Noticed this staining on my 3.5 year olds molar this week. She has deep grooves and pits (as do my other kids). I'm scared this may be a cavity?!! It doesn't feel sticky but it's definetly a stain and a deep crevice. What are your thoughts? She sees the dentist on Tuesday. I don't know how she will handle it, if it's something bad! I appreciate all advice! Here's s picture!