Shock absorption and dispersion capability of a novel five-layer mouthguard sheet material.

There is a growing need for a mouthguard sheet material with higher shock absorption and dispersion capacity than those obtained by conventional materials. A five-layer mouthguard sheet material was previously developed using laminated ethylene vinyl acetate and polyolefin copolymer resin. In this study, the shock absorption capacity and dispersion capability of the new sheet material were investigated and compared with those of other materials. Impact testing for the new sheet material showed that the force required to displace the sheet by 1 mm was significantly higher at all thicknesses (p<0.001), whereas the puncture energy and displacement were significantly lower than those for ethylene vinyl acetate (p<0.05). The five-layer mouthguard sheet material successfully absorbed and resisted shock. Therefore, the sheet material potentially increases resistance to applied deformation in teeth and alveolar bone and maintains structure. The five-layer sheet material could expand the range of mouthguard products and help prevent oral trauma.

Mechanical characterization of aesthetic orthodontic brackets by the dynamic indentation method.

The objective of this study is to investigate the mechanical properties, such as the dynamic hardness and indentation elastic modulus, of commercially available aesthetic orthodontic brackets, such as ceramic and plastic brackets, by the dynamic micro-indentation method. Five ceramic brackets, which were made of alumina (both monocrystalline and polycrystalline forms) or zirconia, and two plastic brackets, which were made of glass fiber-reinforced polycarbonate or polyamide, were tested. There were significant differences in the mechanical properties of the monocrystalline and polycrystalline alumina brackets. The mechanical properties of the glass fiber-reinforced plastic bracket were significantly superior to these of the non-glass-fiber-reinforced plastic bracket. The differences in the crystal structures of the ceramic brackets surface affected the dynamic hardness and indentation elastic modulus. Furthermore, the short glass fibers contained in the plastic bracket might contribute to the improvement of the mechanical properties.

Evaluation of the mechanical behavior of bulk-fill and conventional flowable resin composites using dynamic micro-indentation.

The purpose of this research was to investigate the mechanical behavior of commercially available bulk-fill and conventional flowable resin composites using the dynamic micro-indentation method. The effect of inorganic filler content on mechanical properties was also assessed. Weight percentages of the inorganic filler in the resin composite were measured using the ashing technique. The results showed that dynamic hardness and elastic modulus tended to increase with inorganic filler content. Furthermore, the differences in mechanical properties between top and bottom surfaces were less pronounced in bulk-fill flowable resin composites compared with conventional flowable resin composites. In conclusion, the mechanical properties of bulk-fill flowable resin composites are affected by filler content. Moreover, bulk-fill flowable resin composites have a higher polymerization depth than conventional flowable resin composites when sample thickness is 4 mm.

A study on the characteristics of resin composites for provisional restorations.

In this study, we evaluated the characteristics of five commercial resin composites used for provisional restorations. The inorganic filler contents of the resins were measured, and three-point bending, wear, surface hardness, water absorption, and staining tests were performed. The specimens underwent additional three-point bending tests after water storage and undergoing thermal stresses at 5°C and 55°C (10,000 cycles). Data were analyzed using one- or two-way analysis of variance and Bonferroni post-hoc tests. Pearson's correlation coefficient was used for pairwise comparisons. Each resin composite presented with different mechanical properties, based on variations in the inorganic filler content. The flexural strength of each resin composite was significantly decreased after water storage. There has a positive correlation between flexural strength and dynamic hardness but a negative correlation between flexural strength and maximum wear depth. The types and contents of the inorganic fillers, the composition of the monomer in the resin matrix, and the addition of plasticizers can affect the properties of the material.

Effects of material and coefficient of friction on taper joint dental implants.

