Surface topography, hardness, and frictional properties of GFRP for esthetic orthodontic wires

• Published in: Journal of biomedical materials research. Part B, Applied biomaterials Vol. 104; no. 1; pp. 88 - 95
• Main Authors: Inami, Toshihiro, Tanimoto, Yasuhiro, Yamaguchi, Masaru, Shibata, Yo, Nishiyama, Norihiro, Kasai, Kazutaka
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.01.2016; Wiley Subscription Services, Inc
• Subjects: Biocompatibility; biomechanics; Biomedical materials; Brackets; Ceramics; Chromium; Chromium base alloys; Chromium nickel alloys; Cobalt; Cobalt base alloys; Composite materials; Electron microscopy; fiber-reinforced composite; Fibers; Friction; Glass - chemistry; Glass fiber reinforced plastics; Hardness; Humans; Intermetallic compounds; Materials research; Materials science; Mechanical properties; Mechanics (physics); Nickel; Nickel base alloys; Nickel compounds; orthodontic; Orthodontic Wires; Orthodontics; Plastics; Polycarbonate; Polymers; Properties (attributes); Pultrusion; Reinforced plastics; Scanning electron microscopy; Stainless steel; surface characterization; Surface properties; Surface roughness; Surgical implants; Titanium; Titanium base alloys; Titanium compounds; Topography; Wire; orthodontic; fiber-reinforced composite; biomechanics; surface characterization; mechanical properties
• ISSN: 1552-4973; 1552-4981
• DOI: 10.1002/jbm.b.33372

In our previous study, glass-fiber-reinforced plastics (GFRPs) made from polycarbonate and glass fiber for esthetic orthodontic wires were prepared by using pultrusion. The purpose of the present study was to investigate the surface topography, hardness, and frictional properties of GFRPs. To investigate how fiber diameter affects surface properties, GFRP round wires with a diameter of 0.45 mm (0.018 in.) were prepared incorporating either 13 μm (GFRP-13) or 7 μm (GFRP-7) glass fibers. As controls, stainless steel (SS), cobalt-chromium-nickel alloy, β-titanium (β-Ti) alloy, and nickel-titanium (Ni-Ti) alloy were also evaluated. Under scanning electron microscopy and scanning probe microscopy, the β-Ti samples exhibited greater surface roughness than the other metallic wires and the GFRP wires. The dynamic hardness and elastic modulus of GFRP wires obtained by the dynamic micro-indentation method were much lower than those of metallic wires (p < 0.05). Frictional forces against the polymeric composite brackets of GFRP-13 and GFRP-7 were 3.45 ± 0.49 and 3.60 ± 0.38 N, respectively; frictional forces against the ceramic brackets of GFRP-13 and GFRP-7 were 3.39 ± 0.58 and 3.87 ± 0.48 N, respectively. For both bracket types, frictional forces of GFRP wires and Ni-Ti wire were nearly half as low as those of SS, Co-Cr, and β-Ti wires. In conclusion, there was no significant difference in surface properties between GFRP-13 and GFRP-7; presumably because both share the same polycarbonate matrix. We expect that GFRP wires will deliver superior sliding mechanics with low frictional resistance between the wire and bracket during orthodontic treatment.