Little is known about implications of temperament for children who receive nitrous oxide inhalation sedation (N₂O/O₂) for dental care. The aim of this study was to investigate whether child temperament is associated with success in N₂O/O₂. Child-caregiver dyads were enrolled from patients aged 36–95 months receiving dental care with N₂O/O₂ at a university-based pediatric dental clinic. To assess child temperament, 48 caregivers completed the Children's Behavior Questionnaire Short Form. Patient behavior was abstracted from Frankl scores recorded in the patient's chart. The overall behavioral failure rate was 15% (n = 7/48). There was no significant difference in sedation outcome associated with sex, health, insurance status, or complexity of treatment provided. Sedation outcome was significantly associated with the broad temperament domain of Effortful Control and its subscales Attentional Focusing and Inhibitory Control. The Negative Affectivity subscales of Frustration, Sadness, and Soothability and the Extraversion/Surgency subscales Activity and Impulsivity were also significantly associated with sedation outcome. The results of this study suggest that Effortful Control is associated with behavior during dental treatment with N₂O/O₂. The subscales of Attention Focusing, Inhibitory Control, Frustration, Fear, Sadness, Soothability, Activity, and Impulsivity may also be important determinants of child behavior during dental treatment.