Multiple factors, including fear, appeared to be associated with local anesthesia failure during nonsurgical endodontic treatment, according to a new study published in the International Endodontic Journal.
Therefore, patients presenting with several clinical risk factors should undergo fear screenings before treatment, and anesthetic strategies should be pursued proactively, the authors wrote.
“An informed approach that includes an effective two-way interaction, effective listening, and asking permission before initiating treatment steps, has been shown to improve trust and support,” wrote the study's lead author, Dr. Ronald Ordinola-Zapata, MS, PhD, of the University of Minnesota (Int Endod J, May 18, 2026).
Despite ongoing improvements in anesthetic drugs and delivery methods, local anesthesia failure continues to pose a major clinical challenge. Without sufficient anesthesia, patients may experience pain and lose confidence in dental treatment, which can compromise treatments and patients' lifelong attitudes toward oral health. Recognizing the factors behind these failures is essential to enhancing patient care in endodontics.
To identify factors linked to local anesthesia failure during nonsurgical endodontic treatment, data were collected from 1,704 patients from the National Dental Practice-Based Research Network study "Predicting Outcomes of Root Canal Treatment (PREDICT),” according to the study.
Local anesthesia failure during treatment was defined as patient-reported pain of 3 or more on a 0- to 10-point scale. Pretreatment factors included patient demographics, psychosocial constructs, and pretreatment clinical findings, including abnormal sensitivity to cold and biting. After adjusting for clustering with generalized estimating equations, characteristics with a p-value of < 0.1 were entered into a model to identify independent associations linked with failed anesthesia.
Of the patients, 16% reported local anesthesia failure, the authors wrote. Multiple factors were linked with failure. These factors were:
- Age; specifically being < 55 years old (p = 0.05)
- Dental treatment fear (p = 0.005)
- Treatment of mandibular teeth (p = 0.005)
- Greater numbers of abnormal pretreatment clinical findings (p = 0.02)
Furthermore, there were protective factors, like undergoing endodontic treatment by an endodontist (p = 0.002), the authors wrote.
However, the study had multiple limitations, including that the study design did not allow for causal inference, they wrote.
“These findings support pre-treatment fear screening and proactive anaesthetic strategies in patients presenting with multiple clinical risk factors,” Ordinola-Zapata and colleagues wrote.
