What does 歯が欠ける mean?


I would like to know what does 歯が欠ける mean: Lacking teeth? Broken teeth?

Context: 人の幸せを素直に喜べないやつ理解出来なさすぎて、また歯が欠けた。

My translation:

I can't barely understand people who cannot honestly be glad for other's
happiness, 「???」.

How would you translate the expression 歯が欠ける?

Thank you so much in advance for your help!




This is not an idiom, and また歯が欠けた means "my tooth was chipped again (because I
clenched my theeth)". Although I haven't seen something like this before, I
can imagine this person said this to express his uncontrollable frustration.
Perhaps this is an exaggerated joke, and he did not chipped his tooth in
reality.




This is not an idiom, and また歯が欠けた means "my tooth was chipped again (because I
clenched my theeth)". Although I haven't seen something like this before, I
can imagine this person said this to express his uncontrollable frustration.
Perhaps this is an exaggerated joke, and he did not chipped his tooth in
reality.

