We all may appreciate the difference between the positive impact made by a smile of pearly-white teeth and the repulsion triggered by yellowed and blackened rotten teeth, but the health issues run much deeper: as our medical knowledge grows, we are discovering that many diseases originate from dental cavities where microbes teem and nest, causing inflammations in many organs and tissues, most notably in the heart, kidneys, and joints.

The use of herbal sticks for cleaning teeth dates back to around 3500 BC, the time of the Babylonians. In several works of Ancient Greek and Roman literature, chewable sticks to aid dental and mouth hygiene are mentioned [1]. Hippocrates (355 BC) advises rubbing a ball of cotton wrapped around a stick and dipped in honey on teeth, to maintain dental hygiene, whereas Romans used pastes obtained from gumwood [2]. Dental hygiene is coming throughout history.

Arabs utilized the miswak for many years [3]. The Japanese used wooden sticks called “koyoji” and Jews used wooden sticks called “kesam.” In the 1920s, in some rural areas across the United States, a stick of blood-twig was used for rubbing on the teeth [3]. And according to a Chinese encyclopedia published in the seventeenth century, the first-ever toothbrush was made in China, in 1498.

Prophet Muhammad, peace be upon him, warned those of his Companions who visited him with bad teeth about the need for dental hygiene (Ahmad ibn Hanbal, Musnad 1/214):

“I oft reiterated my recommendations to you about the miswak.” (Bukhari, Jum’a 8; Nasai, Taharah 5; Ahmad ibn Hanbal, Musnad 3/143; Darimi, Wudhu’ 18)

“(The Archangel) Gabriel counseled me to use the miswak so much that I thought a verse might be revealed about the miswak to decree its use as obligatory for all.” (Ibn Majah)

Obviously he assigned the utmost importance to dental hygiene. It should be noted here that the Araq tree (Salvadora persica) from which the miswaq is obtained has features that are not present in other trees, and the Prophet particularly specified using the roots of that tree as the miswak.

Research has been conducted to discover the scientific and modern medicinal effects of the miswak, which has been used by Muslims in adherence to the Prophet’s practice. In 2010, a Ph.D. study at Karolinka Institute, Sweden, provided a significant message about its effectiveness [4] (Picture 1).

The Araq tree, which is used as the miswak across a geography spanning from Africa to the far east, is a short tree or bush with a slanted trunk, and it is easy to chew its spongy roots, parts of which generally expand and soften when dipped in water (Picture 2).

The roots of the Araq tree are washed to remove the soil, and approximately 1 cm from the tip of the root stick is peeled to be used as the toothbrush. The stick is pummeled or chewed until the fibers become softer (Picture 3). Fresh and soft miswak are preferable: If the miswak is dry, it is advised to dip it in freshwater for 24 hours before use. It is better to peel frequently, so the tip is renewed. The most practical advice is to use the peeled tip until it loses its tang and fragrance, because the fragrant components indicate the beneficial effect of the miswak. According to a study, using the same tip for more than 24 hours lowers its cytotoxic ability to get rid of microbes.

The practice of using miswak in the Muslim World is widespread in Asia, Africa, and some regions in the Middle East. As many Muslims opt for miswak use to maintain a practice of the Prophet, the World Health Organization (WHO) also advises and encourages the use of miswak as an effective dental hygiene tool along with the conventional toothbrush. The miswak is easy to use and effective; it also has chemical properties that help control dental plaque. Based on the basic information we have about the miswak, we can easily say that deeper research is needed for its different components, like its fibers, essence, and essential oils.

Antibacterial effects of the miswak

The antibacterial activities of the essences obtained by crushing different roots of the miswak have been analyzed by microbiological techniques. It was discovered that the miswak essence has a very strong antibacterial effect, predominantly against Gram-negative bacteria, including mouth-cavity microbes like Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans. Two additional studies conducted on five different types of bacteria i.e. Streptococcus mutans, S. faecalis, S. aureus, Haemophilus influenzae, Salmonella enterica, and Candida albicans, and a type of fungus [5, 6, 7, 8] revealed that the miswak essence stops the reproduction of micro-organisms, has a lower effect on Lactobacillus acidophilus, is active against Herpes simplex virus which causes blistered lesions, and suppresses acid production.

