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ePaper created 2017-03-17, 11:08:54 | version 1.38.0
B i o m a t e r i a l s f o r o n l a y b o n e g r a f t s Fig. 5 Fig. 5 Scanning electron microscopy image of pore morphology of cancellous bovine bone (50× magnification) by Dr. Michael Bufler. (Courtesy of Geistlich Pharma, 2014) Regarding xenogeneic graft resorption, Araújo et al. in a dog study showed that the Geistlich Bio-Oss block graft is capable of retaining its di- mension with moderate amounts of new bone formed at the base of the graft, while autogenous block grafts undergo 30% and 50% graft resorp- tion.71 Likewise, De Santis et al. demonstrated superior volumetric stability of deproteinized bovine bone mineral compared with autogenous block grafts harvested from the mandibular ramus in a dog study (0.2 mm vs. 0.9 mm of hor- izontal resorption, respectively).73 Histological and histomorphometric outcomes Animal studies have shown that both bovine Geistlich Bio-Oss and equine eHac (Geistlich Pharma) blocks demonstrated similar histolog- ical results. In the early stages of healing, the grafts were surrounded by fibrovascular con- nective tissue with no signs of necrosis, osteol- ysis or tissue degeneration.66 In contrast, Schwarz et al. showed that, after 12 weeks of healing, bovine bone had no signs of degrada- tion, while equine bone presented with an in- crease in osteoclasts and multinucleate giant cells.67 Additionally, it was shown that the amount and extent of bone ingrowth was higher for equine bone blocks, although this was not of statistical significance. Moreover, Araújo et al. evidenced the lesser osteogenic capacity of xenogeneic blocks, compared with autoge- nous grafts, by means of mineralized tissue (47.5 ± 5.0% vs. 23.3 ± 3.0%, respectively).17 Similarly, findings by De Santis et al. illustrated the poor incorporation of the block graft into the pristine bone for horizontal ridge augmentation, demonstrating that, while 77% of the autoge- nous bone presented with vital mineralization, only 5.9% of the deproteinized bovine bone could be identified as new bone formation.73 Therefore, it depends upon the clinician’s judg- ment regarding whether it is preferable to main- tain the space or improve predictability by en- suring faster bone turnover. F u t u r e d i r e c t i o n s In order to facilitate bone graft adaptation, speed up the surgical procedure and limit any potential graft mobility or dead space, prefabrication of graft scaffolds using advanced computed Journal of Oral Science & Rehabilitation Volume 3 | Issue 1/2017 27