In a crossover, randomized, placebo-controlled, double-blind study, 40 volunteers will receive the following formulations: hydrogels containing LAs (local anesthetic) - lidocaine and prilocaine (both at 2.5%) encapsulated in CLN (XAN-CLN) or not (XAN-CLN ), EMLA (topical anesthetic available on the market) and placebo hydrogel. The formulations will be applied for 2 minutes, bilaterally on the palatal mucosa (first premolar region), in two distinct sessions. Soon after removal of the topical formulation, an AL will be performed at the region using 0.3 mL of anesthetic solution at an injection speed of 1 mL/min. Pain resulting from needle insertion and LA injection will be measured using two visual analog scales (VAS).

Dental treatment presents numerous innovations, but the pain associated with the administration of local anesthesia (LA) continuous to be a traumatic procedure for many patients. Although we use topical anesthetics (TA) to reduce pain, the commercially available formulations are only effective in preventing the pain of the needle puncture.

This project aims to evaluate the clinical efficacy of xanthan-based hydrogels (2%) containing LAs encapsulated in nanostructured lipid carriers (CLN), reducing pain during puncture and injection of LA in the palatine mucosa. In a crossover, randomized, placebo-controlled, double-blind study, 40 volunteers will receive the following formulations: hydrogels containing LAs - lidocaine and prilocaine (both at 2.5%) encapsulated in CLN (XAN-CLN) or not (XAN-CLN ), EMLA and placebo hydrogel. The formulations will be applied for 2 minutes, bilaterally on the palatal mucosa (first premolar region), in two distinct sessions. Soon after the removal of the topical formulation, an AL will be performed at the region using 0.3 mL of anesthetic solution at an injection speed of 1 mL/min. The computerized Morpheus® anesthetic injector will be used in order to control the variables of volume and injection speed. Pain resulting from needle insertion and LA injection will be measured using two visual analog scales (VAS). Hydrogels containing CLN are expected to have good mechanical properties and allow the permeation of LAs efficiently through the oral mucosal epithelium. In addition, they can improve the efficacy of topical anesthesia in order to perform a painless LA in the palatal mucosa.

Inclusion Criteria:

• Healthy participants
• No lesions in the study area
• Have already been submitted to local anesthesia without intercurrence

Exclusion Criteria:

• Used any drugs that change the pain sensibility 1 week before
• Smokers
• Alcoholic

The participant and the applicator don't know which formulation was applied because these were named A, B, C, and D and the applicator doesn't have access to the data of which formulation was titled by each letter.