I have two friends whose kids had some teeth that "rotted" as they came in.
 In both of these cases maternal illnesses with fever during the eighth month
of pregnancy were implicated. Other breastfed kids  in the same families had
nursed a lot at night yet had healthy teeth. The dentists (in separate cities
and different times) both said that the enamel for baby teeth is laid down in
utero and that the nighttime nursing may have exacerbated the problem, it
probably didn't cause it. These kids probably would have had MUCH worse teeth
if they hadn't been breastfed.

It has always bothered me that while most kids who nurse at night do not have
problems with their teeth, many bottlefed kids do have problems with their
teeth - yet breastfed kids are advised to follow the same "rules" as
bottlefed kids. This seems to be an apples and oranges comparison.  There are
many other factors to consider (maternal heath and diet during pregnancy,
dental hygiene, genetics,  sugar intake during the day, etc. ). It seems to
have more to do with our culture's disapproval of meeting our children's
nighttime needs. I think it is simplistic to use the fear of dental problems
as a reason to discourage a normal, natural part of the nursing relationship.

Here! Here! to Sue Jacoby's post (26 Nov 1995). I totally agree! I was
thinking many of the same things. Allergies, teething, distractability during
the day, and reduced milk supply due to the pregnancy, etc. are legitimate
and typical reasons for the baby to nurse a lot AND for this mother to be
particularly worn out. These things are not going to go away if this mother
lets the baby "cry it out". Dr. Sears' "The Fussy Baby" and Sandy Jones'
"Crying Baby, Sleepless Nights" are pretty helpful for suggestions and
support in coping with high needs babies. Implying to the mother that her
parenting choices are  somehow unhealthy or atypical can only add to her
isolation and stress.

 Some babies are needier than others at night. Some moms are better able to
handle sleep disruption better than others. Trying to limit nighttime nursing
in a determined baby can often lead to more problems. People who haven't
experienced the intensity of those needs seem to have trouble understanding
the importance of nighttime nursing to some kids in some families. "Letting
them cry it out" catches up with you when you have a high needs (or even not
so high needs) baby.  Almost by definition, high needs babies don't let you
get away with the easy way out. A worn out mother needs support,
understanding, and time more than she needs rescuing and quick fixes.
Although it can be difficult to keep up, it is NORMAL for a baby to turn to
his mother for comfort and NORMAL for her to respond. It is TYPICAL to be
stressed out and tired when you are pregnant and nursing a six month old.

(I guess this topic really pushes my buttons. I thought this would be a short
post about teeth.)

Marie of WI LLLL & MOM of a serious nighttime nurser (who finally  "slept
through the night" at age 3 and has perfect teeth at age 5)