The ruling on using a Toothbrush with bleeding
Question :
After abstaining (from eating when starting the fast) is it permissible for me to brush my teeth with paste, and if it is permissible, does the small amount of blood that comes from the teeth during brushing break the fast?
Answer:
There is no harm in rubbing the teeth with water, the toothstick and the toothbrush after beginning the fast. Some people (scholars) have declared using the toothstick disliked for the fasting person after midday, because it removes the foul taste in the mouth of the fasting person. However, the correct view is that it is recommended to use the toothstick at the beginning of the day and its end, and that its use does not remove the bad taste in the mouth. It only cleans the teeth and mouth from odors, smells and leftover particles of food. In reference to using paste, it seems most evident that it is disliked due to what it contains of fragrance and because it has a taste that mixes with the spit, and one cannot be certain that he won't swallow it. Therefore, whoever needs it may use it after Sahur (predawn breakfast) and before the time for abstaining from food. If a person uses it during the daytime and makes sure he does not swallow any of it, there is no harm in that if there is a need. If a light amount of blood comes from the teeth while the person is rubbing them with the brush or the toothstick, that does not break the fast. And Allâh knows best.
Source:
Ash-Shaykh Ibn Jibreen
Fatawa Islamiyah, Vol. 3 Page 263