They are both grinding teeth to suck blood.

磨牙吮血，杀人如麻。

youdao

It is very useful for us to develop the quality of grinding teeth adn add the knowledge on grinding teeth.

这对于提高磨齿质量，加深对磨齿的认识是非常有用的。

youdao

Some of those body parts are already under pressure from long hours at the computer, restless sleep, grinding teeth and poor posture.

有些身体部位早已因长时间看电脑、睡眠不足、磨牙和姿势不当等承受了很大的压力。

youdao

She wasn't eating. She had terrible stomach pains. She started clenching her jaw and grinding her teeth at night.

VOA: special.2010.04.22

How, present and former members of Tony Blair's accident-prone cabinet must ask themselves between grinding teeth, does the man get away with it?

ECONOMIST: The riddle of Jack Straw

If left untreated, however, teeth grinding can sometimes damage the teeth or cause headaches and TMJ (temporomandibular joint) pain.

CNN: What can I do about teeth grinding?

Make sure to discuss all of your options and let your doctor know if you're grinding your teeth.

CNN: Dental screening that could save your life