title: Twenty-year follow-up of root filled teeth in a Swedish population receiving high-cost dental care.
abstract: OBJECTIVE
  To study the 20-year survival rate and periapical status of root filled teeth in a Swedish population requiring high-cost dental care and to identify factors related to survival and normal periapical status at follow-up.
  
  
  METHODS
  The study population comprised 104 patients selected from four local health insurance districts with treatment plans including radiographs submitted for approval for reimbursement from the Swedish National Dental Insurance in 1977. In 1998, a clinical and radiographic follow-up examination was conducted, to register the status of 449 teeth identified as root filled at baseline. Differences in tooth survival and periapical status at follow-up, with reference to periapical status and quality of root filling at baseline, were analysed by chi-square tests. Multiple regression analysis was used to describe tooth survival and normal periapical status at follow-up, with the explanatory baseline variables: tooth type, type of restoration, type of post, quality of root filling, periapical status, marginal bone loss and caries. Differences were considered significant at a 5% level.
  
  
  RESULTS
  Two hundred and ninety (65%) of the root filled teeth survived at follow-up. Baseline variables associated with low odds for tooth survival were mandibular molar, maxillary premolar, prefabricated posts other than screw posts, severe marginal bone loss, caries and apical periodontitis (AP). Normal periapical status at follow-up was registered in 49% of the root filled teeth. Baseline variables associated with low odds for normal periapical status (high risk for AP) at follow-up were mandibular molar, maxillary premolar, AP, severe marginal bone loss and inadequate root filling quality. Of the root filled teeth with AP at baseline, 42% had been left untreated during the observation period, and at follow-up, the AP persisted in 57% of these teeth.
  
  
  CONCLUSIONS
  After 20 years, 65% of the root filled teeth had survived and one-third remained with a sound periapical condition, without any further treatment. Almost half of the APs registered at baseline were left without treatment, and more than half of them persisted after 20 years.
authors.affiliation: Department of Endodontics, Faculty of Odontology, Malmö University, Malmö, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Petersson
authors.affiliation: Department of Endodontics, Faculty of Odontology, Malmö University, Malmö, Sweden.
authors.forename: H
authors.identifier: http://orcid.org/0000-0003-4290-2283
authors.initials: H
authors.lastname: Fransson
authors.affiliation: Department of Endodontics, Faculty of Odontology, Malmö University, Malmö, Sweden.
authors.forename: E
authors.initials: E
authors.lastname: Wolf
authors.affiliation: Department of Periodontology, Institute of Odontology, University of Gothenburg, Gothenburg, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Håkansson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019232:Dental Restoration Failure / Q000191:economics / Q000706:statistics & numerical data; D005260:Female; D005500:Follow-Up Studies; D017048:Health Care Costs; D006801:Humans; D007347:Insurance, Dental / Q000191:economics* / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D012390:Root Canal Therapy / Q000191:economics*; D013548:Sweden; D055815:Young Adult
keywords: apical periodontitis; endodontics; epidemiology; follow-up studies; treatment outcome