Quantification of compact bone microporosities in the basal and alveolar portions of the human mandible using osteocyte lacunar density and area fraction of vascular canals

Abstract

Based on the orientation of the osteons, the basal portion and the alveolar portion of the body of the human mandible can be distinguished. In the compact bone, two types of microporosities can be quantified, the osteocyte lacunae and the vascular canals. Our aim was (i) to perform three-dimensional reconstruction of osteocyte lacunae to suggest an efficient means of sampling to estimate their numerical density and (ii) to compare bone microporosities in the basal and the alveolar portions of ten mandibles. Using optical disector, we estimated the density of osteocyte lacunae, and using a stereological point-counting technique, we quantified the area fraction of the vascular canals. The diameter of the lacunae was 14±3μm. While the fraction of vascular canals was comparable in both parts of the body of the mandible, the numerical density of osteocyte lacunae was higher (p=0.007) in the alveolar portion (17056±1264/mm(3)) than in the basal portion (14522±665/mm(3)). The lacunar and vascular microporosities were statistically independent of each other. As this is the first three-dimensional counting of osteocyte lacunae, we discuss the relation of this parameter to the biomechanics of the mandible, and we compare our data with previously used two-dimensional methods. We present an efficient sampling method that is useful for the histological description of bone microporosities. When taking into account the spatial characteristics of lacunae, the locally specific numerical density of lacunae can be easily assessed with the three-dimensional counting method, which is not biased by the variation in size and orientation of the lacunae.