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


Kol Torah proudly presents this Halachic piece written by Rabbi Dr. Ephraim Rudolph ‘98, a TABC alumus. His discussion on the permissibility of tooth brushing on Shabbat will be continued in the next few weeks.

The halachot regarding brushing teeth on Shabbat were discussed by many of the Poskim of the previous generation, including R. Moshe Feinstein, R. Yosef Dov Soloveitchik, R. Ovadia Yosef, and R. Shlomo Zalman Auerbach. In 2002, R. Aryeh Lebowitz published a comprehensive review of the halachic issues relevant to brushing teeth on Shabbat.[1] However, new research about the mechanism through which toothpaste improves oral health may have implications that warrant a second look at some of these halachic issues.


R. Moshe Zweig ruled that brushing teeth is prohibited on Shabbat because of the prohibition of refuah on Shabbat[2]. R. Zweig bases his view on a Tosefta (Shabbos 13:17) that states that it is forbidden to rub one’s teeth with “sam,” medicine, when it is intended for the purpose of refuah; it is permissible only if done solely for the purpose of eliminating bad breath[3]. R. Zweig felt that toothpaste is akin to the “sam” mentioned in the Tosefta, and it is therefore forbidden to be used on Shabbat.[4]

The majority of Rabbonim and Poskim did not share this view.[5] Most of the responsa on brushing teeth on Shabbat were written when the prevailing belief was that toothpaste and brushing only prevent future tooth decay from occurring but do not heal existing cavities. The prevalent perception was that brushing with the help of toothpaste removes food that is stuck on the teeth, and thereby prevents cavities from developing. Since brushing was perceived as solely preventative, most authorities maintained that it is not forbidden on Shabbat due to the prohibition of refuah. As R. Ovadia Yosef explained, preventing cavities by removing food from the teeth is not called refuah. It is simply “mavriach ari,” “chasing away a lion” – it removes something bothersome, but cures no illness.

However, recent research has shown that in addition to preventing plaque build-up on teeth, tooth brushing may, in fact, heal existing tooth decay. Thus, R. Zweig’s opinion that brushing teeth is prohibited on Shabbat as a form of refuah may warrant reconsideration.

Cavities develop because bacteria build up on teeth and form plaque, or dental biofilm. This plaque feeds on the sugars in food and produces acid. In the demineralization process, the acid “dissolves” the main component of tooth enamel, making the tooth soft and susceptible to bacterial penetration and cavity development.[6]

For many years, the scientific community assumed that fluoride prevents tooth decay only by preventing the demineralization process.[7] However, recent research has shown that fluoride not only prevents demineralization, but it also repairs existing demineralization.[8] Fluoride facilitates remineralization, or the re-hardening of areas that have been previously damaged by bacteria, and it can reverse small damage, such as white spots (“white lesions”)[9]. According to many, the main way in which fluoride prevents tooth decay is actually through remineralization, not the prevention of demineralization[10]. Research in the remineralization process has progressed to the extent that new toothpaste technology that enhances the remineralization abilities of toothpaste and fluoride is being developed and marketed.[11]

Through remineralization, fluoride arrests or reverses the progression of a carious lesion. Although the white spot will probably still be noticeable on a radiograph because the tooth will never remineralize completely, the use of fluoride does improve the outcome.[12] Professional use of fluoride, over-the-counter toothpastes, and prescription extra-strength fluoride toothpastes reverse dental caries. Thus, tooth brushing not only prevents decay, but it also treats areas with existing decay, and it therefore may be viewed as refuah and not only “mavriach ari.”[13] The risk of developing dental caries depends on many factors, including genetics, food intake, and strains of bacteria in one’s mouth, oral hygiene habits, age, and access to fluoridated water[14]. Every person is unique in the cause of his or her carious lesions. Furthermore, there is a wide range of caries susceptibility. There are people who regularly brush their teeth and still develop cavities and those who never brush their teeth and never develop cavities. Even per individual, their caries risk and development can vary over time. For those people who have a minimal caries risk – they either never or rarely developed a cavity or they used to have many cavities but have not had a cavity for many years[15] – the remineralization process probably provides very little support in maintaining disease-free teeth. Even without fluoride their teeth would remain healthy. However, for the significant portion of the population that has a caries problem and develops cavities constantly, remineralization is vital in the fight against the disease. It is for this significant portion of the population that remineralization may be viewed as refuah.

