Reinforcement of a self-setting calcium phosphate cement with different fibers

A water-based calcium phosphate cement (CPC) has been used in a number of m edical and dental procedures due to its excellent osteoconductivity and bon e replacement capability. However, the low tensile strength of CPC prohibit s its use in many unsupported defects and stress-bearing locations. Little investigation has been carried out on the fiber reinforcement of CPC. The a ims of the present study, therefore, were to examine whether fibers would s trengthen CPC, and to investigate the effects of fiber type, fiber length, and volume fraction. Four different fibers were used: aramid, carbon, E-gla ss, and polyglactin. Fiber length ranged from 3-200 mm, and fiber volume fr action ranged from 1.9-9.5%. The fibers were mixed with CPC paste and place d into molds of 3 x 4 x 25 mm. A flexural test was used to fracture the set specimens and to measure the ultimate strength, work-of-fracture, and elas tic modulus. Scanning electron microscopy was used to examine specimen frac ture surfaces. Fiber type had significant effects on composite properties. The composite ultimate strength in MPa (mean +/- SD; n = 6) was (62 +/- 16) for aramid, (59 +/- 11) for carbon, (29 +/- 8) for E-glass, and (24 +/- 4) for polyglactin, with 5.7% volume fraction and 75 mm fiber length. In comp arison, the strength of unreinforced CPC was (13 +/- 3). Fiber length also played an important role. For composites containing 5.7% aramid fibers, the ultimate strength was (24 +/- 3) for 3 mm fibers, (36 +/- 13) for 8 mm fib ers, (48 +/- 14) for 25 mm fibers, and (62 +/- 16) for 75 mm fibers. At 25 mm fiber length, the ultimate strength of CPC composite was found to be lin early proportional to fiber strength. In conclusion, a self-setting calcium phosphate cement was substantially strengthened via fiber reinforcement. F iber length, fiber volume fraction, and fiber strength were found to be key microstructural parameters that controlled the mechanical properties of CP C composites. (C) 2000 John Wiley & Sons, Inc.