Nanorobots and Challenges Faced by Nanodentistry

Abstract

Predicting the future of any major technology is difficult. Nanorobotics is the technology of creating machines or robots at or close to the microscopic scale of a nanometer (10−9 m). More specifically, nanorobotics refers to the hypothetical nanotechnology engineering discipline of designing and building nanorobots; devices ranging in size from 0.1 to 10 μm and constructed of nanoscale or molecular components. With the modern scientific capabilities, it has become possible to attempt the creation of nanorobotic devices and interface them with the macro world for control. There are countless such machines that exist in nature and there is an opportunity to build more of them by mimicking nature. When we gain access to hold the nanorobots, we will be able to treat very rapidly a number of diseases. Their first useful application was in medicine to identify and destroy cancer cells but the most interesting applications may be in dentistry. Dental nanorobots could be constructed to destroy caries-causing bacteria or to repair tooth blemishes where decay has set in, by using a computer to direct these tiny workers in their tasks. The present article aims to provide an early glimpse on the impact and future implication of nanorobotics in dentistry.

Keywords: Nanodentistry, Nanotechnology, Nanorobots

INTRODUCTION

Nano is derived from greek word for 'dwarf. Nanotechnology is the science of manipulating matter measured in the billionths of meters or nanometer, roughly the size of 2 or 3 atoms. 1

Researchers have predicted that high-tech and effective management at the microscopic level, termed nanotechnology, will become an important part of future dental and periodontal health.2

The growing interest in the future of dental applications of nanotechnology lead to the emergence of nanodentistry which involves the maintenance of oral health by the use of nanomaterials, biotechnology and dental nanorobotics.3

According to nanorobotic theory “nanorobots are microscopic in size, it would probably be necessary for very large numbers of them to work together to perform microscopic and macroscopic tasks”. 4,5

HISTORY

One of the first mentions of the distinguishing concepts in nanotechnology (but predating the use of that name) was in 1867. At that time, James Clerk Maxwell proposed, as a thought experiment, a tiny entity known as Maxwell’s Demon that was able to handle individual molecules.6 The term nanotechnology was coined by Prof. Kerie E. Drexler, a researcher and writer of nanotechnology.7 Humans have been using nanotechnology for a long time without realizing it. The processes of making steel, vulcanizing rubber and sharpening a dental instrument all rely on manipulations of nanoparticles. Richard Zsigmondy studied nanomaterials in the early 20th century, and later discoveries culminated in ideas presented by Nobel Prize winning physicist Richard Feynman in a lecture called “Plenty of Room at the Bottom” in 1959, in which he explored the implications of matter manipulation. 8 Applications began in the 1980s with the invention of the scanning tunneling microscope and the discovery of carbon nanotubes and fullerenes. 9

WHAT ARE NANOROBOTS?

Nanorobots are theoretical microscopic devices measured on the scale of nanometers (1 nm equals one millionth of 1 mm). When fully realized from the hypothetical stage, they would work at the atomic, molecular and cellular level to perform tasks in both the medical and industrial fields that have here to fore been the stuff of science fiction. 10

These are computer controlled robotic devices constructed of nanometer scale components to molecular precision, usually microscopic in size. 11

Components of Nanorobots 11,12

• 100nm manipulating arms,
• 10 nm sorting rotors for molecular-by-molecular purification,
• Smooth super hard surfaces made of atomically flawless diamond.

Nanorobotics in Dentistry

The growing interest in the future of dental applications of nanotechnology is leading to the emergence of a new field called nanodentistry. Nanorobots induce oral analgesia, desensitize tooth, manipulate the tissue to re-align and straighten irregular set of teeth and to improve durability of teeth. Further nanorobots are used to do preventive, restorative, curative procedures.10

VARIOUS POSSIBLE USES OF NANOROBOTS IN DENTISTRY ARE

Tooth repair

Tooth repair by dental nanorobots involve manufacturing and installation of a biologieally autologous whole replacement teeth that includes mineral and cellular components i.e Complete Dentition Therapy. 13 Nanodental techniques involve genetic engineering, tissue engineering, tissue regeneration procedures for major tooth repair. 4,10.

