Micro-computed Tomography Analysis Research Articles

Nanostructured TiO2 Surface Enriched with CeO2 over Ti Metal for Enhanced Cytocompatibility and Osseointegration for Biomedical Applications.

The present study aims to analyze the thermal regulation of the Ce3+/Ce4+ ratio on the nanonetwork titania layer over the titanium (Ti) surface developed by the alkali-mediated surface modification approach. The effect of sequential heat treatment from 200 to 800 °C was evaluated for its surface characteristics such as morphology, phase formation, roughness, hardness, hydrophilicity, etc. Surface oxidation by temperatures up to 600 °C demonstrated a progressive increase in the Ce4+ (CeO2) content with a rutile TiO2 network layer over the Ti surface. In contrast, a bulk reduction with increased Ce3+ (Ce2O3) content was observed at 800 °C. Heat treatment at 800 °C was also characterized by an improved nanohardness and roughness with a distorted surface network layer. The coexistence of Ce4+/Ce3+ (CeO2/Ce2O3) on a porous titania layer displayed a noticeable enhancement in antibacterial activity, which was evaluated against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The surface-modified sample heat-treated at 600 °C and enriched with a high Ce4+/Ce3+ ratio revealed enhanced cell compatibility toward MG-63 in terms of cell adhesion, noncytotoxicity, and mitochondrial membrane potential with higher extracellular matrix mineralization. Further, in vivo bone defect investigations in a rat model using additively manufactured cancellous Ti scaffolds functionalized with surface incorporation of Ce ions heat-treated at 600 °C demonstrated significant enhancement in the osseointegration potential observed from histological and micro-computed tomography analyses. The upregulation of osteogenic marker genes (ALP, OCN, OPN, OSX, and RUNX2) at the implantation site evaluated by reverse transcription polymerase chain reaction confirmed the osteogenic potential of ceria surface functionalization. Hence, the Ce-incorporated nanostructured titania layer predominantly possessing a high Ce4+/Ce3+ ratio or CeO2 content on Ti metal is expected to reduce the risk of implant-related infections and improve cellular responses in orthopedic applications.

Abaloparatide Enhances Bone Regeneration in Extraction Socket Dental Implant Defects: An Experimental InVivo Study.

Abaloparatide (ABL) is a synthetic parathyroid hormone-related protein analog developed as an anabolic drug to treat osteoporosis. ABL increases bone mineral density (BMD) of the long bones and spine; however, the influence of ABL on alveolar bone regeneration remains unknown. This study assessed the effects of systemic ABL administration on tooth extraction socket healing and dental implant osseointegration in a preclinical rodent model. Sprague-Dawley rats received daily subcutaneous injection of ABL (25 μg/kg) or vehicle (VEH) at the time of maxillary first molar (M1) extraction surgery; animals underwent either: (1) unilateral M1 extraction followed by sacrifice at 10 or 42d or (2)bilateral M1 extraction followed by staged implant placement in osteotomies with standardized defects and sacrifice at 21or 28d. Micro-computed tomography (micro-CT) analysis demonstrated that ABL increased bone volume fraction (p = 0.004) and bone mineral density (BMD) (p = 0.006) of regenerated extraction sockets at 42d. Micro-CT of the femur validated systemic effects of ABL, showing greater trabecular BMD after 6 (p < 0.01), 9 (p < 0.001), and 14 (p < 0.001) weeks of treatment. Histomorphometry confirmed a higher mineralized bone area with ABL treatment in extraction sockets at 42d (p = 0.03) and in the regenerated peri-implant bone at 21d post-implant placement (p = 0.01) compared to control. Systemic ABL administration enhances osteogenesis in extraction sockets prior to implant placement and accelerates peri-implant bone formation in the early phase of healing in the present rodent model.

