Key PointsQuestionWhat is the effect of a sensory-adapted dental environment (SADE), compared with a regular dental environment (RDE), on the physiological stress of autistic children?FindingsIn this randomized crossover trial including 162 autistic children, children exhibited significantly lower physiological stress in SADE compared with RDE in all phases of the dental visit, suggesting decreased sympathetic activity and increased relaxation during dental care in SADE.MeaningThese findings suggest that using a SADE during dental cleanings was a safe and efficacious way to improve dental experiences for autistic children.