Response: It is enough to use the miswaak which the Prophet (sal-Allaahu 'alayhe wa-sallaam) has recommended for the mouth whilst fasting rather than the atomisers for the mouth. There is no problem in using the atomiser as long as nothing reaches the throat. However, it is befitting not to dislike the odour (of the mouth) resulting from the fast, since it is indicative of obedience to Allaah as it is beloved to Allaah. It is mentioned in a hadeeth: ((The odour emmanating from the mouth of one who is fasting is more pleasant to Allaah than the smell of musk)).
Shaykh Ibn Fowzaan
Fataawa Ramadhaan – Volume 2, Page 501, Fatwa No.457;
al-Muntaqaa min Fataawa ash-Shaykh Saalih ibn Fowzaan – Volume 3, Page 130.fatwaonline.com