SCIENTIFIC BACKGROUND (REVIEW OF LITERATURE)
The topic of nanotechnology
within dentistry has been chosen to observe where current technology has been
developed and employed and where the future of nanotechnology may take the
field of dentistry.
A lecture titled “There is
plenty of room at the bottom” was delivered at Caltech in 1959 by American
Physicist Richard Feynman, this was publicised as the inspiration of
nanotechnology as a scientific field.
The definition of Nanotechnology refers
to the engineering and development of functional systems at a molecular level. It
deals with structures that are less than 100nanometers or smaller in at least one dimension, one nanometer is 1
billionth or 10?9 of a meter (Mnyusiwalla, Daar & Singer,
2003). The word “Nano” is derived from the Greek word for “Dwarf”.
The ideology of nanotechnology is to control individual atoms and molecules to
produce functional and usable structures. To compare the size of a nanometer, a
single ant is 5million nms in length (Gao, 2014). Through understanding the concept of
nanotechnology, you are able to change macroscopic properties of materials at
the molecular level (Silva,
Currently, there are two
techniques for employing nanotechnology. (Appendix I)
The first is the “Bottom-up”
This technique aims to create
larger structures by creating an assembly of smaller components, gaining in
complexity the larger the structures become. Beginning
with the design and synthetisation
of custom-made molecules that have the
ability to self-assemble into macroscopic structures. These methods are used
today by pharmaceutical companies which manufacture a wide variety of chemical
2008). This is currently the cheapest way of producing nanomaterials, however, the complexity of newer materials can
quickly add on to production costs.
Secondly, the “Top-down” technique.
This method uses much larger
machines that are directed to create the much smaller devices, this is where
large materials are carved down into nanoscale structures in very precise
patterns. This allows highly complex structures to be created from hundreds of
millions of precisely placed nanostructures (Zhang & Webster, 2009).
Richard Siegel the founding Director of the Rensselaer Nanotechnology Center broadly
categorized nanomaterials into 4-dimensional types of materials based on their
chemical composition, shape and the size of the crystallites and interfaces
Shrivastava, Qian, Dordick & Siegel, 2012) (See appendix
Zero (Atomic clusters and
One (Multilayered crystallites
Two (Ultrafine grained
overlays or layers)
consisting of equiaxed nanometer grains)
Nanostructures that are connected
to create nanomaterials are as followed; metal and silica nanoparticles and
gold nanocrystals, nanopores, nanoparticles, nanorods, nanofibers, nanospheres,
nanoshells and dendrimers (Silva, 2004).
Sharma et al., 2010,
categorises nanodentistry as a broad term coined by the clinical use of
nanotechnology and its application to the dental clinical environment, by
furthering development in this area a near perfect oral health will be
attainable through emerging biotechnologies this includes the following areas
which will be discussed in further detail. Nanorobotics, nanodiagnostics and Nanomaterials within
The development of
nanocomposites has been in response to the issues of using them in posterior
restorations. It has addressed the issues of shrinkage, occlusal strength,
microhardness and wear resistance (Saunders, 2009).
The development in the use of
nanocomposites patented in response to the persistent and discouraging issues
of polymerization shrinkage, strength, microhardness, and wears resistance
essential in posterior occlusal applications (Reference). Over the last few years there has been rapid
advances in restorative composites, all efforts are being made to achieve
advances in physical properties and being able to achieve patients satisfaction
in terms of aesthetic appearances (Chen, 2010).
Nanorobots have a diameter of about 0.5–3 microns and made
of components sized from 1–100 nm. The
primary material used will be carbon, in the form of diamond. Nanorobots would
be programmed prior to placement within the oral cavity, allowing clinicians to
accurately complete procedures at a cellular level.
Nanorobots could be introduced into the oral cavity through
a colloidal suspension which would allow the robots to act as instructed.
– Local Anaesthesia
This could be through providing local anesthesia. The
solution would be deposited at the gingival margin, where the nanorobots would
travel towards the dentin and pass through into the pulp via dentinal tubules.
They would be guided by temperature
differences, and positional steering by a computer controlled by the dental
practitioner. Upon reaching the desired location, the robots will be able to
selectively stop sensation within the tooth. When the treatment has been
completed, the robots will restore sensation and exit the tooth, upon exiting
the robots will become functionless and be rinsed away.
This could prove to become advantageous as anesthesia will be fast, and reversible. (Verma &
– At home Dental Care
Nanorobots could be introduced into toothpaste and mouthwashes, once used this would deposit the dentifrobots around the oral cavity. These
would then proceed to continuously patrol the soft and hard tissues breaking
down harmful bacteria into harmless substances, while continuously interrupting
calculus production (Dalai
et al., 2014).
They could be used for further treatment
of Dentin hypersensitivity; they
can use organic materials in localized areas and apply these to the dentinal
tubules and be able to effectively occlude specific tubules to provide a rapid
relief from hypersensitivity.
Diagnosis and treatment of Oral cancer
There are a few different ways nanotechnology has helped
with the detection of oral cancers along with the potential to have a more
accurate treatment with lower doses of drugs administered to patients. As some
of these are novel methods, the efficacy is unproven overall, however it is
promising once they have been refined that oral cancer screening will become
part of the clinical session.
These are nanomaterials that bind to the proteins that are
unique within the cancerous cells, when illuminated with an ultraviolet light
the cancerous cells will be brightly illumined leaving other cells as normal.
Perfectly showing the margins and area of the cancerous growth. (He, Want, Quan
& Yu, 2015)
Other areas have begun to be explored including the
Nanoscale Cantilevers – Flexible beams that bind to
molecules associated with cancerous cells.
Nanotubes – These are half the size of a molecule of DNA,
they can detect the presence of cancer but also help to pinpoint the exact
location of the changes.
Nanopores – These are small holes that would allow DNA to
pass through each strand at a time (Alok et al., 2013).