I have heard brushing teeth fast breaks the fast, is this true? If this is true please give some refrence.
there are only 3 things that break the fast - eating, drinking and sexual intercourse.
brushing is not included in any of these, so if you brush your teeth with a plain miswak or brush with a toothbrush that has no toothpaste on it, then this is fine.
however, if you brush with toothpaste then some will undoubtedly get swallowed with the saliva and break the fast.
thus, when brushing teeth, it is the swallowing of toothpaste that breaks the fast and not the act of brushing.