Osteogenic Potential of Porous Titanium: An Experimental Study in Sheep

Objectives: Due to its excellent biocompatibility and favorable osteogenic properties, highly porous TiO₂ granules has been proposed as a promising material for non-resorbable synthetic bone grafts in the restoration of large bone defects, and for bone augmentation in dental applications. The aim of this study was to investigate the osteoconductive properties and biological performance of porous titanium granules used in osseous defects adjacent to the maxillary sinus in sheep.
Methods: The present study was approved by the Ethics Committee of the StSMU (98/4, 10/03/2011) and was performed on 12 sheep (Stavropol breed) in accordance to sheep sinus augmentation models described by Sauerbier et al., 2010; Seoane et al., 2012; and Barbone et al., 2013. Calibrated defects were prepared in the subantral region of sheep and were randomized into test and control group. The test defects were grafted with porous titanium granules (PTG), whereas control defects were left empty (sham). Defects were left for healing for 30, 60, and 90 days. After healing, the grafted areas were removed and finally osteoconductivity was analyzed by using x-ray (OPG) and by qualitative histology on decalcified sections with different stains.
Results: At three time periods post-transplantation, the regenerated bone height were 3.3 ± 0.6 mm in the PTG-grafted group, and 0.3 ± 0.5 mm in the untreated control group. Histopathological photomicrographs showed at 30 days that the titanium granules got overgrown and integrated in connective tissue fibers. On day 90 the titanium-bone interconnection adhered closely to the defect walls with no interface in between. After 3 months the bone trabeculae got some well-ordered structure, the collagen fibers got arranged in parallel rows and forming thin trabecular arcs anastomosing very closely. Over the time schedule of the study significantly more new bone formed in PTG-grafted defects compared with sham. The control group showed significantly less expression of key inflammation cells, but with no significant difference in key inflammation cells compared with the experimental groups.
Conclusions: Porous titanium can offer as an effective alternative to calcium phosphate and bone collagen based materials used for subantral augmentation of the maxillary bone in cases of dental implantation.