Application of Nano-Technology in Dentistry;Past, Present and Future

Submitted to department of oral medicine and diagnostic sciences at the college of dentistry, king Saud University in partial fulfillment of course 491 DDS 2013

Course director: Ali Al Refai.

Supervisor: Dr. Abdullah Mohamed Alsoghier

Students names: Abdullah Almotreb, Mohammad Aldhafyan, Omar Alshehri, Ahmad Albakri, Yasser Alrayes, Yazeed Alsanie, Emad Alamri.

Abstract:Nano-technology deals with extremely tiny matters so their development is sophisticated. But with science demands its development become urgent in medicine and dentistry in particular. Nano-technology will help and improve the human health in many aspects. Nano-medicine and Nano-dentistry need to go through and overcome the obstacles and difficulties of the Nano-technology application in their field. So, more and easier understanding of the diseases nature, more diagnostic tools and this will bring more effective and efficient therapeutic and preventive methods and properties. Many applications are already available in the market and many others are under investigation. This report will highlight in brief most applications of Nano-technology in medical and dental fields.

Introduction:

Nano-technology can be definedas engineering at a very smallscale, and this term can be

applied to many areas of research and development, frommedicine to manufacturing to computing, and even to textiles and cosmetics .It is

considered to be a thrilling science that manipulate mattermeasured in the billionths of meters or Nano-meters and thisnew area of scientific development promises more productivity for less energy. It offers ways to create smaller, cheaper, lighter and faster devices that can do more and cleverer things, usesless raw materials and consumeless energy. (1, 2)

Nano-technology originates from the Greek word meaning “dwarf”. A Nano-meter is one billionth (10-9) of a meter, which is tiny, only the lengthof ten hydrogen atoms, or about one hundred thousandth of the width of a hair. Although scientists have manipulated matter at the Nano- scale for centuries, calling it physics or chemistry, it was not until a new generation of microscopes was invented in the nineteen eighties in IBM, Switzerland that the world of atoms and molecules could be visualized and managed. (1, 2)

Although Nano-technology has been around since the beginning of time, the discovery of Nano-technology has been widely attributed to the American Physicist and Nobel Laureate Dr. Richard Phillips Feynman. In December 29, 1959 at the annual meetingof the American Physical Society meeting at California Institute of Technology. Feynman talked about the storage of information on a very small scale, writing and reading in atoms, about miniaturization of the computer, building tiny machines, tiny factories, and electronic circuits with atoms. (1, 2)

Today, the revolutionary development of Nano-technologyhas become the most highly energized discipline in

science and technology. A large amount of research is being devoted to the development of Nano- composites of different types for various applications, including structural materials, high performance coatings, catalysts, electronics, photonics and biomedical systems. (1)

Nano-technology can be used for loads of different things in many different industries. That’s why Nano-technology is such a marvelous thing: It’s not limited to one thing or even to a small group of things; it can be used for many different things in any field you can think of. Below is a list of several differenttasks that Nano-technology canaccomplish and examples of thewonderful abilities that it can provide the people who work in these fields. (1, 2)

Applications of Nano-Technology:

Medicine:

Advances in the medical implementations of Nano-technology have resulted in the formation of a new field called Nano-medicine. This concept was first put forward in 1993 by Robert A. Freitas Jr. and was defined as observing, controlling, andtreating the biological systems of the human body at the molecular level using Nano-structures and Nano-devices. (2)

The application of Nano-technology to healthcare also called Nano-medicine requires the intersection of many disciplines including biology,chemistry, physics, chemical and mechanical engineering, material science and clinical medicine. The early efforts inNano- medicine were focused onimproving the properties of already available therapeutic and diagnostic modalities. More recently there have been several entirely novel therapeutic and diagnostic modalities that have emerged through the supramolecular assembly of simpler componentswhich would have been impossible to develop without Nano-scale engineering. (3)

“Therapeutics” was generally defined to include drugs, vaccines, and biological thoseare intended to directly remedy a medical condition. The uses for each of the confirmed and likely therapeutic products were grouped into nine categories based on the approved or intended use: cancer treatment, hepatitis, (other) infectious diseases, anesthetics, cardiac/vascular disorders, inflammatory/immunedisorders, endocrine/exocrine disorders, degenerative disorders, and others. The number of approved products issimilar across all the categories. However, about two-thirds of the investigational applications identified are focused on cancer treatment. (4)

It has been implemented in thetreatment of many chronic diseases such as diabetes mellitus, cardio vascular diseases and neuropathic ones.(4)

Diabetes mellitus:

DM is associated with high morbidity and mortality, primarily mediated by the development of chronic vascular changes over time. Asthe invasive multiple injections of precisely calculated amounts of insulin present a significant deterioration of the life quality of diabetic patients the first and best establishedNano-medical approaches has focused on oral or inhalative,hence non-invasive, delivery of insulin, additional to other less well studied administration routes.

