Two days ago I noticed a tiny black mark on DD's (aged 4.5)back molar. It looks just like a tiny bit of food stuck there but it is absolutely not budging. I've now Googled and have frightened myself that it might be a cavity. Has anyone experienced this?> What does the dentist do? I feel awful about it...I'm a stickler for twice-daily good teeth brushing. My DCs have a healthy diet with lots of fruit and veg (is the fruit the problem??) and DD will only have a very occasional sweet at a party. They drink diluted apple juice, water or milk. Help!