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Background: In recent years, the use of conometric systems to connect dental implant abutments and prosthetic caps has been advocated because they seem to eliminate the side effects reported when using screw- and cement-connected prosthetic restorations. Objectives: The present case study is focused on conometric connection characterization and its performance in terms of the microarchitecture of peri-implant soft tissues by using a cross-linked approach based on optical microscopy and three-dimensional imaging. Methods: Two dental implants were characterized using micro-CT and another identical one was implanted into a patient; the latter was retrieved 45 days later due to changes in prosthetic needs. Afterward, the peri-implant soft tissues were investigated using synchrotron-based phase contrast imaging, histology, and polarized light microscopy. Results: Micro-CT analysis showed perfect adhesion between the abutment and prosthetic cap; histology and polarized light microscopy showed that connective tissue was richly present around the abutment retrieved from the patient. Moreover, the quantitative evaluation of connective tissues using synchrotron imaging, supported by artificial intelligence, revealed that this tissue was rich in mature collagen, with longitudinal and transverse collagen bundles intertwined. The number and connectivity of transverse bundles were consistently greater than those of the longitudinal bundles. Conclusion: It was found that the peri-implant soft tissue was already mature and well organized after only 45 days of implantation, supporting the hypothesis that conometric connections contribute to the significant stabilization of peri-implant soft tissues.

Introduction Children exposed to trauma are vulnerable to developing post-traumatic stress disorder (PTSD) and other adverse mental health outcomes. In low-and middle-income countries (LMICs), children are at increased risk of exposure to severe trauma and co-occurring adversities. However, relative to high-income countries, there is limited evidence of the factors that predict good versus poor psychological recovery following trauma exposure in LMIC children, and the role of caregiver support in these high-adversity communities.Methods and analysis We will conduct a longitudinal, observational study of 250 children aged 8–16 years and their caregivers in South Africa, following child exposure to acute trauma. Dyads will be recruited from community hospitals following a potentially traumatic event, such as a motor vehicle accident or assault. Potential participants will be identified during their hospital visit, and if they agree, will subsequently be contacted by study researchers. Assessments will take place within 4 weeks of the traumatic event, with 3-month and 6-month follow-up assessments. Participants will provide a narrative description of the traumatic event and complete questionnaires designed to give information about social and psychological risk factors. Child PTSD symptoms will be the primary outcome, and wider trauma-related mental health (depression, anxiety, behavioural problems) will be secondary outcomes. Regression-based methods will be used to examine the association of psychosocial factors in the acute phase following trauma, including caregiver support and responding, with child PTSD and wider mental health outcomes.Ethics and dissemination Ethical approvals have been granted by Stellenbosch University and the University of Bath, with additional approvals to recruit via hospitals and healthcare clinics being granted by the University of Cape Town, the Department of Health and the City of Cape Town. Study findings will be disseminated via publication in journals, workshops for practitioners and policy-makers, and public engagement events.

Phase-contrast X-ray imaging is becoming increasingly considered since its first applications, which occurred almost 30 years ago. Particular emphasis was placed on studies that use this technique to investigate soft tissues, which cannot otherwise be investigated at a high resolution and in a three-dimensional manner, using conventional absorption-based settings. Indeed, its consistency and discrimination power in low absorbing samples, unified to being a not destructive analysis, are pushing interests on its utilization from researchers of different specializations, from botany, through zoology, to human physio-pathology research. In this regard, a challenging method for 3D imaging and quantitative analysis of collagenous tissues has spread in recent years: it is based on the unique characteristics of synchrotron radiation phase-contrast microTomography (PhC-microCT). In this review, the focus has been placed on the research based on the exploitation of synchrotron PhC-microCT for the investigation of collagenous tissue physio-pathologies from solely human samples. Collagen tissues’ elasto-mechanic role bonds it to the morphology of the site it is extracted from, which could weaken the results coming from animal experimentations. Encouraging outcomes proved this technique to be suitable to access and quantify human collagenous tissues and persuaded different researchers to approach it. A brief mention was also dedicated to the results obtained on collagenous tissues using new and promising high-resolution phase-contrast tomographic laboratory-based setups, which will certainly represent the real step forward in the diffusion of this relatively young imaging technique.

