There are specific rules for you in Islam fasting. If you search on internet whether can you brush your teeth in Ramadan or not you will find both answers Yes or No. Most scholars and books vote for no. You can not brush your teeth in Ramadan fasting because it will break your fast. On the other hand, some today scholars vote for yes it means that your fast will not break.
Listen! Islam is a religion of Taqwa(piety). It demands from you to be careful. So, I suggest you don’t brush your teeth during Fast. It will break your fast or not but you have to be careful and you always have try to leave suspect to gain Allah’s mercy.
If you are not clear now and you are still disturb due to disgusting smell of your mouth then read this Hadith Qudsi for you and motivate yourself:
Verily the smell of the mouth of a fasting person is better to Allah than the smell of musk.
When to do tooth brush in Fasting?
You can brush your teeth after sunset to dawn. If you will brush your teeth in fasting your fast will break or become makroh. So avoid it.
Can you replace tooth brush to Miswak during Fast?
Yes it is best idea to replace tooth brush with Miswak. Miswak is a tooth cleaning wood stick. It will not break your fast and you will find the blessing to revive the Sunnah. Miswak is a healthy step to clean teeth and it has many benifts for your health too.