Steve Martin may have been onto something back in the ’70s with his Let’s Get Small album. In today’s dental materials, it’s the little things that are reaping big rewards. But when we’re talking small, we’re talking nano-small. Nanotechnology, often in the form of fillers used in composite resins, is helping to solve myriad problems that have plagued that restorative material from the get-go.
Following generation after generation of composite dental materials that suffered from either lack of strength or lack of esthetics, nanotechnology is giving clinicians the chance to have the best of both in one material. Add to that, improvements in compressive, mechanical, and tensile strength, fracture resistance, polishability, dimensional stability, and handling characteristics — and you can pretty much drop the mic.
Nanotechnology and the Filler Factor
Fillers used in composite resin restorative materials are typically composed of substances ranging from colloidal silica, bioglass, ceramics, and zirconia to titanium hydroxyapatite and silver. 1Shashirekha G, Jena A, Mohapatra S. Nanotechnology in dentistry: clinical applications, benefits, and hazards. Compend Contin Educ Dent. 2017;38:e1–e4. Among the most important characteristics for fillers, however, are particle size, shape and density.
Generations of dental composites have taught us that when the variously shaped particles that make up a material are all large, strength may be enhanced at the expense of polishability. Likewise, when all the particles are small, especially when the filler density is low, strength may suffer while polishability is stellar. Additionally, a highly filled composite tends to shrink less than one with a lower fill ratio. So a highly filled material, featuring a mix of particle sizes and shapes seems to be key — especially when the size range is measured in nanometers. 2Stone R. Small miracles. Mentor. 2018;9(3):26–30.
In the quest to create durable restorations that offer high esthetics and low polymerization shrinkage, clinicians have found an ally in nanotechnology — through nanofillers. Many nanocomposites feature varying shapes of particles and clusters smaller than 100 nm. That’s about the same size as particles found in smoke. 3Stone R. Small miracles. Mentor. 2018;9(3):26–30.
In a nutshell, nanofilled restorations offer good strength and optical properties, while decreasing polymerization shrinkage, which can leave margins vulnerable. Many can also be safely placed in bulk. 4Stone R. Small miracles. Mentor. 2018;9(3):26–30.
In dentistry, it’s not just composite resins that benefit from nanotechnology. New ceramic materials used in indirect restoration and bone-grafting materials are also beneficiaries. And because they are so small, nanoparticles can penetrate cells, improving the delivery of medications and enhancing infection control. 5Shashirekha G, Jena A, Mohapatra S. Nanotechnology in dentistry: clinical applications, benefits, and hazards. Compend Contin Educ Dent. 2017;38:e1–e4.
For example, new strategies for caries management and prevention are possible due to nanomaterial antibacterial properties. 6Stone R. Small miracles. Mentor. 2018;9(3):26–30. Nanomaterials also have the ability to mimic some of the properties of natural tissue. This allows them to facilitate biointegration, a desirable quality in light of a current emphasis in dentistry on implants, tissue regeneration and minimally invasive practices. 7Shashirekha G, Jena A, Mohapatra S. Nanotechnology in dentistry: clinical applications, benefits, and hazards. Compend Contin Educ Dent. 2017;38:e1–e4.
For instance, nanocoatings are being used on implants to make them more subject to osseointegration. Such coatings include nanostructured diamond, nanostructurally processed hydroxyapatite, and nanostructured metalloceramics. 8Sree L, Balasubramanian B, Deepa D. Nanotechnology in dentistry – a review. Int J Dent Sci Res. 2013;2:40–44.
Nanotechnology on the Horizon
Other developments on the horizon include the use of nanorobots in anesthesia, and the ability to print new enamel. 9Shashirekha G, Jena A, Mohapatra S. Nanotechnology in dentistry: clinical applications, benefits, and hazards. Compend Contin Educ Dent. 2017;38:e1–e4. 10Bilby e. Why get a filling when you could print a smile? Available here. Accessed October 16, 2018.
But because many of these materials remain hydrophobic, maintenance of a dry field is still paramount to their success. Systems such as Isolite offer clinicians a great chance for restoration success. Even when moisture-tolerant materials are being used, Isolite systems can still provide tissue retraction, added illumination, a bite block to ease jaw strain and suction to keep patients comfortable. Try all of that with cotton rolls and a dental dam.