Abstract
Calcium phosphate cement (CPC) can conform to complex bone cavities and set in‐situ to form bioresorbable hydroxyapatite. The aim of this study was to develop a CPC‐collagen composite with improved fracture resistance, and to investigate the effects of collagen on mechanical and cellular properties. A type‐I bovine‐collagen was incorporated into CPC. MC3T3‐E1 osteoblasts were cultured. At CPC powder/liquid mass ratio of 3, the work‐of‐fracture (mean ± sd; n = 6) was increased from (22 ± 4) J/m^2^ at 0% collagen, to (381 ± 119) J/m^2^ at 5% collagen (p ≤ 0.05). At 2.5–5% of collagen, the flexural strength at powder/liquid ratios of 3 and 3.5 was 8–10 MPa. They matched the previously reported 2–11 MPa of sintered porous hydroxyapatite implants. SEM revealed that the collagen fibers were covered with nano‐apatite crystals and bonded to the CPC matrix. Higher collagen content increased the osteoblast cell attachment (p ≤ 0.05). The number of live cells per specimen area was (382 ± 99) cells/mm^2^ on CPC containing 5% collagen, higher than (173 ± 42) cells/mm^2^ at 0% collagen (p ≤ 0.05). The cytoplasmic extensions of the cells anchored to the nano‐apatite crystals of the CPC matrix. In summary, collagen was incorporated into in situ‐setting, nano‐apatitic CPC, achieving a 10‐fold increase in work‐of‐fracture (toughness) and two‐fold increase in osteoblast cell attachment. This moldable/injectable, mechanically strong, nano‐apatite‐collagen composite may enhance bone regeneration in moderate stress‐bearing applications. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009