Complete dentition replacement was the basis for research by Chan et al,who recreated dental enamel, the hardest tissue in the human body, by using highly organized microarchitectural units of nanorods.14,15

Tooth durability and appearance

Nanodentistry has given material that is nano-structured composite material, sapphire which increases tooth durability and appearance. Upper enamel layers are replaced by covalently bonded artificial material such as sapphire. Like enamel, sapphire is a somewhat susceptible to acid corrosion. Sapphire has the best standard whitening sealant, cosmetic alternative. 10

Nanocomposite

New restorative nanomaterial to increase tooth durability is nanocomposites. This is manufactured by nano-agglomerated discrete nanoparticles that are homogeneously distributed in resins or coatings to produce nanocomposites (Feltech O Universal Restorative). The nanofiller include an aluminaesilicate powder having amean particle size of about 80nm and an 1:4 ratio of alumina to silica. The nanofiller has a refractive index of 1.503, it has superior hardness, modulus of elasticity, translucency, esthetic appeal, excellent colour density, high polish and 50% reduction in filling shrinkage. They are superior to conventional composites and blend with a natural tooth structure much better. 10,16

Nanorobotic dentifrice (Dentifrobots)

Subocclusal dwelling nanorobotic delivered by mouthwash or toothpaste could patrol all supragingival and subgingival surfaces atleast once a day, metabolising trapped organic matter into harmless and odorless vapors and performing continuous calculus debridement. These invisibly small dentifrobots [1-10 micRon], crawling at 1- 10 microns/sec, would be inexpensive, purely mechanical devices, that would safely disactivate themselves if swallowed and would be programmed with strict occlusal avoidance protocol.17

Nano impression

Nanofillers are integrated in vinylpolysiloxanes, producing a unique addition of siloxane impression materials. The material has better flow, improved hydrophilic properties and enhanced detail precision.4

Impression materials are available with nanotechnology application (Nano Tech Elite H-Dþ). The main advantage of this material is that it has better flow, improved hydrophilic properties hence fewer voids at margin, better model pouring & enhanced detail precision.10,16

Dentin hypersensitivity

Dentin hypersensitivity is a pathological phenomenon caused by changes in pressure transmitted hydrodynamically to the pulp. This is based on the fact that hypersensitive teeth have eight times higher surface density of dentinal tubules and tubules with diameters twice as large as non-sensitive teeth.16 Reconstructive dental nanorobots selectively and precisely occlude specific dentinal tubules within minutes, using native biologic materials, offering patients a quick and permanent cure from hypersensitivity.3

Orthodontic treatment

Sliding a tooth along an archwire involves a frictional type of force that resists this movement. Use of excessive orthodontic force might cause loss of anchorage and root resorption. In a study published by Katz, a reduction in friction has been reported by coating the orthodontic wire with inorganic fullerene-like tungsten disulphide nanoparticles (IFeWS2), which are known for their excellent dry lubrication properties.18

In future, orthodontic nanorobots could directly manipulate the periodontal tissues, allowing rapid and painless tooth straightening, rotating and vertical repositioning within minutes to hours. 16,19

Inducing Oral Anaesthesia

In the era of nanodentistry, a colloidal suspension containing millions of active analgesic micron-size dental robots will be instilled on the patient’s gingiva. After contacting the surface of the crown or mucosa, the ambulating nanorobots reach dentin by migrating into the gingival sulcus and pass painlessly through the lamina propria or through 1e3 mu thick layer of loose tissue at the CEJ. Upon reaching the dentin, they enter the dentinal tubules upto le4 mu depth and proceed toward the pulp guided by a combination of chemical gradient, temperature differentials and positional navigation under nanocomputer control. Thus the migration of nanorobots from tooth surface to the pulp occurs in l00 s. Once installed in the pulp, they establish control over nerve impulse, analgesic nanorobots commanded by the dentist shut down all sensitivity in any particular tooth requiring treatment. When the dentist presses the hand held control, the selected tooth is immediately anaesthetized. After the procedure is completed, the dentist orders the nanorobots to restore all sensation and egress from the tooth.3,20

