THE BIOLOGICAL EFFECT OF NATURAL BONE-MINERAL ON BONE NEOFORMATION ONTHE RABBIT SKULL

The aim of this study was to evaluate the effect of deproteinized bovi ne bone graft material on new bone formation in a guided bone regenera tion model system. In 20 rabbits, a periosteal skin flap was raised un covering the calvaria. A form stable hemispherical dome made of poly-l actic acid (PLA) was placed onto the roughened calvaria. Prior to plac ement, the dome was either filled with peripheral blood alone (control group, 8 rabbits), or with blood and OsteoGraf(R)/N-300 (test group, 12 rabbits). The wound was closed for primary healing. Morphometric as sessment of 1- and 2-month undecalcified histologic specimens revealed better tissue fill in the test domes at 1 month (test 99%, control 55 %) (P < 0.05) and 2 months (t, 100%; c, 82%). The fraction of the new bone within the regenerated tissue was higher in the test specimens at 1 month (t, 22%; c, 12%) (P<0.05) and 2 months (t, 34%; c, 24%). The fraction of the entire space underneath the domes occupied by bone was higher in the test at 1 month, but higher in the controls at 2 months . The fraction of the bone substitute material in contact with bone in creased from 1 month (34%+/-14) to 2 months (45%+/-5). The surface fra ction of osteoblast layers was tendentially higher in the test at 1 mo nth but higher in the control specimens at 2 months. In both test and control, initially woven bone was formed which underwent subsequent re modeling. Cellular degradation of the deproteinized bone graft was fre quently detected. It is concluded that deproteinized bovine bone miner al has osteoconductive properties and can initially accelerate new bon e formation during guided bone regeneration by increased recruitment o f osteoblasts.