Routine Dental Visit Turns Tragic
What began as a standard dental appointment ended in heartbreak for 9-year-old Silvanna Moreno. On March 18, 2025, she d**d just hours after a procedure at Dreamtime Dentistry in Vista, California.
Cause of D**th Ruled an Accident
More than two months later, the San Diego County Medical Examiner’s Office classified her death as an accident. The report listed the cause as “methemoglobinemia following nitrous oxide administration.”
Methemoglobinemia, or MetHb, occurs when nitrous oxide affects hemoglobin, reducing oxygen delivery to the body’s tissues and causing hypoxia. According to the Cleveland Clinic, the condition is rare and can appear with blue or purple lips, skin, or nails—or sometimes show no symptoms at all.
Health Background Before the Procedure
The day before her three-hour procedure, Silvanna had a fever and took children’s Tylenol, according to People. She was a new patient at the clinic, referred for a root canal on a molar.
During the procedure, the dentist extracted several baby teeth along with one decayed permanent tooth. Dr. Ryan Watkins, the clinic’s anesthesiologist, described Silvanna as a healthy child with a history of regular checkups. He stated she had passed the office’s standard preoperative evaluation and was an appropriate candidate for outpatient general anesthesia, NBC News reported.

Events After the Procedure
The Medical Examiner’s report explained that after the procedure, Silvanna was moved to a recovery room. Her mother told investigators that she appeared “out of it, intermittently opening her eyes and mumbling incomprehensibly.”
On the way home and after arriving, Silvanna continued to sleep. About 30 minutes later, her breathing slowed. Despite attempts to wake her, she remained unresponsive. Paramedics rushed her to the hospital, where she was pronounced d**d.
Family and Public Reaction
Dr. Watkins expressed his sorrow: “We are profoundly saddened by the tragic loss of Silvanna Moreno, and our hearts continue to go out to her family during this incredibly difficult time.”
Past Controversies
Watkins has a previous history of investigation. In 2016, a 54-year-old man nearly d**d under his general anesthesia care. The Dental Board of California found that a drug administered during that procedure caused the man’s heart to stop. Watkins was placed on probation from 2020 to 2023.