Thanks to Dr. Palmer for all his good work on behalf of breastfeeding.  I
did want to add that there can be genetic (hereditary) enamel porosity
(generally crummy enamel, but nothing obvious to the naked eye).  My mother
has it, I got it, but my two sisters didn't, my youngest of three children
also got it, but the older two didn't.  Most of my teeth have crowns, more
than a few have had root canals, and the rest are full of fillings.
Alexander had to have fillings in most of his baby teeth.  In addition to
his crummy enamel, he had very "crenellated" molars with very deep grooves
that were difficult to keep clean.  Those have now been filled in with
fillings.  I would be very surprised to see classic "nursing bottle caries"
where the front incisors are all rotten in a breast-fed baby, even one who
nurses throughout the night until they are 3 or 4, simply because the milk
must be actively removed from the breast, and comes out in the back of the
mouth, where it goes right down the throat, and doesn't "pool" around the
baby's front teeth.  The case described on LactNet last week of the "ridge"
(actually a crevice, according to the mom) across the upper front incisors
near the gums is known as "linear enamel hypoplasia" and that particular
part of the enamel is forming around the time of birth.  Various sorts of
stress, such as those from a difficult labor, can lead to an interruption of
enamel formation, leading to a line of linear enamel hypoplasia where the
enamel is very thin or not formed at all, which can be subject to decay,
regardless of feeding method.

Re: women with enormously elongated breasts.  I've certainly seen my share
of these in Mali -- ones where the child could literally stand three feet
from mom, holding onto the end of mom's breast and nursing, even walking
around behind mom's back, holding onto the breast the whole time.  I've also
seen cases where the mother could offer her breast to the child while the
child was tied to the mother's back - either directly back over the mother's
shoulder, or around the side under her armpit.  These kids didn't seem to
have any trouble nursing or getting milk -- the tissue between the mother's
chest wall and the "breast" out at the end seemed to be just skin (obviously
ducts too) and the "milk" was down in the "breast" where it could be
accessed just like any other.

Kathy Dettwyler