Three-dimensional printing technologies are becoming increasingly attractive for their versatility; the geometrical customizability and manageability of the final product properties are the key points. This work aims to assess the feasibility of producing radiopaque filaments for fused deposition modeling (FDM), a 3D printing technology, starting with zinc oxide (ZnO) and polylactic acid (PLA) as the raw materials. Indeed, ZnO and PLA are promising materials due to their non-toxic and biocompatible nature. Pellets of PLA and ZnO in the form of nanoparticles were mixed together using ethanol; this homogenous mixture was processed by a commercial extruder, optimizing the process parameters for obtaining mechanically stable samples. Scanning electron microscopy analyses were used to assess, in the extruded samples, the homogenous distribution of the ZnO in the PLA matrix. Moreover, X-ray microtomography revealed a certain homogenous radiopacity; this imaging technique also confirmed the correct distribution of the ZnO in the PLA matrix. Thus, our tests showed that mechanically stable radiopaque filaments, ready for FDM systems, were obtained by homogenously loading the PLA with a maximum ZnO content of 6.5% wt. (nominal). This study produced multiple outcomes. We demonstrated the feasibility of producing radiopaque filaments for additive manufacturing using safe materials. Moreover, each phase of the process is cost-effective and green-oriented; in fact, the homogenous mixture of PLA and ZnO requires only a small amount of ethanol, which evaporates in minutes without any temperature adjustment. Finally, both the extruding and the FDM technologies are the most accessible systems for the additive manufacturing commercial apparatuses.

Mechanical stimuli are regulators not only in cells but also of the extracellular matrix activity, with special reference to collagen bundles composition, amount and distribution. Synchrotron-based phase-contrast computed tomography was widely demonstrated to resolve collagen bundles in 3D in several body districts and in both pre-clinical and clinical contexts. In this perspective study we hypothesized, supporting the rationale with synchrotron imaging experimental examples, that deep learning semantic image segmentation can better identify and classify collagen bundles compared to common thresholding segmentation techniques. Indeed, with the support of neural networks and deep learning, it is possible to quantify structures in synchrotron phase-contrast images that were not distinguishable before. In particular, collagen bundles can be identified by their orientation and not only by their physical densities, as was made possible using conventional thresholding segmentation techniques. Indeed, localised changes in fiber orientation, curvature and strain may involve changes in regional strain transfer and mechanical function (e.g., tissue compliance), with consequent pathophysiological implications, including developmental of defects, fibrosis, inflammatory diseases, tumor growth and metastasis. Thus, the comprehension of these kinetics processes can foster and accelerate the discovery of therapeutic approaches for the maintaining or re-establishment of correct tissue tensions, as a key to successful and regulated tissues remodeling/repairing and wound healing.

This experimental study aims at filling the gap in the literature concerning the combined effects of hydroxyapatite (HA) concentration and elementary unit cell geometry on the biomechanical performances of additively manufactured polycaprolactone/hydroxyapatite (PCL/HA) scaffolds for tissue engineering applications. Scaffolds produced by laser powder bed fusion (LPBF) with diamond (DO) and rhombic dodecahedron (RD) elementary unit cells and HA concentrations of 5, 30 and 50 wt.% were subjected to structural, mechanical and biological characterization to investigate the biomechanical and degradative behavior from the perspective of bone tissue regeneration. Haralick’s features describing surface pattern, correlation between micro- and macro-structural properties and human mesenchymal stem cell (hMSC) viability and proliferation have been considered. Experimental results showed that HA has negative influence on scaffold compaction under compression, while on the contrary it has a positive effect on hMSC adhesion. The unit cell geometry influences the mechanical response in the plastic regime and also has an effect on the cell proliferation. Finally, both HA concentration and elementary unit cell geometry affect the scaffold elastic deformation behavior as well as the amount of micro-porosity which, in turn, influences the scaffold degradation rate.

