0046 Calcium Phosphate Cement: High Early-Strength with DCPD and Absorbable Fibers
E.F. BURGUERA, H. XU, S. TAKAGI, and L. CHOW, American Dental Assocation Foundation, Gaithersburg, MD, USA

Calcium phosphate cement (CPC) sets to form resorbable hydroxyapatite and is promising for dental, periodontal and craniofacial use.  OBJECTIVES:  To develop a CPC with fast-setting and high strength in the early stage of implantation.  METHODS:  Two methods were combined to impart high early-strength to the cement: the use of dicalcium phosphate dihydrate (DCPD) with a high solubility (which formed the cement CPCD) instead of dicalcium phosphate anhydrous (which formed conventional CPCA), and the incorporation of absorbable fibers.  A 2x8 design was used to test two materials (CPCA and CPCD) and 8 reaction times: 15 min, 30 min, 1 h, 1.5 h, 2 h, 4 h, 8 h, and 24 h.  An absorbable fiber was incorporated at 25% volume fraction.  RESULTS:  The Gilmore needle method measured a hardening-time (mean ± sd; n = 4) of (15.8±0.5) min for CPCD, significantly faster than (81.5±5.3) min for CPCA (Tukey's multiple comparison at 0.95), at a powder:water ratio of 3:1.  SEM revealed the formation of nano-sized rod-like hydroxyapatite crystals and platelet crystals.  At 30 min, the flexural strength (mean ± sd; n = 5) was 0 MPa for CPCA, (4.2±0.3) MPa for CPCD, and (10.7±2.4) MPa for CPCD-fiber specimens, significantly different from each other (Tukey's at 0.95).  The high early-strength of CPCD-fiber cement matched the reported strength for cancellous bone and sintered porous hydroxyapatite implants.  The composite strength Sc was correlated to the matrix strength Sm: Sc = 2.16 Sm, with correlation coefficient R = 0.93.  CONCLUSION:  Substantial early-strength was imparted to a moldable, self-hardening and resorbable hydroxyapatite via two synergistic approaches: dicalcium phosphate dihydrate with a high solubility, and absorbable fibers.  The new fast-setting and strong cement may help prevent catastrophic fracture or disintegration in moderate stress-bearing dental and bone repairs.  Support: NIDCR DE14190 and DE11789, NIST, and ADAF.

Seq #16 - Cements: Physical and Chemical Behavior
2:00 PM-4:00 PM, Wednesday, 9 March 2005 Baltimore Convention Center 315

Back to the Dental Materials: III - Ceramics and Cements Program
Back to the IADR/AADR/CADR 83rd General Session (March 9-12, 2005)

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