Needle-insertion pain during dental local anesthesia remains one of the strongest triggers of dental anxiety. Conventional topical anesthetics show limited penetration through the thick palatal mucosa and often provide insufficient suppression of insertion pain. Microneedle (MN) patches have emerged as a minimally invasive drug-delivery platform capable of enhancing transmucosal permeability and topical anesthetic efficacy. This randomized, double-blind, crossover clinical trial evaluated the efficacy and safety of a benzocaine-loaded MN patch applied to the palatal mucosa prior to local anesthesia. Twenty adult patients requiring bilateral maxillary premolar scaling and root planing received MN or placebo patches in two study periods separated by a one-week washout. The primary outcome was the presence or absence of needle-insertion pain. Secondary outcomes included injection-phase pain assessed using a 100-mm visual analogue scale (VAS), numbness or discomfort at the application site, vital signs, and adverse events. Needle-insertion pain was reported in 2 of 20 cases (10%) under the MN patch condition, compared with 14 of 20 cases (70%) under the placebo patch condition, demonstrating a significantly lower incidence with the MN patch (p = 0.00049). In contrast, VAS scores for injection-phase pain did not differ significantly between conditions. No clinically relevant numbness, mucosal irritation, or MN-related adverse events were observed, and vital signs remained stable throughout both study periods. The benzocaine-loaded MN patch selectively attenuated superficial needle-insertion pain while maintaining an excellent safety profile. The absence of an effect on deeper injection-phase pain is likely attributable to the substantial thickness of the palatal mucosa. These findings support the clinical utility of MN-assisted transmucosal anesthesia as a novel drug-delivery modality in dentistry and provide a foundation for the development of minimally invasive analgesic systems.
Kiriishi et al. (Thu,) studied this question.