NANODENTISTRY
FACT OR FICTION?
TITUS L. SCHLEYER, D.M.D., PH.D.
Witnessing the beginning of a truly groundbreaking advance in technology is a rare opportunity. When the first transistor was developed in 1947, few foresaw the development of microcomputers and modern telecommunications, and the changes they would engender. Yet, in hindsight, the course of events is not surprising. The microcomputer revolution progressed on the basis of trends that were clearly recognizable at its outset.
Skepticism is a natural reaction when we are presented with a radically new method and its potential uses. Skepticism helps us filter the valuable from the worthless, the permanent from the ephemeral, and the rational from the preposterous. Thus, some familiar questions arise when reading "Nanodentistry" by Freitas.1 What are "nano" and "nanotechnology"? Is nanotechnology feasible? How long will it take for real-world applications to arrive? What does nanotechnology mean for dentistry and for me? This commentary answers some of these questions.
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DEFINING NANOMETER
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Nano is derived from 
o
, the Greek word for dwarf, and usually is combined with a noun to form words such as nanometer, nanotechnology or nanorobot. A nanometer is 10–9 meter, or one-billionth of a meter. Since it is not easy to visualize the scale of a nanometer, a comparison with concepts and objects of appreciable dimensions is helpful. If the height of an average human being were scaled up to stretch from the Earth to the moon, then each of the person’s atoms would be about the size of a baseball (approximately 10 centimeters in diameter). A nanometer then would be about five baseballs in a row.
To use another analogy, a spot one-tenth of a millimeter in diameter is just barely visible to the naked eye. A single cell has a diameter of approximately 20 micrometers (or one-fiftieth of a millimeter), or about five times smaller than that which we can see. The nucleus of a cell is approximately 8 mm in diameter. A typical blood-borne nanorobot will measure approximately 1 mm in diameter,2 or eight times smaller in diameter than the nucleus of a cell. Even at this size, a spherical nanorobot can still contain tens of billions of atoms.
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MANIPULATING MATTER
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Simply put, nanotechnology is about manipulating matter, atom by atom. Just as robots assemble cars in factories from a set of predefined parts, nanorobots will assemble things from atomic and molecular building blocks. Nanorobots exert precise control over matter. Currently, we can grow only certain almost-perfect crystals in very simple patterns. Nanorobots will allow us to construct such crystals, molecule by molecule, as incredibly fine-grained atomic structures, following a detailed blueprint. Assembling any object of tangible size this way may seem like a slow and tedious process. However, billions of nanodevices working together on the same object cut the required time by many orders of magnitude. Buildings constructed of a single crystal of diamond, nanorobots performing repairs in single cells, and intelligent and dynamic environments all are part of the vision of nanotechnology.
The number of scientists who question whether nanotechnology is possible at all is steadily shrinking. It is not hard to see why. Nanotechnology is based on known laws of physics and chemistry, not theories that still need to be proved. In "Engines of Creation," Drexler3 explains that "[i]n a race toward the limits set by natural law, the finish line is predictable even if the path and the pace of the runners are not. ... So however futuristic they may seem, sound projections of technological possibilities are quite distinct from predictions. They rest on timeless laws of nature, not on the vagaries of events."
Leonardo da Vinci (1452–1519) offers an historical precedent. He designed a multitude of workable devices for excavating, metalworking, transmitting power and other purposes. However, many of his inventions could not be built for several centuries because the required types of materials, manufacturing methods and human expertise did not exist. Similarly, the molecular differential gear (Figure
) is simply awaiting the time when we can actually build it. Many other blueprints for nanodevices have been published.2,4
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Figure. A molecular differential gear (an arrangement of gears connecting two axles that permits one axle to revolve faster than the other). Reprinted with permission of the Institute for Molecular Manufacturing. Molecular nanotechnology research supported by IMM. Available at: "www.imm.org". Accessed Oct. 1, 2000. Copyright 1997, Institute for Molecular Manufacturing; design by K. Eric Drexler, Ph.D.
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When will we see the first practical applications of nanotechnology? The Foresight Institute has offered the $250,000 Feynman Grand Prize (named after the late Nobel Prize–winning physicist Richard Feynman) to the first researcher or researchers who develop two devices: a basic nanorobot and a nanocomputer.5 Christine Peterson, president of the Foresight Institute, estimates that the prize will be claimed between 10 and 30 years from now. Because the initial nanodevices will be basic, prototypical units, commercial applications will follow years later.
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EFFECT ON DENTISTRY
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What effect will medical nanorobotics have on the dental profession and the individual dentist? In the near term, none. However, it is not too early to consider, evaluate and attempt to shape potential effects. Nanotechnology will change dentistry, health care and human life more profoundly than many developments of the past. As with all technologies, nanotechnology carries a significant potential for misuse and abuse on a scale and scope never seen before. Nanodevices cannot be seen, yet carry powerful capabilities. However, they also have the potential to bring about significant benefits, such as improved health, better use of natural resources and reduced environmental pollution. These truly are the days of miracle and wonder.
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FOOTNOTES
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Dr. Schleyer is an associate professor and chair, Department of Dental Informatics, Temple University School of Dentistry, 3223 N. Broad St., TU 600-00, Philadelphia, Pa. 19140, e-mail "titus{at}dental.temple.edu". Address reprint requests to Dr. Schleyer.
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REFERENCES
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- Freitas RA Jr. Nanodentistry. JADA 2000;131:1559–65.
- Freitas RA Jr. Nanomedicine. Vol. I. Basic capabilities. Georgetown, Texas: Landes Bioscience; 1999. Available at: "www.nanomedicine.com". Accessed Oct. 1, 2000.
- Drexler KE. Predicting and projecting. In: Drexler KE. Engines of creation: the coming era of nanotechnology. New York: Anchor Press/Doubleday; 1986. Available at: "www.foresight.org/EOC/". Accessed Oct. 1, 2000.
- Drexler KE. Nanosystems: molecular machinery, manufacturing, and computation. New York: John Wiley & Sons; 1992.
- Foresight Institute. Feynman grand prize. Available at: "www.foresight.org/GrandPrize.0.html". Accessed Oct. 1, 2000.
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TOP
DEFINING NANOMETER
MANIPULATING MATTER
