Mucoadhesive patch versus benzocaine gel for reducing injection pain: a split-mouth randomized clinical trial.

BACKGROUND

Minimizing pain during dental injections is essential for enhancing patient comfort and reducing anxiety-driven treatment avoidance.

PURPOSE: To evaluate a novel, engineered bilayer mucoadhesive patch designed to optimize drug bioavailability and reduce injection pain compared to a benzocaine gel.

STUDY DESIGN, SETTING, AND SAMPLE: Split-mouth randomized clinical trial at Mashhad University of Medical Sciences involving 36 healthy patients requiring bilateral maxillary dental extractions.

PREDICTOR VARIABLE: The primary predictor was the delivery format of the topical anesthetic agent. The novel 20% benzocaine mucoadhesive patch featured a bilayer design: a base layer composed of a chitosan-gelatin-glycerin matrix, and an adhesive layer containing sodium carboxymethylcellulose, gelatin, pectin, 20% benzocaine (ethyl 4-aminobenzoate), and methylene blue. Participants randomly received either 20% benzocaine gel (applied for 30 s) or the 20% benzocaine mucoadhesive patch (applied for 10 min) on buccal and palatal sites of the right or left side. Local anesthesia was administered following a 10-minute washout interval between the left and right sides.

MAIN OUTCOME VARIABLE(S): Pain was quantified via the Sound, Eye, Motor (SEM) scale and the 11-point Numeric Rating Scale (NRS-11).

COVARIATES: Covariates included age, sex, and baseline anxiety level, assessed via the Beck Anxiety Inventory.

ANALYSES: Shapiro-Wilk, Wilcoxon signed-rank, Mann-Whitney U, and Spearman correlation tests (α = 0.05).

RESULTS

NRS-11 scores were significantly lower in the patch group for both buccal and palatal injections (P < 0.05). SEM scores were significantly lower in the patch group at the palatal site (P = 0.011), but not at the buccal site (P = 0.075). Sex, age, and baseline anxiety level were not associated with pain scores.

CONCLUSIONS AND RELEVANCE: The 20% benzocaine mucoadhesive patch resulted in lower self-reported pain during both buccal and palatal injections, and lower observer-rated pain during palatal injections, compared to the 20% benzocaine gel.

TRIAL REGISTRATION: Iranian Registry of Clinical Trials (IRCT) IRCT20230125057218N1. Registered on 10 October 2023, https//en.irct.ir/trial/71,206.