What is this cod liver oil and butter thing? I never heard of it. My daughter is 6 and has a tartar problem behind her lower front teeth, and one of those teeth looks brown in an area in the back. Luckily, this is a baby tooth and she will lose it soon anyway. It looks like it is on the inside of the tooth. She of course won't OP, being six, it is hard enough to get her to let me help her brush. So, what is this about the cod liver oil and butter? I'd like to learn about it for her.