Administration of Bisphosphonate Preparations to Mice with Mild-type Hypophosphatasia Reduces the Quality of Spontaneous Locomotor Activity

Hypophosphatasia (HPP) is a congenital bone disease caused by tissue-nonspecific mutations in the alkaline phosphatase gene. It is classified into six types: severe perinatal, benign prenatal, infantile, pediatric, adult, and odonto. HPP with femoral hypoplasia on fetal ultrasonography, seizures, or early loss of primary teeth can be easily diagnosed. In contrast, pediatric, adult, and odonto types of HPP over 4 years of age are less likely to be diagnosed because they do not have typical symptoms. Consequently, it may be misdiagnosed as common osteoporosis, and treatments incompatible with HPP may be implemented. The purpose of this study was to analyze the effects of bisphosphonate preparations administration on the femur of Akp2+/− mice, a mild-type HPP mice model. Zoledronic acid (Zol) was subcutaneously administered to 4-week-old Akp2+/− mice at 1 mg/kg (volume: 200 μL) once a week for a total of 5 times. Afterward, spontaneous locomotor activity analysis was performed, and serum and femur bones were collected at 9 weeks of age. Additionally, micro-computed tomography (CT) analysis, histological analysis, and analysis of the expression levels of various marker proteins and genes were performed. Age-matched Akp2+/+ mice served as controls. The results demonstrated that the administration of Zol to Akp2+/− mice, compared to Akp2+/+ mice, insufficiently promotive bone formation, torn femoral head cartilage, and decreased spontaneous locomotor activity. Therefore, it is important to accurately diagnose patients with mild-type HPP.

Effects of 3D Printing Parameters on the Flexural Properties of Semi-Crystalline PEKK

Fused filament fabrication (FFF), a leading additive manufacturing (AM) methodology has revolutionised the production of 3D objects. FFF enables the manufacture of complex geometries not achievable with traditional manufacturing methods. This study investigates the use of the high-performance polymer, polyetherketoneketone (PEKK) for advanced AM applications in the growing field of in-space manufacturing (ISM), where lightweight recyclable metal alternatives can greatly reduce launch payloads. Utilising a response surface methodology, this research examines the effects of print speed, layer thickness, nozzle temperature, and build platform temperature on PEKK's mechanical, physical, and thermal properties.Optimum print conditions for maximising the flexural modulus were identified as 30mm/s print speed, 0.1mm layer thickness, 380°C nozzle temperature, and 140°C build platform temperature. These parameters improve the material's crystallinity by extending its residence time in the printer's heated chamber. This prolonged exposure facilitates better molecular alignment and reduces thermal gradients, leading to a 30% enhancement in crystallinity compared to conditions with higher print speeds and greater layer thicknesses. Scanning Electron Microscopy (SEM) and micro-computed tomography(µCT) analyses revealed that layer thickness significantly influences void formation, with thinner layers yielding superior interlayer bonding and reduced void volume. Differential Scanning Calorimetry (DSC) confirmed that increased crystallisation had a direct impact on flexural modulus, increasing it to 3682MPa, approaching 80% of PEKKs injection moulding performance. This study highlights the complex relationships between the FFF parameters and PEKK's mechanical properties, highlighting its potential for industrial and ISM applications.

Enhanced Osseointegration of Titanium Alloy Bone Implants Coated With Carob-calcium Hydroxide Nanoparticles: A Comparative Study.

This study aimed to evaluate the osseointegration properties of titanium bone implants coated with carob-mediated calcium hydroxide nanoparticles biomechanically, radiographically, and histologically on rabbit tibias. Forty coated and forty uncoated titanium alloy bone implants were inserted into 20 New Zealand rabbits; each tibia received 2 implants. The rabbits were sacrificed after 4 or 8 weeks, and samples were retrieved for biomechanical evaluation through removal torque test to assess the bond between implant and bone, radiographic evaluation through microcomputed tomography analysis to compare the bone-to-implant contact percentage and bone volume of the peri-implant area, scanning electron microscopic and histologic evaluation through hematoxylin and eosin stain. Statistical analyses between pairs of means were conducted using the independent t test. Multiple comparisons between the study groups across time intervals were performed using a 2-way analysis of variance. P-values ≤0.05 were considered statistically significant. Higher removal torque values (P<0.01) were needed to remove the coated implants when biomechanically tested. In addition, the microcomputed tomography evaluation revealed a higher bone-to-implant contact percentage (P<0.05) in favor of coated implants. In addition, the 4-week healing interval of the coated implants showed no significant difference when compared with the 8-week healing interval of the uncoated implants biomechanically and radiographically, suggesting early osseointegration. The findings of this study imply that coating titanium implants with carob-mediated calcium hydroxide nanoparticles improved and fastened osseointegration and bone ingrowth, resulting in early osteogenesis and shortening the treatment time.

