If someone were to ask: Is the effect of brushing one’s teeth with toothpaste comparable to dissolving gum or to firm, hard gum?

The answer is that it is closer to dissolving gum. Therefore, we say that a fasting person should not use toothpaste while fasting, because it can reach the throat without his intending it. It penetrates readily and is also readily absorbed into the saliva. Thus, we say: If you wish to clean your teeth, wait until the sun has set, then clean them. Nevertheless, using toothpaste does not invalidate the fast.

His statement, “Kissing is disliked for one whose desire it arouses”: Kissing falls into three categories:

The first category is that it is not accompanied by desire at all, such as a person kissing his young children, kissing someone returning from travel, or the like. This has no effect and no ruling with respect to fasting.

The second category is that it arouses desire, but the person is safe from invalidating his fast through ejaculation or the emission of pre-seminal fluid—if we hold that the emission of pre-seminal fluid invalidates the fast. According to the madhhab, kissing is disliked for such a person.

The third category is that he fears his fast may be invalidated, either through ejaculation or through the emission of pre-seminal fluid—if we hold that pre-seminal fluid breaks the fast; and it has previously been stated that the correct view is that it does not break the fast. This is prohibited if he thinks ejaculation is likely—for example, if he is a young man with strong desire and intense affection for his wife. There is no doubt that such a person is in danger if he kisses his wife in this state. It is therefore said of someone in this situation that it is prohibited for him to kiss, because he is exposing his fast to invalidation.