There was an extensive thread on Lactnet on this topic within the last year.
Check the Archives under dental caries.

Having one child with serious decay from age one, I have concluded that it
was due to the incomplete enamel areas of her primary teeth. Her teeth
continued to decay long after she was no longer feeding at the breast and
continued despite brushing after anything that entered her mouth.  She did
continue eating, though she had NO sweets from age 2 'till her primary teeth
were gone, but she still had 4-5 new cavities every 4 months when we visited
the dentist.

I attribute her inadequate enamelling to my prenatal diet that was deficient
in calcium. I have since learned that the small amount of calcium in
prenatal vitamins combined with my high protein and other phosphorus intake
were the probable cause of my insufficient calcium assimilation.  I had
symptoms of ca. deficiency during my pregnancy that I didn't know at that
time was due to that cause.

I also discovered after my second child that I am allergic to( or have a
"sensitivity to", if you prefer) dairy products.  I believe that
assimilation of nutrients is interefered with when there is an allergy to a
given food.

With my second baby I took responsibility for my own nutrition and focused
on calcium and magnesium, and didn't overeat proteins, and avoided such high
phosphorus substances as colas and root beer.  I didn't rely on dairy
products for my calcium intake.

Baby #2 nursed much more at night than baby #1 and continued for 4 years.
She had no cavities because she had solid enamel on her teeth.

If a child has inadequate enamelling of teeth there will probably be some
decay caused by her feeding "all night."  There will be some decay caused by
her feeding at all. But if cavity-free is what we are aiming for, then the
only solution is to suspend ALL eating and drinking until these teeth are
replaced by the permantent teeth. Actually, even that wouldn't stop the
decay, just slow it.

The many benefits of breastfeeding, including at nighttime, far outweigh the
negative effects of cavities in the primary teeth.  Our years in the dental
chair were hard, but Lia learned a healthy respect for dental health and we
went through it all together.  And I know that if I had weaned her, her
overall health, including emotional, would have been compromised...and her
teeth would have continued to decay. Remember, the benefits of breastfeeding
are life-long.

Patricia Gima, IBCLC
Milwaukee

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