How do I animate my model's mouth?

Question

I am trying to do a mouth animation here. I want to add mouth bones to my model so it can speak/talk/show facial expressions.

My model:

-comes with a .pmx/MMD armature with no mouth bones.
-head mesh has more than one loose part (One basic face mesh, neck+ back head).
-the eyes/face are image textures (wrapped on the basic face mesh).
-the insides of the mouth is a loose part.
-tongue is not moveable

I tried editing the mesh, however there are a few problems.
-Editing process is slow and tiring.
-The loose parts break apart when editing

So to animate it, I only have to move the shape of the mouth and teeth. But how do I do that?

Here's a picture of my model's mesh, loose parts and armature respectively:

I want my editing process to be as simple as possible. Please help me!

Answer 1

The better way to animate facial emotions is using Shape keys. Of course, you can use bones for facial animation, but shape keys for facial animation easier and quicker to create, and the result will be more precise and controllable. You can learn how to make shape key animation from a lot of tutorials, for example:

https://www.youtube.com/watch?v=YDu6y_2jFg0&ab_channel=SouthernShotty

For speak animation 6 vizems is enough, to make all variations of lip animation, and 6 basic face emotions (happy, sad, angry, afraid, surprised, discoursed) should be enough for generating all variations of facial animation