Dear Patricia,
    As a former dental hygienist, whose reference books are packed away in the
attic, it was always my understanding that the x-rays emitted where obviously
targeted to the film on the other side of the tooth and there is minuscule
"scatter radiation"....hence, the prophylactic wearing of the lead
shield.....radiation can be accumulative in the body, according to my
radiology training (six months in radiology technology school in the early
70's) but the milliamps and kvp settings are adjusted and time exposure is
limited and the new machines mandated in the US are "fast" and use ultraspeed
film for dental x-rays, unlike some other therapeutic or diagnostic
series....I have never heard of breastfeeding being contraindicated, as in
irradiated milk, after routine 4 bitewings or a 16 film full-series or the
longer exposure panorex/panalipse.....
    It always was, and still is, a common question from  the moms, just like
local anesthetics, but we always urge the mom to continue nursing....

Jan Ellen Brown, RDH, IBCLC  Who worked Christmas eve and day and saw many
BFing moms and babes in Charlotte, NC, one who was diagnosed early with
meningitis because the mom caught the seizure activity (rhythmic arm and leg
spasms) during a nursing session and is hospitalized for ten days but at
breast!