Calcium phosphate cements: Optimization toward biodegradability

Calcium phosphate (CaP) materials are widely used in bone regeneration due to their bioactive and osteoconductive properties. Current clinical applications often involve injectable CaP cements (CPCs), which can be delivered through minimally invasive procedures. These cements are composed of a powder and liquid phase that harden in situ. Despite their advantages, CPCs face a significant limitation: poor degradation rates. Ideally, CPCs should degrade in sync with new bone formation. Prior research has explored macroporosity as a potential solution to enhance degradation. However, the mechanisms and outcomes of such strategies remain unclear. This gap motivated a review of experimental approaches to improve CPC biodegradability. The goal is to better understand how material properties influence biological performance in bone repair. No prior work has fully resolved the relationship between CPC structure and degradation rates.

This review aims to evaluate how CPCs can be optimized for biodegradability while maintaining their osteoconductive properties. The focus is on identifying strategies that enhance degradation rates without compromising structural integrity. The paper addresses the specific problem of CPCs degrading too slowly to support new bone formation. The motivation stems from the clinical need for biomaterials that adapt to bone healing timelines. The study reviews experimental methods used to introduce macroporosity into CPCs. It also assesses how these modifications affect biological performance in pre-clinical models. The goal is to synthesize evidence on the most effective approaches to CPC degradation control. The authors aim to provide a framework for future CPC development in bone regeneration.

The review approach includes a comprehensive analysis of experimental procedures used to modify CPCs. The primary strategy examined is the introduction of macroporosity to increase surface area. The methods section details how macroporosity is achieved through various fabrication techniques. These include foaming agents, particulate leaching, and freeze-drying methods. The review also considers how these techniques influence the mechanical and structural properties of CPCs. Biological performance is evaluated using pre-clinical bone defect models. The authors compare the degradation rates of CPCs with and without macroporosity. The analysis includes data on how these changes affect new bone formation and overall healing outcomes.

The strongest finding is that introducing macroporosity into CPCs significantly increases their degradation rates. Studies show that CPCs with macroporosity degrade faster than conventional CPCs. This is attributed to increased surface area available for interaction with the biological environment. The review reports that CPCs with porosity levels above 60% degrade more rapidly. In pre-clinical models, CPCs with macroporosity showed accelerated new bone formation. The data suggests that porosity levels above 70% may lead to excessive degradation. The authors note that CPCs with 50–60% porosity offer a balance between degradation and structural integrity. These findings suggest that controlled porosity is a viable strategy for improving CPC biodegradability.

The authors conclude that macroporosity is a promising strategy to enhance CPC degradation rates. The review suggests that porosity levels between 50–60% optimize degradation without compromising structural integrity. The findings indicate that CPCs with controlled macroporosity can better support new bone formation. The authors propose that further research is needed to refine porosity control methods. They emphasize the importance of balancing degradation rates with mechanical stability. The review highlights the need for standardized testing protocols to evaluate CPC performance. The authors suggest that future studies should focus on long-term biological outcomes. The synthesis of current evidence supports the use of macroporosity as a key factor in CPC development.