Brushing Teeth on Shabbat: A Reevaluation in Light of Recent Research – Part Four by Rabbi Dr. Ephraim Rudolph DDS


Kol Torah proudly presents this fourth part of a very significant Halachic piece written by Rabbi Dr. Ephraim Rudolph, a TABC alumnus. His discussion on the permissibility of tooth brushing on Shabbat will be concluded in this issue. This issue will begin by discussing another possible reason to permit brushing teeth on Shabbat, namely the leniency afforded to a Refuah She’aino Nikeret.

Refuah She’aino Nikeret

One might argue that toothpaste should be permitted as a ma’achal beri’im because most people still think that brushing teeth only prevents future cavities by removing plaque from the teeth. One of the explanations for why ma’achal beri’im is permitted on Shabbat is that it is unclear to the observer that the item is ingested for refuah purposes, as it is commonly taken by healthy individuals; it is a “refuah she’einah nikeret.”[1] Similarly, since most people are not aware of how fluoride really works, when people brush their teeth, it is refuah she’einah nikeret. Even though tooth-brushing constitutes refuah, one is not aware that refuah is taking place.

This argument may be questionable. Refuah she’einah nikeret may possibly refer only to a situation in which others will misinterpret what is taking place because of the normal usage of the item, not because people in general do not understand how the item is used.

However, according to Rav Weiss, who holds that the prohibition of refuah is based on the public perception and not science, perhaps the leniency of refuah she’einah nikeret is also based on the perception and not on science. But, as pointed out earlier, there may come a time when the general population does know that fluoride rebuilds teeth.

Rabbi Jachter adds an additional reason to the refuah she’einah nikeret approach. As noted, the impact of tooth brushing varies by individual and even varies from time to time for each individual. Thus, since absent a professional evaluation one cannot know if he is actually engaging in an act of refuah, tooth brushing should be considered refuah she’einah nikeret. Thus, since it is difficult to assess one’s dental health and since current scientific thinking is subject to some debate and is liable to change in time, it is reasonable to argue that tooth brushing should be evaluated from a common sense perception which is, as stated by Rav Ovadia Yosef, that one is simply mavriach ari and not engaged in an act of refuah when brushing his teeth.

However, Rabbi Jachter’s insight would only regard the medicinal aspect of toothpaste. With regards to the vitamin aspect of fluoride, however, almost all scientists are in agreement as to its benefit and also almost everyone can assume that the fluoride is strengthening or fortifying their teeth even without the diagnosis from a professional.

In summary, if many people are considered cholim with regard to their teeth, the heter of ma’achal beri’im may not apply. Even if that is not the case, and population-wise it could be that the non-cholim segment is large enough to create a ma’achal beri’im status, the classification of ma’achal beri’im may still not apply if fluoride is considered to be a type of medication. This would depend on whether or not aspirin is a ma’achal beri’im. Although one might argue that toothpaste is comparable to vitamins, which are permitted by some Poskim as a ma’achal beri’im, other Poskim do not permit vitamins on Shabbat. Also, although many people are not aware of how fluoride affects their teeth, that may not indicate that fluoride is in fact a ma’achal beri’im. However, based on the teshuva of Rav Weiss, as well as the insight of Rabbi Jachter, it may still be possible to utilize the heter of refuah she’einah nikeret and ma’achal beri’im.

Routine Medication

Rabbi Jachter suggests another leniency based on the opinions that the prohibition of refuah does not apply to an activity performed routinely. Shemirat Shabbat Kehilchata (34: note 76) cites Rav Shlomo Kluger and the Chazon Ish, who permit taking medicine on Shabbat if it is part of a routine that was established before Shabbat. Rav Yosef Adler cites Rav Yosef Dov Soloveitchik who reported that Rav Chaim Soloveitchik adopts the same approach. For example, if someone is taking antibiotics for ten days, he may take the antibiotics on Shabbat as well. A reason to be lenient in this situation is that the concern that one may grind medicine on Shabbat is moot, as one usually obtains the medicine before Shabbat if he knows that he must take this medicine for a specific period of time.

According to this approach, there should not be concern for refuah regarding tooth brushing since it is done on a daily basis. Research has shown that a frequent, constant low concentration of fluoride is critical for the remineralization success and therefore it is important to brush on a daily basis[2].

Rabbi Jachter notes, though, that Rav Moshe Feinstein (Teshuvot Igrot Moshe Orach Chaim 3:53), Rav Shlomo Zalman Auerbach (cited in Shemirat Shabbat Kehilchata 34: note 76), and Rav Eliezer Waldenberg (Teshuvot Tzitz Eliezer 8:15:15:15) express serious reservations about this lenient approach.

Brushing for non- health reasons

The Mishnah (Shabbat 14:3) writes that one is not allowed to drink “may dekalim” for refuah but one may drink it to quench one’s thirst. Rashi (Shabbat 109b s.v. may) writes that this leniency refers only to healthy people; only healthy people are allowed to use the medication may dekalim for a non-medicated use. Many Rishonim disagree with Rashi and hold that even sick people are allowed to use medication for non-medicated purposes[3]. The Biur Halacha discusses this topic and concludes that most Rishonim reject Rashi, but he is still uncertain how to resolve this issue[4].

