My son ended up w/ a cavity (small, and on the back of one of his upper central incisors) at 18 months that had to be filled (no novacaine because it was superficial for the most part). Anyway, we night nurse a lot, that's just the way things are around here. Our ped dentist is supposedly the most BFing friendly in the area and he strongly discouraged nursing at night :( I tried to have DS cut back a bit and that lasted ummm...about one night ;) He's 20 months now and still nursing lots at night.
The American Dental Association policy actually does discourage night nursing after the first tooth erupts :( Apparently they and the AAP are trying to get their ideas into alignment so hopefully they'll change their policies. There is plenty of research out there saying BFing at night does *NOT* cause cavities. We've always consistently brushed DS's teeth at least before bedtime. I'm not sure what happened to cause his cavity (part of it is probably the shape of his teeth...on the back of his upper central incisors it is sort of cusp shaped...the cavity was in the cusp). After reading I decided we'd do the best we could to brush frequently throughout the day (we brush 4-5 times a day since the cavity was discovered) and we introduced xylitol products (check out spry gel if you are interested).
Our dentist did not mention xylitol or any other alternatives to night weaning. When we went back to actually have the tooth filled, I explained DS has constipation issues, isn't a big solids eater, and that we were going to continue night nursing. I did say we introduced xylitol (which he was in favor of but of course never mentioned it until I brought it up) and we were doing that multiple times a day and being as careful as possible about brushing. He seemed okay with it after I made him aware night weaning was NOT happening around here.
Sadly he is the most BFing friendly ped dentist in the area. He didn't make me feel like a pervert, but seemed convinced night nursing was to blame. There is research out there on both sides, but it is a combo of food on the teeth plus milk that creates an environment where cavities can take hold. Also, the presence of strep mutans, (which xylitol helps eliminate) which explains why some kids get them and some don't.
I'm dealing w/ our dentist. DS has a follow up in December. We'll see how it goes. I will say if our dentist had made me feel like a pervert for nursing DS, I would not return. I can deal with his advice to night wean (by disregarding it completely LOL) but the hint that it is perverse in some way would upset me tremendously. Totally inappropriate on his part. If he wants to give dental advice, fine, but his opinion on your BFing "relationship" with DS should be off limits.