Histological and biomechanical studies of two bone colonizable cements in rabbits

We have developed two colonizable bone cements: the first is a partially re sorbable bisphenol-alpha-glycidyl methacrylate (Bis-GMA)-based cement (PRC) and the second is a calcium phosphate cement (CPC), PRC is composed of alu minous silanized ceramic and particles of a bioresorbable polymer embedded in a matrix of Bis-GMA, CPC consisted of tricalcium phosphate, monocalcium phosphate monohydrate, dicalcium phosphate dihydrate, and xanthane, Both ce ments were implanted into cavities drilled in rabbit femoral and tibial con dyles, After 2, 4, 12, and 24 weeks of implantation, histological observati ons and biomechanical tests were performed. With CPC, a progressive osteoin tegration with a concomitant biodegradation in the presence of macrophages were observed. The mechanical study revealed a decrease of the compressive strength until the 4th week, followed by a slight increase. There was a gen eral decrease in the elastic modulus with time. Moreover, by week 4, the hi stological study showed that the new bone was in direct contact with CPC ma rgins. No inflammation was observed during the observation period. With PRC , the osteointegration as well as the biodegradation were slight, but its c ompressive strength was higher than that of cancellous bone and CPC (p < 0. 05) at all observation periods. Its elastic modulus was greater than that o f cancellous bone and CPC until the 4th week, then fell under the values of the cancellous bone. (Bone 25: 41S-45S; 1999) (C) 1999 by Elsevier Science Inc. All rights reserved.