Some metabolic changes as wellas differences in blood flow, intestinal barrier function, or body composition can vary the bioavailability of novel Nano-particulated insulin medicines in elderly. They facilitate blood glucose management by non-invasive glucose measurement as well asinsulin administration mainly by delivering the fragile protein as protected and targeted formulation via nasalor oral route. (5)

Cardiovascular diseases:

For the treatment of CVD, one of the major foci of the application of Nano-technologyfor its research has been the directed imaging and therapy of atherosclerosis, restenosisand over cardi-ovascular conditions. Nano-scale contrast agents have emerged as multifaceted modalities that can be used to identify and characterize the early stages of disease before the development of pathological manifestations.

Nano-particles various Nano-technology applications are being investigated for the treatment of atherosclerosis and restenosis, including Nano-carriers for drug delivery and devices such as mechanical stents, possessing Nano-scale components. (6)

Alzheimer's disease:

Nano- have been also implemented in the treatment of Alzheimer's disease (AD), it is a devastating neurodegenerative disorder and

the most common form of dementia among people over theage of 65 years.

Generally, pharmaceuticals, including most small molecules, do not cross the blood-brain barrier BBB. The Nano-technology-based strategies have gained tremendous importance, as someof them are capable of overcoming the limitations inherent to BBB passage. Theseinclude various types of lipidic, polymeric, inorganic,and other types of Nano-particles (NPs) for controlleddrug delivery and release pertinent to various CNS conditions.The development of future effective treatments for neuronal degeneration will depend on early-diagnosis methods based on the detectionand quantification of soluble AD biomarkers. (7) Nano- technology in Microbiology:

During the past 40 years, the importance of the microbial cell surface in biology, medicine, industry, and

ecology has been increasingly recognized. (8)

Traditionally, probing of the cell surface architecture relies on transmission (TEM) and scanning (SEM) electron microscopy techniques, these approaches are very demanding in terms of sample preparationand analysis and are only applied in a few laboratories worldwide.

However, recent advances in atomic force microscopy (AFM) are helping to overcome these problems by providing three-dimensional images of hydratedcells and membranes with Nano-meter resolution, and enablingresearchers to probe a varietyof molecular forces and physical properties on cell surfaces, including the unfolding pathways of single membrane proteins and thus thenumber of publications in which AFM is applied to microbiological samples has increased continuously over the past years, indicating

that a new field is born, i.e.Nano- microbiology. (8)

Drugs and Nano-Technology:

The pathophysiological condition and anatomical changes of diseased or inflamed tissues offers many advantages for the delivery ofvarious Nano-technological products. (9)

Drug loading onto Nano-particles modifies cell and tissue distribution and leads to a more selective delivery of biologically active compounds to improve drug efficacy and reduces drug toxicity. (10)

The final aim of pharmaceutical research is thedelivery of any drug at the right time in a safe and reproducible manner to a specific target at the required level all of which alters, destroy, or reduce absorption of nearly all macromolecules, thus reducing their bioavailability. As a result, millions of diabetics worldwide have to self-administered insulin injections daily, provoking a high percentage of negligence in this treatment. (10)

Nano-Dentistry:Over the year, the developmentof Nano-dentistry will allow nearly perfect oral health by the use of Nano-materials and biotechnologies. (11)

The advantage Nano-technology is to be more integration of these Nano-scale structures into larger material components and systems, keeping the control and construction of new and improved materials at the Nano- scale. (11)Various possible uses of dentistry as a follows:

Nano-composites:

From material view in Nano-technology the Nano-fills are dental composites in which allthe fillers are in the 1–100 nm range. Two types of Nano-particles have been synthesized and utilized for preparing the Nano-fill dentalcomposites. The first of theseis the most common and are Nano-metric particles which are essentially on dispersed non-aggregated and non-

agglomerated particles of silica.The second type is Nano-clusters from silica sols only. (12)

