Is the fast valid for one who tastes the flavor of temporary filling or anesthesia while fasting, or if blood reaches her stomach after a tooth extraction? And does removing the cotton placed in the spot of the extracted tooth affect the fast?

Swallowing blood intentionally invalidates the fast. However, if it reaches the throat unintentionally, it does not invalidate it. Swallowing the filling material used for a tooth intentionally invalidates the fast, as does swallowing saliva mixed with the taste of the material or the anesthetic. If the fast was obligatory, then it must be made up; otherwise, it is recommended. It is permissible to make up the six days of Shawwal if the fast observed was not valid.