I think it would be genuinely horrifying if Hellbat's teeth worked like the hinged structures ( solenoglyphous fangs ) seen in the viper family of snakes — when in use in biting, at least. They do however retract into his skull when at rest. Second sketch is before more development, but !
⚠️ Third image ( there are 3 sketches ) below cut has robot gore ! It's at the bottom with a warning
The structure would be a custom modification with a potential spring latch mechanism to release, as reploids who are humanoid don't need such monstrous features — but my headcanons are Hellbat was initially a mutos turned humanoid, as to lessen human fear and better blend in with the public. Teeth that were once tools were modified, but the combination of animal features were left more - so to avoid major changes and modifications being further made. Structures are a combinations of actual vampire bat teeth, so act more as sheers, sharp to the point you wouldn't even feel it — unless he bites down fully.
But he was modified to have a more human - like structure, so his method of using teeth in more human forms have changed immensely, and if we do a comparison of the strongest bite force ever recorded in a human ( as he is a machine, after all ) , he could definitely have an intense bite of 975 PSI. Heck, even then, average human is 162 PSI, while weak compared to most animals yeah, it's still fairly impressive.
But, given Mutos are basically made for war, I gave him the ability to bite and tear if it means an advantage is gained — albeit, such an ability is lost in his mutos form, as he can attack far more easily, so up close combat is far riskier. Still, he could definitely cause damage either way.
Slowly recovering, gotta move my hand, entertain myself up while quarantine until early December. Go watch https://youtu.be/53cpU7VcThI that I redraw based on it; & watch her other stuff too! Can’t help it Rachel exudes Leviathan. xD