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Evolution tree of tooth-brush
Elena Novitskaya

October 1, 2002
A simple and understandable object a tooth brush has innumerous versions. Nevertheless, the versions can be classified and structured according to the trends of engineering systems evolution.

Interactive tree of tooth-brush evolution:

Civilization which likes very much to delight itself with pleasant but not at all useful delicacies, would have continuously suffered from caries if it had not understood in the earliest days of our history that one could avoid many troubles by brushing teeth after meals.
But how should we brush them? For instance, one can chew some fibred rough plant. It would be even better to use a stick with the end macerated to fibers. Such a stick will clean not only the chewing surfaces, but also the front and inner ones. The Chinese perfected that simple device: they were just the people who invented the first tooth brush a bunch of bristles on a bony or bamboo handle. Bristles were attached perpendicular to the handle so that it was more convenient to use it, and the technology of fixing bristles in the longitudinal slit of the handle was quite simple and reliable.
The invention of plastic allowed the shape of the handle and the head, as well as the arrangement of bristles to be changed at one's desire. In the fifties, unsanitary bristle was replaced with nylon.
At that point, the staged-gradual evolution of the toothbrush stopped and it started evolving in many directions at the same time. Each element of the brush tends to perform its functions ideally. For this purpose methods aimed at perfecting different elements are used and a combination of several new ideas produces a startling effect!

Structure of a tooth brush:

The bristle interacts with teeth and removes dental deposits and remnants of food from between the teeth. Bristle consists of several rows of bunches and bunches are composed of bristles, normally nylon ones. The head transmits to the bristle the force applied by the user to the handle, and serves as a base for attaching the bristle. This is a rigid flat element, normally made of plastic. The handle allows holding the tooth brush and transmitting the force to the head. The handle is normally an oblong plastic element of a considerable length.

The tooth brush functions and problems that arise while using the tooth brush
The main function:

The tooth brush removes deposits from teeth.
This function is performed with high quality and effectiveness, but it would be better if the use of the tooth brush also prevents dental diseases. Contradictions occur in the way of efficiency and quality:
1.Teeth have uneven surface, but it is necessary to provide high-quality cleaning of both protrusions and hollows.
2.Food remnants must be removed from the slits between the teeth, but the slits are difficult-to-reach places.
3.It is not easy to reach the internal surfaces of teeth, but this should be done for providing efficient cleaning.

Accompanying functions:
The toothbrush must be safe
for tooth enamel, gums, internal surfaces of cheeks and other soft tissues, must not hurt or infect. Several contradictions occur:
1.To effectively clean teeth, the bristles must be stiff enough, but stiff bristles hurt gums, while soft bristles are safe for gums but ineffective in cleaning.
2.The brush head must be stiff in order to transmit friction force, but such a head can hurt soft tissues.
3.The user applies a considerable force to the handle in order to provide effective cleaning of teeth, but this force, transmitted to the head and bristle, can hurt soft tissues.
4.Multiple germs appear on the tooth brush under certain conditions, which is unsanitary. This process is even faster under conditionally extreme circumstances (for instance, while travelling).
The tooth brush must be convenient
for tactile interaction with gums, teeth and hand. The following problems occur:
1.Human teeth differ in shape. There are several types of teeth (cutting teeth, canine teeth…) and special shapes of head and bristle suit best different zones.
2.Possiblities of opening the mouth are not limitless, but the tooth brush must reach all hard-to-get places at the minimal opening of the mouth.
3.Sometimes, the hand is wet and the brush can be held unreliably.
4.It is necessary to apply additional force to hold and to efficiently clean teeth, but the process, on the contrary, requires that the hold be flexible and movable.

Evolution lines of brush elements

The bristle cut shape (of a bunch as a whole and of an individual bristle) must be matched with the peculiarities of teeth structure (with teeth as a whole and with each individual tooth). The problem is solved by changing the geometry of the bristle surface and by the surface segmentation.

Geometrical evolution of the bristle surface:
A flat
cut is poorly matched.
A concave cut corresponds to the arcuate shape of a denture.
A spherical cut (inside bunches are below outside ones) allows proper cleaning of the uneven surface of masticatory teeth.
There is a brush with bunches inclined to different sides. Its bunches have different height and width; the surface of such a brush is combined and complex. .


(Evolution of the brush bristle a bunch and an individual bristle is also subjected to the same tendency. Initially, a nylon bristle had a flat cut. Then new technologies allowed the end to be rounded off. Now, on the contrary, some bristles of the brush have a pointed conical end and serve for better cleaning of teeth near gums. They are safe because they are made of very soft material. 


Initially, a bunch of bristles also had a flat cut. But such a brush provides only superficial cleaning. For the brush to reach hard-to-get places between teeth, bristles were beveled. More precise technologies made it possible to “sharpen” a bunch giving it a conical shape. To increase safety, the cut was made spherical. In a new type of brushes, a bunch has bristles of different height. The softest ones jut out; the rest of the bristles are also of different height. Such a combined shape fully meets the requirements of favoring and quality cleaning.) 


