[An experimental comparative study of hydroxyapatite and tricalcium-phosphate as bone substitutes].

Hydroxyapatite (HAP) and beta tricalcium-phosphate (TCP) were implanted into the femoral distal metaphysis of 18 adult mongrel dogs. X-ray pictures were periodically taken following surgery, and the animals were sacrificed at 2, 4, 8, 12, 24 weeks, and 1, 2 years postoperatively. The undecalcified specimens were stained using Cole HE stain. During 2 years following surgery, both radiological and macroscopic examinations revealed no significant change in either HAP or TCP. In the undecalcified specimens, an apparent change in configuration was only noticed in the TCP, but there was no difference in the degree of new bone formation between HAP and TCP implants. At 2 years postoperatively, the Ca/P ratios of the HAP and TCP implants remained constant. The results of this study therefore suggest that TCP is a promising autograft extender.