The Poskim debate whether or not one has to Kasher their mouth before Pesach. The rationale to require such a procedure is that most people have some type of dental work done, such as a silver filling (amalgam), a white filling (composite), or a crown. These items are made out of different materials which, if used for cookware, would require some type of kashering for Pesach. Therefore, the question is: since these materials come in contact with Chametz in the mouth, do they require kashering for Pesach? This issue of Kashering ones mouth also applies to milk and meat. Does one needs to Kasher their mouths in between milk and meat? This question sounds funny because no one is concerned with Kashering their mouths in between milk and meat - it seems rather bizarre - but as we shall see, there may not be so much difference between fillings and pots.
The whole discussion revolves around the halachic concept of Ta’am (taste). When two foods are cooked together, the taste of each one is transferred to the other. Taste is not just transferred between foods; rather, it is also transferred to the Keli (utensil) in which the foods are being cooked. The flavors that get absorbed into other foods and vessels are called Beli’ot. The vessel does not just absorb Beli’ot; rather, it gives off Beli’ot as well. This means previous Beli’ot absorbed in the pot (even if the pot is has been cleaned) are released during a subsequent cooking process and enter the food being cooked. It is therefore forbidden to cook meat in a milk pot, since the milk Beli’ot will be released by the pot and enter into the meat, rendering the food non-Kosher. Furthermore, the Ta’am of the meat will be absorbed by the pot, making the pot unusable due to the fact that it has a mixture of milk and meat Belio’t (Yoreh Dei’ah 93:1).
This concern should apply to dental fillings as well. For example, the fillings will absorb the taste of a hot piece of pizza, and then, when the person has some hot chicken soup, the taste of the cheese will be released from the filling and enter the chicken soup. Additionally, the taste of the soup will be absorbed by the filling, making the filling now have meat and milk Beli’ot. Any hot food placed in the mouth thereafter will cause a release of milk/meat (i.e. non-Kosher) Beli’ot. So, at first glance, it appears that fillings should follow the same rules as pots. Why, then, is the common practice to not worry about this issue? Even if there is no reason to be concerned normally, shouldn’t we be stricter when it comes to Pesach? And if we should be Machmir, how would we go about kashering our mouths?
Many authorities actually discuss the issue of Ta’am and Beli’ot in the mouth with regards to dentures. Is there a need to Kasher dentures, or have various pairs of dentures for milk, meat, and Pesach? A denture is an appliance that has fake teeth which one wears to replace their missing teeth; it is not fixed into the mouth, but rather can be put in and taken out. Even though the bulk of the discussion revolves around dentures, there are many ideas that are presented in those discussions that apply to permanent fillings as well. Some of the many Poskim who write about this topic are Tzitz Eliezer (9: 25), Minchat Yitzchak (8:37), and Darchei Teshuvah (Yoreh Dei’ah 89:11). We will, for the most part, present and discuss the approaches of Rav Ovadia Yosef in Yechaveh Da’at 1:8 and Rav Shlomo Zalmun Auerbach in the Minchat Shlomoh 2: 47. We will begin to discuss these approaches next week.