Based on this, perhaps it could be argued that if people would like to brush on Shabbat, they do so purely for hygienic and esthetic reasons. People know that missing one morning brush will not affect their health and so they could have in mind that they are brushing only to have clean, fresh and good-smelling mouths[5]. Maybe it could be argued that since most Rishonim are lenient in this scenario and it is not certain that toothpaste is refuah, and perhaps the heter of ma’achal bri’im does apply to toothpaste, as well as Rav Schachter’s heteir, it would be permissible for these individuals to brush their teeth on Shabbat as they are brushing their teeth for non-medicinal purposes. Rabbi Jachter believes that this is the implicit intention of those Bnei Torah who brush their teeth on Shabbat.


In addition to possibly violating the prohibition of refuah on Shabbat, tooth-brushing might potentially violate the prohibition of memarayach (spreading), a toladah of memachek (smoothing)[6]. R. Ovadia Yosef maintained that tooth-brushing does not pose a problem of memarayach because in order to violate the malacha, one has to have intention that the substance that he is spreading will remain on the surface. This is not the intention, he writes, of one who spreads toothpaste on his teeth; his intention is only that the toothpaste should facilitate the removal of plaque, not that it remain on his teeth[7].

However, based on the new understanding of the mechanism of fluoride, there are new instructions for brushing teeth: one should have the toothpaste remain on the teeth for at least two minutes and then spit it out, without rinsing after brushing[8]. In order for fluoride to provide its health benefits, it must remain on the teeth for a significant period of time. Accordingly, if one brushes properly and follows the new guidelines, then he indeed intends to have the toothpaste remain on the teeth. Furthermore, the longer toothpaste remains on plaque, the more likely the antimicrobials in the toothpaste will be able to penetrate the biofilm and kill the bacteria, thereby reducing or preventing gingivitis[9].

It is possible to argue that R. Yosef meant that one has to intend that the substance should remain on the surface for a significant amount of time, which is still not the case regarding toothpaste. Additionally, R. Soloveitchik ruled that tooth-brushing is not a problem of memarayach, as memarayach is violated only when the new and smooth outer coating remains on the surface on which it is applied[10]. Toothpaste does remain on the surface in a significant way for a long period of time.


The new research regarding how toothpaste prevents cavities may significantly impact the halachot of brushing teeth on Shabbat. The halachic topics of refuah on Shabbat, the status of preventative medication, ma’achal beri’im, and memarayach must be re-addressed as the new science might undermine the lenient approaches of Rav Soloveitchik and Rav Ovadia Yosef to allow tooth-brushing on Shabbat. However, we have presented new rulings from Rav Asher Weiss and Rav Herschel Schachter, as well as other possibilities, that may enable the lenient position to remain intact despite these developments. Those who follow the lenient approach and brush their teeth on Shabbat should consult with their Rav to see if they are still permitted to do so. In addition, Rabbi Jachter notes that many people who adopt the strict approach of Rav Moshe Feinstein regarding tooth-brushing on Shabbat use either mouthwash or liquid toothpaste, formulated to avoid concern for memarayach. Based on the new research, without the leniencies mentioned, these items may also be prohibited on Shabbat due to the prohibition of refuah on Shabbat.

[1] See previous issue.

[2] Rošin-Grget K1, Peroš KSutej IBašić K, “The cariostatic mechanisms of fluoride,”Acta Med Acad. 42:2 (Nov 2013): 179-88; Nóbrega DF1, Fernández CEDel Bel Cury AATenuta LMCury JA, “Frequency of Fluoride Dentifrice Use and Caries Lesions Inhibition and Repair,” Caries Res. 50:2 (March 2016;):133-40.

[3] See Biur Halacha Orach Chaim 328 dibbur hamatchil aval

[4] ibid

[5] Some may object and claim that this may be an issue of ha’ramah, circumventing the halacha, and only those individuals who brush daily for hygienic reasons and not health reasons can utilize this leniency. Also, even though a constant low level of fluoride is necessary for remineralization, missing one morning brushing will not greatly affect the process.

[6] Memarayach is the prohibition of spreading a substance onto a surface. The consistency and density of that substance determines whether the violation is Biblical or Rabbinic. If the substance is a pliant solid,memarayach constitutes a Biblical prohibition; if the substance is a semi-solid, it would only be a Rabbinic injunction. Most Poskim, such as R. Yosef (Yabia Omer, Orach Chaim 4:27:1), maintain thatmemarayach with toothpaste would at most violate a Rabbinic prohibition. In his article, R. Lebowitz (n.5) notes that it is possible to argue that there is a Biblical prohibition involved here as well based on a slightly different understanding of which substances are Biblically forbidden.

[7] Yabia Omer, Orach Chaim 4:27.

[8] K. Sjögren, J. Ekstrand, and D. Birkhed, “Effect of Water Rinsing After Toothbrushing on Fluoride Ingestion and Absorption,” Caries Res 28 (1994): 455-9.

[9] P.D. Marsh, “Microbiological Aspects of the Chemical Control of Plaque and Gingivitis,” J Dent Res 71 (1992): 1431–8.

[10] Nefesh HaRav, pp. 168-9.

A Lechi on Every Utility Pole? - A Report from the Field – Part One by Rabbi Chaim Jachter

Brushing Teeth on Shabbat: A Reevaluation in Light of Recent Research – Part Three by Rabbi Dr. Ephraim Rudolph DDS