A California dentist who treated a 9-year-old girl shortly before her tragic passing after a standard procedure had previously been put on probation for a past mistake, records reveal.

In 2020, Dr. Ryan Watkins faced disciplinary action for a 2016 event where a 54-year-old man experienced cardiac arrest after Watkins administered anesthesia for a dental procedure.

As stated in a complaint with the Dental Board of California, Watkins was accused of “unprofessional conduct” for “clearly excessively administering drugs or treatment” to the patient, referred to as “MK.”

The man had seen Watkins approximately three times before the dental surgery and was considered to be in “excellent health” and was a triathlete. 

Silvanna Moreno, 9, died following oral surgery. (GoFundMe)

Watkins said that “the dosage administered was appropriate for the patient’s age and weight, following established medical protocols.”

“Any interactions or negative side effects were not due to dosage but instead due to her rare but undiagnosed/undetected medical condition,” Watkins shared in a statement with Fox News Digital. 

According to an autopsy report from the San Diego County Medical Examiner’s Office, authorities ruled that her manner of death was an accident caused by “methemoglobinemia in the setting of recent nitrous oxide administration.” 

“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,” Watkins said. 

Stepheny Price is a writer for Fox News Digital and Fox Business. She covers topics including missing persons, homicides, national crime cases, illegal immigration, and more. Story tips and ideas can be sent to stepheny.price@fox.com