Bruxism. A problem that troubles me whenever I am angry. And, due to malocclusion issues, I will thus have my left wisdom teeth taken out pretty soon (whether before or after Easter, I cannot tell). The right ones, however, will not be removed.
Already Thor's billy goats were called Gnasher and Grinder, and the Bible mentions a lot "gnashing of teeth", especially in conjunction with wailing (screaming in pain like a banshee; do not confuse with whaling, although I have to admit that whaling is something even more gruesome) when it comes to the punishment of the sinners in hell (AKA the lake of fire, the fiery furnace, the Gehenna, the underworld... many expressions to mean "hell" are used throughout the Good Book).
It already struck me as a kid that there was so much gnashing of teeth in the Abrahamic Hell. As stated in, for instance, the Gospel of Matthew's parables of the weeds and of the fishing net.
The picture painted in these parables is pretty descriptive; the Judge placing the righteous on his right and the sinners on his left (or sinister, to continue with the puns), and casting the latter into the lake of fire or fiery furnace, where there shall be wailing and gnashing of teeth.
Now the original Greek word used by Matthew (if this Matthew was really the author) for gnashing of teeth (ὁ βρυγμὸς τῶν ὀδόντων) happens to be the same root (as in tooth root, get another pun?) as our scientific term bruxism:
βρυγμος noun - nominative singular masculine
brugmos broog-mos': a grating (of the teeth) -- gnashing.
Right, that was all I had to say. On how Thor's goats and the Gospels prove that bruxism is an issue as old as time (and maybe older, as seen when other apes gnash their teeth to intimidate!). I struggle with this problem (daytime bruxism, due to anger), and thus, I am having my left wisdom teeth taken out. Only those on the left, mind: that makes two.