What was supposed to be a routine dental visit turned into a tragedy for 9-year-old Silvanna Moreno who died on March 18, 2025, a few hours after receiving dental procedure at Dreamtime Dentistry in Vista, California.

Now, more than two months after her tragic passing, the San Diego County Medical Examiner’s Office ruled her death an accident.

The cause of death was listed as “methemoglobinemia in the setting of recent nitrous oxide administration.”

MetHb happens when haemoglobin is impacted by nitrous oxide, which lowers oxygen transport to tissues and results in hypoxia, as explained by the Cleveland Clinic.

It is an uncommon blood condition that affects the way red blood cells carry oxygen throughout the body. Continues…