PURPOSE: The aim of this study was: (1) to compare the coefficients of friction between commercially pure titanium (cpTi), titanium (Ti) alloy, and yttria-stabilized zirconia (YSZ) and: (2) to investigate the dynamic behavior of an implant system before, during, and after loading, by transient dynamic three-dimensional finite element analysis (FEA). METHODS: Coefficients of friction were measured by a ball-on-disk frictional wear testing device. The preload in the screw shaft was calculated from geometric parameters. Two abutment model designs were created, namely a Ti alloy abutment model with a porcelain-fused-to-metal super structure and a YSZ abutment model with a porcelain-fused-to-zirconia super structure. Transient dynamic three-dimensional FEA was performed on ANSYS Workbench Ver. 15.0. RESULTS: The coefficients of friction of YSZ/cpTi, YSZ/Ti alloy, Ti alloy/cpTi, and Ti alloy/Ti alloy were 0.4417, 0.3455, 0.3952, and 0.3489, respectively. The preload generated in the abutment screw of the FEA model was set to be 158 N. Significantly differences were not found in the maximum von Mises equivalent stress between the Ti alloy and YSZ abutment models before, during, and after loading. CONCLUSION: The findings indicate differences in the coefficients of friction of cpTi, Ti alloy, and YSZ before, during, and after loading. Fractures caused by stress did not depend on the use of different materials (Ti alloy and YSZ) at the abutment.

Effects of polishing on surface roughness and hardness of glass-fiber-reinforced polypropylene.

Removable partial dentures (RPDs) with resin-clasp retentive parts, which are known as non-metal-clasp dentures (NMCDs), have been used as alternatives for conventional RPDs with metal clasp, in case of aesthetic prosthodontic treatments. In this study, a profilometer and dynamic micro-indentation tests were used to investigate the effects of polishing on the surface properties such as surface roughness (Ra), dynamic hardness, and elastic modulus of high-rigidity glass-fiber-reinforced thermoplastics (GFRTPs) composed of E-glass fibers and polypropylene for NMCDs. The Ra values of the GFRTPs after polishing were significantly lower than those before polishing. The values were close to the Ra threshold level of 0.2, which corresponds to an acceptable surface smoothness for denture base materials. Polishing did not significantly change the dynamic hardnesses and elastic moduli of the GFRTPs. The fiber loading did not greatly affect the micromechanical properties of the GFRTPs because the glass-fiber reinforcement is embedded in the polypropylene matrix.

Effect of the demineralisation efficacy of MDP utilized on the bonding performance of MDP-based all-in-one adhesives.

OBJECTIVES: The amounts of calcium salt of 10-methacryloyloxydecyl dihydrogen phosphate (MDP-Ca salt) and dicalcium phosphate dihydride (DCPD) with an amorphous phase produced by the demineralisation of enamel and dentin were determined using commercial MDP-based 2-hydroxyethyl methacrylate (HEMA)-containing and HEMA-free all-in-one adhesives. The effect of the amount of MDP-Ca salt produced on bonding performance to enamel and dentin was then characterized. METHODS: Three types of commercial HEMA-containing adhesives (Scotchbond Universal Adhesive, Clearfil Tri-S Bond ND, Clearfil Tri-S Bond ND Quick), a commercial HEMA-free adhesive (G-Bond Plus) and an experimental HEMA-free adhesive were used. The reactant residues of each adhesive were prepared after interacting with enamel and dentin samples for 60 s. The amounts of MDP-Ca salt and amorphous DCPD produced were determined using a phosphorous-31 nuclear magnetic resonance technique. Enamel and dentin bond strengths were measured for each adhesive, with and without thermocycling. RESULTS: The amounts of MDP-Ca salt and amorphous DCPD formed after interacting with enamel and dentin differed among the five adhesives and were independent of their pH values. Enamel showed a strong positive-correlation of the bond strength of the all-in-one adhesives to the amount of MDP-Ca salt produced, however, the dentin showed a weak negative-correlation. CONCLUSION: The HEMA-free all-in-one adhesives showed a greater efficacy to demineralise the enamel and dentin than the HEMA-containing all-in-one adhesives. The dentin showed a different effect of the amount of MDP-Ca salt produced on the bonding performance compared with enamel. CLINICAL SIGNIFICANCE: The enamel bond strength of MDP-based all-in-one adhesives strongly contributes to the demineralisation efficacy by the incorporation of MDP, in contrast to the dentin bond strength. However, the efficacy of MDP-based all-in-one adhesives to demineralise the enamel and dentin is not directly related to the pH value of the MDP-based all-in-one adhesive.

Glass fiber-reinforced thermoplastics for use in metal-free removable partial dentures: combined effects of fiber loading and pigmentation on color differences and flexural properties.

