Anesthetic Efficacy of a Combination of Hyaluronidase

The inferior alveolar nerve (IAN) block is the most frequently used injection technique for achieving local anesthesia for mandibular restorative and surgical procedures. However, the IAN block does not always result in successful pulpal anesthesia. Failure rates of 8 to 67% have been reported in experimental studies. Clinical studies in endodontics have found failure with the IAN block occurring between 38 and 81% of the time.

The use of hyaluronidase as an adjunct to local anesthesia has been well documented in ophthalmological surgery. Hyaluronidase is an enzyme that hydrolyzes the hyaluronic component of the intercellular ground substance. Hence, the viscosity of the tissue is reduced, permitting a wider spread of injected fluids. Early studies in dentistry found that an IAN block was more easily attained and was more complete when hyaluronidase was added to a procaine/epinephrine solution. However, Eckenhoff and Kirby found hyaluronidase did not increase the incidence of successful regional nerve blocks. Recently, Malamed reported, by way of Internet communications, that dentists had an increased interest in the use of hyaluronidase, although he cautioned that research trials should be completed before its widespread use.
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Because hyaluronidase may increase success of an IAN block, the purpose of this prospective, randomized, double-blind study was to determine the anesthetic efficacy of buffered lidocaine (24 mg) with epinephrine (12 |jug) compared with buffered lidocaine (24 mg) with epinephrine (12 jxg) plus hyaluronidase (150 USP units) in IAN blocks.