title: Comparative assessment of the incidence of vertical root fractures between conventional versus surgical endodontic retreatment.
abstract: OBJECTIVE
  Vertical root fractures (VRFs) are a common cause of tooth loss. Little evidence exists though, relating the incidence of VRFs to the type of endodontic retreatment. This retrospective study aimed at evaluating the impact of conventional versus surgical endodontics on root canal-filled teeth with VRFs.
  
  
  METHODS
  Over a period of 13 years, 200 endodontically retreated teeth from 192 patients with VRFs were extracted and further examined. VRFs were assessed in relation to age, gender, tooth group, clinical signs, extension on the root surface, patency, as well as type of endodontic retreatment and restoration. Statistical analysis was conducted using a Cox PH Model, Chi-squared, Wilcoxon rank-sum, and Log rank tests at a significance level of 5 %.
  
  
  RESULTS
  The majority of teeth with VRFs (62.31 %) had undergone the combination of conventional root canal retreatment and apical surgery. Women (64.06 %) presented VRFs more frequently than men (35.94 %) at the mean age of 51.1 and 55.1 years, respectively. Maxillary first (17.5 %) and second (16.5 %) premolars, restored by a resin-based material without a post (56.28 %) were more susceptible to VRFs. Apically initiated (84.1 %) VRFs could be diagnosed more easily on radiographs.
  
  
  CONCLUSIONS
  The type of endodontic treatment strongly correlated with VRFs. The prevalence of VRFs in teeth having undergone both conventional and surgical endodontic retreatment could be attributed, among others, to additive dentin damage related to the aforementioned endodontic procedures.
  
  
  CONCLUSIONS
  The possible involvement of endodontic retreatment in the multifactorial etiology of VRFs needs to be taken into consideration in clinical practice.
authors.affiliation: Department of Operative Dentistry and Periodontology, Center for Dental Medicine, Medical Center, University of Freiburg, Hugstetterstrasse 55, Freiburg, 79106, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Karygianni
authors.forename: M
authors.initials: M
authors.lastname: Krengel
authors.forename: M
authors.initials: M
authors.lastname: Winter
authors.forename: S
authors.initials: S
authors.lastname: Stampf
authors.forename: K T
authors.initials: KT
authors.lastname: Wrbas
mesh_terms: D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012390:Root Canal Therapy / Q000009:adverse effects* / Q000379:methods; D014082:Tooth Fractures / Q000209:etiology*