The study of the organizational kinetics in the area surrounding the transmucosal part of dental implants promises to ensure an accurate diagnosis of the healing process, in terms of osseointegration and long-term implant success. In this demonstrative work, the morphological, qualitative and quantitative characteristics of 3D images of collagen bundles obtained by synchrotron-based high-resolution X-ray tomography were analyzed. Data analysis was performed using deep learning algorithms, neural networks that were applied on multiple volumes extracted from connective portions of different patients. The neural network was trained with mutually consistent examples from different patients; in particular, we used a neural network model, U-Net, well established when applying deep learning to datasets of images. It was trained not only to distinguish the collagen fibers from the background, but also to subdivide the collagen bundles based on the orientation of the fibers. In fact, differently from conventional thresholding methods, deep learning semantic segmentation assigns a label to each pixel, not only relying on grey level distribution but also on the image morphometric (shape or direction) characteristics. With the exception of Pt2 biopsies that, as confirmed by the polarized light investigation, were shown to present an immature tissue condition, the quantity, the anisotropy degree and the connectivity density of transverse bundles were always demonstrated to be higher than for longitudinal ones. These are interesting and new data; indeed, as collagen bundles are organized in an intertwining pattern, these morphometric and 3D complexity parameters, distinguished in transversal and longitudinal directions, give precise indications on the amount and distribution of connective tissue forces exerted during the healing process.

In a scaffold-based approach for bone tissue regeneration, the control over morphometry allows for balancing scaffold biomechanical performances. In this experimental work, trabecular geometry was obtained by a generative design process, and scaffolds were manufactured by vat photopolymerization with 60% (P60), 70% (P70) and 80% (P80) total porosity. The mechanical and biological performances of the produced scaffolds were investigated, and the results were correlated with morphometric parameters, aiming to investigate the influence of trabecular geometry on the elastic modulus, the ultimate compressive strength of scaffolds and MG-63 human osteosarcoma cell viability. The results showed that P60 trabecular geometry allows for matching the mechanical requirements of human mandibular trabecular bone. From the statistical analysis, a general trend can be inferred, suggesting strut thickness, the degree of anisotropy, connectivity density and specific surface as the main morphometric parameters influencing the biomechanical behavior of trabecular scaffolds, in the perspective of tissue engineering applications.

Introduction: Dental implant placement can be challenging when insufficient bone volume is present and bone augmentation procedures are indicated. The purpose was to assess clinically and histologically a specimen of 30%HA-60%β-TCP BCP 3D-printed scaffold, after 7-years.Case Description: The patient underwent bone regeneration of maxillary buccal plate with 3D-printed biphasic-HA block in 2013. After 7-years, a specimen of the regenerated bone was harvested and processed to perform microCT and histomorphometrical analyses.Results: The microarchitecture study performed by microCT in the test-biopsy showed that biomaterial volume decreased more than 23% and that newly-formed bone volume represented more than 57% of the overall mineralized tissue. Comparing with unloaded controls or peri-dental bone, Test-sample appeared much more mineralized and bulky. Histological evaluation showed complete integration of the scaffold and signs of particles degradation. The percentage of bone, biomaterials and soft tissues was, respectively, 59.2, 25.6, and 15.2%. Under polarized light microscopy, the biomaterial was surrounded by lamellar bone. These results indicate that, while unloaded jaws mimicked the typical osteoporotic microarchitecture after 1-year without loading, the BCP helped to preserve a correct microarchitecture after 7-years.Conclusions: BCP 3D-printed scaffolds represent a suitable solution for bone regeneration: they can lead to straightforward and less time-consuming surgery, and to bone preservation.

Abstract Background Personalized maxillary expansion procedure has been proposed to correct maxillary transversal deficiency; different protocols of stem cell activation have been suggested and rapid maxillary expansion (RME) is the most commonly used among clinicians. The present study aimed to quantify in three-dimensions (3D) the osteo-regeneration of the midpalatal suture in children submitted to RME. Methods Three patients (mean age 8.3 ± 0.9 years) were enrolled in the study to preform biopsy of midpalatal suture. Two patients (subjects 1 and 2) were subjected to RME before biopsy. The third patient did not need maxillary expansion treatment and was enrolled as control (subject 3). Midpalatal suture samples were harvested 7 days after RME in subject 1, and 30 days after RME in subject 2. The samples were harvested with the clinical aim to remove bone for the supernumerary tooth extraction. When possible, maxillary suture and bone margins were both included in the sample. All the biopsies were evaluated by complementary imaging techniques, namely Synchrotron Radiation-based X-ray microtomography (microCT) and comparative light and electron microscopy. Results In agreement with microscopy, it was detected by microCT a relevant amount of newly formed bone both 7 days and 30 days after RME, with bone growth and a progressive mineralization, even if still immature respect to the control, also 30 days after RME. Interestingly, the microCT showed that the new bone was strongly connected and cross-linked, without a preferential orientation perpendicular to the suture’s long axis (previously hypothesized by histology), but with well-organized and rather isotropic 3D trabeculae. Conclusions The microCT imaging revealed, for the first time to the authors’ knowledge, the 3D bone regeneration in children submitted to RME.

