Addition of mannitol increases effectiveness of dental nerve block anesthesia

Allowing a patient to be comfortable and pain-free during surgical and restorative dental procedures is an essential part of the process. The most commonly used local anesthetic injection for lower teeth is the inferior alveolar nerve (IAN) block. However, failure rates ranging from 10 to 39 percent have been reported. The current issue of the journal Anesthesia Progress presents a study testing the efficacy of adding a solution of mannitol to the anesthetic typically used in IAN blocks. Forty adult subjects participated in the study, receiving an IAN block at each of three separate appointments at least one week apart. The study compared the effectiveness of the standard anesthetic, lidocaine with epinephrine, to the effectiveness of two different volumes of lidocaine with epinephrine plus 0.5 M mannitol. Mannitol is a sugar alcohol that occurs naturally in fruits and vegetables. It is rapidly excreted by the kidneys. Though its impact is short-lived, mannitol has the positive effect of opening the perineurial membrane. It is believed that, in cases of IAN block failure, the perineurial barrier around the nerve does not allow complete diffusion of the anesthetic into the nerve trunk. The addition of mannitol apparently allows enhanced permeability, increasing the success of an IAN block when administered concurrently. After injections of the IAN block solutions, subjects' pain levels were measured by an electric pulp test of their mandibular teeth at 4-minute intervals for 60 minutes. The study concluded that the addition of mannitol to lidocaine with epinephrine significantly increased the effectiveness of the anesthesia.