Does the volume of supplemental intraligamentary injections affect the anaesthetic success rate after a failed primary inferior alveolar nerve block? A randomized-double blind clinical trial

AimTo investigate the efficacy of 0.2mL vs. 0.6mL of 2% lidocaine when given as a supplementary intraligamentary injection after a failed inferior alveolar nerve block (IANB). MethodologyNinety-seven adult patients with symptomatic irreversible pulpits received an IANB and root canal treatment was initiated. Pain during treatment was recorded using a visual analogue scale (Heft-Parker VAS). Patients with unsuccessful anaesthesia (n=78) randomly received intraligamentary injection of either 0.2mL or 0.6mL of 2% lidocaine with 1:80000 epinephrine. Root canal treatment was reinitiated. Success after primary injection or supplementary injection was defined as no or mild pain (HP VAS score 54mm) during access preparation and root canal instrumentation. Heart rate was monitored using a finger pulse oximeter. The anaesthetic success rates were analysed with Pearson chi-square test at 5% significance levels. The heart rate changes were analysed using t-tests. ResultsThe intraligamentary injections with 0.2mL solution gave an anaesthetic success rate of 64%, whilst the 0.6mL was successful in 84% of cases with failed primary IANB. ((2)=4.3, P=0.03). There was no significant effect of the volume of intraligamentary injection on the change in heart rate. ConclusionsIncreasing the volume of intraligamentary injection improved the success rates after a failed primary anaesthetic injection.