Symmetric and well-organized connective tissues around the longitudinal implant axis were hypothesized to decrease early bone resorption by reducing inflammatory cell infiltration. Previous studies that referred to the connective tissue around implant and abutments were based on two-dimensional investigations; however, only advanced three-dimensional characterizations could evidence the organization of connective tissue microarchitecture in the attempt of finding new strategies to reduce inflammatory cell infiltration. We retrieved three implants with a cone morse implant–abutment connection from patients; they were investigated by high-resolution X-ray phase-contrast microtomography, cross-linking the obtained information with histologic results. We observed transverse and longitudinal orientated collagen bundles intertwining with each other. In the longitudinal planes, it was observed that the closer the fiber bundles were to the implant, the more symmetric and regular their course was. The transverse bundles of collagen fibers were observed as semicircular, intersecting in the lamina propria of the mucosa and ending in the oral epithelium. No collagen fibers were found radial to the implant surface. This intertwining three-dimensional pattern seems to favor the stabilization of the soft tissues around the implants, preventing inflammatory cell apical migration and, consequently, preventing bone resorption and implant failure. This fact, according to the authors’ best knowledge, has never been reported in the literature and might be due to the physical forces acting on fibroblasts and on the collagen produced by the fibroblasts themselves, in areas close to the implant and to the symmetric geometry of the implant itself.

Maxillary sinus augmentation is often necessary prior to implantology procedure, in particular in cases of atrophic posterior maxilla. In this context, bone substitute biomaterials made of biphasic calcium phosphates, produced by three-dimensional additive manufacturing were shown to be highly biocompatible with an efficient osteoconductivity, especially when combined with cell-based tissue engineering. Thus, in the present research, osteoinduction and osteoconduction properties of biphasic calcium-phosphate constructs made by direct rapid prototyping and engineered with ovine-derived amniotic epithelial cells or amniotic fluid cells were evaluated. More in details, this preclinical study was performed using adult sheep targeted to receive scaffold alone (CTR), oAFSMC, or oAEC engineered constructs. The grafted sinuses were explanted at 90 days and a cross-linked experimental approach based on Synchrotron Radiation microCT and histology analysis was performed on the complete set of samples. The study, performed taking into account the distance from native surrounding bone, demonstrated that no significant differences occurred in bone regeneration between oAEC-, oAFMSC-cultured, and Ctr samples and that there was a predominant action of the osteoconduction versus the stem cells osteo-induction. Indeed, it was proven that the newly formed bone amount and distribution decreased from the side of contact scaffold/native bone toward the bulk of the scaffold itself, with almost constant values of morphometric descriptors in volumes more than 1 mm from the border.

This study aimed to compare two different bulk-filling techniques, evaluating the internal and external adaptation of class II resin-composite restorations, by analysing the gap formation using microcomputed tomography (µ-CT) and scanning electronic microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS). Two standardized mesio/disto-occlusal (MO/DO) cavities were prepared in eight extracted human third molars that were divided, according to the filling technique used, in the following two groups (n = 4): BG (Bulk&Go group) and BT (Bulk Traditional group). After universal bonding application, followed by the light curing, all teeth were restored using a bulk-fill composite. Specimens were scanned with µ-CT to evaluate 3D interfacial gaps. Acquired µ-CT data were analysed to quantify the gap formation. Complementary information to the µ-CT analysis were obtained by SEM. Thereafter, the chemical composition of tooth–restoration interface was analysed using EDS. The µ-CT analysis revealed gaps formation at the tooth–restoration interface for both the BG and BT groups, while within the restoration, only in the BT group there was evidence of microleakage formation. The scanning electron micrographs of both groups showed that the external marginal integrity of the restoration was preserved, while EDS showed the three different structures (tooth surface, adhesive layer and resin composite) of the tooth–restoration interface, highlighting the absence of gap formation. In both BG and BT, the two filling techniques did not show significant differences regarding the internal and external marginal adaptation of the restoration. To achieve a successful restoration, the clinician could be advised to restore a class II cavity using a single increment bulk-filling technique (BG), thus treating it as a class I cavity.

