Effective topical anesthetic agents and techniques.

What conclusions can be drawn concerning intraoral topical anesthesia? First, a variety of agents have been shown to have a pharmacologic effect. When used as a single agent, lidocaine is effective at concentrations between 5% and 20%. There is evidence of a dose response with lidocaine [17]. The combination of 2.5% lidocaine and 2.5% prilocaine has been shown to be a reliable agent; however, at the time of writing, this mixture is not licensed for intraoral use. Benzocaine is effective when used alone at a concentration of 20% and when combined at a dose of 15% with 1.7% amethocaine. Second, a crucial factor governing effectiveness is the time of application. One study cited in this paper [23] has shown an effect occurring in the maxillary buccal sulcus after a 1-minute application. Others [17,25] have shown that a 2- to 3-minute application at the same site is no better than placebo. The differences in these studies may be caused by the use of different test stimuli, such as the gauge of the needle used and the depth of insertion. When applied for 5 minutes, it seems that success is guaranteed when used in the buccal fold of either jaw. Finally, the site of application is important. Palatal mucosa is more resistant to the effects of topical anesthetics than other intraoral sites investigated. There is no evidence that topical anesthetics have any value in reducing the discomfort of deep regional block administrations such as inferior alveolar nerve block injections.