title: Five-year follow-up study of tooth extraction after nonsurgical endodontic treatment in a large population in Taiwan.
abstract: OBJECTIVE
  Nonsurgical retreatment, apical surgery and tooth extraction are three major untoward events following nonsurgical root canal treatment (NSRCT). The purpose of this study was to assess untoward events and total tooth extraction after NSRCT in a large population of dental patients in Taiwan.
  
  
  METHODS
  A total of 1,588,217 teeth treated with NSRCT in Taiwan in 2000 were analyzed for the first untoward event and total tooth extraction over a 5-year follow-up period.
  
  
  RESULTS
  The first untoward event occurred in 192,488 (12.1%) teeth within the first 5 years posttreatment. Nonsurgical retreatment was performed on 69,273 (36.0%) of these teeth, 4741 (2.5%) received apical surgery, and 118,474 (61.5%) were extracted. In addition, 1,463,312 (92.1%) teeth treated with NSRCT were retained in the oral cavity, and 124,905 (7.9%), including 24,499 (19.6%) anterior teeth, 33,356 (26.7%) premolars, and 67,050 (53.7%) molars were extracted within the 5 years of follow-up. Of these 124,905 teeth, 5869 (4.7%) were extracted after nonsurgical retreatment, 562 (0.4%) after apical surgery, and 118,474 (94.9%) after the first untoward events. There were significantly more molars (54.5% vs. 43.3%) and significantly fewer anterior teeth (19.0% vs. 27.5%) extracted in private clinics than in hospitals (p<0.001). The overall tooth extraction rate was significantly greater in hospitals (10.0%) than in private clinics (7.7%, p<0.001). However, tooth extraction procedures were almost evenly distributed over the 5-year follow-up period, with the annual incidence being close to 20%. The overall mean tooth extraction time was significantly greater in private clinics (2.52+/-1.43 years) than in hospitals (2.29+/-1.50 years, p<0.001).
  
  
  CONCLUSIONS
  We conclude that tooth extraction (61.5%) is the most common of the three untoward events, and approximately 95% of tooth extractions are performed at the time of the first untoward event. NSRCT is still a valuable dental procedure in Taiwan because of the high rate (92.1%) of tooth retention after 5 years of follow-up.
authors.affiliation: Department of Health, The Executive Yuan, Elite Dental Clinic, Department of Public Health, College of Public Health, National Taiwan University, Taipei, Taiwan.
authors.forename: Shih-Chung
authors.initials: SC
authors.lastname: Chen
authors.forename: Ling-Huey
authors.initials: LH
authors.lastname: Chueh
authors.forename: Hsin-Ping
authors.initials: HP
authors.lastname: Wu
authors.forename: Chuhsing Kate
authors.initials: CK
authors.lastname: Hsiao
mesh_terms: D005500:Follow-Up Studies; D006801:Humans; D012390:Root Canal Therapy / Q000379:methods*; D014081:Tooth Extraction