Efficacy of four local anaesthesia protocols for mandibular first molars with symptomatic irreversible pulpitis: A randomized clinical trial

Aim: To examine the efficacy rate of four anaesthetic protocols in mandibular first molars with symptomatic irreversible pulpitis (SIP). Methodology: One hundred and sixty patients with a diagnosis of SIP were included in this randomized clinical trial. Patients were randomly allocated into four treatment groups (N = 40) according to the administered technique: Group 1 (IANB): standard inferior alveolar nerve block (IANB) injection; Group 2 (IANB + IO): standard IANB followed by a supplemental intraosseous infusion (IO) injection; Group 3 (IANB + PDL): standard IANB followed by a supplemental periodontal ligament (PDL) injection; Group 4 (IANB + BI): standard IANB followed by a supplemental buccal infiltration. Patients rated pain intensity using a verbal rating scale when the root canal treatment procedure was initiated, that is, during caries removal, access preparation and pulpectomy. Heart rate changes were recorded before, during and after each injection. The anaesthetic efficacy rates were analysed using chi-square tests, age differences using one-way anova, gender differences using Fischer Exact tests whilst heart rate changes were analysed using Kruskal–Wallis tests. Statistical significances were set at p <.05 level. Results: All the included patients were analysed. No differences in the efficacy rate were found in relation to the age or gender of the participants amongst the study groups (p >.05). IANB + IO injections had a significantly higher efficacy rate (92.5%) when compared to other techniques (p <.05), followed by IANB + PDL injections (72.5%), IANB + BI injections (65.0%), with no significant differences between the IANB + PDL or IANB + BI injections (p >.05). IANB injection alone had a significantly lower rate (40%) compared to the other techniques (p <.05). A transient but significant rise in the heart rate was recorded in 60% (24/40) of patients who received the IANB + IO injection compared to other groups (p <.05). Conclusions: Inferior alveolar nerve block injection alone did not reliably permit pain-free treatment for mandibular molars with SIP. The use of an additional IO supplemental injection provided the most effective anaesthesia for patients requiring emergency root canal treatment for SIP in mandibular posterior teeth.