Experts Challenge Primacy of Mandibular Block

Laird Harrison

October 06, 2011

October 6, 2011 — The inferior alveolar nerve block (IANB) is often ineffective, and too few dentists are well versed in alternative approaches to anesthesia in the mandible, leading experts write in a special edition of the Journal of the American Dental Association.

In an introduction provocatively titled, "Is the Mandibular Nerve Block Passé?" Stanley F. Malamed, DDS, a professor of anesthesia and medicine at the University of Southern California in Los Angeles, writes that dentists should also learn about the Gow-Gates mandibular nerve block, Akinosi-Vazirani (closed-mouth) mandibular nerve block, periodontal ligament injection, and intraosseous anesthetic injection, which are the subjects of other articles in the supplement.

Another article in the supplement argues that mandibular infiltration using articaine also offers promise.

IANB is still useful, but failure rates are high, reaching 81% in lateral incisors, Dr. Malamed writes.

"You need to know it, but you need to know more," Daniel Haas, DDS, PhD, a professor of dentistry at the University of Toronto in Ontario, Canada, told Medscape Medical News.

Dr. Malamed gave 4 reasons why it is harder to achieve anesthesia in the mandible than in the maxilla:

  • in the mandible the cortical plate of bone in adults is thicker, making it harder for the anesthetic to diffuse;

  • the soft tissue at the injection site is thicker and can deflect needles;

  • it is difficult to locate he inferior alveolar nerve; and

  • there is a possibility of accessory innervation.

Many dental schools teach alternative approaches in addition to the IANB. These other approaches are not technically more difficult, but dentists often forget how to do them, said Dr. Haas. "They don't see other dentists doing them," he said. "You get comfortable with what you know. And once you're out in practice, it's difficult to learn something new."

There is nothing wrong with trying the IANB, but if it does not work, the practitioner should be ready to fall back on the Gow-Gates or the Akinosi-Vazirani techniques, said Dr. Haas, who wrote an article describing the technique for these 2 procedures.

In the Gow-Gates nerve block technique, the practitioner administers anesthetic at the neck of the condyle, which requires that the patient open very wide. The procedure is particularly useful when there is evidence of anatomical variability or accessory innervation, Dr. Haas said.

In the Akinosi-Vazirani nerve block technique, the patient's mouth is closed, and the dentist fills the pterygomandibular space with anesthetic. In addition to being useful in the same circumstances as the Gow-Gates maneuver, the Akinosi-Vazirani technique is helpful in cases of trismus or difficulty in seeing intraoral landmarks for IANB; for example, if the patient's tongue blocks the site, said Dr. Haas.

The disadvantage of the Akinosi-Vazirani procedure is that it could be harder to see landmarks if the patient's mouth is closed.

A separate article in the supplement, published by Paul A. Moore, DMD, PhD, MPH, professor of pharmacology and epidemiology, and chair, Department of Dental Anesthesiology, School of Dental Medicine, University of Pittsburgh in Pennsylvania, and colleagues, describes the periodontal ligament and intraosseous techniques. In the periodontal ligament technique, practitioners use high injection pressure to force anesthetic through the periodontal ligament into the cancellous medullary bone surrounding a tooth.

For the intraosseous technique, they mechanically perforate the thick cortical plate between the roots of the teeth to permit deposition of the anesthetic into the medullary bone surrounding the tooth.

Both techniques have some limitations and counterindications, but both can be used when the IANB fails, the authors write.

A final article in the supplement, published by John Meechan, PhD, a senior lecturer at Newcastle University in Newcastle upon Tyne, United Kingdom, looks at mandibular infiltration.

Although infiltration is usually not considered effective in the mandible, the advent of articaine, which came onto the US market in 2000, has spurred new consideration of this approach. A couple of studies have found infiltration with articaine to be as effective in achieving pulpal anesthesia in mandibular first molars in some healthy patients.

"Articaine for infiltration has shown some success, generally not by itself, but as a supplement," John Yagiela, DDS, PhD, professor emeritus at the University of California, Los Angeles, told Medscape Medical News.

Dr. Yagiela, who was not among the authors of the supplement, agreed that practitioners should get trained in other techniques to use when the IANB fails, and said they could even use the Gow-Gates or Akinosi-Vazirani maneuvers as first-line approaches.

"We have a lot of options now that we didn't have in the past," he said. "It's terrific for patients."

Dr. Yagiela and Dr. Haas have disclosed no relevant financial relationships. Dr. Malamed is a consultant to Septodont and OnPharma. Dr. Meechan is a paid consultant to 3M, Septodont, and Dentsply.

J Am Dental Assoc. 2011:142(suppl 3):3S-24S.

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