The constant drooling has led to an angry rash around his chin

Q. My 18-month old daughter has terrible problems with her teeth. She is missing enamel on two teeth and has a number of cavities and brown patches on her teeth, in particular her front top teeth. I took her to the doctor recently and he said it is because I breastfeed her during the night. She eats very healthy snacks, and I don’t give her sweets, juice, or other junk foods. What can I do about her teeth? I am not convinced that breastfeeding is causing these problems.