Dagang Guo1, Kewei Xu, Xiaoyun Zhao
1State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xianning Western Road No. 28, Xi'an, Shaan X: 710049, China. dgguo@mailst.xjtu.edu.cn
Researchers developed a new bone cement containing strontium to improve mechanical and biological properties. The cement was made from tetracalcium phosphate, strontium hydrogen phosphate, and other compounds. They tested how different strontium-to-calcium ratios affected the cement's strength and compatibility with body tissues. The cement reached a peak strength of 66.57 MPa at 5 days, which is comparable to human bone. It also showed favorable pH levels and setting times. Cytotoxicity tests indicated the cement is safe for use in nonloading bone repair sites. These findings suggest the cement could be used clinically for such applications.
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Area of Science:
Background:
Current bone cements lack sufficient mechanical strength for long-term use. Calcium phosphate cements are widely used but often fall short in compressive strength. Strontium addition has been proposed to improve cement properties. However, the exact impact of strontium ratios remains unclear. No prior work had resolved how Sr/(Sr+Ca) molar ratios affect compressive strength. This gap motivated the development of a new Sr-containing hydroxyapatite cement. Researchers have shown that pH stability is crucial for clinical compatibility. This paper investigates how Sr incorporation affects cement properties.
Purpose Of The Study:
The aim was to develop a new Sr-containing hydroxyapatite cement with improved properties. The study focused on optimizing the Sr/(Sr+Ca) molar ratio in cement powder. Researchers wanted to test the mechanical and biological performance of the cement. They aimed to determine the optimal setting time and compressive strength. The motivation was to create a cement suitable for nonloading bone repair sites. They also wanted to evaluate cytotoxicity of Sr-containing cement extracts. The researchers proposed that Sr addition could enhance cement biocompatibility. This study sought to validate the clinical potential of Sr-HAP cement.
The cement achieved a peak compressive strength of 66.57 MPa at 5 days, matching human bone values.
A 5% Sr/(Sr+Ca) ratio in CPC-1 yielded optimal compressive strength and biocompatibility.
This ratio ensures pH stability (7.0–7.6) and proper setting times for clinical use.
SBF was used to assess compressive strength changes over time in a simulated biological environment.
Main Methods:
The cement was synthesized using TTCP, DSPA, DCPA, phosphate acid, and water. Researchers varied the Sr/(Sr+Ca) molar ratio in the cement powder composition. Cement pastes were mixed in a 1:1 powder-to-liquid weight ratio. Processing parameters like pH, setting time, and compressive strength were measured. Cements were immersed in simulated body fluid to assess strength over time. Compressive strength was tested at 1, 5, and 14 days post-immersion. Cytotoxicity was evaluated using serial extracts of the cement. No harmful impurities were detected in the final hardened cement product.
Main Results:
The final cement product was nonstoichiometric Sr-containing hydroxyapatite. pH values of cement pastes ranged from 7.0 to 7.6 at a 1:1 powder-to-liquid ratio. Initial setting time was 4–11 minutes, and final setting time was 10–17 minutes. Compressive strength increased from 1 to 5 days and then decreased by 2 weeks. CPC-1 with 5% Sr/(Sr+Ca) had a peak strength of 66.57 MPa at 5 days. Strength dropped to 44.75 MPa at 2 weeks, matching human bone values. Cytotoxicity tests of Sr-containing cement extracts showed positive results. These findings suggest clinical potential for nonloading bone repair applications.
Conclusions:
The Sr-containing cement achieved mechanical properties suitable for bone repair. The cement reached peak compressive strength at 5 days post-immersion. Cytotoxicity tests indicate the cement is biocompatible for clinical use. The Sr/(Sr+Ca) ratio of 5% in CPC-1 provided optimal mechanical performance. The pH of cement pastes remained within a safe range for biological tissues. Setting times were consistent with clinical requirements for bone cement use. The absence of harmful impurities supports the safety of the final cement product. These findings align with the authors' claim that Sr-HAP cement is suitable for nonloading sites.
Strength increased from 1 to 5 days, peaked, then decreased by 2 weeks.
The authors suggest it is suitable for repairing nonloading bone sites based on cytotoxicity results.