PURPOSE: The purpose of this study was to investigate the combined effects of fiber loading and pigmentation on the color differences and flexural properties of glass fiber-reinforced thermoplastics (GFRTPs), for use in non-metal clasp dentures (NMCDs). METHODS: The GFRTPs consisted mainly of E-glass fibers, a polypropylene matrix, and a coloring pigment: the GFRTPs with various fiber loadings (0, 10, and 20mass%) and pigmentations (0, 1, 2, and 4mass%) were fabricated by using an injection molding. The color differences of GFRTPs were measured based on the Commission Internationale de l'Eclairage (CIE) Lab color system, by comparing with a commercially available NMCD. The flexural properties of GFRTPs were evaluated by using a three-point bending test, according to International Standards Organization (ISO) specification number 20795-1. RESULTS: The visible colors of GFRTPs with pigment contents of 2mass% were acceptable for gingival color, and the glass fibers harmonized well with the resins. The ΔE* values of the GFRTPs with pigment contents of 2mass% obtained by using the CIE Lab system were lowest at all fiber loadings. For GFRTPs with fiber contents of 10 and 20mass% at 2mass% pigment content, these GFRTPs surpassed the ISO 20795-1 specification regarding flexural strength (> 60MPa) and modulus (> 1.5GPa). CONCLUSIONS: A combination of the results of color difference evaluation and mechanical examination indicates that the GFRTPs with fiber contents of 10 or 20mass%, and with pigment contents of 2mass% have acceptable esthetic appearance and sufficient rigidity for NMCDs.

Color stability of glass-fiber-reinforced polypropylene for non-metal clasp dentures.

PURPOSE: The purpose of this study was to investigate the color stability of a glass-fiber-reinforced thermoplastic (GFRTP), for use in non-metal clasp dentures (NMCDs). METHODS: GFRTPs composed of E-glass fibers and polypropylene with 2 mass% of pigments were fabricated using injection molding. According to our previous study on the optimum fiber content for GFRTPs, we prepared GFRTPs with fiber contents of 0, 10, and 20 mass% (GF0, GF10, and GF20). Commercially available NMCD and PMMA materials were used as controls. The color changes of GFRTPs at 24h, and at 1, 2, and 4 weeks of coffee immersion at 37°C were measured by colorimetry, using the Commission Internationale de l'Eclairage (CIE) Lab system. The color stabilities of the GFRTPs were evaluated in two units: the color difference (ΔE∗) and National Bureau of Standards (NBS) units. RESULTS: After immersion, none of the GFRTPs showed visible color change. From the colorimetry measurement using the CIE Lab system, the ΔE∗ values of the GFRTPs were 0.65-2.45. The NBS values of the GFRTPs were 0.60-2.25, all lower than the threshold level of 3.0, demonstrating clinically acceptable color changes. On the other hand, an available polyamide-based NMCD material exhibited "appreciable" color change, as measured in NBS units. CONCLUSIONS: The results indicate that the GFRTPs showed clinically acceptable color stability and might be satisfactory for clinical use. Therefore, GFRTPs are expected to become attractive materials for esthetic dentures.

Effect of fiber content on flexural properties of glass fiber-reinforced polyamide-6 prepared by injection molding.

The use of non-metal clasp denture (NMCD) materials may seriously affect the remaining tissues because of the low rigidity of NMCD materials such as polyamides. The purpose of this study was to develop a high-rigidity glass fiber-reinforced thermoplastic (GFRTP) composed of E-glass fiber and polyamide-6 for NMCDs using an injection molding. The reinforcing effects of fiber on the flexural properties of GFRTPs were investigated using glass fiber content ranging from 0 to 50 mass%. Three-point bending tests indicated that the flexural strength and elastic modulus of a GFRTP with a fiber content of 50 mass% were 5.4 and 4.7 times higher than those of unreinforced polyamide-6, respectively. The result showed that the physical characteristics of GFRTPs were greatly improved by increasing the fiber content, and the beneficial effects of fiber reinforcement were evident. The findings suggest that the injection-molded GFRTPs are adaptable to NMCDs because of their excellent mechanical properties.

Fabrication and physical properties of glass-fiber-reinforced thermoplastics for non-metal-clasp dentures.

