Answered by Shaykh Amjad Rasheed
Has a person’ fast broken if some food goes down his throat from what was between his teeth?
If some food has passed through one’s teeth and he wasn’t able to distinguish it and get it out before it went down his throat, his fast has not been broken, for he is excused.
However, if he was able to distinguish it and get it out, and he didn’t, then his fast is broken. For this reason, a fasting person should clean between his teeth at night, as is stated in the Tuhfa and its super-commentaries.
Amjad Rasheed
[Translated by Sr. Shazia Ahmad]