Are all toothpastes and mouthwash (listerine) and (scope) flavored floss kosher to use?
Is it not problomatic to brush teeth on shabbat even with liquid toothpaste since one may bleed?
According to the strict halachah, toothpastes do not require a hechsher, and are all kosher to use (see Har Tzvi, Yoreh De’ah 95). The reason for this is that they are not food, and are considered pagum–not suitable for consumption. In addition, there is no intention of swallowing the toothpaste, and tasting alone is only prohibited due to the concern that one might swallow the food, which does not apply for toothpaste. The same reasoning would seemingly apply to mouthwash. However, it is generally customary to apply kashrus standards to these products, and many have some kashrus supervision.
Concerning bleeding gums: If somebody knows that his gums generally bleed upon brushing, he may not brush teeth on Shabbos. However, if a person’s gums generally don’t bleed upon brushing, he need not be concerned for the possibility of bleeding.