Trail suggests rapid injection technique for inferior alveolar nerve block was more uncomfortable but more effective

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The aim of this study was to compare both the effectiveness of the anaesthesia and the pain with deposition between fast and slow inferior alveolar nerve block (IANB) injection techniques.

Patients attending a dental emergency department and requiring endodontic management were randomised to receive either fast (n=30) or slow (n=30) IANB injections using 3.6 mL of 2% lidocaine with 1:200,000 epinephrine. The slow injections were performed over 120 seconds the fast injections over 30 seconds with the needle being kept in place for another 90 seconds. After 15 minutes, if profound lip numbness was not recorded, the block was considered unsuccessful, and the patients were excluded from the study. Anaesthesia was considered a success if no pain or weak/mild pain during endodontic access preparation and instrumentation.

  • One patient receiving rapid injection did not have profound lip numbness at 15 minutes and was excluded from the study.
  • None of the techniques gave 100% success rate.
  • There was no significant difference between the anesthetic success rates of slow and rapid injections
  • Slow injections had a 43% success rate (13 /30 patients),
  • Rapid injections had a 51% success rate (15 /29 patients)
  • Slow injections produced less solution deposition pain than rapid injections with a mean visual analogue scale score of 73 ± 26 compared with 89± 23 for rapid injections.

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The authors concluded

the rate of injection has no effect on anaesthetic success of IANB of 3.6 mL of 2% lidocaine with 1:200,000 epinephrine. Slow injections were more comfortable and produced less pain than rapid injections.


Aggarwal V, Singla M, Miglani S, Kohli S, Irfan M. A Prospective, Randomized Single-blind Evaluation of Effect of Injection Speed on Anesthetic Efficacy of Inferior Alveolar Nerve Block in Patients with Symptomatic Irreversible Pulpitis. Journal of Endodontics ;in press ; Available online 27 September 2012



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