A New Method of Topical Anesthesia by Using Anesthetic Solution in a Patch

IntroductionWe investigated the effects of topical anesthesia of the oral mucosa by using an adhesive patch instilled with 2% lidocaine hydrochloride solution.MethodsThe subjects were 20 healthy adult volunteers who gave written informed consent. Each patient was treated in a randomized crossover fashion with a hemostatic adhesive patch instilled with one of the following agents: 2% lidocaine hydrochloride with 12.5 μg/mL epinephrine, 2% lidocaine hydrochloride, 20% ethyl aminobenzoate, or physiological saline solution. A cotton ball containing 20% ethyl aminobenzoate was also tested. The adhesive patch or cotton ball was placed on the gingivobuccal fold of the maxillary right canine for 2 or 5 minutes. Then, a 33-gauge or 30-gauge needle was inserted to a depth of 2 mm. Insertion pain was evaluated with a visual analog scale (VAS) and a 4-level verbal rating scale immediately after needle removal. Efficacy of analgesia was calculated from the verbal rating scale.ResultsThe VAS was lower and the efficacy of analgesia was higher on 33-gauge needle insertion than on 30-gauge needle insertion in all treatments. The VAS was also significantly lower and the efficacy of analgesia was higher in the lidocaine groups than in the other groups. Adding epinephrine did not enhance the anesthetic effect of lidocaine hydrochloride.ConclusionsTopical mucosal anesthesia with an adhesive patch containing 2% lidocaine hydrochloride solution is simple and may be more effective than conventional methods.