Segmentation of the bristle surface:
A wavy
cut cleans an uneven surface well, at the same time it acts softly, while a toothed cut allows getting into slits. The “chessboard” structure of the surface with protrusions (when some bunches are higher and others are lower) increase possibilities. If the unevenness of the bunch heights is matched with the unevenness of the heights of individual bristles, then an unpredictable variety of variants occur which can satisfy the most “sophisticated” teeth.


Bristle can be Activated by adding objects:
(Adding objects is not an arbitrary process. It is subjected to the segmentation tendencies: we start with introducing a solid substance and finish with a field, having passed through powder, liquid, gas, etc.).
If powder is applied to the brush bristles in advance, it is convenient for a one-time compactness.
If we provide tight packing, then toothpaste can be applied to a tooth brush in advance.
A cleaning liquid (for instance, bactericidal) can be supplied through tubules made inside the bristles. Or microgranules filled with such liquid can be sealed in the bristles.
According to the same principle, an aromatic tooth brush can be made by introducing microgranules with aromatizer (gas).
There is a tooth brush with an ionizer that generates healthy ions on the bristle points.
A tooth brush with ultrasound cleans teeth best of all. Microvibrations easily remove deposits.
A tooth brush is known that creates electric field in the process of cleaning and charges the enamel so that it repels deposits.
A tooth brush with ultraviolet will be soon invented. It will generate a bacterium-killing field.


Bristle has the parameter “rigidity”, and teeth and gums need different rigidity. Users also require special rigidity.
These requirements must be Coordinated:
All tooth brushes have the same rigidity. That was the situation immediately after the nylon had been invented, and the absence of choice did not satisfy users.
There are several versions of bristles, and one can choose a suitable brush. Only part of the problem is solved in this case: if the bristle is soft, it is safe for gums, but does not clean teeth properly, and vice versa.
The problem was solved when they started manufacturing tooth brushes with bunches of different rigidity the bunches that contacted the gums were made softer.
The useful property can be intensified by uniting bristles of different rigidity in one bunch - long bristles are softer and short ones are rigid enough.


The head safety is directly connected with its shape: the rigid edges of a rectangular end harm gums or at least cause disagreeable sensations. The head's shape started changing its geometrical evolution occurred.
To make the head safe for gums, the end became rounded.
Then the head became elliptic.
The spherical surface of the head has not been found so far, but such a head will certainly improve safety and add pleasant tactile sensations.
There is a tooth brush with 0-shape hole in the middle of the head. The hole whirls a water flow while washing the tooth brush.
There is also a triangular tooth brush. It is not so safe, but is gets to the most hard-to-reach parts of a denture.


A rigid monolithic head transmits force very well, but it is so inflexible! For the head to reach better all the parts and to adapt itself to various conditions and needs, it is necessary to add Danymicity to it.
The front edge of the tooth brush is the most important, because it is assigned a part of reaching and cleaning the most hard-to-get places. A section of the head was separated from the rest of its body by changing the tilt angle.
A tooth brush has been patented (though not offered for sale as yet) in which each row of bristles is attached to a separate element. The elements have movable joints and create a shape-adaptable tooth brush head.
The next step must be an elastic head capable of both transverse and longitudinal bend.
Giving ample scope to our imagination, we can imagine a head composed of a flexible shell filled with liquid or gel that transforms ideally in each section of a denture.


Mono-bi-poly is a tendency to increasing the number of useful parts in one object.
But the human thought did not stop on an ordinary tooth brush with one cleaning head (mono-brush). Tooth brushes appeared with two heads at opposite ends or with two parallel heads (bi-brushes). (Let us specify that those brushes had a special function of cleaning artificial teeth.)
The tooth brush “Caprice” is a poly-brush invented by Igor Ivanov. It has five (!) heads of various shapes and rigidity united in one block with a revolving supply.
Now we are waiting for a new mono-brush with all positive properties of the above-mentioned poly-brush.


Initially, the shape of a handle was flat and straight. Its geometry evolved according to the general tendency.
Initially, the shape of a handle was flat and straight. Its geometry evolved according to the general tendency.
A rounded shape is more convenient, so the handle's surface became somewhat convex (conventionally cylindrical).
Even more convenient is the shape that is slightly widened in the center and narrowed towards the ends with spherical surfaces.
But a really ergonomic handle has a complex, sculptural, combined surface matched with the hand shape and the peculiarities of gripping and transmitting force.
And the best version is the handle composed of a compliant but elastic shell filled with liquid or gel, or even with gas.


