Endochondral vs. intramembranous demineralized bone matrices as implants for osseous defects

This study focuses on the difference in regenerative capacity between endoc hondral and intramembranous demineralized bone matrices (DBMs) when implant ed into bony defects. It also focuses on the possible influence of the type of skeletal recipient site (orthotopic or heterotopic). Of 34 Wistar rats, 10 served as a source of DBM, and 24 were divided into two groups of 12 an imals. In group A identical defects were produced in the parietal bones, wh ereas in group B the defects were produced in each radius. The right defect s were implanted with endochondral DBM and the left defects were implanted with intramembranous DBM. Descriptive and/or histomorphometric analyses wer e performed by means of light and polarized microscopy, and radiography (gr oup B). Right and left data were compared to disclose differences in bone-h ealing capacity. The quantitative results demonstrated that endochondral DB M displays a greater regenerative capacity than intramembranous DBM when im planted heterotopically. The different clinical performances of endochondra l and intramembranous bone grafts might be explained on the basis of the me chanical rather than the osteoinductive principle. The qualitative results suggest that the type of bone deposition induced by the DBMs is not related to the type of implanted DBM. Recipient site characteristics and/or enviro nmental factors seem decisive in the occurrence of either types of ossifica tion.