title: Genetic Variants in Cyclooxygenase-2 Contribute to Post-treatment Pain among Endodontic Patients.
abstract: BACKGROUND
  Nonsteroidal anti-inflammatory drugs (NSAIDs) have a well-established analgesic efficacy for inflammatory pain. These drugs exert their effect by inhibiting the enzyme cyclooxygenase (COX) and are commonly used for the management of pain after endodontic treatment. There are 2 distinct isoforms of COX: COX-1, which is constitutively expressed, and COX-2, which is primarily induced by inflammation. Previous studies have shown that functional human genetic variants of the COX-2 gene may explain individual variations in acute pain. The present study extends this work by examining the potential contribution of the 2 COX isoforms to pain after endodontic treatment.
  
  
  METHODS
  Ninety-four patients treated by endodontic residents at the University of North Carolina School of Dentistry were enrolled into a prospective cohort study. Data on potential predictors of post-treatment pain were collected, and all patients submitted saliva samples for genetic analysis. Nonsurgical root canal therapy was performed, and participants recorded pain levels for 5 days after.
  
  
  RESULTS
  In this study, 63% of patients experienced at least mild pain after root canal therapy, and 24% experienced moderate to severe pain. The presence of pretreatment pain was correlated with higher post-treatment pain (P = .01). Elevated heart rate (P = .02) and higher diastolic blood pressure (P = .024) were also correlated with decreased post-treatment pain. Finally, we identified genetic variants in COX-2 (haplotype composed of rs2383515 G, rs5277 G, rs5275 T, and rs2206593 A) associated with post-treatment pain after endodontic treatment (P = .025).
  
  
  CONCLUSIONS
  Understanding the genetic basis of pain after endodontic treatment will advance its prevention and management.
authors.affiliation: Private Practice, School of Dentistry, University of North Carolina, Chapel Hill, North Carolina.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Applebaum
authors.affiliation: Center for Pain Research and Innovation, School of Dentistry, University of North Carolina, Chapel Hill, North Carolina.
authors.forename: Andrea G
authors.initials: AG
authors.lastname: Nackley
authors.affiliation: Center for Pain Research and Innovation, School of Dentistry, University of North Carolina, Chapel Hill, North Carolina.
authors.forename: Eric
authors.initials: E
authors.lastname: Bair
authors.affiliation: Center for Pain Research and Innovation, School of Dentistry, University of North Carolina, Chapel Hill, North Carolina.
authors.forename: William
authors.initials: W
authors.lastname: Maixner
authors.affiliation: Center for Pain Research and Innovation, School of Dentistry, University of North Carolina, Chapel Hill, North Carolina. Electronic address: Asma_Khan@unc.edu.
authors.forename: Asma A
authors.initials: AA
authors.lastname: Khan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D051545:Cyclooxygenase 1 / Q000235:genetics*; D051546:Cyclooxygenase 2 / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D006239:Haplotypes; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009657:North Carolina; D010146:Pain / Q000201:enzymology* / Q000235:genetics* / Q000503:physiopathology; D020641:Polymorphism, Single Nucleotide; D015995:Prevalence; D011446:Prospective Studies; D012390:Root Canal Therapy / Q000009:adverse effects*; D014495:Universities; D055815:Young Adult
chemical_list: D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496511:PTGS1 protein, human; C496540:PTGS2 protein, human
keywords: Cyclooxygenase-1; cyclooxygenase-2; odontogenic; postoperative pain; single nucleotide polymorphism