The objective was to develop adental composite material thathad the mechanical strength, wear resistance, fracture resistance, more polishing surface, and strong surface morphology after toothbrush abrasion and increase the esthetic Nano-technology has

enabled the production of Nano-dimensional filler particles, which are added either singly or as Nano-clusters into composite

resins. Nano-fillers are different from traditional fillers in size. (13)

Hybrid fillers are large and dens particles average size is1 micro, this particles can't be subdivide under normal abrasive. In contrast to hybrid filler the Nano-composite is more abrasion resistant(wear by breaking offindividual primary particles rather than plucking out the larger secondary particle fromthe resin) and more smooth surface produce and do not reflect light Since particlesin the wavelength of visible light (0.4 to 0.8 μm). (13)

Impression materials:

Nano-fillers are integrated invinylpolysiloxans, producing aunique edition of siloxane impression materials. The material has got advantages ofbetter flow, improved hydrophilic properties, hence

fewer voids at the margin and better model pouring and enhanced detail precision. (14)

Impact of Nano-technologyon Dental Implants:

The dental implants are commonused in dental surgery for restoring teeth; the natural bone surface has a roughness of Approximately 100 nm and such Nano- details are therefore important on the surfaces of implants. Roughingthe implant surface at the Nano- scale level is importantfor the cellular response thatoccurs in the tissue. (15)

Nano-structured hydroxyapatitecoatings for implant have attracted attention during thelast decade. Hydroxyapatite promotes bone formation aroundimplant, increases Osteo-blasts function such as adhesion proliferation and mineralization.

However, it is unlikely that bulk synthetic hydroxyapatite will be used as load bearing implants, since fracture toughness and flexural

strengths (<140 m Pa) are low(Ogiso et al. 1996). Currently,In-framat, Inc (Farmington, Connecticut, USA) is developing next generation Nano-structured hydroxyapatitecoating using a room temperature electrophoretic deposition technique. New families of “smart” Nano-phase(i.e. grain size less than 100nm in at least one direction) coatings that will enhance bone integration and promote better device fixation are being developed by Spire Biomedical Inc. (Bedford Massachusetts, USA). These Nano-phase coatings are modified to selectively encourage hard tissue growth on implant while discouraging the format of soft-tissue growth that can result in implant failure. (15)

New coating technologies have also been developed for applying hydroxyapatite (HA) and related calcium phosphates(Cap), the mineral of bone, onto the surface of implants, But Titanium implants treated with a Nano-structured calciumsurface coat were inserted into femur of rats.( Moreover,Ogawa et al). They found an

increased surface area by up to 40% and a greater strength of osseointegration for the Nano-structured compared to anacid-etched surface. (15)

The goal of Nano-technology isto build active and intelligent implant and structures that will interact with their surroundings, respond to environmental change, deliver appropriate molecules or drug and activelydirect cellular. Showing bone healing at the Nano-rough surface. (15)

Orthodontics:

Orthodontic Nano-robots can directly manipulate all of theperiodontal tissues, includinggingival, periodontal ligament, cement, and alveolarbone. They can correct, rotate, or vertically reposition the teeth within a

few hours in a pain-free manner. (15)

In study published by katz, a reduction in friction has beenreported by coating the orthodontic wire with inorganic fullerene-like tungsten disulfide Nano-particles, which are known fortheir excellent dry lubrication properties.

A new stainless-steel wire that uses Nano-technology is being studied that combines ultra-high strength with good deformability, corrosion resistance, and surface finish. (15)

Hypersensitivity cure:

Dentin hypersensitivity may becaused 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)

Dental Nano- robots could selectively and precisely occlude selected tubules in minutes, using native logical materials, offering patients aquick and permanent cure. (16)

Painless anesthesia:

to induce local anesthesia, the dental professional will instill a colloidal suspensioncontaining millions of active analgesic micrometer sized dental Nano- robot particles on the patient's gingiva aftercontacting the surface of the crown or mucosa, the ambulatory Nano- robots reach the dentin by passing into thegingival sulcus and passing painlessly through the lamina propria. (16)

On reaching the dentin the Nano- robots enter the dentinal tubule holes 1-4 microns in diameter and

proceed towards the pulp, guided by combination of chemical gradient. (16) Nano-technology and cancer:

Currently, there are numerous techniques that are used for cancer treatment. But each technique has its own limitations and adverse effects. Surgical treatment (excision of the tumor) is usually the first choice of treatment preferred by physicians. However, surgical excision is not effective whenthe cancer cells have infiltrated the nearby vital organs or have spread to distant parts of the body (metastasis). Surgical excision is preferred for the removal of larger tumors. (17)

