The Effect Of Solid Additive On The Properties Of α-Tricalcium Phosphate Bone Cement

α-tricalcium phosphate（α-TCP）bone cement is a kind of promising bone graft materials with good biocompatibility,biodegradability,controllable self-setting property in bodies.Hydroxyapatites（HA）with different degree of crystallization and different morphology,and the mixtures of compounds which contain Ca and P elements with Ca/P ratios from 1.67 to 5were prepared in this paper,and their effect as solid additive agents on the properties ofα-TCP bone cement was studied.Based on this,the effect of nano SiO₂ and MHPO₄·3H₂O on the setting time,mechanical properties and setting reaction were investigated.Crystallization process plays an important role on the morphology,crystallization and dispersion of HA.HA made by direct drying precursor is irregular short needlelike crystals with poor crystallization;calcined HA is agglomeration of sphere-like particles;hydrothermal HA is nanorods with good dispersion.The hydrothermal HA brought highest compressive strength of 54 MPa to bone cement while the setting time was 9 minutes.Theα-TCP bone cement added HA made by direct drying precursor have lowest compressive strength which is only 43 MPa.During the preparation of Ca and P compound mixtures,additive amount of Na₂CO₃ and processing methods of precursor can lead to the different relative amount of HA,CaO,CaCO₃and Ca（OH）₂ in the product.When adding the mixtures intoα-TCP bone cement,the calcined product has better performance than hydrothermal one.Theα-TCP bone cement achieved best performance when the amount of Ca（OH）₂ or Ca（OH）₂ and CaO of additive is about 30%and amount of HA or HA and CaCO₃ is about 70%,while the compressive strength is 56 MPa and setting time is ranging from 11 to 13 minutes.With the nano SiO₂ addition amount increasing form 0 by 6%,the compressive strength and setting time ofα-TCP bone cement decreased from 56 MPa to 23 MPa and from 13 to 7minutes,respectively.With the addition amount of MgHPO₄·3H₂O increasing form 0 by 6%,the compressive strength ofα-TCP bone cement gradually decreased from 56 MPa to 4 MPa,and the setting time increased from 13 to 18 minutes.