Dd's teeth were looking like that too. They were like that for quite some time and then we took her into the dentist and she had two tiny cavities there. I don't think that layer of yellow necessarily means cavities, but the two front teeth do seem more prone to them. In our case, dd didn't even need anethesia to get the two front teeth filled. If it turns out your dd does have cavities, it may be as easy for her as well. They just sort of covered them with resin or whatever they use. They looked a whole lot better! It didn't take long for the yellow layer to show up again. Within a few days it was back. It's fairly difficult to brush that away. G/L and sorry I couldn't be of more help.