I wanted to add to the dental discussion from a slightly different
perspective.  My children are all older teenagers. They were all breastfeed
(18mos/2+years and 4 yrs). No special diet, no special dental care. Their
teeth are cratered and pitted but none have had problems with decay. (maybe
4 cavities amoung the three of them). What has caused problems is their bone
density.  The 19yr old had his wisdom teeth removed last summer -- a 2hr
local anaesthetic operation took 5 hrs as they could not get through the
bone to remove the impacted teeth!  The 17 year old has had to have two
infant molars pulled in the past year as they were not allowing the adult
teeth to erupt. In this case the teeth were anchored in the bone and the
bone was incredibly dense. Again the procedure was complicated by this fact.
I think the poor dentist was in worse shape than my son who took it all in
stride. The dentist looked like he'd had a major work out. Is this density
genetic?  Probably, it is unheard of for a member of our family to break a
major bone, but I suspect the breastfeeding is also a component.  They just
laid down bone that was close to their genetic potential.
        I am sure we all know people with light frames and bones which seem
to break easily.  These are often the women most at risk of osteoporosis who
work hard at maintaining their calcium intake and excersize.  They are
trying to lay down the maximum bone density, to meet their genetic
potential.  Why can we not accept the same concept with teeth.
Breastfeeding is PART of obtaining the genetic maximum but we all start from
a different spot.  I wonder if the problem the dental profession is having
is that they view breastfeeding as a feeding method and not as a way of
optimizing nutrition. As an aside I would love to see research into the
impact extended (2 yrs plus) breastfeeding has on rates of osteoporosis in
high risk families.  That is rates in the women who were breastfed not the
ones doing the breastfeeding.