Preliminary Comparison of Missed Blocks with 4% Articaine and 2% Lidocaine both with 1:100,000 epinephrine on Inferior Alveolar Nerve Block Injections

Abstract

<>Objectives

To determine if there is a  difference in missed inferior alveolar nerve block rates, using the conventional approach, between 4% articaine with 1:100,000 epinephrine and 2% lidocaine with 1:100,000 epinephrine

<>Background and Rationale

After introduction of articaine into the marketplace, it gained a reputation among dentists who used it as having superior anesthetic efficacy over lidocaine.  Many claim that when they try to the IANB with articaine that they “don't miss as often.” These claims are admittedly anecdotal because a clinical study focused on this claim has not been carried out. 

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<>Research Design

Double-blind, randomized, controlled clinical trial.

<>Sample

The patients, 18 and up, are recruited from the oral surgery resident clinic, mainly for dental extractions. A power analysis performed with the G*Power 3.1 software with an alpha level of 0.05, demonstrates that 932 subjects would give 80% power to detect a difference of +/- 5% in rates of missed blocks.  A total of 1000 participants are sought to ensure an adequate number of subjects to draw definitive conclusions.

<>Measurement / Instrumentation

Two tests are used to determine if adequate IAN anesthesia has resulted within 15 minutes after injection:  1) subjective information is obtained from the participant asking if their lower lip feels swollen.  2) No pain from a 25 gauge needle inserted in the alveolar mucosa just inferior to gingiva and anterior to the cuspid region puncturing periosteum.

<>Study procedures

Local anesthetic cartridges of articaine and lidocaine have their labels removed and replaced with a clear label containing the 6-digit random number. The patient receives one standard inferior alveolar nerve block injection with one of the blinded anesthetic cartridges. If the patient required nerve blocks on both sides the side is randomly chosen by the following criteria: odd random numbers for right side, even random numbers for left side. If the patient reports feeling numb prior to the 15 minute limit, a fresh local anesthetic needle is used to touch the oral mucosa next to the canine tooth on the same side to verify that the patient's soft tissues are numb. If the patient reports not feeling numb at 15 minutes after injection, the injection is considered a failure.

<>Data Analysis

The Fisher exact test is used to compare operator variability as well as any differences based on anesthetic type. This is appropriate because it is unpaired proportional data from two independent groups. 

Results

2 operators administered 217 inferior alveolar nerve blocks. The number of missed injections for 4% articaine was 4 compared to 8 for 2% lidocaine resulting in a miss rate of 4.2% for 4% articaine and 6.6% for 2% lidocaine. These were not significantly different (p = 0.5555).  The number of injections failing to obtain profound soft tissue anesthesia was 9 for 4% articaine compared to 18 for 2% lidocaine resulting in a miss rate of 9.4% for 4% articaine and 14.9% for 2% lidocaine.  These were not significantly different (p = 0.3008).

Conclusion

With the limited number of missed blocks obtained in this study, we were unable to find a statistically significant difference between the two solutions tested as of yet.  More research subjects (~1000) should be completed to enhance the statistical power to determine the difference in rates if one exists or to be able to draw the conclusion that there is no difference.

<>I.                   Bibliography

1.  Mikesell P, Nusstein J, Reader A, Beck M, Weaver J.  A comparison of articaine and lidocaine for inferior alveolar nerve blocks.  Journal of Endodontics 2005:31.

2.  Claffey E, Reader A, Nusstein J, Beck M, Weaver J.  Anesthetic efficacy of articaine for inferior alveolar nerve blocks in patients with irreversible pulpitis.  Journal of Endodontics 2004:30.