The essential oil obtained from miswak essence includes 70% benzyl isothiocyanate, 9.4% limonene, 8.7% I-pinene and 2.55% flavonoid. As the miswak’s main antibacterial component, benzyl isothiocyanate kills bacteria by forming protrusions on their cell membranes. The volatile nature of this substance may open doors to new practices requiring antibacterial treatment. It has been proven that fresh miswak is effective at preventing the formation of dental plaque and gum inflammation, and it has also been acknowledged that it may play a potential role in preventing periodontal diseases.

The miswak essence hinders acidic (pH) conditions causing tartar and dental plaque, leads to a long-term increase of pH in the mouth, stimulates saliva flow in the parotid glands (located in front of both ears), and prevents tartar formation.

It is necessary to conduct further lab and clinical research to augment the positive results shown so far about the effects of the miswak against the inflammation of the palate and gums, as well as its antiviral and antifungal activities. Some research has additionally suggested that the miswak has antioxidant, analgesic, and anti-inflammatory effects. It is claimed that potassium chloride, salvadourea (a urea derivative), alkaloids, and oleic and linoleic acids in the miswak sap increase the viscosity of saliva, helps it to soak into hard-to-reach corners in the mouth, and contributes to overall dental hygiene. It is reported that a substance named Xylitol in the miswak essence suppresses acid production and the reproduction of mutant streptococci [9, 10].

An interesting substance in the miswak oil

Benzyl-isothiocyanates are effective molecules in the defense systems of several plants such as cabbage, watercress, and broccoli. Secreted after damage to plant tissues, benzyl isothiocyanate forms a protective antibacterial layer on the damaged part of the plant. While dental plaque and tartar are mechanically removed by rubbing the miswak on teeth, this action also helps the substance secreted from the miswak reach deeper parts of the oral cavity. It is especially proven that benzyl isothiocyanates are strongly effective as bactericide on Gram-negative bacteria and have minimal effect on Gram-positives.

Lab tests conducted on animals indicate that these components also have anti-carcinogenic activity, and people who get isothiocyanates by nutrition have a lower risk of cancer. It is fascinating that the miswak, too, has the same substance.

While introducing a new set of ethical principles, Prophet Muhammad, peace be upon him, revoked some customs and habits inherent to the pagan culture before Islam (Age of Ignorance) and kept others. Using miswak was a practice among the Arabs in the region; the Prophet encouraged its use and emphasized its benefits. Eventually, Muslims have adopted it as not only a habitual practice, but also as a healthy spiritual activity and are keeping the memory of the Prophet alive.

