Clinical and Psychosocial Predisposing Factors Associated With Anaesthesia Failure During Non‐Surgical Root Canal Treatment: A National Dental Practice‐Based Research Network Study

ABSTRACT Aim This study aimed to identify dentist, patient, and pre‐treatment clinical characteristics associated with local anaesthesia failure during non‐surgical endodontic treatment. Methodology Data were collected from the National Dental Practice‐Based Research Network study entitled “Predicting Outcomes of Root Canal Treatment (PREDICT)”, which included 1723 patients. Local anaesthesia failure during treatment was defined as patient‐reported pain of 3 or greater on a 0‐to‐10‐point scale. Pre‐treatment factors included patient demographics, psychosocial constructs, and pre‐treatment clinical findings (e.g., abnormal sensitivity to cold, biting, percussion, palpation). Characteristics with p < 0.1 (after adjustment for clustering with generalized estimating equations) were entered into a model to identify independent associations with failed anaesthesia, and odds ratios were calculated to measure the strength of these associations. Results A total of 16% of patients reported intra‐operative local anaesthesia failure. Failure was associated with patient age < 55 years ( p = 0.05), dental treatment fear (“some” to “extremely afraid”) ( p = 0.005), mandibular teeth ( p = 0.005), and greater numbers of abnormal pre‐treatment diagnostic findings ( p = 0.02). Protective factors included having treatment done by an endodontist ( p = 0.002), and the patient being non‐Hispanic White ( p = 0.007). Comparisons of local anaesthetic techniques by dentist type (general dentist vs. endodontist) showed statistically significant differences in the bivariate analysis, but none remained significant after adjustment for clustering of patients within dentist. Conclusions Local anaesthesia failed in 16% of cases. Pre‐treatment fear was the only significant psychosocial predictor of intra‐operative pain. Failure was more likely in mandibular teeth and when multiple abnormal tests were present pre‐operatively (e.g., cold sensitivity, percussion tenderness). Younger patients reported more pain, and endodontists had lower pain rates than general dentists.