I've never understood why dental and vision care are separated from the rest of health care. Does the rest of the world treat them as exceptions? And at what point will my health insurance treat something like an infected tooth?
There's no such thing as a dental "emergency." Tooth problems happen slowly over months and years. There's no dental equivalent to a heart attack or cancer.
It's pretty much all preventive care - regular cleanings and x-rays. That would be like expecting your car insurance to pay for your oil change. You know you have to do it.