Somewhere that I can't find now, I read a comment on breastfeeding and
caries that went off like a flashbulb for me:

Let's suppose that the breastfed toddler *is* more prone to cavities than
his cupfed counterpart.  Which will contribute more, in your particular
family, to the overall physical and emotional health of your child -
continuing to nurse and having to have some dental work done, or weaning
in order to have carie-free baby teeth?

Diane Wiessinger, MS, IBCLC, LLLL  Ithaca, NY