ABSTRACT
Advances in modern dental materials provide patients and practitioners a number of choices from which to create more pleasing and natural-looking restorations. So we should learn the characteristics of each tooth-colored materials and to base their judgment of which type to use on in-depth consideration of the many products available.

KEYWORDS : Nanotechnology , Nanocomposite , Dentistry, Composite

Definition:
Nanotechnology is the design, fabrication, characterisation and utilization of materials, structures and devices, which are less than one hundred nanometres in at least one dimension” 'Nano-technology' is the production technology to get the extra high accuracy and ultra fine dimensions, i.e. the preciseness and fineness on the order of 1 nm (nanometer), 10(superscript)-9 meter in length. The name of 'Nano-technology' originates from this nanometer.

• Nanocomposites are a recent development on the market. They contain filler particles with sizes less than 10 nm (0.01 µm) and are claimed to provide increased aesthetics, strength and durability

There are 2 nominal approaches
1.Top-down making nanoscale structures by machining, coating, atomisation, dispersion and etching techniques. However, these milling procedures usually cannot reduce the filler particle size below 100nm (1/1000um).
2. Bottom-up (“molecular nanotechnology”) applies to building organic and inorganic structures atom-by-atom, or molecule-by-molecule (for composite).

Nanoparticles
• Two types
1.Nanomeric (NM) - Monodisperse nonaggregated and nonagglomerated silica nanoparticles.
2. Nanoclusters (NC)- It is formed by partially fusing or sintering some of these nanometer-sized particles.

• The silica particles are treated with 3-methacryloxypropyltrimethoxysilane,(MPTS) using proprietary method.
• MPTS is a bifunctional coupling agent, contains a silica ester function on one end for bonding to the inorganic surface and a methacrylate group on the other end to make the filler compatible with the resin before curing to prevent any agglomeration or aggregation.
• It also allows chemical bonding of the NM filler to the resin matrix during curing.
• NC fillers are of two types:
1.The first type consist of Zirconia-silica particles synthesized from a colloidal solution of silica and a Zirconly salt. The primary particle size ranges from 2-20nm, while the spheroidal agglomerated particles have a broad size distribution of 0.6um.
2. The second type are synthesized from 75nm primary particles of silica, has broad secondary particles size distribution with a 0.6 um average.
The surfaces of both types of NC are treated with MPTS coupling agent to provide compatibility and chemical bonding with the organic resin. Resin matrix/system;
• Bisphenol A glycidyl dimethacrylate,
• Ethoxylated bisphenol A dimethacrylate,
• Triethylene glycol dimethacrylate,
• 1,6-bis-2,4,4-trimethylhexane.
Properties:
• T.S – 80- 87 Mpa.
• C.S – 426- 458 Mpa.
• Flexural strength – 153-177 Mpa
• Fracture resistance – 1.0-1.3.
• Wear – 0.01-0.04mm3.
• Volumetric shrinkage – 2.0-2.09%
• The commercial material is available in 3 translucent shade, 7 enamel, 13 body shades and 7 dentin shades.

Advantages:
1. Superior hardness.
2. Superior flexural strength.
3. Superior modulus of elasticity.
4. Superior translucency, excellent color density, high polish and polish retention.
5. Excellent handling property.
6. About 50% reduction in filling shrinkage.
• Trade names of Nanocomposite:
1. Filtek Z350 (3M).
2. Ceram.X (Dentsply).
Other uses of nanotechnology in dentistry.
• Nanosolution – AdperO single Bond adhesive.
• Impression material- NanoTech Elite H-D+.
• Orthodontic purpose.
• Implantology.
Conclusion:
Advances in modern dental materials provide patients and practitioners a number of choices from which to create more pleasing and natural-looking restorations. So we should learn the characteristics of each tooth-colored materials and to base their judgment of which type to use on in-depth consideration of the many products available.

References:
1.European Dental Materials Conference, September 1-2, 2005: Nanomaterials / Nanotechnology in Dentistry: http://www.ucc.ie/academic/restorative/edmc/programme.html
2.Foresight Institute: Recent Articles on Medical Nanomaterials, Nanobiotechnology, or "Nanomedicine" / compiled by Robert A. Freitas Jr.:http://www.foresight.org/Nanomedicine/NanoMedArticles.html
3.Nature Nanotechnology [forthcoming October 2006]: http://www.nature.com/nnano/index.html
4.Shahed University Dental Research Center: 1st Seminar on Nanotechnology Application in Dentistry; June 15, 2006: http://www.nano.ir
5.Freitas Jr RA. Nanodentistry.J. Amer. Dent. Assoc. 131(November 2000):1559-1566.
6.http://www.rfreitas.com/Nano/Nanodentistry.htm
7.http://jada.ada.org/cgi/content/abstract/131/11/1559
8.Jhaveri HM, Balaji PR Nanotechnology: The future of dentistry JProsthodont20055(1):15-17.
9.Kong LX, Peng Z, Li SD, Bartold PM. Nanotechnology and its role in the management of periodontal diseases. Periodontol 2000. 2006;40:184-96.
10.Malamud D, Bau H, Niedbala S, Corstjens P. Point detection of pathogens in oral samples. Adv Dent Res. 2005 Jun;18(1):12-6.

Dr. Manjul Tiwari MDS ,Oral Pathology & Microbiology Senior Lecturer ,Hindustan Institute of Dental Sciences Plot No. 32-34 , Knowledge Park – III Greater Noida -201306 Uttar Pradesh