References

1. Wu, C.D., Darout, I.A. and Skaug, N. (2001): Chewing sticks: timeless natural toothbrushes for oral cleansing. Journal of Periodontal Research 36, 275-84.
2. Hyson, J.M., Jr. (2003): History of the toothbrush. Journal of the History of Dentistry 51, 73-80.
3. Bos, G. (1993): The Miswak, an aspect of dental care in Islam. Medical History, 37, 68-79.
4. Sofrata, A. H. (2010): Salvadora persica (Miswak). An effective way of killing oral pathogens. Thesis for doctoral degree (Ph.D.). From the Division of Periodontology, Department of Dental Medicine, Karolinska Institutet, Stockholm, Sweden.
5. Al-Lafi, T. and Ababneh, H. (1995): The effect of the extract of the Miswak (chewing sticks) used in Jordan and the Middle East on oral bacteria. International Dental Journal, 45, 218-222.
6. Almas, K., Al-Bagieh, N. And Akpata, E. (1997): In vitro antimicrobial effect of extracts of freshly cut and 1-month-old miswak (chewing sticks). Biomedical Letters, 56, 145-149.
7. Almas, K. (1999): The antimicrobial effects of extracts of Azadirachta indica (Neem) and Salvadore persica (Arak) chewing sticks. Indian Journal of Dental Research, 10, 23-26.
8. Almas, K. (2001): The antimicrobial effects of seven different types of Asian chewing sticks. Odontostomatolgie Tropicale, 24, 17-20.
9. Kakuta, H., Iwami, Y., Mayanagi, H. and Takahashi, N. (2003): Xylitol inhibition of acid production and growth of mutans Streptococci in the presence of various dietary sugars under strictly anaerobic conditions. Caries Research, 37, 404-409.
10. Miyasawa, H., Iwami, Y., Mayanagi, H. and Takahashi, N. (2003): Xylitol inhibition of anaerobic acid production by Streptococcus mutans at various pH levels. Oral Microbiology and Immunology, 18, 215-219.

The surfaces of soap bubbles have a very important feature. These surfaces which have minimum surface-tension potential energy also have minimum areas. That is, soap bubbles or clusters have a natural tendency to minimize area for the volumes they enclose. Two different frames and the areas formed are shown in Figure 1. For a given closed frame, at least one such minimal area can be formed; however, mathematicians have had to strive to prove it.

The famous mathematician Richard Courant (1888–1972), together with his students, did soap bubble experiments with various frames.

Minimal areas can also be formed by using more than one closed frames. Figure 2 shows the minimal surfaces obtained by holding two circular frames parallel. If the frames are kept too far from each other, no surface will form. If they are kept sufficiently near to each other, surfaces similar to those shown in Figures 2a and 2b will be obtained. If they are kept close enough to each other, then three minimal surfaces adjacent to each other as shown in Figure 2c can form.

The minimum energy principle is commonly observed not only in living organisms, but also in lifeless matter. A chain will take the shape which produces the least potential energy of attraction when it is fastened at two points onto a rod as shown in Figure 3. This form (function) is called “catenary” in mathematics.

The areas which are formed as a result of rotating the catenary curve around an axis A are called catenoids. Two different types of catenoids are shown in Figures 4a and 4b. As presumed, catenoids are minimal areas and can be obtained by the use of soap bubbles. If such formations were selected and used in everyday utensils, such as glasses, dishes and so forth, ideal shapes which cause the least loss of heat could be designed.

If the katenoid shown in Figure 5a is cut from its edge as shown in Figure 5b and turned by being slightly extended, a helical form or a helicoid will be obtained as shown in Figure 5f. This helicoid also is a minimal surface. Architects have widely used this form in spiral-shaped staircase structures. See Fig. 6.

Fig. 1-Closed frames and soap film surfaces formed1 Fig. 2a&b–Single foam film surfaces over two parallel circular frames1 Plus, the perpetual screw system which is widely in use in technology is also in a form similar to this geometry.

If a cylinder of the smallest volume that can house a helicoid is drawn (Fig.7a) and the lines on which the surface and the cylinder intersect are marked, then a double helix structure (Fig. 7b) is obtained; this is used in modeling DNA molecules which are the genetic codes of living species.

There are two elementary principles related to soap bubbles. The first principle says that if a bubble touches a surface that supports it, it unites with that surface in a way to make 90° angles. The soap bubble on that plain surface forms into a semi-spherical shape and the angle between the bubble surface and the supporting surface will be 90° at every point of contact. The second principle says that if three soap bubble surfaces come together, they form 120° angles along a line. If soap films come together within a tetrahedron frame as in figure 8, then the angles between the lines will be 109° 28′ 16″.

