title: Frequency of nonodontogenic pain after endodontic therapy: a systematic review and meta-analysis.
abstract: BACKGROUND
  Little is known about ill-defined pain that persists after endodontic procedures, including an estimate of the problem's magnitude. We conducted a systematic review of prospective studies that reported the frequency of nonodontogenic pain in patients who had undergone endodontic procedures.
  
  
  METHODS
  Nonodontogenic pain was defined as dentoalveolar pain present for 6 months or more after endodontic treatment without evidence of dental pathology. Endodontic procedures reviewed were nonsurgical root canal treatment, retreatment, and surgical root canal treatment. Studies were searched in four databases electronically, complemented by hand searching. A summary estimate of nonodontogenic tooth pain frequency was derived using random-effects meta-analysis.
  
  
  RESULTS
  Of 770 articles retrieved and reviewed, 10 met inclusion criteria, and nine had data on both odontogenic and nonodontogenic causes of pain. A total of 3,343 teeth were enrolled within the included studies and 1,125 had follow-up information regarding pain status. We identified 48 teeth with nonodontogenic pain and estimated a 3.4% (95% confidence interval, 1.4%-5.5%) frequency of occurrence. In nine articles containing data regarding both odontogenic and nonodontogenic causes of tooth pain, 56% (44/78) of all cases were thought to have a nonodontogenic cause.
  
  
  CONCLUSIONS
  Nonodontogenic pain is not an uncommon outcome after root canal therapy and may represent half of all cases of persistent tooth pain. These findings have implications for the diagnosis and treatment of painful teeth that were previously root canal treated because therapy directed at the tooth in question would not be expected to resolve nonodontogenic pain.
authors: Division of TMD & Orofacial Pain, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA. nixdorf@umn.edu
authors: Donald R
authors: DR
authors: Nixdorf
authors: Estephan J
authors: EJ
authors: Moana-Filho
authors: Alan S
authors: AS
authors: Law
authors: Lisa A
authors: LA
authors: McGuire
authors: James S
authors: JS
authors: Hodges
authors: Mike T
authors: MT
authors: John
mesh_terms: D006801:Humans; D010149:Postoperative Pain / Q000209:etiology*; D011446:Prospective Studies; D012390:Root Canal Therapy / Q000009:adverse effects*; D014098:Toothache / Q000209:etiology*