Cryosurgery is another surgical technique that is used for freezing and killing the tumor cells. Chemotherapy is the treatment of cancer with anticancer drugs. These drugs are used as pills, intravenous injections, or topical applications. Chemotherapeutic drugs may destroy healthy tissue along

with cancer cells and carcinomatous tissue (cytotoxicity). (17)

Another technique of cancer treatment is radiation therapy, which uses radiation energy to destroy cancer cellsand reduce the size of tumors.Bone marrow transplantation and peripheral blood stem celltransplantation are done to restore stem cells that are destroyed by high doses of radiation or chemotherapy. Immunotherapy, sometimes called biological therapy, biotherapy, or biological response modifier (BRM) therapy, is a treatment technique that utilizes the human body’s immunesystem to destroy cancer cells. (17)

Gene therapy is an experimental treatment that involves introducing genetic material into the cancer cellsto destroy the cells. Angiogenesis inhibitors are also currently being evaluatedin clinical trials. (17)

Laser therapy uses high intensity laser to treat cancer. Laser can be used to shrink or destroy tumors.

Laser therapy is most commonlyused to treat superficial tumors on the surface of the body or the lining of internalorgans. To overcome the disadvantages of current cancer treatment techniques, the scientific community has turned toward Nano-technology to develop newer and more effective drug carrier systemsto safely shepherd the anticancer drugs to the cancercells. (18)

Nano-technology appears balanced to provide devices, capable of sensitive and specific anatomic, molecular and biologic imaging; selective therapy of tumors; and low toxicity, resulting ina significant improvement overthe current standard of care. Multi-functionality is the keyadvantage of Nano-particles over traditional approaches. Targeting ligands, imaging labels, therapeutic drugs, andmany other functional modalities can be integrated into the Nano-particles to allow for targeted molecular imaging and molecular therapy of cancer. (18)

The Nano-materials have the inherent advantage of possessing unique functional properties for cancer detection and treatment. Nano-material is classified in the size domain of proteins and cells. Hence, they have been used as biological tags by interfacing the Nano-particleswith biocompatible molecules (biological small organic molecules or bioinorganic interface). Different kinds ofNano-particles suitable for drug and gene delivery probingDNA structures, etc., exist. They include liposomes, polymeric Nano-paticles (Nano-spheres and Nano-capsules, solid lipid particles, Nano-crystals, polymer therapeuticssuch as dendrimers, fullerenesand inorganic Nano-particles, eg., gold and magnetic Nano-particles). (19)

Dendritic polymeric Nano- devices can detect cancer cells, identify cancer signature, and provide targeted delivery of anti-cancer therapeutics. Carbon Nano-tubes scan down DNA, and look for single nucleotide polymorphism. Nano-wires having the unique properties

of selectivity and specificity, can be designed to sense molecular markers of malignant cells. (19)

The quantum dots are Nano-sized semiconductors that can emit light in all colours. Theexamples are semiconductor Nano-crystals and core-shell Nano-crystals. They are applied, particularly in cancer imaging studies. For the past few years, quantum dots (QDs) have been an area of intense research. They haveunique physical properties andthey can be exploited for the detection of cancerous tumors.QDs have enough surface area to combine therapeutic agents and tumor specific modalities for the combined results of drug delivery, imaging and tissue engineering. The advantages of QDs are that they have a single light source and that different sizes of QDs preserve the narrow emission of each particle. (19)

The gold Nano-particles have asize-tuned optical property which helps in absorbing and scattering light from the visible to the near infra-red

region. The earliest studied gold Nano-particles are gold Nano-spheres. Gold Nano-spheres (also known as gold colloids) of 2 nm to over 100 nm in diameter can be synthesized by controlled reduction of an aqueous HAuCl4solution using different reduction agents under varyingconditions. (19)

Nano-tech based cancer therapeutics and diagnosis, over the past decade, has evolved from Nano-sized drug particle to functional Nano-material that is capable of delivering heat, ionizing radiation and chemotherapeuticagents. (20)

Gold Nano-particles have been shown to enhance the antiproliferation and apoptosis of human hepatoma cells induced by Paclitaxel, achemotherapeutic drug. (20)

Oral Cancer:

