Silvanna Moreno, a nine-year-old girl, tragically died after a dental procedure under anesthesia in Vista. Following the procedure and subsequent discharge, she was found unresponsive at home. The medical examiner cited methemoglobinemia, linked to nitrous oxide, as the cause of death. Dr. Ryan Watkins, who administered the anesthesia, stated the procedure appeared complication-free, though reports indicate a past disciplinary record.