Elsevier

Journal of Endodontics

Volume 41, Issue 8, August 2015, Pages 1214-1218
Journal of Endodontics

Clinical Research
Genetic Variants in Cyclooxygenase-2 Contribute to Post-treatment Pain among Endodontic Patients

https://doi.org/10.1016/j.joen.2015.04.021Get rights and content

Abstract

Introduction

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.

Section snippets

Study Participants

Patients were recruited from the University of North Carolina (UNC) at Chapel Hill School of Dentistry Graduate endodontic clinic. The inclusion criteria were patients of age ≥18 years old and American Society of Anesthesiologists class I or II. Patients who were taking corticosteroid medications and those unable to take ibuprofen were excluded from the study. This study was approved by our institutional review board, and written informed consent was obtained from all study participants.

Patient Characteristics

This study enrolled 69 subjects (39 men and 30 women) 18–85 years of age for whom we obtained baseline data, postoperative data, and salivary DNA. Subject demographics and baseline characteristics are displayed in Table 1. Of the 69 subjects, 48 were self-identified as white, 7 as black, 7 as Hispanic, 6 as Asian, and 1 as other. Only 12 subjects (17%) reported preoperative pain within the past 24 hours on the day of enrollment. Pulpal and periapical diagnoses varied across patients.

Discussion

We used a prospective cohort study to identify phenotypic, physiologic, and genetic factors that contribute to the incidence and intensity of postoperative pain after endodontic treatment. Among patients presenting to the UNC School of Dentistry for root canal treatment, the incidence and intensity of pain after nonsurgical root canal treatment reached its maximum within the first 24 hours of treatment, when 63% of patients reported pain (mean = 1.88 ± 0.28). Nearly 25% of patients reported day

Acknowledgments

Elizabeth Applebaum and Andrea G. Nackley contributed equally to this study.

The authors thank Dr Jason Lambert for his help.

Supported by the American Association of Endodontists Foundation to Elizabeth Applebaum, NIH/NINDS R01 NS072205 to Andrea G. Nackley, NIH/NINDS P01 NS045685 to William Maixner and Andrea G. Nackley, and NIH/NIDCR U01 DE017018 to William Maixner.

The authors deny any conflicts of interest related to this study.

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