Minimizing discomfort from dental needle injections is important for patient comfort and to reduce anxiety-related avoidance of care. This randomized clinical trial evaluated whether a novel bilayer mucoadhesive patch delivering 20% benzocaine provides superior analgesia for maxillary buccal and palatal injections compared with conventional 20% benzocaine gel.
The investigation was a split-mouth randomized clinical trial conducted at Mashhad University of Medical Sciences. Thirty-six healthy patients who required bilateral maxillary extractions were enrolled. The split-mouth design meant each participant received both interventions on opposite sides, allowing within-subject comparison of topical anesthetic delivery formats.
The experimental topical consisted of a 20% benzocaine mucoadhesive patch with a bilayer structure. The base layer was composed of a chitosan–gelatin–glycerin matrix. The adhesive layer included sodium carboxymethylcellulose, gelatin, pectin, 20% benzocaine (ethyl 4-aminobenzoate), and methylene blue. The comparator was a standard 20% benzocaine gel applied per the protocol described below.
Participants were randomized to receive either the 20% benzocaine gel or the 20% benzocaine mucoadhesive patch on the buccal and palatal mucosa of one side (right or left). The gel was applied for 30 seconds. The mucoadhesive patch was applied for 10 minutes. There was a 10-minute washout interval between procedures performed on the two sides before local infiltration anesthesia was administered. This timing allowed assessment of the topical agent’s effect immediately prior to injection.
Primary pain outcomes were captured using two scales. Patient-reported pain intensity was measured with the 11-point NRS-11 (Numeric Rating Scale). Observer-rated pain behavior was assessed with the SEM (Sound, Eye, Motor) scale. Covariates recorded and analyzed included age, sex, and baseline anxiety level assessed via the Beck Anxiety Inventory.
Data distribution was evaluated with the Shapiro–Wilk test. Within- and between-group comparisons used nonparametric tests including the Wilcoxon signed-rank and Mann–Whitney U tests. Associations with covariates were assessed using Spearman correlation. Analyses used a significance threshold of α = 0.05.
Self-reported pain on the NRS-11 was significantly lower when the mucoadhesive patch was used compared with benzocaine gel for both buccal and palatal injections (P < 0.05). Observer-rated pain via the SEM scale was significantly lower in the patch group at the palatal injection site (P = 0.011). SEM scores at the buccal site did not differ significantly between patch and gel (P = 0.075).
Sex, age, and baseline anxiety (Beck Anxiety Inventory score) were not associated with pain scores in this study. The authors report no significant correlations between these covariates and either NRS-11 or SEM outcomes.
In this split-mouth randomized trial of 36 patients undergoing bilateral maxillary extractions, the 20% benzocaine mucoadhesive patch produced lower patient-reported injection pain for both buccal and palatal infiltrations compared with a 20% benzocaine gel. Observer-rated pain (SEM) was also lower with the patch for palatal injections but not significantly different for buccal injections. The findings suggest the bilayer mucoadhesive patch may enhance topical anesthetic effectiveness at the mucosal surface and reduce injection discomfort, particularly for palatal anesthesia.
This trial was registered in the Iranian Registry of Clinical Trials (IRCT20230125057218N1) and was registered on 10 October 2023. The study received ethical approval from the Research Ethics Committee of the Faculty of Dentistry, Mashhad University of Medical Sciences (IR.MUMS.DENTISTRY.REC.1402.003) and was conducted in accordance with the Declaration of Helsinki and CONSORT reporting guidelines. Written informed consent was obtained from all participants or their legal guardians. The authors declared no competing interests.
Details such as exact numeric pain score means, standard deviations, confidence intervals, and sample size calculation parameters were not included in the abstract. Full-text data would be required to review effect sizes, adverse events, and other secondary outcomes. The summary reports the statistical significance results and the materials used in the mucoadhesive patch as presented in the source abstract.