Nanorobot analgesia offers greater patient comfort, reduces anxiety, no needles, greater selectivity, controllability of analgesic effect; fast and completely reversible action; avoidance of side effects and complications.19

CHALLENGES FACED BY NANODENTISTRY

1. Engineering challenges

• Feasibility of mass production technique
• Precise positioning and assembly of molecular scale part
• Manipulating and coordinating activities of large numbers of independent microscale robots simultaneously.

2. Biological challenges

• Developing biofriendly nanomaterial Ensuring compatibility with all intricate of human body

3. Social challenges

• Ethics
• Public acceptance
• Regulation and human safety.21

Engineering challenges: There is a problem in the feasibility of mass production technique. Precise positioning and assembly of molecular scale part is a challenge for them. Manipulating and coordinating activities of large numbers of independent microscale robots simultaneously is a difficult task. Even though the field of nanorobotics is fundamentally different from that of the macro robots due to the differences in scale and material, there are many similarities in design and control techniques that eventually could be projected and applied. Due to the modern scientific capabilities, it has become possible to attempt the creation of nanorobotic devices and interface them with the macro world for control. There are countless such machines which exist in nature and there is an opportunity to build more of them by mimicking nature. Now a days these nanorobots play a vital role in the field of Bio Medicine & dentistry, especially in the treatment of cancer. It also helps to remove the defected part in our DNA structure and some other treatments that have the greatest aid to save human lives.22,23

Biological challenges: It is essential to develop bio friendly nanomaterial and ensure compatibility with all intricate of human body. In general, smaller particles are more bioactive and toxic. Their ability to interact with other living systems increases because they can easily cross the skin, lung, and in some cases the blood/brain barriers. Once inside the body, there may be further biochemical reactions like the creation of free radicals that damage cells.

While the body has built-defense for natural particles it encounters, the danger of nanotechnology is that it is introducing entirely new type of particles. Some experts believe that the body is likely to find toxic. 21

Social challenges: Highest at risk are workers employed by manufacturers producing products that contain nanoparticles. The National Institute for Occupational Safety and Health (NIOSH) reports over two million Americans are exposed to high levels of nanoparticles. NIOSH publishes safety guidelines and other information for those employed in the nanoindustry.22,23

CONCLUSION

All these current developments in technology direct clinicians a step closer to nanorobots, as simple operating tools in the near future. As Dr. H. G Wells rightly quoted “What on earth would man do with himself if something did not stand in his way?” Nanodentistry has strong potential to revolutionize dentistry to diagnose and treat diseases. Dr. Gregory Fahy described nanorobots as “living organisms, naturally existing, fabulously complex systems of molecular nanotechnology”.19

Nano-dentistry faces many significant challenges in bringing its promises to fruition. 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 need to be proved .Basic engineering problems from precise positioning and assembling of molecular scale parts to economical mass production, to biocompatibility and the simultaneous coordination of the activities of large numbers of independent micron scale robots, comes in the way. In "Engines of creation", Drexler explains that "in a race toward the limit 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." There are larger social issues of public acceptance, ethics, regulation and human safety that must be addressed before molecular nanotechnology can enter the modern medical armamentarium.

• What effect will nanorobotics have on the dental profession and the individual dentist?
• However it is not too early to consider, evaluate and aftempt to shape potential eftects.
• Nanotechnology will change dentistry, health care and human life more profoundly than many developments of the future
• These truly are the days of miracle and wonder.

REFERENCES