As somebody who's tried using a miswak [0] teeth-cleaning twig out of curiosity, I can say with confidence it's not the same experience as using a modern toothbrush. It's capable of cleaning your teeth effectively, but it's slower and more difficult than a modern toothbrush. The angle of the bristles makes a huge difference. When the bristles face forward like with a teeth-cleaning twig your lips get in the the way a lot more. Sideways bristles are easier to use.
[0] https://en.wikipedia.org/wiki/Miswak