Teachers as nurses

Why is it that certain teachers will demand a nurse's opinion on something, only to disregard it immediately? 

Exhibit A: A teacher sent a student down to my office with a note about an "abscess" in her mouth. I had the third grader open wide, and found her pointing to an incoming tooth that, while not growing in straight, looked totally healthy. Pink, not red, nothing oozing, no inflammation. I called her mom to tell her about it, and had a pleasant conversation in which we agreed that she'd make an appointment with the dentist, and I'd keep her at school and send her back to class. Later in the day at lunch, that student's teacher stormed into my office to ask why I wasn't doing anything more about the supposed abscess. I asked her as politely as I could if she had even looked in her student's mouth, as it all looked good in there to me. No, she admitted, but her student had called it an abscess so she figured it was infected. Okay...Pardon me for not accepting self-diagnoses by third graders...Even after I explained why I did not believe anything was terribly wrong with the student, she was still clearly peeved and stormed back out - apparently my opinion was the wrong opinion.