The effect of a needle-free injection system on dental injection pain in children: a randomised cross-over clinical trial

Background: This study aimed to compare pain perception and behavioral responses in pediatric patients during dental injections using needle-free (NF) or traditional injection methods (TMs) over two consecutive dental visits. Methods: This randomized, clinical crossover study involved 28 children aged 6 to 12 years who exhibited positive or absolute positive behavior according to the Frankl Behavior Scale and required dental anesthesia for bilateral operative procedures on their primary maxillary molars. The children were randomly assigned to receive both the NF and TM injections, for a total of 56 injections. Patients who underwent filling or pulpotomy treatment on a primary maxillary molar received anesthesia with both techniques at a one-week interval. At each visit and after the administration of anesthesia, the patients’ pain levels were assessed using the Wong-Baker Faces Pain Rating Scale (Wong-Baker) and the Face, Legs, Activity, Cry, Consolability scale. The data were recorded, and statistical analyses were performed using paired t-tests or Wilcoxon nonparametric tests and Chi-square tests. Statistical significance was defined as a p ≤ 0.05. Results: There was no significant difference between the NF system and the TM according to the Wong-Baker scores. However, there were significant differences in the amount of anesthetic solution and duration of the analgesic effect between the first and second visits for both injection methods, respectively (p = 0.003 for NF-TM and p < 0.0001 for the TM-NF groups). Conclusions: In this study, the NF system and the TM exhibited similar results when evaluated using different pain scales. However, the NF injection system may be a promising approach when working with uncooperative children. Clinical Trial Registration: ClinicalTrials.gov PRS ID: NCT06541925.