Porosity of human mandibular condylar bone

Abstract

Quantification of porosity and degree of mineralization of bone facilitates a better understanding of the possible effects of adaptive bone remodelling and the possible consequences for its mechanical properties. The present study set out first to give a three-dimensional description of the cortical canalicular network in the human mandibular condyle, in order to obtain more information about the principal directions of stresses and strains during loading. Our second aim was to determine whether the amount of remodelling was larger in the trabecular bone than in cortical bone of the condyle and to establish whether the variation in the amount of remodelling was related to the surface area of the cortical canals and trabeculae. We hypothesized that there were differences in porosity and orientation of cortical canals between various cortical regions. In addition, as greater cortical and trabecular porosities are likely to coincide with a greater surface area of cortical canals and trabeculae available for osteoblastic and osteoclastic activity, we hypothesized that this surface area would be inversely proportional to the degree of mineralization of cortical and trabecular bone, respectively. Micro-computed tomography was used to quantify porosity and mineralization in cortical and trabecular bone of ten human mandibular condyles.The cortical canals in the subchondral cortex of the condyle were orientated in the mediolateral direction, and in the anterior and posterior cortex in the superoinferior direction. Cortical porosity (average 3.5%) did not differ significantly between the cortical regions. It correlated significantly with the diameter and number of cortical canals, but not with cortical degree of mineralization. In trabecular bone (average porosity 79.3%) there was a significant negative correlation between surface area of the trabeculae and degree of mineralization; such a correlation was not found between the surface area of the cortical canals and the degree of mineralization of cortical bone. No relationship between trabecular and cortical porosity, nor between trabecular degree of mineralization and cortical degree of mineralization was found, suggesting that adaptive remodelling is independent and different between trabecular and cortical bone. We conclude (1) that the principal directions of stresses and strains are presumably directed mediolaterally in the subchondral cortex and superoinferiorly in the anterior and posterior cortex, (2) that the amount of remodelling is larger in the trabecular than in the cortical bone of the mandibular condyle; in trabecular bone variation in the amount of remodelling is related to the available surface area of the trabeculae.

Development and characterization of a xenograft material from New Zealand sourced bovine cancellous bone

“…2,40,45,46 The porosity of the BHA material is similar to the porosity of human cancellous bone, which has a porosity of 70% or greater allowing the exchange of nutrients and waste. 47,48 In addition, it has been reported that a pore diameter of 300 lm is essential for vascularization and bone ingrowth 39,49 and the results of our study, with respect to SEM and l-CT analysis is in accordance with these values. Hence, it can be suggested that the BHA scaffold is suitable for bone tissue regeneration.…”

A finite element model of the bone remodelling process using a stochastically generated frame model of the trabecular bone

“…Az így kialakított háló zatban 80 μm rúdátmérőt alkalmazva 70,4%-ra adódik a rendszer po ro zitása. A megkívánt -irodalmi adatok alap ján felvett 18,19,20,21 -kö-zelítőleg 70% értékű porozitást (a csont hézagtérfogatának és teljes térfogatának szá-zalékos aránya) a csomópon tok és az azok közötti összeköttetések szá mának változ tatásával lehetett elérni, az átla gos rúdhossznak és a rúdátmérőnek a fenti értékeken tartása mellett. A modellezés során az egyes tra beculákat kör keresztmetszetűnek és lineári -san rugalmasnak feltételeztük, így a rudak anyagtulajdonságai két anyag jellem zővel, a Young modulussal és a Poisson ténye zővel leírhatóak.…”

Stochastically generated finite element beam model for dental research

“…To this geometric conformation belongs 315 µm average length of the trabeculae, which using 80 µm beam diameter results in 70,4 % porosity value (Table 1). To achieve the required approximately 70 % porosity (percentage value of voids volume of bone material in proportion to the volume of the whole cube) -according to literary data [3,5,10,13] -the number of the nodes and the applied linkings were changed, with the length and diameter kept on the abovementioned values. The trabeculae themselves are considered to have circular cross-section, to be lineal and have elastic material behaviour characterized by two micro material constants of Young's modulus and Poisson's ratio, the values of which are also drawn upon the literature (Table 1).…”