What began as a routine dental visit ended in tragedy for 9-year-old Silvanna Moreno, who died on March 18, 2025, just hours after undergoing a dental procedure at Dreamtime Dentistry in Vista, California.
Now, more than two months later, the San Diego County Medical Examiner has ruled her death an accident. The cause: methemoglobinemia in the setting of recent nitrous oxide administration—a rare condition where red blood cells can’t carry oxygen effectively, causing hypoxia. According to the Cleveland Clinic, symptoms can include bluish lips, skin, or nails.
Silvanna, reportedly healthy and with no known conditions, had taken children’s Tylenol for a fever the day before her three-hour procedure, which included extractions of baby teeth and one decayed permanent tooth.
Dr. Ryan Watkins, the clinic’s anesthesiologist, confirmed she passed pre-op evaluation. Post-procedure, Silvanna appeared groggy and unresponsive. She stopped breathing at home, and attempts to revive her failed.
Watkins was previously on probation (2020–2023) after a 2016 case involving a fatal anesthesia error.
“We are profoundly saddened,” he stated. A GoFundMe page was created to support the grieving family.