Bone Regeneration After Sinus Floor Elevation in an Intact Sinus or a Sinus With Prior Large Membrane Perforation: A Preclinical Study Using a Rabbit Sinus Model.

To determine bone regeneration following sinus floor elevation (SFE) at sites with or without prior sinus membrane perforation. The sinus membranes in the maxillary sinuses of 12 rabbits were intentionally perforated (≥ 5 mm) on one side, followed by application of a collagen matrix. SFE was performed on both sinuses after 8 weeks of healing, presenting two groups: SFE with a previous large sinus membrane perforation (group SFE_Perf), and in an intact sinus (group SFE). The animals were euthanized at 2 and 4 weeks after SFE. Micro-computed tomographic and histomorphometric analyses were performed. The amount of newly formed bone within the augmented area did not differ significantly between the two groups at 2 weeks and 4 weeks (4.7 ± 1.0 mm2 vs. 5.3 ± 1.4 mm2 and 9.2 ± 1.7 mm2 vs. 10.8 ± 2.2 mm2, respectively, mean ± SD; p > 0.05). However, the amount of newly formed bone near the middle of the sinus membranes was significantly greater in group SFE than in group SFE_Perf (p < 0.05). There was no significant difference in the augmented volume. Fewer subepithelial glands and denser collagen fibres within the sinus membranes were observed in group SFE_Perf than in group SFE. A large perforation of the sinus membrane followed by an 8-week healing period did not jeopardize new bone formation following SFE.

A Novel Series of Coumarin Derivatives That Exert Osteoblastogenic Effects in Mesenchymal Stem Cells and Osteogenic Effects in Ovariectomized Female Rats.

Osteoporosis is treated with oral and parenteral resorption inhibitors and parenteral osteogenic drugs. However, orally active small-molecule osteogenic drugs are not clinically available. Natural coumarin derivatives, such as osthole, exert osteoblastogenic effects. In the present study, novel 4,6-substituted coumarin derivatives were synthesized, and their osteoblastogenic effects were assessed in a bone mesenchymal stem cell line (ST2 cell), and structure-activity relationships were discussed. Among the derivatives tested, the osteoblastogenic effects of 2-oxo-4-[4-(tetrahydro-2H-pyran-4-yloxymethyl)phenyl]-2H-chromene-6-carboxamide (11m) and 2-oxo-4-[4-(tetrahydro-2H-pyran-4-ylmethoxy)phenyl]-2H-chromene-6-carboxamide (29v) were potent: EC200 for increasing alkaline phosphatase (ALP) activity were 34 and 24 nM, respectively. The maximal plasma concentrations (Cmax) of 11m and 29v (10 mg/kg, per os (p.o.)) in female rats were 3637 and 975 nM, respectively, resulting in high Cmax/EC200 ratios of 105.9 and 40.8, respectively, indicating possible osteoblastogenic effects in vivo. Compound 11m (10 mg/kg, p.o., 8 weeks) was previously reported to increase plasma bone-type ALP activity as well as femoral metaphyseal and diaphyseal cortical bone volumes and mineral contents in micro-computed tomography analyses of ovariectomized female rats (OVX rats). Compound 29v at the same dose also exerted osteoblastogenic and osteogenic effects in OVX rats; however, these effects were weaker than those of 11m. Furthermore, 11m and 29v inhibited cyclin-dependent kinase 8 (CDK8) activity, suggesting that their osteoblastogenic effects involved the suppression of CDK8. In conclusion, a synthetic 4,6-substituted coumarin structure is a useful scaffold for osteoblastogenic and osteogenic compounds via the inhibition of CDK8, and 11m and 29v have potential as anti-osteoporotic drugs that exert osteogenic effects on cortical bone.

