In Bemidbar 19:16, the Torah mentions impurity conveyed by a person's bone. From this, the gemara learns out that those parts of a corpse that convey impurity are those parts that are like a bone in two respects: a person is born with them, and if removed they don't grow back (Niddah 55a).

One of the body parts thus excluded is teeth, on the grounds that a person is not born with them. But a person is born with them, they just haven't yet extended through the gums. My question, therefore, is in two parts:

1) Were the rabbis mistaken, thinking that because the teeth aren't yet visible they therefore don't exist?

2) By suggesting that the teeth don't exist yet did the sages mean that they're just not visible?

In the case of 1), does that mean that there is a valid reason to consider teeth as conveyers of impurity, now that we know that a baby is born with them? And in the case of 2), does that mean that other body parts that are not yet visually apparent (such as testes, in the case of boys) also therefore don't convey impurity in a corpse?

  • 3
    en.wikipedia.org/wiki/… CYLD but it seems the teeth aren't completed at birth FWIW.
    – Double AA
    Commented Jan 8, 2016 at 7:11
  • @DoubleAA - where are you seeing that? Looking at that website, I'm only seeing substantiation of the idea that teeth are fully formed by the time the baby is born...
    – Shimon bM
    Commented Jan 8, 2016 at 7:27
  • 1
    If I'm reading it right, it says in the chart that the primary (not adult) teeth begin development in utero, but finish forming the crowns a few months after birth and finish securing their roots years later.
    – Double AA
    Commented Jan 8, 2016 at 7:30
  • @DoubleAA - I'm not seeing that, but I'll check after Shabbos from an actual computer. Thanks! Shabbat shalom.
    – Shimon bM
    Commented Jan 8, 2016 at 7:36

1 Answer 1


It shouldn't matter - even if a baby were born with fully emerged teeth, they would "grow back" when they are replaced with his adult teeth. (With regard to your last question, in normal/typical fetal development, the testes descend before birth. The norm would presumably determine the halacha as far as designating the purity-class of the organ, even for those instances where the organ emerged post-partum.)

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