Wet hands, a slippery surface of a handle. It is not allowed to change the hands' properties, so we changed the properties of the handle surface, that is, we segmented the surface.
Ribs on separate sections or on the entire surface of the handle make it possible to hold the tooth brush more strongly.
Pimples instead of ribs are more agreeable to the touch and produce the effect of massage.
But both ribs and pimples, or, rather, the cavities between them have an unpleasant property to accumulate dirt, while an elastic surface copes with slipping and, at the same time, it is more healthful.


And now let us think about the problems of safety, effort coordination and penetrability. All the three problems are solved at one stroke by one method by making the joint between the head and the handle Dynamic.
A one-piece joint is replaced with a hinge that allows bend within small limits.
Two hinges cause a considerable improvement of mobility.
The next step is an “accordion” a goffered section of plastic that increases the joint flexibility.
Then, in order to prevent dirt accumulation in the accordion cavities, the joint section is made monolithic, smooth, but from a flexible, elastic material.
Having skipped some steps, let us imagine that the head is separated from the tooth brush but is held and controlled by a magnetic field. Such a head will be absolutely adaptable and movable.


Tooth brush as a whole.
The tooth brush is the main part of the engineering system designed for cleaning teeth (besides the tooth brush, the system includes tooth paste, a user's hand and a user's head for controlling the process), and every engineering system tends to ideality, that is, to the full absence of itself with the simultaneous preservation of the function performance. It can approach this blessed state by two methods: first, by the direct method it is trimmed until it disappears at all; and second, by a sideway by performing more and more accompanying functions until the main function is lost among them.

Trimming the tooth brush:
In an engineering system that includes a tooth brush, we are not allowed to change teeth, hands and a head. Let us confine ourselves to a tooth brush.
The tooth brush is trimmed quantitatively. Instead of throwing one tooth brush after another, we separate and throw away only the used head and attach a new one to the handle.
The tooth brush without a handle. Or, rather, a finger inserted in a ring-brush or a tooth brush-fingerstall plays the role of a handle.
An all-cast brush which is put on a finger. Its bristle is made of the same material as the cover for the finger. It is not as good as nylon but performs its function.
A tooth brush that does not need a handle or replacement of a handle. This tooth brush is given the form of a denture. It is inserted in a mouth and is moved by jaws.
We propose the idea of a “chewing brush” bristles on an elastic shell, a kind of tooth hedgehog. One has just to chew it carefully.
There is already an object based on this principle, it even does not have any bristles. We mean chewing gum. However, it is not very effective.
The novel by Max Fry describes an absolutely ideal tooth brush: it is enough to rinse one's mouth with a special liquid and the teeth are cleaned, cured and protected against all diseases once and for all.


Additional functions:
Let us try to imagine a dream tooth brush (at the previous step, we have already imagined an ideal, a full absence of a brush with the preservation of its function). Such a brush cleans teeth perfectly and provides preventive measures. But this is the purpose of any tooth brush. In addition, it informs us that it is time to replace it, but at the same time it is always sterile. It also informs us about the tooth cleaning rules. It teaches this useful procedure to a child (without participation of parents). And it gives joy!

The indicator of the service life may be different. Chemical: some bristles change their color (fade) with use. Mechanical: there is a rotating calendar on the handle and indicators for the beginning and end of use. Forced: non-durable bristle is used, the tooth brush is thrown away after the bristle has fluffed and the brush has become inconvenient to use. 


Preserving sterility. Covers both for the entire tooth brush and for its head only. A tooth brush with a handle-cover. This scheme has been realized by a thousand of various methods. A brush that is always sterile before use, because it is disposable (inexpensive and easy-to-utilize). A tooth brush with detachable heads is the evolution of the same idea. Besides, a tooth brush may be placed not only in a cover, but, also, for instance, in a bacterium-killing liquid. Or in a bactericidal field. Such devices are already available. And the best of all would be a self-sterilizing tooth brush (we have not found such yet). For instance, after use, a microbe- or dirt-neutralizing substance or field is supplied to the bristles through the head.


A tooth brush-trainer. A tooth brush with a timer signals some minutes after you have started cleaning your teeth. A tooth brush with a counter of motions performs the same function but less obtrusively. An acoustic tooth brush can acquaint you with the rules of care after your teeth. Or a silent tooth brush with the same rules presented in the form of pictures or text on the handle.


A tooth brush can also make the tooth-cleaning procedure more attractive for a child. For instance, a tooth brush-toy presenting some well-known character. A tooth brush-rattle which emits sound only when used properly. A musical tooth brush. Bright, beautiful, with pictures. A tooth brush with fruit (chocolate, candy) smell.

All the above brushes with their attractive design and palette cope with the task of giving joy. Pleasant tactile sensations delight a palm that holds a tooth brush and teeth that are carefully and effectively treated by intellectual bristles. In addition, having a prestigious high-tech tooth (which combines all the above-mentioned novelties) tickles one's vanity! Let alone the most important result beautiful and healthy teeth!


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Authors: Nikolay Shpakovsky, Elena Novitskaya