What is the ruling on the fast of one who regurgitated some food from the stomach to the throat and swallowed it, or swallowed his saliva after cleaning his teeth and doubted the presence of toothpaste in it?

If some food rises to the mouth and is swallowed unintentionally, it does not invalidate the fast. However, swallowing it intentionally when it was possible to expel it invalidates the fast and requires a make-up day. If food reaches the throat and you then intentionally draw it back and swallow it, your fast is broken. But if you swallow it unintentionally, your fast is valid. As for swallowing saliva present in the oral cavity unintentionally, it does not invalidate the fast, even if it has the taste of toothpaste.