9-Year-Old Girl Dies Hours After Undergoing Dental Procedure – Her Cause of Death Officially Revealed

What was meant to be a simple dentist appointment turned into a tragedy for one elementary school student. Her family is running a fundraiser that has helped them give her a dignified burial and honor her memory.

According to reports, nine-year-old Silvanna Moreno from Southern California died on March 18, 2025, just hours after undergoing a dental procedure at Dreamtime Dentistry in Vista, California. The cause of her death has now been released.

The San Diego County Medical Examiner's Office revealed that her cause of death was methemoglobinemia (MetHb) following recent nitrous oxide administration. MetHb occurs when nitrous oxide affects hemoglobin, reducing oxygen delivery to tissues and causing hypoxia.

The Cleveland Clinic explains that MetHb is a rare blood disorder affecting how red blood cells deliver oxygen throughout the body. While not everyone experiences symptoms, nearly all individuals with this condition have skin, nails, or lips that turn a distinctive shade of blue or purple. In severe cases, the condition can be life-threatening.

According to her autopsy, Moreno had been referred for surgery after experiencing tooth pain in October 2024. Although she had a fever the day before the procedure, it subsided with children's Tylenol. On the day of surgery, she reported a headache but exhibited no signs of distress.

She received anesthesia at 10 a.m. for a three-hour procedure and was later moved to a recovery room before being discharged. During the ride home, Moreno appeared "out of it," snored heavily, and could briefly open her eyes and stand.

After arriving home, she remained asleep for about 90 minutes. Her snoring grew quieter, prompting her grandmother to check her heart rate. After two checks and no response, 911 was called at 4:46 p.m.

Emergency responders transported her to Rady Children's Hospital, where she was found in asystole. Despite resuscitation efforts, she was pronounced dead at 5:44 p.m. Asystole is a condition in which the heart's electrical system fails, causing it to stop pumping.

This condition is also known as "flat-line" or "flat-lining" because it causes the heart's electrical activity to appear as a flat line on an electrocardiogram.

Dr. Ryan Watkins, a board-certified dental anesthesiologist at Dreamtime Dentistry with over 20 years of pediatric experience, confirmed in an email sent via a public relations firm that Moreno had surgery that day.

In a statement he signed, he confirmed that the little girl's death "occurred several hours after her completed dental procedure." He also stated that MetHb is an "extremely rare condition that can occur with nitrous oxide administration" and emphasized that Moreno showed no warning signs during the procedure.

The licensed dentist maintained that her oxygen saturation levels were normal throughout. He also noted that Dreamtime Dentistry had thoroughly reviewed the child's medical and dental history and adhered to their standard of continuous monitoring.

The manner of death was ruled accidental. Following the child's unexpected death, Dreamtime Dentistry released a statement through Watkins.

The dentist expressed deep sorrow over the patient's death. He stated that the child was referred due to her young age and severe situational anxiety and was continuously monitored during the procedure by an experienced anesthesiologist.

Following the surgery, she was discharged awake, with stable vital signs and intact protective reflexes, in accordance with post-anesthesia protocols. Dreamtime Dentistry cooperated fully with the medical examiner, who conducted an investigation.

Watkins emphasized that privacy laws limit the details they can disclose and cautioned against speculation, noting it could increase the family's pain. He reaffirmed that patient safety remains their highest priority and extended condolences to the family.

After Moreno's death, a woman named Nicole Cázares Enriquez organized a fundraiser on behalf of her mother, Itzel De Jesús. Her GoFundMe fundraiser goal was $10,000, but has already amassed $19,190.

Enriquez revealed that Moreno was a third grader at Sherman Elementary School in San Diego. She was known for her bright spirit, always greeting others with a smile and a hug. Friends described her as kind, caring, and happy, and she was a devoted big sister to her brother Roberto.

The little girl is survived by her mother, her father, Roberto Moreno; her siblings, Isis, Fabián, and Roberto Nicolás; her grandmothers, Mónica De Jesús and Florida Huerta; her grandfather, Manuel De Jesús; and a large extended family of aunts, uncles, and cousins. The family is still mourning the immense loss of her joyful presence.

The fundraiser sought community support to help cover Moreno's funeral costs, aiming to give her a farewell that reflects the joy and love she brought to others. All donations were meant to go directly toward funeral expenses.

The family expressed deep gratitude for the thoughts, prayers, and generosity offered during this difficult time. Services were held on Wednesday, March 26, at 9:00 a.m. at Cypress View Mausoleum and Crematory.

Dreamtime Dentistry is conducting a thorough internal review and has pledged to implement additional safety measures. Watkins extended condolences to Moreno's family and requested privacy for them during their time of grief.