Optimization of a calcium phosphate based bone cement formulationPart of:
Calcium phosphate cements (CPCs) have been increasingly used for bone grafting due to their biocompatibility and rapid osteointegration. Neocement is a commercial CPC whose setting is initiated by adding 38% of a liquid phase (LP) to a solid phase composed by two calcium phosphate types and a small amount of chitosan. In this work, the effect of changing the proportion of the liquid phase and chitosan content on the biomechanical properties and handling performance of this CPC was investigated.
Samples with different proportions of liquid phase (LP 30%, 38%, 42% and 50%) were prepared. Additionally, for LP 38%, formulations without chitosan or with half of its base concentration were studied.
The increase of the LP content from 30% to 50% led to an increase in the initial setting time from 6.5 min to 24 min, and in the final setting time from 7.5 min to 32 min. Moreover, varying the amount of chitosan did not alter the setting times significantly. Mechanical properties were evaluated after setting for 6 days. Concerning the resistance to compression, the increase in LP content to 50% lowered this parameter from 9.5 to 0.8 MPa. The materials hardness decreased about 70% when moving from 30% to 50% LP. For both properties, the effect of the chitosan content was less significative than the one of LP. Injectability measures showed that all formulations could be injected except LP 30%.
The obtained results demonstrate that for LP42% the resistance to compression and hardness of the materials assume suitable values for their use as bone defect fillers with adequate setting times for application in reachable trabecular bone defects. Nevertheless, only samples with 38% and 42% LP present good injectability. Although chitosan content did not affect significantly the analyzed properties, further studies are needed to evaluate its influence in improving osteoinduction.