Experimental model of bone response to xenografts of bovine origin (Endobon): a radiological and histomorphometric study.

OBJECTIVE To carry out a radiological and histomorphometric evaluation of bone response to bovine bone implants inserted in rabbits' tibiae. MATERIALS AND METHODS Twenty New Zealand rabbits weighing 3900-4500 g were used. Twenty bovine bone implants (Endobon) in granulated form of 500-1000 μm granulometry were inserted in the proximal metaphyseal area of the animals' right tibia and 20 control areas were located in the proximal metaphyseal area. Following implantation, the animals were sacrificed in four groups of five, after 1 month, 2 months, 3 months and 4 months, respectively. Anteroposterior and lateral radiographs were taken. Samples were sectioned at 5 μm and stained using Hematoxylin-Eosin and Masson's trichromic. RESULTS After 4 months, radiological images showed complete repair of the bone defects. No healed or residual bone alterations attributable to the presence of the implant were observed. Histomorphometric analysis at 4 months showed the presence of a higher density of newly formed bone with mean values for new bone, residual graft material and non-mineralized connective tissue of 22.8 ± 1.5%, 39.4 ± 2.3% and 37.7 ± 2.5%. There were no statistically significant differences in the length of cortical formation with bovine bone, 98.8 ± 1.1%, compared with the control group, 99.1 ± 0.7%, at the end of the study period. CONCLUSIONS The biomaterial used in the study was shown to be biocompatible, osteoconductive and non-resorbable and as such a possible bone substitute that does not interfere with normal reparative bone processes.