The Steiner problem which is an elementary problem in mathematics can be solved by the application of the 90° and 120° principles. The Steiner problem investigates how n points over a surface can be united in the shortest way by a web. Two transparent surfaces are connected with thin and parallel pins of equal lengths and then dipped into a soapy solution. When it is taken out, soap films will form. These films have a 90° angle with the supporting transparent surfaces and when three soap films come together, they connect at 120° angles with one another.

When observed from above, the intersecting lines between the soap film and one of the surfaces give the shortest web which unites the points in n numbers. How four points are united is shown in Figure 9a and how five points are united is shown in Figure 9b. Someone seems to have equipped lifeless objects such as soap bubbles with the ability to solve complex problems like a math genius.

Periodically repeated minimal areas have been observed on walls separating organic and inorganic substances in the skeletons of certain sea animals like the sea urchin and the starfish. Figure 10 shows the micro structure of a sea urchin’s skeleton. It has calculated that the geometry of its skeleton has perfectly been shaped in such a way as to prevent the extension of possible cracks.

Experiments with soap bubbles have been a source of inspiration also for architects. Such experiments have yielded inspiration for roof and tent designs. The German architect Frei Otto is one of the most eminent names in this regard. Figure 11 shows the minimal areas which Frei Otto managed to obtain by dipping hair-thin threads in soapy water.

In order for such a soap bubble model to be converted into an architectural structure, it is carefully photographed and precisely measured. Later, solid models are made and tested in wind tunnels. The tensile pressures likely to form under loads of wind and snow are measured by special precision instruments. In real structures, thin steel cables having high tensile strengths replace the hairy threads, and transparent plastic and synthetic materials replace the soap bubble film.

Figure 12 shows roof of the Munich Olympic Stadium, Figure13 shows the roof of the Munich Olympic Athletic Arena and Figure 14 shows the roof of the Olympic Swimming Arena in the same city. All these roofs have been designed and erected using the minimal surfaces obtained from soap bubble experiments.

Children love playing with soap bubbles very much; they usually blow a round circle after dipping a wand into soapy water and then watch the bubbles flying out of it. However, it is not only children who play with soap bubbles and soap films. Scientists have, for hundreds of years, been doing experiments with soap bubbles, developing mathematical theories, obtaining various surfaces and transferring the compiled data into technology.

Experiments with soap bubbles have been a source of inspiration also for architects. Such experiments have yielded inspiration for roof and tent designs.

2) These roofs can easily be erected, dismantled and transported to elsewhere, whereas traditional buildings cannot easily be re-located.

3) These structures which are designed according to tensile strengths are very sturdy all over, whereas the tensile pressures of classical buildings are so high that extremely heavy materials such as concrete and brick are used in order to balance the pressure.

The structures of light and strong materials granted to living things are splendid. The lightness and endurance of our skeleton system, the perfect endurance in the stems of slender plants such as wheat and barley, the extremely thin and elastic structure of a fly’s wing, and thousands of similar examples can be given.2 The word of German architect Frei Otto in this subject are expressive: “Biology has become indispensable for architecture.” Witnessing similar perfections also in inanimate structures such as soap bubbles proves that laws in nature originate from the same hand.

Obtaining minimal surfaces has become much easier as a result of immense increases in computer capabilities. Extremely complicated minimal surfaces which can be obtained through computer-aided-designs and calculations have become easily available as alternatives to soap bubble experimentations. If we, as human beings, are aiming to realize developments in science and technology, we should look,more carefully and meditatively, at events which are seemingly simple and unimportant around us and we should also discover the beauties and perfections that God has granted us and put them into service of humanity. The more our designs are compatible with the laws of nature, the higher our chances of success will be.

References

• S. Hilderbrandt, A. Tromba, The Parsimonious Universe, Springer-Verlag, New York, 1996.
• M. S. Polatöz, Tabiatta Mühendislik (Engineering In Nature), Kaynak Publications, Izmir, 2003.
• A. B. Smith, The stereom microstructure of the echinoid test. Special Papers in Palaeontology, 25, 1–85, 1981.