Development and Clinical Evaluation of New Topical Anesthetic Formulations for Dental Care

To provide safe dental care, it is important to minimize the pain associated with the initial injection of the local anesthetic. For this purpose, a topical anesthetic is preliminarily applied to the area where a needle will be inserted in a clinical setting. In this study, we prepared new topical anesthetic formulations with favorable intra-oral retentivity and an excellent anesthetic effect, and clinically evaluated their efficacy. We used 4% lidocaine solution as an anesthetic drug and gelatin, agar, and a food thickener as a base to prepare new topical anesthetic formulations. The subjects rested in a supine position on a chair for dental practice prior to the following experiments. Firstly, about 0.2 g of the sample was applied at a test site. One minute later, the sample was removed, and a 30 G dental injection needle was inserted into the test site. The agar/gelatin-based formulation containing gelatin of 2% and agar of 1% had a moderate solidity at 25°C and a moderate fluidity at 37°C. This formulation showed a significantly greater depth than any of the commercially available topical anesthetics. The results of the present study demonstrated that the agar/gelatin-based formulation showed an excellent analgesic effect against pain associated with needle insertion.