What began as a routine dental procedure ended in tragedy for 9-year-old Silvanna Moreno, who died just hours after treatment at Dreamtime Dentistry in Vista, California, on March 18, 2025.According to the San Diego County Medical Examiner, Silvanna died from *“methemoglobinemia in the setting of recent nitrous oxide administration”*—a rare condition that prevents blood from carrying oxygen properly.

Silvanna had undergone a lengthy three-hour procedure, including a root canal and multiple extractions. Dreamtime Dentistry said she was a new patient and was deemed *“an appropriate candidate for outpatient general anesthesia.After the procedure, Silvanna appeared drowsy and unresponsive.

Her mother recalled she was *“out of it,”* only opening her eyes briefly and mumbling. Once home, her condition worsened, and 911 was called when she wouldn’t wake up. She was pronounced dead at the hospital.We are profoundly saddened by the tragic loss of Silvanna Moreno,”* said anesthesiologist Dr. Ryan Watkins.
The case underscores the rare but serious risks of dental sedation in children.