Long-term Outcome of Patients with Persistent Pain Following Root Canal Treatment: The National Dental Practice-Based Research Network

Abstract

About 10% of patients report persistent pain 6 months after root canal treatment (RCT). Little is known about the longer-term outcomes of such patients, their additional care, or factors associated with chronification of their persistent pain. We aimed to measure the longer-term outcomes of patients found to have persistent pain at 6 months and assess for characteristics that differed among patients whose persistent pain continued at 3-years post-RCT versus those whose pain resolved. Finally, we explored long-term pain outcomes of the available specific diagnoses that had been derived for the persistent pain at 6 months after RCT. Forty-five patients previously found to have persistent pain 6 months following RCT from the National Dental Practice Based Research Network were approached for a 3-year follow-up, and 27 participated (60%) in the survey. Frequency of self-reported pain (occurring ≥1day(s) in the past month with an average intensity of ≥1/10), its impact on the ability to carry out daily activities, and additional utilization of healthcare were measured. Differences in patient-, pain-, tooth-, dentist-related characteristics were assessed between those patients who continued to experience persistent pain and those whose pain resolved by the 3-year follow-up. Pain outcomes were also assessed in the light of the specific diagnoses derived for the persistent pain by a board-certified endodontist and an orofacial pain practitioner at 65±41 days (~8 months) post-RCT using the data available from the nested study on patients in Midwest region. Five (19%) patients met criteria for pain at 3.4 years (range: 3.1-3.9) post-RCT, which was moderate in intensity, occurred for about 3 days in the preceding month, and for only one patient, kept them from usual activities and work. Patients whose persistent pain resolved since 6-month follow-up received similar amounts of additional care within each follow-up time window as those whose pain continued. Yet, cumulatively over the 3 years, 4/5 (80%) patients whose pain continued received dental care with no reduction in average pain intensity. Longer duration of pre-operative pain and higher intensity and interference of persistent pain at 6 months were found among patients with pain chronification. Specific diagnoses for the persistent pain at 6 months after RCT were available for 15/27 (56%) patients and included odontogenic (6), temporomandibular disorder (TMD) (5), mixed odontogenic-TMD (1), persistent dento-alveolar pain disorder (1), and pain-free by the time of evaluation (2). Ten (77%) out of the 13 examined patients improved over the 3 years regardless of the diagnosis or treatment. Eleven (85%) of them had TMD and/or headache either as co-morbid unrelated diagnoses (6, 46%) or the causes (6, 46%) of the persistent tooth pain. Chronicity of persistent pain at 3 years post-RCT was infrequent. Most patients improved without additional treatments, and those who received additional care did not necessarily have reduced pain. Our preliminary study indicates that chronification of pain may be associated with characteristics previously identified to be related to chronification of pain. Patients presenting for initial RCT and suffering persistent pain after it might need to be carefully evaluated and managed for various orofacial pain conditions mimicking or co-existing with odontogenic pain to improve short- and long-term treatment outcomes.