Articaine Found Superior to Lidocaine in Meta-Analysis

Laird Harrison

June 22, 2011

June 22, 2011 — Articaine works better than lidocaine for infiltrations, but the evidence for superiority in mandibular blocks is still weak, researchers reported in the May issue of the Journal of the American Dental Association.

"When we considered infiltration data only, we found that the results of our meta-analysis indicated that articaine is an estimated 3.81 times more likely to produce anesthetic success than is a similar volume of lidocaine," write the researchers, from the University of Michigan, Ann Arbor, and led by Ryan G. Brandt, DDS.

Introduced to the US market in April 2000, articaine has steadily grown in popularity, reaching 25% of total dental anesthetic sales in 2007, second to lidocaine's 54%, the researchers said. Because articaine contains a thiophene ring, as opposed to the benzene ring in lidocaine and other amide local anesthetics, it is more soluble in lipids, and thus diffuses better through nerve membranes.

Some randomized controlled trials have reported a superiority for this newer agent, but others have been equivocal, and a few have reported a greater risk for adverse events. "It does seem like articaine is significantly better in some types of anesthesia, but there are reports of paresthesia that have some people concerned," Sean Boynes, DMD, who has published previous research on articaine, told Medscape Medical News.

The University of Michigan researchers combed the literature for randomized controlled trials and found 13 they considered to be designed well enough to provide useful data. Combining the data from these studies in a meta-analysis, they found that articaine was 2.44 times (95% confidence interval [CI], 1.59 - 3.76; P < .0001) more likely to successfully anesthetize patients than lidocaine overall.

However, when they broke these data down into subgroups (infiltrations and mandibular blocks), they found that the odds ratio was only 1.57 in favor of articaine, which was still statistically significant but weaker (95% confidence interval [CI], 1.12 - 2.21; P = .009).

In addition, when they further narrowed the data for mandibular blocks to anesthesia in inflamed teeth, they found that the advantage for articaine was not statistically significant, with an odds ratio of 1.61 for articaine (95% CI, 0.74 - 3.53; P = .23).

The research still leaves a lot of questions about articaine, coauthor Mathilde C. Peters, DMD, PhD, told Medscape Medical News. "Whether a clinician uses it in a particular situation depends on the health of the patient and how the patient has been behaving, what kind of treatment you have been doing, and what the local situation is," said Dr. Peters. "You have to take clinical expertise into consideration."

Dr. Boynes said he thought technical skill may be a key factor: Because articaine diffuses better, it may allow a clinician to achieve anesthesia without getting as close to the nerve as would be necessary using lidocaine. "The theory is that articaine can help you if you're not accurate with the inferior alveolar nerve block," he said.

Articaine is slightly more expensive. Dr. Boynes' clinic pays $30.95 for a box of 50 cartridges of articaine (with 1:100,000 epinephrine; Septocaine, Septodont), and $24.75 for the same amount of lidocaine. However, Dr. Boynes said it was not the expense but concern about parathesia that makes him hesitate to use articaine for mandibular blocks.

Looking at closed claims, researchers at the University of Toronto have found a small but significant increased risk for parathesia when articaine is used in mandibular blocks. The meta-analysis by the University of Michigan team was not designed to assess adverse events, including parasthesia, as it only included a combined total of 1022 injections. In a 2009 study for the Journal of the Canadian Dental Association, researchers at the University of Toronto, Ontario, Canada, estimated that the incidence of paresthesia was 1 per 609,000 injections.

In addition, some of the studies included in the meta-analysis said nothing at all about complications associated with the injections.

So where does this leave the practicing dental professional?

Dr. Boynes, who is now director of dental medicine at Caresoft Carolina in Society Hill, South Carolina, uses articaine for infiltration and lidocaine for mandibular blocks. "I would do a block with lidocaine, and if I need a supplemental injection around the tooth, do it with articaine," he said.

The study authors have disclosed no relevant financial relationships. Dr. Boynes has served as research consultant to Novocol of Canada, Inc, and Novalar Pharmaceutical, Inc, regarding the development of new anesthetics for dentistry. He has also served as investigator for US Food and Drug Administration–required phase II, phase III, and phase IV clinical research contracts awarded by Wyeth Consumer Healthcare; Novocol of Canada, Inc; Novalar Pharmaceutical, Inc; Hospira; and Pfizer Pharmaceuticals.

J Am Dent Assoc. 2011;142:493-504. Abstract

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