In addition to causing remineralization of the tooth enamel, brushing teeth treats gingivitis, an inflammation of the gums that occurs predominantly among people who do not regularly brush their teeth. The mechanics of brushing removes the plaque and bacteria that elicit this inflammatory response. In addition, the antimicrobial antiseptic ingredients in all toothpastes approved by the American Dental Association reduce and prevent gingivitis[16].

Furthermore, besides fluoride being able to act on the tooth, it has been shown that fluoride also has the ability to act directly on bacteria; it is bactericidal (kills bacteria) and bacteriostatic (stops bacteria from reproducing)[17]. Moreover, some toothpastes contain additional ingredients that are antimicrobial[18]. Research has proven that regular toothpastes can kill the bacteria that create cavities and cause gingivitis[19].

Based on this research, the Shulchan Shlomo quotes Rav Shlomo Zalman Auerbach as presenting the possibility that if toothpaste can disinfect bacteria from the tooth and reduce inflammation of the gums, then it may be considered refuah[20].

Thus, brushing teeth can provide refuah for people with the early stages of the cavity process or gum disease. Since a significant percentage of the population has at least some dental cavities and/or gingivitis, tooth-brushing may be considered refuah for many people, and may therefore present a problem on Shabbat[21].


We will, God willing, continue our discussion next week by presenting a variety of reasons to justify a lenient approach to this issue.

[1] R. Aryeh Lebowitz, “Brushing Teeth on Shabbat,” The Journal of Halacha and Contemporary Society 44 (Fall 2002), pp. 51-79.

[2] Chazal prohibited the use of medicine, and subsequently most forms of refuah on Shabbat, in order to avoid the possibility that one might come to grind the ingredients on Shabbat (shechikat samamanim), which would violate the melacha of tochen The prohibition is limited to one who experiences “meichush b’alma,” mild pain and discomfort. See Shulchan Aruch 328:1.

[3] The Rambam (Hilchot Shabbat 21:24) and the Shulchan Aruch (Orach Chaim 328:36) cite this Tosefta as the Halacha.

[4] Ohel Moshe 2:98.

[5] Yabia Omer 4:29-30, Ketzot Hashulchan 8:99

[6] This is a simplification of the process; demineralization is more complicated and entails the lowering of the pH of the oral cavity. There are two main aspects of brushing that help prevent cavities: the mechanical removal of the biofilm and the fluoride that is incorporated in the toothpaste. Mechanical removal of the dental biofilm, through brushing, is very important; however, the incorporation of fluoride in toothpaste is a critical and necessary addition in the prevention of cavities. This article is not diminishing the importance of the mechanical removal aspect of brushing teeth but is merely focusing on the fluoride aspect of brushing.

[7] See Frank E. LawMargaret H. Jeffreys, and Helen C. Sheary, “Topical Applications of Fluoride Solutions in Dental Caries Control,” Public Health Rep. 76(4) (April 1961): 287–90; O. Fejerskov, A. Thylstrup, and M.J. “Rational Use of Fluorides in Caries Prevention: A Concept Based on Possible Cariostatic Mechanisms,” Acta Odontol Scand. 39(4) (1981): 241-9. In the 1960s, it was thought that when fluoride is incorporated into a developing tooth, it makes the tooth stronger by creating stronger chemical bonds than the chemical bonds that naturally exist in the tooth. Because the teeth become stronger, the tooth is less susceptible to demineralization. The concept of “systemic fluoride” led to the implementation of water fluoridation and the use of fluoride tablets. It was later discovered that fluoride prevents demineralization in a completely different way, which is related to the concentration of the fluoride ion on the surface of the tooth. The concept of “topical fluoride” is now the prevailing view of how fluoride prevents demineralization.

[8] E. Hellwig and A.M.Lennon, “Systemic Versus Topical Fluoride,” Caries Res. 38(3) (May-Jun 2004): 258-62.

[9] A. Dijkman, E. Huizinga, J. Ruben, and J. Arends, “Remineralization of Human Enamel in Stu after 3 Months: The Effect of Not Brushing Versus the Effect of an F Dentifrice and an F-Free Dentifrice,” Caries Res. 24 (1990): 263-6. Fluoride slows demineralization and enhances re-mineralization in multiple ways. The exact mechanism of how this is accomplished is beyond the scope of this article; John Hicks, Franklin Garcia-Godoy, and Catherine Flaitz, “Biological factors in dental caries: role of remineralization and fluoride in the dynamic process of demineralization and remineralization (part 3),” The Journal of Clinical Pediatric Dentistry 28 (3) (2004)

