Reference: Fataawa al-Lajnah ad-Daa.imah lil-Buhooth al-‘Ilmiyyah wal-Iftaa. – Fatwa No.6132
Fataawa Ramadhaan – Volume 2, Page 480, Fatwa No. 422
Question: Does the blood that comes out from between the teeth accidentally, break the fast?
What if it is from other than himself, i.e. that someone had hit him accidentally?
Response: Blood which comes out from between the teeth accidentally does not break the fast, whether it is from oneself or having been hit.
And with Allaah lies all the success, and may Allaah send prayers and salutations upon our Prophet Muhammad ﷺ and his family and his companions.