During root canal and tooth filling procedures, there is a high chance of water droplets entering the throat, and thus being swallowed. This breaks the fast. Therefore, it is better to undergo these procedures after the fast. However, if due to a severe necessity, a person undergoes these procedures, and water droplets do not enter their throat, their fast remains valid. On the other hand, if water droplets do enter their throat, their fast is deemed invalid and it becomes obligatory for them to perform qaza for that day’s fast.