Effect of cryoanaesthesia on pain during intraoral anaesthetic puncture in children: a randomised controlled non-inferiority trial

PURPOSE: Effective pain control during local anaesthetic administration is essential in paediatric dentistry. Although topical anaesthetic gels are widely used, concerns remain about dosage control. Cryoanaesthesia has emerged as a non-pharmacological alternative. This randomised controlled trial aimed to evaluate the non-inferiority of cryoanaesthesia compared with 20% benzocaine gel in reducing self-reported pain during mandibular infiltrative anaesthetic puncture in children. METHODS: Forty children aged 6 to 9 years, each with at least one mandibular primary molar requiring treatment under local anaesthesia, were included. Participants were randomised to receive either cryoanaesthesia or 20% benzocaine gel as the topical anaesthetic intervention. Self-reported pain was assessed using the Visual Analogue Scale immediately after initial anaesthetic puncture. Pre-operative child and parental anxiety, as well as the child's behaviour during anaesthesia, were also evaluated. A one-sided Student's t-test for non-inferiority was applied to compare mean pain scores between groups. Multiple linear regression was performed to identify potential associations between independent variables and self-reported pain. RESULTS: The mean age of the participants was 7.63 ± 1.23 years. Mean self-reported pain scores were 38.50 ± 41.20 in the benzocaine group and 38.00 ± 36.54 in the cryoanaesthesia group. Non-inferiority of cryoanaesthesia was not demonstrated (mean difference: 0.50 ± 4.69, 95% CI -24.42 to 25.42, p = 0.22). A statistically significant association was observed between negative behaviour and self-reported pain (β = 45.21; 95% CI 18.68 to 71.74; p < 0.001). CONCLUSION: The non-inferiority of cryoanaesthesia compared with 20% benzocaine gel for mandibular topical anaesthesia in children could not be demonstrated. CLINICAL TRIAL REGISTRY: Brazilian Registry of Clinical Trials-REBEC (Identifier: RBR-74w5bt4), available at https://ensaiosclinicos.gov.br/rg/RBR-74w5bt4 , registered on March 12th, 2025.