Oral mucosal analgesia quantitatively assessed by argon laser-induced thresholds and single-evoked vertex potentials

The aim of this study is to quantitate the efficacy of a new topical anesthetic applied to the oral mucosa. Nociceptive pinprick thresholds and single-evoked vertex potentials (VP) elicited by high-intensity argon laser stimuli are used as measures of analgesia. After 5 minutes of occlusion (Orahesive Oral Bandages, ConvaTec) with a eutectic mixture of local anesthetics (EMLA cream, Astra), nociceptive pinprick thresholds on the tongue and gingiva are higher than those taken during nonocclusion. In a double blind-placebo controlled experiment, VPs were elicited every 1 minute for 19 minutes by single laser stimuli applied to the mucosa of the lower lip. After occlusion with EMLA cream for 3 minutes, VPs were significantly reduced when compared to those with placebo cream. One minute after removal of the EMLA cream, the spectral power of the single-evoked VP decreased significantly by 63.3%, the root-mean-square amplitude decreased by 42.7%, and the subjective pain perception (estimated on visual analogue scales) decreased by 88%. A significant reduction in single-evoked VPs was detected until 13 minutes after the removal of the EMLA cream. Oral mucosal analgesia may be quantitated by argon laser-induced nociceptive pinprick thresholds and single-evoked VPs.