Rashi: They are fine, white and arranged like wool, and the order of a flock of ewes selected from the rest of the flock. They are given by number to a wise and proper shepherd to be careful with their wool; it is used for Milas (refer to 4:1:4:3 and the note there). It is guarded from birth, lest it get dirty. They wash it daily.

Seforno: The teeth (soldiers) resemble Eder ha'Ketzuvos, that their hair was shorn. So they did not take anything from the spoils until they divided it among themselves - "Chilku Shelal Oyveichem Im Acheichem" (Yehoshua 22:8).

Malbim: Teeth are bodily excesses that become thick and are revealed outside, and similarly regarding the Nefesh. The verbal Nefesh depends on physicality to reveal the intellect in its special ways, via laws of logic and comparisons. They are compared to sheep that rise from being bathed [in the river]; their wool was laundered from all filth.

Rashi: This is like Mesom - "Ein Mesom bi'Vsari" (Tehilim 38:4), i.e. complete [Seforno - in Torah and good deeds].

Malbim (Melitzah): There are 16 laws of intellect; four of them are derived via comparisons. From the 16 come another 16 ways to increase understanding, 32 paths in all. They correspond to the 32 teeth - 16 in the upper jaw, and 16 in the lower, one above its counterpart. Their color is uniform; they are identical twins.

Rashi: There is no miscarriage or blemish among them.

Rashi according to the metaphor: This refers to Giborim of Yisrael who, with their teeth, cut off and consume their enemies around them. They distance from theft from Yisrael and from Arayos, lest they be sullied via Aveirah. This praise refers to the 12,000 who fought Midyan. Not one of them was suspected of Arayos - "v'Lo Nifkad Mimenu Ish" (Bamidbar 31:49). Even for theft they were not suspected - "va'Yikchu Es Kol ha'Shalal