Greg, welcome to TalkGraphics.
3D animated modelling is not ever simple, especially work trying to simulate a physical system.

All I can offer is https://duckduckgo.com/?q=3d+animati...brush+bristles.
The Blender link offers two different approaches that you might be able to adopt in your setup.

I must try brushing with pasta, though I doubt flossing would be any good.

Acorn