In regard to Health Care Plans?

I'm wondering why Dental insurance isn't a factor for candidates. Is oral health not vital to a human being? There are a lot of people in this country who have teeth rotting out of their heads, not because they like to look like Jack O' Lanterns, but because they can not afford a dentist nor can they afford Dental insurance. I guess I've always been curious as to why Dental is not included in health care plans. My parents are both retired and need to pay for their dental work out of pocket. They're lucky that they can afford to do so, but a lot of other people can't. Your thoughts?