Recently, non-metal-clasp dentures (NMCDs) made from thermoplastic resins such as polyamide, polyester, polycarbonate, and polypropylene have been used as removable partial dentures (RPDs). However, the use of such RPDs can seriously affect various tissues because of their low rigidity. In this study, we fabricated high-rigidity glass-fiber-reinforced thermoplastics (GFRTPs) for use in RPDs, and examined their physical properties such as apparent density, dynamic hardness, and flexural properties. GFRTPs made from E-glass fibers and polypropylene were fabricated using an injection-molding. The effects of the fiber content on the GFRTP properties were examined using glass-fiber contents of 0, 5, 10, 20, 30, 40, and 50 mass%. Commercially available denture base materials and NMCD materials were used as controls. The experimental densities of GFRTPs with various fiber contents agreed with the theoretical densities. Dynamic micro-indentation tests confirmed that the fiber content does not affect the GFRTP surface properties such as dynamic hardness and elastic modulus, because most of the reinforcing glass fibers are embedded in the polypropylene. The flexural strength increased from 55.8 to 217.6 MPa with increasing glass-fiber content from 0 to 50 mass%. The flexural modulus increased from 1.75 to 7.42 GPa with increasing glass-fiber content from 0 to 50 mass%, that is, the flexural strength and modulus of GFRTP with a fiber content of 50 mass% were 3.9 and 4.2 times, respectively, those of unreinforced polypropylene. These results suggest that fiber reinforcement has beneficial effects, and GFRTPs can be used in NMCDs because their physical properties are better than those of controls. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2254-2260, 2017.

Effect of a dietary supplement on peri-implant bone strength in a rat model of osteoporosis.

PURPOSE: Osteoporosis contributes to impaired bone regeneration and remodeling through an imbalance of osteoblastic and osteoclastic activity, and can delay peri-implant bone formation after dental implant surgery, resulting in a prolonged treatment period. It poses several difficulties for individuals with large edentulous areas, and decreases their quality of life. Consequently, prompt postoperative placement of the final prosthesis is very important clinically. Peri-implant bone formation may be enhanced by systemic approaches, such as the use of osteoporosis supplements, to promote bone metabolism. We aimed to confirm whether intake of synthetic bone mineral (SBM), a supplement developed for osteoporosis, could effectively accelerate peri-implant bone formation in a rat model of osteoporosis. METHODS: Thirty-six 7-week-old ovariectomized female Wistar rats were randomly assigned to receive a standardized diet with or without SBM (Diet with SBM group and Diet without SBM group, respectively; n=18 for both). The rats underwent implant surgery at 9 weeks of age under general anesthesia. The main outcome measures, bone mineral density (BMD) and pull-out strength of the implant from the femur, were compared at 2 and 4 weeks after implantation using the Mann-Whitney U test. RESULTS: Pull-out strength and BMD in the Diet with SBM group were significantly greater than those in the Diet without SBM group at 2 and 4 weeks after implantation. CONCLUSIONS: This study demonstrated that SBM could be effective in accelerating peri-implant bone formation in osteoporosis.

Improved Bone Micro Architecture Healing Time after Implant Surgery in an Ovariectomized Rat.

The present animal study investigated whether oral intake of synthetic bone mineral (SBM) improves peri-implant bone formation and bone micro architecture (BMA). SBM was used as an intervention experimental diet and AIN-93M was used as a control. The SBM was prepared by mixing dicalcium phosphate dihydrate (CaHPO4·2H2O) and magnesium and zinc chlorides (MgCl2 and ZnCl2, respectively), and hydrolyzed in double-distilled water containing dissolved potassium carbonate and sodium fluoride. All rats were randomly allocated into one of two groups: a control group was fed without SBM (n = 18) or an experimental group was fed with SBM (n = 18), at seven weeks old. At 9 weeks old, all rats underwent implant surgery on their femurs under general anesthesia. The implant was inserted into the insertion socket prepared at rats' femur to a depth of 2.5 mm by using a drill at 500 rpm. Nine rats in each group were randomly selected and euthanized at 2 weeks after implantation. The remaining nine rats in each group continued their diets, and were euthanized in the same manner at 4 weeks after implantation. The femur, including the implant, was removed from the body and implant was pulled out by an Instron universal testing machine. After the implant removal, BMA was evaluated by bone surface ratio (BS/BV), bone volume fraction (BV/TV), trabecular thickness (TbTh), trabecular number (TbN), trabecular star volume (Vtr), and micro-CT images. BS/BV, BV/TV, TbTh and Vtr were significantly greater in the rats were fed with SBM than those were fed without SBM at 2 and 4 weeks after implantation (P < 0.05). The present results revealed that SBM improves the peri-implant formation and BMA, prominent with trabecular bone structure. The effect of SBM to improve secondary stability of the implant, and shortening the treatment period should be investigated in the future study.

