Maris Ayin - Teeth Brushing

QUESTION: When I brush my teeth, I sometimes see blood on the brush. Must I rinse it off or is it fine to continue using it?

ANSWER: Rav Chanoch Padwa zt”l (Chaishev Ha’Efod 4:8) initially writes that it would seem that blood on a toothbrush is forbidden due to the prohibition of maris ayin, and it should be rinsed before placing back in your mouth. Although one could argue that the toothbrush itself should serve as a heker (indication) that the blood came from the mouth, Rabbi Padwa does not view this as a strong enough indication. As evidence, he quotes the case highlighted in Shulchan Aruch (Y”D 66:10). If someone bit into a roll and noticed blood on the bitemark in the roll, that area of the roll must be discarded because of maris ayin. Although there are bite marks on the roll which indicate that the blood originated from the mouth, the residual blood that remains after biting into the roll is forbidden. Still, he points out that since the toothpaste is not swallowed - it is spit out - there is room to be lenient. It can also be argued that blood on a toothbrush is more apparent that it originated in your mouth than blood next to teeth marks on a roll. In any event, the concern of blood on a toothbrush is limited to blood that is obvious. However, if the blood is mixed with toothpaste and saliva and is no longer recognizable as blood but only as a red discoloration in the toothpaste, it would be nullified. The Rema (YD 66:10) writes that when something is prohibited due to maris ayin, it is nullified and permitted once it becomes mixed into a larger quantity and is no longer noticeable.

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