The Application of L-Serine-Incorporated Gelatin Sponge into the Calvarial Defect of the Ovariectomized Rats.

Osteoporosis, characterized by decreased bone mineral density due to an imbalance between osteoblast and osteoclast activity, poses significant challenges in bone healing, particularly in postmenopausal women. Current treatments, such as bisphosphonates, are effective but associated with adverse effects like medication-related osteonecrosis of the jaw, necessitating safer alternatives. This study investigated the use of L-serine-incorporated gelatin sponges for bone regeneration in calvarial defects in an ovariectomized rat model of osteoporosis. Thirty rats were divided into three groups: a control group, a group treated with a gelatin sponge containing an amino acid mixture, and a group treated with a gelatin sponge containing L-serine. Bone regeneration was assessed using micro-computed tomography (micro-CT) and histological analyses. The L-serine group showed a significant increase in bone volume (BV) and bone area compared to the control and amino acid groups. The bone volume to total volume (BV/TV) ratio was also significantly higher in the L-serine group. Immunohistochemical analysis demonstrated that L-serine treatment suppressed the expression of cathepsin K, a marker of osteoclast activity, while increasing serine racemase activity. These findings suggest that L-serine-incorporated gelatin sponges not only enhance bone formation but also inhibit osteoclast-mediated bone resorption, providing a promising and safer alternative to current therapies for osteoporosis-related bone defects. Further research is needed to explore its clinical applications in human patients.

Efficacy of Laser Activated versus Sonic Activated Irrigation for Debris Removal in Conservatively Instrumented Root Canals.

To compare the efficacy of laser activated and sonic activated irrigation on the removal of debris in mesial root canal systems of mandibular molars using micro-computed tomographic analysis. Forty-eight mesial roots of extracted mandibular molars with isthmus were selected and randomly allocated into 2 groups: Sonic Group and Laser Group. The root canals were minimally instrumented to a maximum apical file size of 20/06v (DCTaper, SSWhite, NJ). The Sonic Group received irrigant activation using the SmartLite Pro EndoActivator (Dentsply Tulsa, OK) with a 15/02 tip. The Laser Group received irrigant activation using the WaterLase iPlus (Biolase, CA) with a RFT2 tip. The teeth were activated for the same time with the same volume of irrigants. Micro-computed tomographic scans were obtained preinstrumentation, preirrigation, and postirrigation. To quantify debris removal, the air-filled volume was measured preirrigation and postirrigation, and the percentage increase in air-filled volume was calculated. Data were analyzed statistically (independent samples t-test, significance set at 5%). The Laser Group demonstrated a significantly higher mean percentage increase in air-filled volume (37.4%) compared to the Sonic Group (20.2%). This difference was statistically significant (P<.05). The Laser Group was significantly more effective in removing debris compared to the Sonic Group in minimally instrumented root canal systems. However, due to the limitations of this study, further research is needed to assess the impact of laser activated irrigation on clinical outcomes.

RANK IVVY motif plays crucial roles in osteoclastogenesis.

