Nationwide — Silvanna Moreno, a 9-year-old girl from Southern California, died hours after a dental procedure in March. An autopsy revealed she suffered from methemoglobinemia, a rare condition triggered by nitrous oxide, which was used during the procedure. According to People, Silvanna, a third-grader, underwent surgery at Dreamtime Dentistry in Vista after being referred for tooth pain back in October. The procedure was scheduled for March 18. The night before, she had a mild fever that went away after taking children’s Tylenol. The clinic later said they were not informed of any recent illness and would have rescheduled the procedure if they had known.
On the day of surgery, Silvanna mentioned a headache but did not appear sick. She was given anesthesia at 10 a.m. for a three-hour procedure. Afterward, she woke up, moved to recovery, and was discharged.
On the way home, Silvanna seemed unusually sleepy and started snoring heavily. Once home, she remained asleep for about 90 minutes before her breathing slowed. Her grandmother checked her pulse twice, and when she stopped responding, they called 911 around 4:46 p.m.
Silvanna was taken to Rady Children’s Hospital in cardiac arrest. Despite efforts to revive her, she was pronounced dead at 5:44 p.m.
The San Diego County Medical Examiner listed her cause of death as methemoglobinemia. This rare condition prevents the blood from carrying enough oxygen, leading to tissue damage.
Dr. Ryan Watkins, who oversaw the procedure, said Silvanna showed no warning signs and maintained normal oxygen levels throughout. He called the condition extremely rare and said the clinic is now reviewing its safety protocols.
Dreamtime Dentistry extended condolences to the family and asked for privacy during this time.