859:Radiography; D012189:Retrospective Studies; D012390:Root Canal Therapy / Q000706:statistics & numerical data*; D014081:Tooth Extraction; D017211:Treatment Failure; D055815:Young Adult