First and foremost when a doctor encounters a patient, they must be vigilant about diagnosing these diseases and know to rule them out.
During her internship, she primarily trained in dental medicine and lacked clinical experience in this field, which led to the misdiagnosis.
Back then, she personally asked the patient, who said it was a toothache and didn't mention chest pain. If they had, she wouldn't have been foolish enough to say the chest pain turned into a toothache. As it happened, this patient had a cavity. If given some time, to ascertain that it was the entire gum that hurt and not just a single tooth, she might have considered other possible causes.
But an acute patient never gives a doctor time. Death God came too quickly, and the patient's sudden heart attack scared her into a mental shutdown like a computer going offline.
