Does swallowing small pieces of a miswak invalidate the fast?

The fasting person's use of a siwak (tooth-stick) during the day does not harm the validity of the fast, because the Prophet, peace and blessings be upon him, encouraged the use of the siwak at all times and did not exclude the time of fasting. However, the fasting person breaks their fast if they intentionally swallow any particles from the siwak, or if they intentionally swallow saliva mixed with the moisture of the siwak. But if they do so by mistake or forgetfulness, it does not harm their fast.