This work aimed to compare the capability of Streptococcus oralis to adhere to a novel surface, double-etched titanium (DAE), in respect to machined and single-etched titanium. The secondary outcome was to establish which topographical features could affect the interaction between the implant surface and bacteria. The samples’ superficial features were characterized using scanning electron microscopy (SEM) and energy dispersive x-ray spectrometry (EDS), and the wetting properties were tested through sessile methods. The novel surface, the double-etched titanium (DAE), was also analyzed with atomic force microscopy (AFM). S. oralis was inoculated on discs previously incubated in saliva, and then the colony-forming units (CFUs), biomass, and cellular viability were measured at 24 and 48h. SEM observation showed that DAE was characterized by higher porosity and Oxygen (%) in the superficial layer and the measurement of the wetting properties showed higher hydrophilicity. AFM confirmed the presence of a higher superficial nano-roughness. Microbiological analysis showed that DAE discs, coated by pellicle’s proteins, were characterized by significantly lower CFUs at 24 and 48 h with respect to the other two groups. In particular, a significant inverse relationship was shown between the CFUs at 48 h and the values of the wetted area and a direct correlation with the water contact angle. The biomass at 24 h was slightly lower on DAE, but results were not significant concerning the other groups, both at 24 and 48 h. The DAE treatment not only modifies the superficial topography and increased hydrophilicity, but it also increases the Oxygen percentage in the superficial layer, which could contribute to the inhibition of S. oralis adhesion. DAE can be considered a promising treatment for titanium implants to counteract a colonization pioneer microorganism, such as S. oralis.

Tissue engineering has been shown to offer promising approaches for bone regeneration, mostly based on replacement with biomaterials that provide specific environments and support for bone growth. In this context, we previously showed that mesenchymal stem cells (MSCs) and their derivatives, such as conditioned medium (CM) and extracellular vesicles (EV), when seeded on collagen membranes (COL) or polylactide (PLA) biomaterials, are able to favor bone tissue regeneration, especially evidenced in animal model calvary defects. In the present study, we investigated whether the enrichment of a rat calvary defect site with CM, EVs and polyethylenimine (PEI)-engineered EVs could substantially modify the bone remodeling kinetics during defect healing, as these products were reported to favor bone regeneration. In particular, we focused the study, performed by synchrotron radiation-based high-resolution tomography, on the analysis of the bone mass density distribution. We proved that the enrichment of a defect site with CM, EVs and PEI-EVs substantially modifies, often accelerating, bone remodeling kinetics and the related mineralization process during defect healing. Moreover, different biomaterials (COL or PLA) in combination with stem cells of different origin (namely, human periodontal ligament stem cells-hPDLSCs and human gingival mesenchymal stem cells-hGMSCs) and their own CM, EVs and PEI-EVs products were shown to exhibit different mineralization kinetics.

Background: Alveolar bone defects are usually the main concern when planning implant treatments for the appropriate oral rehabilitation of patients. To improve local conditions and achieve implant treatments, there are several methods used for increasing bone volume, among which one of the most successful, versatile, and effective is considered to be guided bone regeneration. The aim of this demonstrative study was to propose an innovative analysis protocol for the evaluation of the effect of photobiomodulation on the bone regeneration process, using rat calvarial defects of 5 mm in diameter, filled with xenograft, covered with collagen membrane, and then exposed to laser radiation. Methods: The animals were sacrificed at different points in time (i.e., after 14, 21, and 30 days). Samples of identical dimensions were harvested in order to compare the results obtained after different periods of healing. The analysis was performed by cross-linking the information obtained using histology and high-resolution synchrotron-based tomography on the same samples. A comparison was made with both the negative control (NC) group (with a bone defect which was left for spontaneous healing), and the positive control (PC) group (in which the bone defects were filled with xenografts and collagen membrane without receiving laser treatment). Results: We demonstrated that using photobiomodulation provides a better healing effect than when receiving only the support of the biomaterial. This effect has been evident for short times treatments, i.e., during the first 14 days after surgery. Conclusion: The proposed analysis protocol was effective in detecting the presence of higher quantities of bone volumes under remodeling after photobiomodulation with respect to the exclusive bone regeneration guided by the xenograft.