RANKL and its receptor RANK play a vital role in osteoclastogenesis. RANK primarily recruits TRAFs to promote osteoclastogenesis but also contains an TRAF-independent motif (IVVY535-538), which mediates osteoclast lineage commitment in vitro. Here, we have developed knockin mice in which inactivating mutations are introduced in the IVVY motif (IVVY to IVAF). Homozygous knockin (RANKAF/AF) mice are viable and born at the expected Mendelian ratio. Micro-computed tomography (μCT) and histomorphometric analyses of femurs of wild type (RANK+/+) and RANKAF/AF mice reveal significant increases in trabecular bone mass in RANKAF/AF compared to age and sex matched RANK+/+ mice due to impaired osteoclastogenesis in vivo. Bone marrow macrophages (BMMs) from RANKAF/AF mice do not form osteoclasts in vitro upon M-CSF and RANKL treatment. RANKL-induced activation of NF-ĸB, ERK, p38 and JNK pathways in RANKAF/AF BMMs remains intact, but RANKL-induced expression of c-Fos and NFATc1 is impaired in RANKAF/AF BMMs. Consistent with the crucial role of the IVVY motif in priming BMMs into the osteoclast lineage, RANKL-primed RANKAF/AF BMMs do not form osteoclasts in response to subsequent Porphyromonas gingivalis (Pg)-stimulation, indicating that the IVVY Motif plays a role in Pg-induced osteoclastogenesis. Mechanistically, RANK IVVY motif mediates Pg-induced osteoclast gene expression by rendering NFATc1 and c-Fos genes responsive to Pg stimulation. Consistently, cell penetrating peptides fused to RANK segments containing the IVVY motif impair Pg-induced osteoclastogenesis by impairing RANKL-activated c-Fos and NFATc1 expression. In conclusion, the RANK IVVY motif plays crucial roles in osteoclastogenesis in vivo and modulates Pg-mediated osteoclast formation in vitro.

Calcification and ecological depth preferences of the planktonic foraminifer Trilobatus trilobus in the central Atlantic.

Understanding the controls behind the calcification and distribution of planktonic foraminifera in the modern ocean is important when these organisms are used for palaeoceanographic reconstructions. This study combines previously reported shell mass data with new shell geochemistry, light microscopy and X-ray micro-computed tomography analyses to dissect various parameters of Trilobatus trilobus shells from surface sediments, investigating the factors influencing their biometry. The goal is to understand which aspects of the marine environment are critical for the calcification and vertical distribution of this species. Trilobatus trilobus is found to produce larger, thinner and overall lighter shells in equatorial regions than in subtropical gyre regions, where the shells are up to 4% smaller, more than 60% thicker and approximately 45% heavier. The skeletal mass percentage together with other calcification metrics (shell weight and thickness) are found to depend primarily on ambient seawater salinity rather than carbonate chemistry. In line with their degree of calcification, on the basis of geochemically reconstructed apparent calcification depths, this group of organisms is found shallower in the water column at the Equator and the subtropical gyres, while its habitat deepens in between these regions at the extra-equatorial sites. Furthermore, it is demonstrated that in the (central) Atlantic, it occupies a density layer slightly below the salinity maximum isopycnal at various depths, presumably by adjusting its shell properties.

Intermediate and Transitory Inflammation Mediate Proper Alveolar Bone Healing Outcome in Contrast to Extreme Low/High Responses: Evidence from Mice Strains Selected for Distinct Inflammatory Phenotypes.

Alveolar bone healing is influenced by various local and systemic factors, including the local inflammatory response. This study aimed to evaluate the role of inflammatory responsiveness in alveolar bone healing using 8-week-old male and female mice (N = 5/time/group) strains selected for maximum (AIRmax) or minimum (AIRmin) acute inflammatory response carrying distinct homozygous RR/SS Slc11a1 genotypes, namely AIRminRR, AIRminSS, AIRmaxRR, and AIRmaxSS mice. After upper right incisor extraction, bone healing was analyzed at 0, 3, 7, and 14 days using micro-computed tomography, histomorphometry, birefringence, immunohistochemistry, and PCRArray analysis. AIRmaxSS and AIRminRR presented the highest and lowest inflammatory readouts, respectively, associated with lowest repair levels in both strains, while intermediate inflammatory phenotypes observed in AIRminSS and AIRmaxRR were associated with higher repair levels in such strains. The better healing outcomes are associated with intermediate inflammatory cell counts, a balanced expression of pro- and anti-inflammatory cytokines and chemokines, increased expression of growth and osteogenic factors and MSCs markers. Our results demonstrate that extreme high and low inflammatory responses are not ideal for a proper bone repair outcome, while an intermediate and transitory inflammation is associated with a proper alveolar bone healing outcome.

