Development and Characterization of Water-Based Porous Calcium Phosphate Bone Cements for Peri-Implant Regeneration: An In Situ Study

Background: Calcium phosphate cements (CPCs) are excellent biomaterials for peri-implant bone regeneration but suffer from slow resorption. This study evaluated whether adding carbonate salts improves the in situ porosity and resorption rate of customized CPCs. Methods: The control group comprised α-tricalcium phosphate (α-TCP) and phosphoserine (3:1 weight-to-weight ratio). The test group incorporated 3 wt.% anhydrous sodium carbonate (Na2CO3) into the powder. Both were hydrated with water at a liquid-to-powder ratio of 300 μL:1 g. Characterization included micro-computed tomography (μCT), scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy with Attenuated Total Reflection (FTIR-ATR), removal torque tests, compression modulus tests, and hardness tests. Results: μCT and SEM confirmed higher porosity and uniform crystal plates in the test group compared to the dense control group. FTIR-ATR spectra showed a distinct CO2 peak at 2349 cm−1 for the test group, confirming gas entrapment. Mechanically, the control group significantly outperformed the test group in removal torque (71.58 ± 5.56 N/cm vs. 41.37 ± 4.54 N/cm) and compression modulus (1248.01 ± 278.21 MPa vs. 195.42 ± 29.55 MPa). Hardness tests showed increased brittleness in the test group (15.31 ± 1.63 vs. 2.01 ± 1.58). Conclusions: Incorporating Na2CO3 successfully induced in situ porosity via gas release but significantly compromised mechanical strength. Further optimization is required to balance porosity and mechanical integrity.