Is it necessary to make up the fast if some food residue stuck in a dental retainer goes down the throat unintentionally?

A fasting person should clean their teeth at night, including any food residue between them. If they intentionally swallow something from it, while being able to remove it, their fast is broken. However, if they swallow it unintentionally, such as it flowing with their saliva to their throat and they were unable to expel it, then their fast is valid, and nothing is due from them.