23/03/2026
“Is 3.6-mL volume of an anesthetic agent more effective than 1.8-mL volume in providing anesthesia for mandibular molars?”
For patients with irreversible pulpitis , research indicates that increasing the volume of the anesthetic agent from 1.8 mL to 3.6 mL significantly improves the success rate of an inferior alveolar nerve block (IANB).
While 1.8 mL is a standard dose, studies on teeth with irreversible pulpitis have shown the following regarding the two volumes:
Success Rates: The success rate of 1.8 mL has been reported to be as low as 14.8% to 27.5%. Doubling that volume to 3.6 mL increased success rates to a range of 39.3% to 77.5%.
Effectiveness: A meta-analysis of these findings determined that 3.6 mL is 2.45 times more likely to result in successful anesthesia than 1.8 mL in these cases.
Biological Basis: The theory for this improvement is that a larger volume fills the pterygomandibular space more thoroughly, exposing a greater length of the nerve trunk to the anesthetic agent. This is particularly important for inflamed pulps, where nerves often have altered resting potentials and a reduced threshold for excitability.
Important Considerations for Clinical Practice:
Despite the improved performance of the 3.6-mL dose, the sources highlight that the overall success rate for achieving profound anesthesia in these teeth remains low. Even with larger volumes, the "hot tooth" is notoriously difficult to anesthetize, and supplemental anesthetic techniques—such as buccal infiltrations, intraligamental injections, or intraosseous injections—are frequently required to ensure a completely pain-free endodontic procedure.
Additionally, these findings specifically apply to mandibular molars; the sources suggest caution when generalizing these volume requirements to other teeth or using anesthetic agents other than lidocaine and articaine.
Source: https://lnkd.in/gU-2TJ_A