[10] Jaime Aparecido Cury and Livia Maria Andaló Tenuta, “Enamel Remineralization: Controlling the Caries Disease or Treating Early Caries Lesions? Braz. Oral Res. 23(11) (June 2009): 23-30; John D. B. Featherstone, “Prevention and reversal of dental caries: role of low level fluoride” Community Dentistry and Oral Epidemeology (Feb 2007)


This article is only referring to the way fluoride helps fight cavities, brushing away the plaque

[11] Steven R. Jefferies, “Advances in Remineralization for Early Carious Lesions: A Comprehensive Review,” Compendium of Continuing Education in Dentistry (April 2014). It is important to note that despite the additional benefits of fluoride, mechanical removal of the biofilm is still an important part of oral hygiene. [12] H.E. Kim, H.K. Kwon, B.I. Kim, “Recovery Percentage of Remineralization According to Severity of Early Caries”, Am J Dent. 26(3) (June 2013): 132-6; F.N. Hattab,  “Remineralisation of Carious Lesions and Fluoride Uptake by Enamel Exposed to Various Fluoride Dentifrices in Vitro,” Oral Health Prev Dent. 11(3) (2013): 281-90; A.R. Prabhakar,  A.J. Manojkumar , and N. Basappa, “In Vitro Remineralization of Enamel Subsurface Lesions and Assessment of Dentine Tubule Occlusion from NaF Dentifrices With and Without Calcium, “J Indian Soc Pedod Prev Dent. 31(1) (Jan-Mar 2013): 29-35; S.G. Damle, V. Bengude, and E. Saini, “Evaluation of Ability of Dentifrices to Remineralize Artificial Caries-Like Lesions, Dent Res J (Isfahan) 7(1) (Winter 2010): 12-7; E. Casals, T. Boukpessi, C.M. McQueen, S.L. Eversole, and R.V. Faller, “Anticaries Potential of Commercial Dentifrices as Determined by Fluoridation and Remineralization Efficiency,” J Contemp Dent Pract. 8(7) (Nov. 2007): 1-10; J. Timothy Wright, Nicholas Hanson, Helen Ristic, Clifford W. Whall, Cameron G. Estrich, Ronald R. Zentz, “Fluoride Toothpaste Efficacy and Safety in Children Younger Than 6 years: A Systematic Review,” Jada 142:2 (Feb. 2014): 182-9; J.A. Cury  and L.M. Tenuta,  “Enamel Remineralization: Controlling the Caries Disease or Treating Early Caries Lesions?” Braz Oral Res. 23(1) (2009): 23-30.


[13] According to this understanding of how fluoride functions, use of toothpaste is very different from cleaning one’s skin, an analogy that Rabbi Lebowitz suggests in his article, note 35.

[14] Robert H. Selwitz, Amid I. Ismail, and Nigel B Pitts, “Dental Caries,” Lancet 369 (2007): 51–59.

[15] Determined by consistent dental visits for exam and cleanings.


[17] R.E. Marquis, “Antimicrobial Actions of Fluoride for Oral Bacteria,” Can J Microbiol. 41(11) (Nov. 1995): 955-64. Fluoride cannot penetrate the tooth to kill the bacteria inside a cavity, but it can render the bacteria that are on the outside of the tooth inactive, thereby preventing cavities. With respect to gingivitis, fluoride’s bactericidal properties can help heal the gingivitis, not merely prevent it.

[18] For example, Colgate toothpaste contains Triclosan.

[19] Marieke P.T. Otten, Henk J. Busscher, Henny C. van der Mei, Chris G. van Hoogmoed, and Frank Abbas, “Acute and Substantive Action of Antimicrobial Toothpastes and Mouthrinses on Oral Biofilm In Vitro,” European Journal of Oral Sciences 119(2) (2011): 151-5. In certain situations, dentists use fluoride-releasing materials to help prevent the tooth from developing recurrent, new decay under a filling or crown.

[20] Shulchan Shlomo Shabbat vol. 3 328:39

[21] The Mishna Berura (328:130) rules that when the benefit of a particular refuah practice could not be accomplished by taking a pill, that practice is permitted on Shabbat. R. Lebowitz notes a number of reasons why this leniency would not apply to toothpaste (see note 32). However, the most important reason is that the benefits of toothpaste can very often be attained through a pill. In areas that do not have fluoridated water, many children take fluoride tablets to strengthen their developing adult teeth. Additionally, if re-mineralization is refuah, then using any of the “Kosher” Shabbat products, like the Shabbat toothbrush and toothpaste, would not be allowed as long as fluoride is one of the ingredients in the toothpaste being used.

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

Noticing the 53rd Card by Rabbi Chaim Jachter