BackgroundDental anxiety is a widespread complication occurring in pediatric patients during dental visits and may lead to undesirable complications. Esketamine may be effective in anxiety. ObjectiveThe objective of this study was to investigate the effect of premedication with a dexmedetomidine-esketamine combination compared with dexmedetomidine alone on dental anxiety in preschool children undergoing dental treatment under general anesthesia. MethodsThis is a prospective, double-blinded, randomized controlled trial. A total of 84 patients were scheduled for elective outpatient dental caries treatment under general anesthesia. Patients were randomly premedicated with intranasal dexmedetomidine (group D) or intranasal dexmedetomidine-esketamine (group DS).The primary outcome was the level of dental anxiety assessed by the Modified Child Dental Anxiety Scale (MCDAS) at 2 h after surgery. Secondary outcomes included level of dental anxiety at 1 day and 7 days after surgery, the incidence of dental anxiety at 2 h, 1 day, and 7 days after surgery, sedation onset time, overall success of sedation, acceptance of mask induction, postoperative pain intensity, incidence of emergence agitation in PACU, adverse reactions, HR, and SpO2 before premedication (baseline) and at 10, 20, and 30 min after the end of study drug delivery. ResultsThe dental anxiety in group DS was lower than that in group D at 2 h, 1 day, and 7 days postoperatively (P = 0.04, 0.004, and 0.006, respectively). The incidences of dental anxiety in group DS were lower than those in group D at 2 h (53 % vs 76 %, P = 0.03), 1 day (47 % vs 71 %, P = 0.04), and 7 days (44 % vs 71 %, P = 0.02) after surgery. Group DS had a higher success rate of sedation (P = 0.03) but showed a lower MAS score (P = 0.005) and smoother hemodynamics (P < 0.01) after drug administration than group D. Group DS showed a significantly lower incidence rate of emergence agitation (P = 0.03) and postoperative pain intensity (P = 0.006) than that in group D during the anesthesia recovery time. The occurrence of adverse reactions was similar in both groups (P > 0.05). LimitationsWe did not analyze and correct for the learning effect caused by repeated applications of the MCDAS and MCDAS scores on the 1 day after surgery were obtained by telephone follow-up. ConclusionsCompared to premedication with dexmedetomidine alone, premedication with intranasal dexmedetomidine combined with esketamine could significantly improve dental anxiety in preschool children undergoing dental treatment under general anesthesia.