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

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, ß-titanium (ß-Ti) alloy, and nickel-titanium (Ni-Ti) alloy were also evaluated. Under scanning electron microscopy and scanning probe microscopy, the ß-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 ß-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.

Interleukin-17 is involved in orthodontically induced inflammatory root resorption in dental pulp cells.

INTRODUCTION: The objectives of this study were (1) to investigate the expressions of interleukin (IL)-17, RANKL (the receptor activator of NF-kappaB ligand), and osteoprotegerin (OPG) in root resorption areas during experimental tooth movement in rats, and (2) to determine the effect of IL-17 on the expressions of RANKL and OPG mRNA from human dental pulp cells. METHODS: Twelve male 6-week-old Wistar rats were subjected to an orthodontic force of 50 g to induce a mesially tipping movement of the maxillary first molars for 7 days. The expression levels of tartrate resistant acid phosphatase (TRAP), interleukin (IL)-17, IL-17 receptor (IL-17R), receptor activator of nuclear factor-kappa B ligand (RANKL), and OPG proteins were determined in dental pulp by immunohistochemical analysis. Furthermore, the effects of IL-17 on the expressions of RANKL and OPG mRNA were investigated using human dental pulp cells in vitro. RESULTS: In the experimental tooth movements in vivo, resorption lacunae with multinucleated cells were observed in the 50-g group. The immunoreactivities for IL-17, IL-17R, and RANKL were detected in dental pulp tissues subjected to the orthodontic force on day 7. Moreover, IL-17 increased the mRNA expression of RANKL from human dental pulp cells in vitro. CONCLUSIONS: The results of this study suggest that IL-17 and RANKL may be involved in the process of orthodontically induced inflammatory root resorption in dental pulp cells.

Color stability of laboratory glass-fiber-reinforced plastics for esthetic orthodontic wires.

OBJECTIVE: In our previous study, glass-fiber-reinforced plastics (GFRPs) made from polycarbonate and glass fibers were prepared for esthetic orthodontic wires using pultrusion. These laboratory GFRP wires are more transparent than the commercially available nickel-titanium wire; however, an investigation of the color stability of GFRP during orthodontic treatment is needed. Accordingly, in the present study, the color stability of GFRP was assessed using colorimetry. METHODS: Preparation of GFRP esthetic round wires (diameter: 0.45 mm [0.018 inch]) using pultrusion was described previously. Here, to investigate how the diameter of fiber reinforcement affects color stability, GFRPs were prepared by incorporating either 13-µm (GFRP-13) or 7-µm glass (GFRP-7) fibers. The color changes of GFRPs after 24 h, and following 1, 2, and 4 weeks of coffee immersion at 37℃, were measured by colorimetry. We evaluated the color stability of GFRPs by two evaluating units: the color difference (ΔE(*)) and National Bureau of Standards (NBS). RESULTS: After immersion, both GFRPs showed almost no visible color change. According to the colorimetry measurements, the ΔE(*) values of GFRP-13 and GFRP-7 were 0.73-1.16, and 0.62-1.10, respectively. In accordance with NBS units, both GFRPs showed "slight" color changes. As a result, there were no significant differences in the ΔE(*) values or NBS units for GFRP-13 or GFRP-7. Moreover, for both GFRPs, no significant differences were observed in any of the immersion periods. CONCLUSIONS: Our findings suggest that the GFRPs will maintain high color stability during orthodontic treatment, and are an attractive prospect as esthetic orthodontic wires.

A review of improved fixation methods for dental implants. Part II: biomechanical integrity at bone-implant interface.

