Evolution and Analysis of the Toothbrush
By Kyle W. Sembera
The following article on the evolution and analysis of the toothbrush was written by Kyle Sembera, a mechanical engineering senior at Lamar University, Beaumont, Tex., as a final assignment for an elective design class. Sembera’s toothy research project was inspired by course professor P.R. Corder who, during a recent visit to the dentist, found himself musing on the merits of modern toothbrush design.
Have you ever tried brushing your teeth with a smashed stick? While today there are many sophisticated options for the orally conscious, during the dawn of civilization, the smashed stick—the earliest predecessor of the modern toothbrush—had a corner on the market. By chewing the end of a soft twig flat, people created a rudimentary brush, which aided in the removal of food particles. Before this method was developed, people may have used a stick similar to a toothpick to perform the task.
Demonstrating the benefits of modern toothbrush technology ME senior Kyle Sembera flashes his pearly whites.
Because of the ubiquitous place toothbrushes hold in modern society, the need no longer exists to brush with a smashed stick, yet some native tribes still use simple sticks to clean their teeth.
This article looks at the origin and evolution of modern toothbrushing and, for those who have ever worried about catastrophic toothbrush failure, assuages fears with a finite-element analysis, comparing a traditionally styled toothbrush to a modern one.
Origin of the Toothbrush
Physical evidence from well-preserved Egyptian tombs dating back over 5,000 years suggests that the Egyptians used toothsticks for dental hygiene. Even before this civilization, the Mesopotamians wrote of the siwak, another version of the basic toothstick. These original toothpicks were most often made from porcupine quills, bird feathers, or wooden thorns.
During eighteenth-and nineteenth-century Europe, ornate metal toothpicks were developed. Serving as both art and status symbol, these were often copper, silver, or even gold.
Currently, some 10 million people in the Middle East and other parts of the world use toothpicks daily as their primary tooth-cleaning mechanism. In fact, toothpicks were used as the primary method for cleaning teeth as late as the early 1950s in some isolated sections of the United States.
The First Toothbrush
In the seventeenth century, Europeans often used rags or sponges dipped in sulfur oil or a salt solution to rub their teeth clean. Sometimes these rags were attached to a stick to help reach the back teeth, but the teeth were essentially being mopped, rather than brushed. From this practice evolved the first toothbrush, invented in 1780 by William Addis of Clerkenwall, England.
Addis attached hairs from the tail of a cow to the end of a whittled thighbone from the same animal, which was reportedly the only bone strong enough to survive the bristle-attachment procedure and still maintain its strength when wet. Eventually, boar hairs replaced the hairs from the cow’s tail. To this day, descendants of William Addis still manufacture toothbrushes at a factory in England.
During World War I, the bones that were being used for toothbrushes were usurped by the soup industry due to the nutritional demands of war. The resultant shortage called for the development of a new toothbrush-handle material. Celluloid handles, constructed by injecting plastic into molds and cooling them in a given shape, met this demand. Then, in the 1920s, a new method of attaching bristles to the handle was developed: drilling holes into the brush head, forcing in bunches of bristles, and securing them with a staple. This method is still used by some manufacturers today.
Prior to World War II, Chinese boar hairs were the favored material for bristles, but during the war a roadblock out of Chung-King impeded the export of these popular hairs. Nylon filament, having been developed in 1938, was an ideal replacement.
The nylon filament came with several advantages, including a dramatic reduction in production costs and the ability to control bristle texture. Manufacturers could also shape the filament tip and vary its diameter for improved performance. Boar hair, on the other hand, often fell out, did not dry well, and was prone to bacterial growth. Although nylon continues to dominate the market today, boar-hair bristles still account for about 10 percent of toothbrushes sold worldwide.
A study of worldwide patent applications between the years 1963-1998 reveals about 3,000 toothbrush patents. The brands, styles and colors of toothbrushes are virtually endless.
One manufacturer markets both a toothbrush with two heads which surround the teeth, claiming it will clean teeth more effectively, and a toothbrush with a built-in tongue scraper, designed to remove bacteria, which builds up on the tongue.
Another manufacturer stresses the importance of maintaining a cleaner toothbrush. Their design incorporates a unique hole in the center of the bristle head, ensuring that all food and other debris is easily rinsed off the brush. Still other manufacturers stress that bristle orientation is key to maintaining clean teeth. They sell toothbrushes with angled bristles, which tackle the teeth at different angles to maximize cleaning effectiveness.
One thing most manufacturers can agree on is the importance of having a handle that assists the user in reaching the back teeth, the most neglected and difficult to reach. One popular remedy has been to angle the toothbrush handle.
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