Andreas Fuchs, Dorothea Kreczy, Theresa Brückner, Uwe Gbureck, Philipp Stahlhut, Melanie Bengel, Andreas Hoess, Berthold Nies, Julia Bator, Uwe Klammert, Christian Linz, Andrea Ewald

• Objectives Magnesium phosphate-based cements begin to catch more attention as bone substitute materials and especially as alternatives for the more commonly used calcium phosphates. In bone substitutes for augmentation purposes, atraumatic materials with good biocompatibility and resorbability are favorable. In the current study, we describe the in vivo testing of novel bone augmentation materials in form of spherical granules based on a calcium-doped magnesium phosphate (CaMgP) cement. Materials and Methods Granules with diameters betweenObjectives Magnesium phosphate-based cements begin to catch more attention as bone substitute materials and especially as alternatives for the more commonly used calcium phosphates. In bone substitutes for augmentation purposes, atraumatic materials with good biocompatibility and resorbability are favorable. In the current study, we describe the in vivo testing of novel bone augmentation materials in form of spherical granules based on a calcium-doped magnesium phosphate (CaMgP) cement. Materials and Methods Granules with diameters between 500 and 710 μm were fabricated via the emulsification of CaMgP cement pastes in a lipophilic liquid. As basic material, two different CaMgP formulations were used. The obtained granules were implanted into drill hole defects at the distal femoral condyle of 27 New Zealand white rabbits for 6 and 12 weeks. After explantation, the femora were examined via X-ray diffraction analysis, histological staining, radiological examination, and EDX measurement. Results Both granule types display excellent biocompatibility without any signs of inflammation and allow for proper bone healing without the interposition of connective tissue. CaMgP granules show a fast and continuous degradation and enable fully adequate bone regeneration. Conclusions Due to their biocompatibility, their degradation behavior, and their completely spherical morphology, these CaMgP granules present a promising bone substitute material for bone augmentation procedures, especially in sensitive areas. Clinical Relevance The mostly insufficient local bone supply after tooth extractions complicates prosthetic dental restoration or makes it even impossible. Therefore, bone augmentation procedures are oftentimes inevitable. Spherical CaMgP granules may represent a valuable bone replacement material in many situations.…