Slowly resorbable and relatively nonresorbable bone cements have been developed to repair various types of defects in bone. A relatively fast-resorbing, porous, biocompatible beta tricalcium phosphate (TCP) cement would be ideal for replacing bone lost as a result of nonresorptive processes. In this investigation the following materials were tested as setting agents for developing a resorbable TCP cement: bovine serum albumin, Carbopol, Hespan, monomers of low-molecular-weight carboxylic acids, orthophosphoric acid, polyvinyl pyrrolidone, and water.
Initial experiments consisted of determining the amounts of setting agent or water or both required to gel the TCP powder. The gel time was monitored at 30-s intervals. The setting hardness was determined by mixing the optimal proportions of TCP and setting agent or water, or both, and monitoring the hardness at 15-min intervals at room temperature for 105 min. Mixtures of TCP and monomers of low-molecular-weight carboxylic acids yielded the most efficient cements. By varying the quantity of acid or combining different acids, or combining both methods, setting times from 30 s to 8 min were achieved for the TCP/polyfunctional acid cements. These cements have been used successfully to repair experimentally traumatized tibiae and femora in rabbits and rats, respectively.