title: Differential Diagnoses for Persistent Pain Following Root Canal Treatment: A Study in the National Dental PBRN.
abstract: BACKGROUND
  Pain present six months following root canal treatment (RCT) may be either of odontogenic or non-odontogenic origin. This is important because treatments and prognoses are different; therefore, the aim of this study was to provide specific diagnoses of patients reporting pain six months after receiving initial orthograde RCT.
  
  
  METHODS
  We enrolled patients from the Midwest region of an existing prospective observational study of pain after RCT. Pain at six months was defined as ≥ 1 day of pain and average pain intensity of at least 1/10 over the preceding month. An endodontist and an orofacial pain practitioner independently performed clinical evaluations, which included periapical and cone-beam computed tomograph (CT) radiographs, to determine diagnoses.
  
  
  RESULTS
  Thirty-eight out of the 354 eligible patients in the geographic area (11%) met the pain criteria, with 19 (50%) consenting to be clinically evaluated. As the sole reason for pain, 7 patients (37%) were given odontogenic diagnoses (4 involving the RCT tooth, 3 involving an adjacent tooth). Eight patients (42%) were given non-odontogenic pain diagnoses (7 from referred temporomandibular disorder [TMD] pain, 1 from persistent dentoalveolar pain disorder [PDAP]). Two patients (11%) had both odontogenic and non-odontogenic diagnoses, while 2 (11%) no longer fit the pain criteria at the time of the clinical evaluation.
  
  
  CONCLUSIONS
  Patients reporting "tooth" pain 6 months following RCT had a non-odontogenic pain diagnosis accounting for some of this pain, with TMD being the most frequent non-odontogenic diagnosis. Dentists should have the necessary knowledge to differentiate between these diagnoses to adequately manage their patients.
authors.forename: Donald R
authors.initials: DR
authors.lastname: Nixdorf
authors.forename: Alan S
authors.initials: AS
authors.lastname: Law
authors.forename: Mike T
authors.initials: MT
authors.lastname: John
authors.forename: Radwa M
authors.initials: RM
authors.lastname: Sobieh
authors.forename: Richie
authors.initials: R
authors.lastname: Kohli
authors.forename: Ruby H N
authors.initials: RH
authors.lastname: Nguyen