Background: Autologous iliac crest is regarded as ‘gold standard’ for alveolar ridge augmentation due to its outstanding transplant competence. Quantification of the entity-specific 3D microarchitecture is fundamental for a better understanding of this feature. To date, no systematic study has been performed comparing alveolar (AB) and anterior iliac crest (IC) bone specimens taken from the same patient regarding parameters of 3D microarchitecture using high-resolution Synchrotron (SR) μ-CT.

Aim/Hypothesis: Microstructural properties could account for the differences in the skills of transplanted bone grafts. Aim of the current study was to identify structural parameters being responsible for the outstanding transplant competence of IC in a comparative investigation using Synchrotron μ-CT.

Materials and Methods: In ten patients, routinely scheduled for alveolar ridge augmentation, bone biopsies were retrieved from each the alveolar bone and iliac crest. The obtained specimens (N = 20) were formalin-fixed, embedded in PMMA and imaged using SR μ-CT (pixel size: 2.2 μm). Quantification of 3D microarchitecture (morphometric parameters, number of osteocyte lacunes, orientation of the vascular canal system) was performed within VOIs by tailored 3D image analysis.

Results: Standard bone morphometric parameters did not show a significant difference between AB and cortical IC, while bone from cancellous IC behaved different to the other entities. An interindividual variation between the patients was detected. Osteocyte lacunar density differed significantly between AB (˜23.000/μm3) and IC (15.000/μm3) and seems to be associated with the orientation of the vascular canal system.

Conclusions and Clinical Implications: Even though morphometric parameters of AB and cortical IC in one patient are similar an interindividual variation can be detected. An increased number of osteocyte lacunae and lower degree of vascular canal system orientation in the AB may suggest a more dynamic physiologic bone turnover. The parameters collected in this study can contribute to the understanding of site-specific differences in microarchitecture and their influence on transplant competence of the bone when used as bone grafts.

Keywords: Synchrotron, Bone microarchitecture, Alveolar ridge augmentation, micro-CT, Osteocyte lacune.