Duhuo Jisheng Decoction in reduction of inflammatory response via Transforming growth factor-β/Smad signaling pathway for repairing rabbit articular cartilage Injury: A Randomized Controlled Trial

ObjectiveThis study aims to investigate the mechanism underlying the effect of Duhuo Jisheng Decoction on the repair of rabbit articular cartilage injury through a reduction in the inflammatory response mediated by the Transforming growth factor (TGF)-β/Smad signaling pathway. MethodsA rabbit articular cartilage injury model was constructed using a ring bone extraction drill. Twenty-four Japanese white rabbits were randomly divided into six groups, namely Sham operation, model, low-dose Duhuo Jisheng Decoction, medium-dose Duhuo Jisheng Decoction, high-dose Duhuo Jisheng Decoction, and positive control groups. The treatment lasted 12 weeks. Gross observation, International Cartilage Repair Society score, Wakitani score, and Micro-computed tomography analysis were used to evaluate the structural repair of cartilage injury. Histology and immunohistochemistry were used to observe the proteoglycan, P-TβRII, P-Smad2, and type II collagen expression levels. Enzyme-linked immunosorbent assay was used to analyze the concentrations of Matrix Metalloproteinase-13 and Syndecan-4 in the joint fluid; and RT-PCR and Western Blot were used to observe the mRNA and protein expressions of ALK5, Sox-9, P-Smad3, and TGF-β1 at the injury repair site. ResultsThe repair effect of cartilage injury, as seen through gross observation and quantitative scoring, was better in all the Duhuo Jisheng Decoction treatment groups than in the model group. The medium dose group of Duhuo Jisheng Decoction had the best repair effect. We observed remarkable structural restoration of cartilage injury in the medium-dose Duhuo Jisheng Decoction group, with the subchondral bone presenting a distinct hierarchy, and parameters such as bone volume fraction and trabecular separation/spacing being significantly augmented. We found high expression levels of proteoglycans, P-TβRII, P-Smad2, and type II collagen. The concentrations of Matrix Metalloproteinase-13 and Syndecan-4 in the joint fluid were significantly lower following treatment. The low gene expression levels of ALK5, Sox-9, P-Smad3, and TGF-β1 in the injury site of the model group could be reversed in the medium-dose Duhuo Jisheng Decoction group. ConclusionDuhuo Jisheng Decoction can repair rabbit cartilage injury and reverse the levels of inflammatory factors in the joint fluid. The mechanism underlying its therapeutic effect is related to the activation of the TGF-β/Smad signaling pathway. This study provides a reliable basis for using Duhuo Jisheng Decoction to treat cartilage injury following knee osteoarthritis.

Advanced soft tissue visualization in conjunction with bone structures using contrast-enhanced micro-CT.

Micro-computed tomography (CT) analysis of soft tissues alongside bone remains challenging due to significant differences in X-ray absorption, preventing spatial inspection of bone remodeling including the cellular intricacies of mineralized tissues in developmental biology and pathology. The goal was to develop a protocol for contrast-enhanced micro-CT imaging that effectively visualizes soft tissues and cells in conjunction with bone while minimizing bone attenuation by decalcification. Murine femur samples were decalcified in ethylenediaminetetraacetic acid and treated with three different contrast agents: (i)iodine in ethanol, (ii)phosphotungstic acid in water, and (iii)Lugol's iodine. Micro-CT scans were performed in the laboratory setup SkyScan 1172 and at the synchrotron radiation for medical physics beamline in synchrotron radiation facility Elettra. Soft and hard tissue contrast-to-noise ratio (CNR) and contrast efficiency after decalcification were measured. In laboratory micro-CT, Lugol's iodine demonstrated a threefold higher CNR in the bone marrow, representing the soft tissue portion, compared with the bone. Contrast efficiencies, measured in synchrotron micro-CT, were consistent with these findings. Higher resolutions and the specificity of Lugol's iodine to cellular structures enabled detailed visualization of bone-forming cells in the epiphyseal plate. The combination of decalcification and the utilization of the contrast agent Lugol's iodine facilitated an enhanced soft tissue visualization in conjunction with bone.

