Synchrotron-Tomography for Evaluation of Bone Tissue Regeneration using rapidly Resorbable Bone Substitute Materials Alexander RACK, Forschungszentrum Karlsruhe – ANKA, Eggenstein-Leopoldshafen, Germany Christine KNABE, Michael STILLER, Christian KOCH, Hannah SELIGMANN, Charité Berlin – Experimental Dentistry (CBF), Germany Simon ZABLER, Hahn-Meitner-Institut Berlin – Department SF3, Germany Gerd WEIDEMANN, Jürgen GOEBBELS, Bundesanstalt für Materialforschung und –prüfung – Division VIII.3, Berlin, Germany Abstract. This article presents a novel approach to evaluate two-dimensional histomorphometric studies of biodegradable ceramic particles by means of element- sensitive, three-dimensional and non-destructive synchrotron-microtomography (SCT). An in vivo animal study was performed in which bone substitute materials (352i, GB9/25) were implanted in the sheep mandible to support the bone regeneration. After 12 and 24 weeks of implantation samples were prepared and investigated using SCT and subsequent 3D image analysis as well as histological evaluation. A comparison of corresponding tomographical and histological slices delivers information about the newly formed bone and its stage of development. Additionally SCT gives insights into the structural changes of the bony tissue in a given defect and the local biodegradation of the bone substitute material in a three- dimensional manner. 1. Introduction The use of oral implants has become a common treatment to replace missing or lost teeth [1, 2]. However, resorption of the alveolar ridge after tooth extraction frequently mandates site development by augmentation before implants can be placed [1, 3, 4]. Therefore, augmentation of the alveolar ridge before implant placement is frequently performed in implant dentistry [3, 4, 5, 6, 7]. The current gold standard for bone reconstruction in implant dentistry is the use of autogenous bone grafts [5, 6, 7]. Among the various techniques to reconstruct or enlarge a deficient alveolar ridge, the concept of guided bone regeneration (GBR) [5] has become a predictable and well-documented surgical approach [8]. The need for localized ridge augmentation prior to the placement of dental implants has been one of the clinical indications for GBR [5]. Using synthetic biodegradable bone substitutes as a membrane-supporting device would simplify GBR, since it avoids second- site surgery [9]. Relatively rapid biodegradation of synthetic biodegradable bone substitutes is desirable, especially prior to dental implant placement, because ideally new bone should form leaving no residual particles that may interfere with preparation of the implant bed at surgery [7]. For example bioactive calcium phosphate ceramics and bioactive glasses are candidate biomaterials which qualify as bone substitutes for this kind of application, since they are widely used in orthopaedics [10, 11]. An ideal bone replacement material should ECNDT 2006 - Th.1.2.2 1