LLLI has much on this. A medical associate who was a dentist told me that dental caries were related in most part to heredity (the hardness or softness of the enamel) and bacteria. Good dental hygiene of erupted teeth was the key, not worrying about night feedings. If the family history was one of susceptibility due to softer enamel, then vigilance was most important. Also, if pooling breastmilk was a concern, moving the child over ususally resulted in swallowing. Sleeping with a bottle of ABM would definitely increase the risk of caries ( teeth bathing in it), but it was his opinion that this was not an issue for bf children. I have found that when bf moms hear about heredity and bacteria, they feel more confortable with this question. Susan Wittner, LLLL, is there a baby boom, my phone is ringing all the time...(I'm so glad they're calling me though)