Oral cancer is any cancerous tissue growth which is presentin the oral cavity. It mostly involves the tongue. It appears as skin lesions, lumpsor ulcers. Tobacco, alcohol,

genetic factors, the human papilloma virus, Immunosuppressed patients (HIVpatients, renal transplant patients) have the highest risk factor for developing oral cancer. and the consumption of spicy food are some of the main aetiological factors which are responsible for oral cancer. (21)

Oral cancer accounts for approximately 2% of all malignant tumors in the UnitedStates and Europe, approximately 30–40% in the Indian subcontinent and more than 90% are squamous cell carcinomas, originating in thetissues that line the mouth and lips. (21)

Dental professionals can play a crucial role by identifying these changes during regular once-a-year dental check-up asan effective method for reducing the incidence and mortality of cancer. (21)

Conventional strategies for cancer intervention include surgery, chemotherapy, and radiation therapy. Taking advantage of their unique properties, most studies of

gold Nano-particle-based cancer therapy have used photothermal therapy for destruction of cancer cells ortumor tissue, which may be potentially useful in the clinical setting. When irradiated with focused laser pulses of suitable wavelength,targeted gold Nano-spheres, Nano-rods, Nano-shells, and Nano-cages can kill bacteria and cancer cells. In one study, all tumors treated withthe near-infrared region (NIR;700-900 nm) laser were ablatedand the mice appeared tumor free for several months while tumors in control animals (NIRlaser treatment without Nano-shell injection) continued to grow. In another study 93% of tumor necrosis and regression was observed in high dose Nano-shell treated group. (21)

Nano-diagnostic in oral cancer:

The Nano-materials have the inherent advantage of possessing unique functional properties for cancer detection and treatment. Dendritic polymeric Nano- devices can detect cancer cells, identify cancer

signature, and provide targeted delivery of anti-cancer therapeutics. Carbon Nano-tubes scan down DNA, and look for single nucleotide polymorphism. Nano-wires having the unique properties of selectivity and specificitycan be designed to sense molecular markers of malignantcells. Nano-particles contrastagents are being developed fortumor detection purposes such as nuclear magnetic resonance imaging. (22)

Many Nano-particles have been investigated for biomedical applicationstargeting cancer.

Saliva meets the demands for inexpensive, noninvasive and easy-to-use diagnostic medium containing proteomic and genomic markers for molecular disease identification. A specialized class of biomarkers found in human saliva that has gained renewedinterest is a unique type of sub-100 nm membrane bound secretory vesicles called “exosomes”. Exosomes are secreted by salivary glands epithelium and released into the salivary fluid via exocytosis. Exosomes possess cell type specific membrane and proteins enclosed in a lipid bilayer. Malignancy and other diseases cause elevated exosomes secretion and tumor-antigene enrichment of exosomes associated with cancer cells. Due to their small size, sensitive and quantitative detection tools are needed and characterization of salivary exosomes. Single vesicle structural and surface molecular details on human saliva exosomes considered as potential non-invasive biomarker resource for oral cancer have been studied

recently using atomic force microscopy (AFM). (22)

Safe use of Nano-particles in cancer care:

The chemical and physiochemical properties of nonoparticles, which enable them to overcome the obstaclesthat traditional medications face, can also results in unique toxicities from these particles. There is the risk of these materials causing cell toxicity, having poor biocompatibility and immunogenicity. Their zeta potential, size, and solubility will all affect theway in which they are cleared from the body, how they will be transported to the diseasedtissue, as well as the reactivity of Nano-particle surface and cytotoxicity. (22)

Nano-particles are approximately the same size asorganelles within cells. Theirsmall size can lead to the disruption of vital cellular functions. There have been also been advances in the development of biocompatible polymers over the past two decades. (22)

These new polymeric materials have lower toxicity than earlier generations of polymers, are biocompatible themselves and often degrade into products which are biocompatible and can easily be cleared from the system andmay be of less toxicity concern than Nano-particles composed of less innocuous materials. Fortunately the toxicity of Nano-materials is not inevitable, and can be managed through carful design with attention to the particle’s size, shape, surface area, charge, state ofaggregation, crystallinity, and potential to generate reactive oxygen species. (21, 22) In order to move promising concepts from research to clinical use, the products must be characterized and an application must be made to the FDA for approval. This bring to light issues with scaling up the production of the Nano-materials under current good manufacturing practices (cGMP) which can be costly and difficult without the proper support. It is also

important to verify the stability of the compounds forstorage. Any degradation in solution can result in changesto the physiochemical properties of the material such as agglomeration. Particle size, surface charge,drug load or drug release profile which can all affect the function of the Nano-particles in vivo. (22)

The dentist in the future willask the patients to rinse witha solution which contains millions of microscopic elements which are called assemblers, which will reveal the presence of oral cancer, even in its incipient stages. One scenario some scientist project is that efficient cancer Nano-medicine may completely eradicate cancer, the second commonest cause of death and hence cause an increase in the population. (22)

Conclusion:

Nano-technology will change dentistry, healthcare, and human life more intensely thanmany developments of the past.As with all technologies, Nano-technology carries a substantial potential for misuse and abuse on a scale and scope never seen before.