Bone remodeling process consists in a slow building phase and in faster resorption with the objective to maintain a functional skeleton locomotion to counteract the Earth gravity. Thus, during spaceflights, the skeleton does not act against gravity, with a rapid decrease of bone mass and density, favoring bone fracture. Several studies approached the problem by imaging the bone architecture and density of cosmonauts returned by the different spaceflights. However, the weaknesses of the previously reported studies was two-fold: on the one hand the research suffered the small statistical sample size of almost all human spaceflight studies, on the other the results were not fully reliable, mainly due to the fact that the observed bone structures were small compared with the spatial resolution of the available imaging devices. The recent advances in high-resolution X-ray tomography have stimulated the study of weight-bearing skeletal sites by novel approaches, mainly based on the use of the mouse and its various strains as an animal model, and sometimes taking advantage of the synchrotron radiation support to approach studies of 3D bone architecture and mineralization degree mapping at different hierarchical levels. Here we report the first, to our knowledge, systematic review of the recent advances in studying the skeletal bone architecture by high-resolution X-ray tomography after submission of mice models to microgravity constrains.

The engineering of large 3D constructs, such as certain craniofacial bone districts, is nowadays a critical challenge. Indeed, the amount of oxygen needed for cell survival is able to reach a maximum diffusion distance of ~150–200 μm from the original vascularization vector, often hampering the long-term survival of the regenerated tissues. Thus, the rapid growth of new blood vessels, delivering oxygen and nutrients also to the inner cells of the bone grafts, is mandatory for their long-term function in clinical practice. Unfortunately, significant progress in this direction is currently hindered by a lack of methods with which to visualize these processes in 3D and reliably quantify them. In this regard, a challenging method for simultaneous 3D imaging and analysis of microvascularization and bone microstructure has emerged in recent years: it is based on the use of synchrotron phase tomography. This technique is able to simultaneously identify multiple tissue features in a craniofacial bone site (e.g., the microvascular and the calcified tissue structure). Moreover, it overcomes the intrinsic limitations of both histology, achieving only a 2D characterization, and conventional tomographic approaches, poorly resolving the vascularization net in the case of an incomplete filling of the newly formed microvessels by contrast agents. Indeed, phase tomography, being based on phase differences among the scattered X-ray waves, is capable of discriminating tissues with similar absorption coefficients (like vessels and woven bone) in defined experimental conditions. The approach reviewed here is based on the most recent experiences applied to bone regeneration in the craniofacial region.

Abstract Background There is an explicit assumption in international policy statements that biodiversity can help in efforts to tackle global poverty. This systematic map was stimulated by an interest in better understanding the evidence behind this assumption by disaggregating the terms and asking - as our review question - which components or attributes of biodiversity influence which dimensions of poverty? Methods We employed a search strategy that covered peer-reviewed and grey literature. Relevant studies included in the map were those that described an interaction by poor people with biodiversity in non-OECD countries and documented some kind of contribution (positive or negative) to different aspects of their well-being. Results A total of 387 studies were included in the final systematic map. Of these 248 met our additional criteria that studies should include a measure of the contribution to poverty alleviation. The studies were widely distributed geographically. Ecological distribution was less well spread, however, with the largest number of studies focussed on forests. We found studies addressing 12 different dimensions of poverty/well-being – although the most commonly studied was income. Similarly we found studies addressing all levels of biodiversity from genes to ecosystems. The largest number of studies was focussed on groups of resources – particularly non-timber forest products. In most cases, abundance was the attribute that made biodiversity important for poverty alleviation/well-being, while diversity was the least frequently noted attribute. Conclusions The map highlights a number of apparent gaps in the evidence base. Very few studies documented any causal link between use of biodiversity and an impact on poverty. In the majority of the studies biodiversity was framed in terms of its value as a resource – in the form of specific goods that can be used to generate tangible benefits such as cash, food fuel. Very few studies explored the underpinning role of biodiversity in ecosystem service delivery for poverty alleviation, and fewer investigated the benefits of diversity as a form of insurance or adaptive capacity. This is where we suggest research should be prioritised.

