What began as a routine dental appointment for 9-year-old Vista third grader Silvanna Moreno on March 18, 2025, ended in tragedy just hours later. After undergoing dental surgery at a local clinic, Silvanna developed a rare complication following anesthesia and was rushed to Rady Children’s Hospital, where she was pronounced dead that evening. Her family has been demanding answers ever since, and her mother has now filed a malpractice lawsuit against the practice and the clinicians involved.
Autopsy finds rare reaction tied to laughing gas
The San Diego County Medical Examiner ruled Silvanna’s death was caused by “methemoglobinemia in the setting of recent nitrous oxide administration” and classified the manner of death as accidental, according to Los Angeles Times. The office noted that nitrous oxide was among the anesthetics used during the procedure and said other commonly administered sedative drugs might also have contributed. Investigators requested to attend the autopsy as part of a broader review of what went wrong that day.
How the day unfolded
According to ABC 10News, Silvanna was placed under anesthesia at about 10 a.m. for roughly three hours of dental work, including a root canal, crowns, fillings and extractions. Afterward, staff monitored her in a recovery area before discharging her to her mother. Relatives say she fell asleep during the drive home and was later found unresponsive that afternoon. Paramedics attempted resuscitation, but she was pronounced dead at Rady Children’s Hospital that evening.
The autopsy listed several medications as contributing conditions alongside nitrous oxide, including dexamethasone, glycopyrrolate, hydromorphone, isoflurane, ketorolac, midazolam, ondansetron, propofol and sevoflurane.
What the lawsuit says
Silvanna’s mother, Itzel De Jesus, filed a malpractice lawsuit on December 29, 2025, against Dreamtime Dentistry, Dr. Ryan Watkins, Dr. Kyung Lee Boen and others, according to DrBicuspid. The complaint argues that Silvanna was discharged while she was “entirely too somnolent” and cites surveillance footage that the suit says shows her being wheeled out and lifted into a car.
The lawsuit contends that if methemoglobinemia had been recognized after the procedure, standard treatment with oxygen and methylene blue could have prevented her death.
Doctor's background and clinic response
Public records show that Dr. Ryan Watkins, the dentist who provided anesthesia in Silvanna’s case, was placed on probation by the Dental Board of California from 2020 to 2023 following a 2016 incident in which a patient suffered cardiac arrest, The Coast News reports.
Dreamtime Dentistry has said in statements to reporters that the clinic followed standard pre-operative checklists and continuous monitoring protocols during Silvanna’s visit. The practice also says it turned over camera footage to investigators and has cooperated with authorities.
How rare is methemoglobinemia?
Medical experts and local reporting describe methemoglobinemia as an uncommon condition that can be inherited or triggered by certain medications frequently used around dental procedures. Topical benzocaine is a well-known trigger, but it was not listed in Silvanna’s autopsy, according to ABC 10News. The medical examiner recommended genetic testing for members of Silvanna’s family to see whether she may have had an undiagnosed predisposition.
Clinicians note that reactions like this are rare but can escalate quickly if the signs are not recognized and treated right away.
Legal outlook
The civil lawsuit remains active in San Diego Superior Court and seeks compensatory damages for the family’s loss, according to DrBicuspid. The San Diego police child-abuse unit briefly investigated Silvanna’s death but later closed its probe, leaving the autopsy findings and the ongoing civil case as the main public records detailing the incident, Los Angeles Times reported.
Silvanna’s family says it is still looking for answers as the litigation moves forward, while the clinic says it is conducting an internal review in addition to cooperating with authorities. The community continues to remember Silvanna as a bright third grader, and her death has renewed local debate about how pediatric anesthesia is handled in outpatient dental settings.