However, they also have potential to bring about majorbenefits, such as better-quality health, better use of natural resources, and reducedenvironmental pollution. Current work is focused on therecent developments, particularly of Nano-particlesand Nano-tubes for periodontalmanagement, the materials developed from such as the hollow Nano-spheres, core shell structures, Nano-composites, Nano-porous materials, and Nano-membranes will play a growing role in materials development for the dental industry.

Nano-medicine needs to overcome the challenges for its application, to improve

the understanding of pathophysiologic basis of disease, bring more sophisticated diagnostic opportunities, and yield more effective therapies and preventive properties. Molecular technology is destined to become the core technology underlying all of 21st century medicine and dentistry.

References:

1) Current perspectives of nanoparticles in medical and dental biomaterials.Journal of Biomedical Research, 2012, 26(3): 143-151.PMID: 23554743 [PubMed].

2) Nanotechnology and dentistry. Eur J Dent 2013; 7:145-151.

3) Nanomedicine: Developing smarter therapeutic and diagnostic modalities.Adv Drug Deliv Rev. 2006 Dec 1; 58(14):1456-9. Epub 2006 Oct 30.PMID: 17070960.

4) The big picture on nanomedicine.Nanomedicine: Nanotechnology, Biology, and Medicine9 (2013) 1–14.

5) Nanomedicine for treatment of diabetes in an aging population Nanomedicine: Nanotechnology.Biology, and Medicine8 (2012) S69–S76

6) Emerging applications of nanomedicine for the diagnosisand treatment of cardiovascular diseases.

7) Nanotechnologies for Alzheimer's disease. Nanomedicine: Nanotechnology, Biology, andMedicine 7 (2011) 521–540

8) Nanomicrobiology. Nanoscale Res Lett (2007) 2:365–372 DOI 10.1007/s11671-007-9077-1

9) The present and future of nanotechnology in human healthcare. Nanomedicine: Nanotechnology, Biology, and Medicine 7 (2011)20-31

10) Emerging nanotechnologies in dentistry. P 369-370

11) 1-An application of nanotechnology in advanced dental materials, American dental association. Oct 2003 vol.134. page1382-1389.

12) future in dentistry ,the Saudi dental journal , 2013 page 49-52 .

13) 3-nanotechnology and dentistry , European journal of dentistry , January 2013 vol.7, page 145-149

14) nanotechnology in dentistry. Indian journal 2006 page 62-64.

15) the Nano era in dentistry . journal of natural science, biology and medicine ,January 2013 vol4 page39-43

16) Current perspectives of nanoparticles in medical and dental biomaterials, Journal of Biomedical Research, 2012, 26(3): 143-151

17) Karthikeyan Subramani, Waqar Ahmed, Emerging Nanotechnologies in

Dentistry .Materials, Processes, and Applications, First edition 2012.

18) applications of gold nanoparticles in cancer nanotechnology, Nanotechnology, science and application 2008:1 17-32.

19) Sneha S. Mantri, Shivkumar P. Mantri, et al 2013, The Nano era in dentistry, Journal of natural science, biology and medicine 2013,vol 4, issue 1.

20) K.M.K.Masthan, N.aravindhababu, K.T.Shanmugam, Abhinav JHA, et al 2012, nanotechnology- its application in oral cancer, journal of clinical and diagnostic research, 2012/4654:2388.

21) Preeti Satheesh Kumar. Satheesh Kumar. Ravindra C. Savadi. Jins John, et al, 2011, nanodentistry: a paradigm shift-from fiction toreality, J Indian prosthodont soc (jan-mar 2011)11(1):1-6.

22) L.C. Hull, et al, highlights of revent developments and trends in cancer nanotechnology

research- view from NCI alliance for nanotechnology incancer, biotechnol Adv (2013),06712.