Effect of Pain Experienced During Previous Endodontic Treatment on Success Rate of Inferior Alveolar Nerve Block in Molars with Symptomatic Pulpitis

Introduction: Despite all efforts and various studies on reasons for and factors affecting a lack of success in inferior alveolar nerve block, profound pulpal anesthesia is often difficult in mandibular molars during endodontic treatment. The aim of this study was to investigate the effect of pain experienced during previous endodontic treatment on success rate of inferior alveolar nerve block (IANB).Materials & Methods: In this cross-sectional study, 100 healthy adult patients with a diagnosis of symptomatic pulpitis in their first mandibular molar were selected and questioned about experience of pain during previous root canal therapy. Each patient received two mandibular nerve block injections by one operator. If lip numbness happened after 15 minutes, endodontic treatment was initiated. During the treatment, the patients were asked to rate the pain during access cavity preparation or upon insertion of the initial file into the root canal on Heft-Parker visual analog scale (VAS). Success was defined as no or mild pain during treatment. The initial pain was analyzed with Mann-Whitney test; age was analyzed with t-test; and success of anesthesia and gender were analyzed with chi-squared test. Statistical significance was set at p value < 0.05.Results: The success rate for the IANB was 30% in the group with pain experience and 74.3% in the group without pain experience during previous endodontic treatment, with significantly higher success rate in the group with no previous pain experience (p value < 0.001).Conclusion: There was a significant relationship between pain experienced during previous endodontic treatment and a lack of success of IANB.Key words: Inferior alveolar nerve block, Pain experience, Symptomatic pulpitis.