Originally Posted by parabellum
if there is decay under the crown, you can feel the crown margin, which feels sharp to your tongue.
Thanks for reply. BUT, if I run my tongue or fingernail vertically down the crown, I come to a groove, so that the crown appears to fit inside whatever substance is underneath, rather than outside it. It is this substance which is 'fraying'. Each sharp strand has an elastic quality to begin with, which, when I work the end with my tongue, frays into tiny fibres. I can't believe this is decaying tooth. So what is it?