PURPOSE: The purpose of this article is to review the mechanical requirements of the tissue-implant interface and analyze related theories. STUDY SELECTION: The osseointegration capacity of titanium implants has been investigated over the past 50 years. We considered the ultimate goal of osseointegration to which form a desirable interfacial layer and a bone matrix with adequate biomechanical properties. RESULTS: Occasionally, the interface comprises porous titanium and bone ingrowth that enables a functionally graded Young's modulus, thereby allowing reduction of stress shielding. However, the optimal biomechanical connection at the interface has not yet been fully clarified. There have been publications supporting several universal mechanical testing technologies in terms of bone-titanium bonding ability, although the separation of newly formed bone quality is unlikely. CONCLUSIONS: The understanding of complex mechanical bone behavior and size-dependent properties ranging from a nano- to a macroscopic level are essential in the biomechanical optimization of implants. The requirements of regenerated tissue at the interface include high strength, fracture toughness related to ductility, and time-dependent energy dissipation and/or elastic-plastic stress distribution. Moreover, a strong relationship between strain signals and peri-implant tissue turnover could be expected, so that ideal implant biomechanics may enable longevity via adaptive bone remodeling.

A review of improved fixation methods for dental implants. Part I: Surface optimization for rapid osseointegration.

PURPOSE: Titanium is a primary metallic biomaterial used in load-bearing orthopedic or dental implants because of its favorable mechanical properties and osseointegration capability. This article reviews the current status of surface optimization techniques for titanium implants, whether such concepts are in the form of sufficiently evidence-based, and highlights the related experimental tools. STUDY SELECTION: A strong emphasis was placed on the enhanced biological responses to titanium implants by modifying the surface finishing process. On this basis, a clear partition of surface chemistry and topography was critical. RESULTS: The intrinsic host tissue response to titanium implants is facilitated by the chemistry or topography of a passive oxide film, although the extent to which the surface characteristics enable rapid osseointegration is still uncertain. CONCLUSION: Besides the fundamental requirements, such as the promotion of osteogenic differentiation, the titanium implant surface should accelerate wound-healing phenomena prior to bone ingrowth toward the surface. Moreover, because initial bacterial attachment to the implant surface is unavoidable, infection control by surface modification is also an important determinant in reducing surgical failure. A desirable surface-biological relationship often needs to be characterized at the nanoscale by means of advanced technologies.

Preparation, mechanical, and in vitro properties of glass fiber-reinforced polycarbonate composites for orthodontic application.

Generally, orthodontic treatment uses metallic wires made from stainless steel, cobalt-chromium-nickel alloy, ß-titanium alloy, and nickel-titanium (Ni-Ti) alloy. However, these wires are not esthetically pleasing and may induce allergic or toxic reactions. To correct these issues, in the present study we developed glass-fiber-reinforced plastic (GFRP) orthodontic wires made from polycarbonate and E-glass fiber by using pultrusion. After fabricating these GFRP round wires with a diameter of 0.45 mm (0.018 inch), we examined their mechanical and in vitro properties. To investigate how the glass-fiber diameter affected their physical properties, we prepared GFRP wires of varying diameters (7 and 13 µm). Both the GFRP with 13-µm fibers (GFRP-13) and GFRP with 7 µm fibers (GFRP-7) were more transparent than the metallic orthodontic wires. Flexural strengths of GFRP-13 and GFRP-7 were 690.3 ± 99.2 and 938.1 ± 95.0 MPa, respectively; flexural moduli of GFRP-13 and GFRP-7 were 25.4 ± 4.9 and 34.7 ± 7.7 GPa, respectively. These flexural properties of the GFRP wires were nearly equivalent to those of available Ni-Ti wires. GFRP-7 had better flexural properties than GFRP-13, indicating that the flexural properties of GFRP increase with decreasing fiber diameter. Using thermocycling, we found no significant change in the flexural properties of the GFRPs after 600 or 1,200 cycles. Using a cytotoxicity detection kit, we found that the glass fiber and polycarbonate components comprising the GFRP were not cytotoxic within the limitations of this study. We expect this metal-free GFRP wire composed of polycarbonate and glass fiber to be useful as an esthetically pleasing alternative to current metallic orthodontic wire.