Jawbone remodeling: a conceptual study based on Synchrotron High-resolution Tomography

Abstract

one of the most important aspects of bone remodeling is the constant turnover mainly driven by the mechanical loading stimulus. the remodeling process produces changes not only in the bone microarchitecture but also in the density distribution of the mineralized matrix-i.e. in calcium concentrations-and in the osteocyte lacunar network. Synchrotron radiation-based X-ray microtomography (microCT) has proven to be an efficient technique, capable to achieve the analysis of 3D bone architecture and of local mineralization at different hierarchical length scales, including the imaging of the lacuno-canalicular network. in the present study, we used microct within a conceptual study of jawbone remodeling, demonstratively focusing the investigation in two critical contexts, namely in the peri-dental and the peri-implant tissues. the microct analysis showed that a relevant inhomogeneity was clearly present in both peri-dental and peri-implant biopsies, not only in terms of microarchitecture and mineralization degree, but also considering the lacunar network, i.e. size and numerical density of the osteocyte lacunae. the correlated histological results obtained on the same samples confirmed these observations, also adding information related to non-mineralized tissues. Despite its demonstrative nature, it was concluded that the proposed method was powerful in studying jawbone remodeling because it revealed a direct correlation of its rate with the lacunar density, as achieved by the analysis of the osteocyte lacunar network, and an inverse correlation with the local bone mineral density, as revealed with the Roschger approach. Remodeling is a process enabling bone tissue to adapt to different physiological conditions and to replace damaged bone with newly-formed bone 1 , producing complete renewal of the entire skeleton mass about every 10 years 2. Several studies have been focused on regenerative properties of bone, but few of them were referred to the jaw sites. Conversely, it must be considered that the jawbone presents unique properties: thus, data regarding other skeletal bones, many of them referred to long bones 3-7 , may not be completely applicable to the jaw 8. Indeed, it is known since long time that the jawbone is remodeled faster than the other skeletal bones 9. This seems to be due to jaw morphogenesis: jaw arises from neural crest cells of the neuroectoderm germ layer and not of the mesoderm; 10 moreover, it undergoes intramembranous, instead of endochondral, ossification 11. Regarding the stem cells derived from the jaw, bone marrow stromal cells exhibit higher osteogenic potential and different characteristics respect to stem cells recruited in other skeletal bones 12-16. Consequently, because of the aforementioned features of the jawbone matrix, even if several studies have been focused on bone remodeling in other skeleton sites, there is a special need of specific investigations referred to the jawbone. One of the most important aspects of jawbone remodeling is the constant turnover mainly driven by the ...

Case Report: Histological and Histomorphometrical Results of a 3-D Printed Biphasic Calcium Phosphate Ceramic 7 Years After Insertion in a Human Maxillary Alveolar Ridge

“…The increasing in terms of mineralized volume of the BCP-based Testsample was correlated to the study of bone architecture at the length-scale pertaining the observation of the osteocyte lacunar network; the same subvolumes investigated for producing the microarchitecture data were also studied for the osteocyte lacunae 3D morphometric analysis (Table 2B): considering the standard deviations, comparable values in Test and in Control sites (both Pd-Ctr and UnL-Ctr), when evaluating Lac.V, Lac.Th, and Lac.Nr. However, the observation of the pure mean values, revealed the same values in Test-sample and the UnL-Ctr samples in terms of lacunar density (Lac.Nr), but an increased mean Lac.Nr in the physiological context of the peri-dental site (Pd-Ctr), in agreement with previous observations (Iezzi et al, 2020).…”

“…However, this Testsample did not participate in mastication for 7 years; thus, it was particularly interesting to study possible alterations with the physiological conditions of the peri-dental bone (Pd-Ctr) and with unloaded controls (UnL-Ctr), (i.e., with bone biopsies spontaneously healed in 12 months after tooth extraction but not participating in mastication). This comparative study, shown in Tables 2A,B, was supported by the data of a recent study (Iezzi et al, 2020). Table 2A showed such comparison in terms of microarchitecture quantitative study: it was observed that the Test-sample turned out to be much more mineralized and bulky not only compared to UnL-Ctr, with an increase of the mineralized volume of 121%, but also compared to the peri-dental physiological context (Pd-Ctr), with an increase by over 61%.…”

“…The newly formed tissues were evaluated by an innovative experimental approach based on histological and X-ray high-resolution tomography (microCT) analysis. MicroCT was widely shown to be a powerful tool for scaffold characterization (Landi et al, 2000;John and Wenz, 2004;Iezzi et al, 2012Iezzi et al, , 2020Giuliani et al, 2018a,b,c), obtaining not only a 3D image of a scaffold, but also providing qualitative and quantitative information on its structure (Renghini et al, 2013;Giuliani et al, 2014Giuliani et al, , 2016. It is possible, starting from CBCT files, to create a 3D prototype of the patient's maxilla/mandible, obtained by transferring the files to specific reconstruction software (Mangano et al, 2015b;Luongo et al, 2016).…”

“…MicroCT images of representative subvolumes of the Testsample (i.e., of the maxilla biopsy grafted with the BCP and retrieved after 7 years, were shown in Figure 1). All tissues, but mineralized bone and residual scaffold, have been made virtually transparent in Figure 1A, while in Figure 1B the Pd-Ctr and UnL-Ctr data were extracted (Iezzi et al, 2020). Mean (std.dev.)…”

Integrated 3D Information for Custom-Made Bone Grafts: Focus on Biphasic Calcium Phosphate Bone Substitute Biomaterials

“…In this context, several computer-aided imaging techniques were used to investigate the microarchitecture of BSBs; in particular, the gold standard for a reliable 3D examination is based on high-resolution X-ray computed tomography (microCT). MicroCT was not only successfully used to reconstruct the morphometry of bone tissue at different length-scales [ 20 , 21 , 22 , 23 , 24 ] and in different environmental and genetic contexts [ 25 , 26 , 27 , 28 ], but it is nowadays the elective technique for the characterization of biomaterials used in bone tissue engineering [ 29 ] and also in dental districts [ 30 , 31 , 32 , 33 , 34 , 35 ].…”