Does the unintentional disintegration of the siwak and its entry into the pharynx invalidate the fast?

Things that unintentionally reach the throat do not break the fast, and similarly, anything that cannot be avoided, such as particles from a miswak, road dust, flies, or sifting flour. This is because a person is not held accountable for that which they did not intend, in accordance with the Almighty's saying: (Allah does not charge a soul except [with that within] its capacity).