Premixed calcium phosphate cements: Synthesis, physical properties, and cell cytotoxicity

Xu, Hockin H.K.; Carey, Lisa E.; Simon, Carl G.; Takagi, Shozo; Chow, Laurence C.

doi:10.1016/j.dental.2006.02.014

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Volume 23, Issue 4 , Pages 433-441, April 2007

Premixed calcium phosphate cements: Synthesis, physical properties, and cell cytotoxicity

Hockin H.K. Xu
- American Dental Association Foundation, Paffenbarger Research Center, 100 Bureau Drive Stop 8546, National Institute of Standards and Technology, Gaithersburg, MD 20899-8546, USA
- Corresponding author. Tel.: +1 301 975 6804; fax: +1 301 963 9143.
Lisa E. Carey
- American Dental Association Foundation, Paffenbarger Research Center, 100 Bureau Drive Stop 8546, National Institute of Standards and Technology, Gaithersburg, MD 20899-8546, USA
- Student Intern from the Johns Hopkins University, Baltimore, MD, USA.
Carl G. Simon Jr.
- Polymers Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8546, USA
Shozo Takagi
- American Dental Association Foundation, Paffenbarger Research Center, 100 Bureau Drive Stop 8546, National Institute of Standards and Technology, Gaithersburg, MD 20899-8546, USA
Laurence C. Chow
- American Dental Association Foundation, Paffenbarger Research Center, 100 Bureau Drive Stop 8546, National Institute of Standards and Technology, Gaithersburg, MD 20899-8546, USA

Received 27 October 2005; received in revised form 9 February 2006; accepted 23 February 2006.

Abstract

Objectives

Calcium phosphate cement (CPC) is a promising material for dental, periodontal, and craniofacial repairs. However, its use requires on-site powder–liquid mixing that increases the surgical placement time and raises concerns of insufficient and inhomogeneous mixing. The objective of this study was to determine a formulation of premixed CPC (PCPC) with rapid setting, high strength, and good in vitro cell viability.

Methods

PCPCs were formulated from CPC powder+non-aqueous liquid+gelling agent+hardening accelerator. Five PCPCs were thus developed: PCPC-Tartaric, PCPC-Malonic, PCPC-Citric, PCPC-Glycolic, and PCPC-Malic. Formulations and controls were compared for setting time, diametral tensile strength, and osteoblast cell compatibility.

Results

Setting time (mean±S.D.; n=4) for PCPC-Tartaric was 8.2±0.8min, significantly less than the 61.7±1.5min for the Premixed Control developed previously (p<0.001). On 7th day immersion, the diametral tensile strength of PCPC-Tartaric reached 6.5±0.8MPa, higher than 4.5±0.8MPa of Premixed Control (p=0.036). Osteoblast cells displayed a polygonal morphology and attached to the nano-hydroxyapatite crystals in the PCPCs. All cements had similar live cell density values (p=0.126), indicating that the new PCPCs were as cell compatible as a non-premixed CPC control known to be biocompatible. Each of the new PCPCs had a cell viability that was not significantly different (p>0.1) from that of the non-premixed CPC control.

Significance

PCPCs will eliminate the powder–liquid mixing during surgery and may also improve the cement performance. The new PCPCs supported cell attachment and yielded a high cell density and viability. Their mechanical strengths approached the reported strengths of sintered porous hydroxyapatite implants and cancellous bone. These nano-crystalline hydroxyapatite cements may be useful in dental, periodontal, and craniofacial repairs.

Keywords: Premixed calcium phosphate cement, Hydroxyapatite, Osteoblast cytotoxicity, Dental restorations, Craniofacial repair