Is it a problem if you swallow food stuck between your teeth after saying a brocha acharona? Is this considered eating without a brocha?
You may swallow it and there is no need to say a bracha. This is for a few reasons, first of all, the poskim say that when food is still in one’s mouth we don’t say that he separated himself from eating it, as it is still in his mouth. Secondly it is not something that is prominent enough to make a bracha on it, and the person doesn’t really have benefit from it.
Maaseh Ish 5-pg. 13, Ohr Ltzion 2-46 (48 ftnt. 45), Vzos Habracha pg. 191-5, Rivivos Efrayim 2-80(36), Chut Shani (Shabbos01 pg. 215, Sharei Habracha 13-24.