All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
There is no harm for cleaning the teeth during the daylight hours in the month of Ramadan as long as it does not nullify the conditions of fasting according to the Hadeeth of the Prophet “Were it not that I would be overburdening my community, I would have ordered them to use the Siwaak (tooth-stick) before every prayer.”
Moreover, ‘Aamir Ibn Rabee'ah narrated that his father said: “I have seen the Prophet using the Siwaak while he was fasting at countless number of times.” [Abu Dawood and at-Tirmithi]
However it is required that when the person is cleaning his teeth with toothpaste or any product, he should make sure that he does not swallow anything of it because if anything goes down his throat, his fast becomes void.
Allah knows best.