Siman 457

(14.) One said that what he had dreamed — that his teeth fell out — alludes to his wisdom being nullified. And he [Rabbainu] said to him: "On the contrary — your foolishness will be nullified, for the translation of 'rock of flint' [shen haselah] is strength etc." (Said the transcriber: See Midrash Rabbah, Numbers, portion 3: "'Tooth' [shen] is only an expression of strength etc.") (Meaning — in jest and wit — for in our region a fool is called choyzhek.)