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ePaper created 2015-11-27, 10:40:38 | version 1.38.0
By Nanova Biomaterials Staff n NovaPro Flow, designed and created by Nanova Biomaterials, is the first commercial dental compos- ite reinforced by nanofibers. The in-house-made hydroxyapatite nano- fibers, composed of calcium phos- phate minerals, are the secret to NovaPro Flow’s high strength, great handling properties and esthetic effects, the company asserts. Teeth, bones and nanofibers have the same structure, all comprising a hard inorganic mineral in a soft organic matrix. For example, the enamel of a tooth is made up of high- volume, needle-like mineral crystals (approximately 15 to 20 nanometers thick and 1,000 nanometers long) in a small-volume, soft protein matrix. Bone and dentin are made up of plate-like crystals (approximately 2 to 4 nanometers thick and up to 100 nanometers long) embedded in a collagen-rich protein matrix. By com- parison, the nanofibers have a thick- ness of less than 100 nanometers in diameter, or 1,000 times smaller than human hair. Most dental composites are com- posed of only nanoparticles, while NovaPro Flow reinforces the compos- ites with nanofibers, which adds sev- eral advantages. The strength found in the nanofibers is because of its one- dimensional nature and large surface area. If you apply a shear force to a bunch of nanoparticles, it is easier for the particles to slide by each other. A fiber, on the other hand, has a solid connection that is stronger to resist bending, shear and tensile forces. In comparison, synthetic bulk hydroxyapatite typically has a ten- sile strength of approximately 50 MPa, which would not be able to reinforce a dental composite. The largesizewouldalsoleadtopolishing problems. The larger surface area of nanofibers provides better transfer of strength for the fiber and the dental composite alike. During World War I, A. A. Griffith discovered the correlation between strengthandthesmallsizeofceramic materials, such as enamel, by test- ing different thicknesses of glass. According to the Griffith theory, these needle-like mineral crystals can reach their theoretical strength, or maximum strength, of a material (several or tens of GPa) when their diameters are in the nanoscale. Microscopic flaws cause a mate- rial to fail, so by creating a nanoscale fiber, itstatistically limits the amount of flaws and provides the ability to reach the material’s maximum strength. In addition, such mineral crystals at nanoscale are not sensitive to cracks or stress concentration, which typically degrades when produced on a micro or macro scale. The fibers are able to bend without breaking. The high strength and low sensitiv- ity to cracks found in natural nano- composites are the same advantages provided by the nanofiber-reinforced NovaPro Flow. exhibitors24 ADA 2015 — November 6, 2015 Strength through nanofiber innovation Ad Here at the ADA TocheckoutNovaProflowforyourself, stopbytheNanovaBiomaterialsbooth, No. 1051. 5 NovaPro Flow (Photo/Provided by Nanova Biomaterials)