In dental districts, successful bone regeneration using biphasic calcium phosphate materials was recently explored. The present study aimed to perform a comparative study between 3D-printed scaffolds produced by laser light stereo-lithography (SLA) and traditionally sintered biphasic calcium phosphate scaffolds by an integrated morphological, morphometric and mechanical analysis. Methods: Biphasic calcium phosphate (30% HA/70% β-TCP) samples, produced by SLA-3D-printing or by traditional sintering methods, were tested. The experimental sequence included: (1) Microtomography (microCT) analyses, to serve as control-references for the 3D morphometric analysis; (2) loading tests in continuous mode, with compression up to fracture, to reconstruct their mechanical characteristics; and (3) microCT of the same samples after the loading tests, for the prediction of the morphometric changes induced by compressive loading of the selected materials. All the biomaterials were also studied by complementary scanning electron microscopy to evaluate fracture regions and surfaces. Results: The characterization of the 3D mineralized microarchitecture showed that the SLA-3D-printed biomaterials offer performances comparable to and in some cases better than the traditionally sintered ones, with higher mean thickness of struts and pores. Interestingly, the SLA-3D-printed samples had a higher ultimate strength than the sintered ones, with a smaller plastic region. Moreover, by SEM observation, it was observed that fractures in the SLA-3D-printed samples were localized in the structure nodes or on the external shells of the rods, while all the traditionally sintered samples revealed a ductile fracture surface. Conclusions: The reduction of the region of plastic deformation in the SLA-3D-printed samples with respect to traditionally sintered biomaterials is expected to positively influence, in vivo, the cell adhesion. Both microCT and SEM imaging revealed that the studied biomaterials exhibit a structure more similar to human jaw than the sintered biomaterials.

This study was designed to quantitatively demonstrate via three-dimensional (3D) images, through the Synchrotron Radiation Phase-Contrast Microtomography (SR-PhC-MicroCT), the osteoinductive properties of a cortico-cancellous scaffold (Osteobiol Dual Block—DB) cultured with human Periodontal Ligament Stem Cells (hPDLSCs) in xeno-free media. In vitro cultures of hPDLSCs, obtained from alveolar crest and horizontal fibers of the periodontal ligament, were seeded onto DB scaffolds and cultured in xeno-free media for three weeks. 3D images were obtained by SR-PhC-microCT after one and three weeks from culture beginning. MicroCT data were successively processed with a phase-retrieval algorithm based on the Transport of Intensity Equation (TIE). The chosen experimental method, previously demonstratively applied for the 3D characterization of the same constructs in not xeno-free media, quantitatively monitored also in this case the early stages of bone formation in basal and differentiating conditions. Interestingly, it quantitatively showed in the xeno-free environment a significant acceleration of the mineralization process, regardless of the culture (basal/differentiating) medium. This work showed in 3D that the DB guides the osteogenic differentiation of hPDLSCs in xeno-free cultures, in agreement with 2D observations and functional studies previously performed by some of the authors. Indeed, here we fully proved in 3D that expanded hPDLSCs, using xeno-free media formulation, not only provide the basis for Good Manufacturing Practice (preserving the stem cells’ morphological features and their ability to differentiate into mesenchymal lineage) but have to be considered, combined to DB scaffolds, as interesting candidates for potential clinical use in new custom made tissue-engineered constructs.

Bone is a complex dynamic tissue undergoing a continuous remodeling process. Gravity is a physical force playing a role in the remodeling and contributing to the maintenance of bone integrity. This article reports an investigation on the alterations of the bone microarchitecture that occurred in wild type (Wt) and pleiotrophin-transgenic (PTN-Tg) mice exposed to a near-zero gravity on the International Space Station (ISS) during the Mice Drawer System (MDS) mission, to date, the longest mice permanence (91 days) in space. The transgenic mouse strain over-expressing pleiotrophin (PTN) in bone was selected because of the PTN positive effects on bone turnover. Wt and PTN-Tg control animals were maintained on Earth either in a MDS payload or in a standard vivarium cage. This study revealed a bone loss during spaceflight in the weight-bearing bones of both strains. For both Tg and Wt a decrease of the trabecular number as well as an increase of the mean trabecular separation was observed after flight, whereas trabecular thickness did not show any significant change. Non weight-bearing bones were not affected. The PTN-Tg mice exposed to normal gravity presented a poorer trabecular organization than Wt mice, but interestingly, the expression of the PTN transgene during the flight resulted in some protection against microgravity's negative effects. Moreover, osteocytes of the Wt mice, but not of Tg mice, acquired a round shape, thus showing for the first time osteocyte space-related morphological alterations in vivo. The analysis of specific bone formation and resorption marker expression suggested that the microgravity-induced bone loss was due to both an increased bone resorption and a decreased bone deposition. Apparently, the PTN transgene protection was the result of a higher osteoblast activity in the flight mice.