Too young to consent?

A 13 year old girl comes into your dental clinic with a very sore tooth and asks you to "fix it" for her. After looking in her mouth you find she needs a large filling on her back lower molar. You try to contact her parents but are not successful. You tell her you can't do the treatment as you need consent and she begs you to do the treatment as she is in real pain. The age of consent is 16years.