Microarchitectural Study of the Augmented Bone Following a Modified Ridge Splitting Technique: Histological and Micro-Computed Tomography Analyses.

Objectives: The aim of this matched prospective cohort study was to examine the microarchitecture of the augmented bone following a modified alveolar ridge splitting procedure and compare it to that of native bone. Methods: In the test group, patients underwent a modified ridge split osteotomy procedure to restore the width of the posterior segment of the mandible. Patients with sufficient bone width for dental implant placement in the posterior region of the mandible following 3-month-long spontaneous healing after tooth removal were included in the control group. In both study groups, bone biopsy samples were harvested and dental implants were placed. Histomorphometry and micro-CT analysis were performed. Results: Altogether, 15 patients were included in this study (7 patients in the test group, with 14 bone core biopsies harvested, and 8 patients in the control group, with 13 bone core biopsies harvested). Percentage bone volume (BV/TV) in the micro-CT analysis (22.088 ± 8.094% and 12.075 ± 4.009% for the test and control group, respectively) showed statistically significant differences between study groups. Conclusions: Based on histological and micro-CT analyses, the modified ridge splitting procedure with autologous bone block harvested from the retromolar area results in a dental implant recipient bone microarchitecture superior to that of the extraction sockets left to heal undisturbed for a 3-month-long healing period.

Rehmannioside A promotes the osteoblastic differentiation of MC3T3-E1 cells via the PI3K/AKT signaling pathway and inhibits glucocorticoid-induced bone loss in vivo

Glucocorticoid-induced osteoporosis (GIOP) is a widespread disease characterized by low bone density. There remains a lack of effective means for osteoporosis. Rehmannioside A (ReA), an iridoid glycoside, exhibits various pharmacological activities. This study aimed to explore the role and mechanism of ReA in osteogenic differentiation of osteoblasts. Cell viability, reactive oxygen species (ROS) generation, and cell apoptosis were assessed using corresponding assay kits. Real-time quantitative polymerase chain reaction, Western blotting, and alkaline phosphatase (ALP) staining were performed to evaluate the osteogenic differentiation of MC3T3-E1 cells. Alizarin red S staining was used to assess the mineralization of MC3T3-E1 cells. Protein expression associated with the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) signaling pathway was analyzed using Western blotting. Micro-computed tomography, histopathological, and immunohistochemical analyses were performed to determine the therapeutic effect of ReA on GIOP in vivo.The results showed that ReA promoted the osteogenic differentiation of MC3T3-E1 cells by regulating the PI3K/AKT signaling pathway and protected mice against glucocorticoid-induced bone loss by promoting osteoblast-mediated bone formation in vivo. The findings of the current study revealed that ReA is a potential therapeutic agent for osteoporosis.

Inhibition of EGFR Pathway Suppresses M1 Macrophage Polarization and Osteoclastogenesis, Mitigating Titanium Particle-Induced Bone Resorption.

The polarization of macrophages towards the pro-inflammatory M1 phenotype and osteoclast overactivation play a significant role in the pathogenesis of aseptic loosening of orthopedic implants. This study sought to examine the expression and activation of macrophages and osteoclasts in implant biopsies with respect to epidermal growth factor receptor (EGFR) signaling and to assess the potential of EGFR inhibition in mitigating titanium particle-induced bone resorption in a cranial resorption murine model. Bone marrow-derived macrophages (BMDMs) were stimulated with Tumor Necrosis Factor-alpha (TNF-α) and Interferon-gamma (IFN-γ) initially. Subsequently, Osteoclast differentiation was initiated after Gefitinib was added to the treatment groups. Male C57BL/6 mice were treated with Gefitinib or 0.5% Carboxymethyl Cellulose-Sodium (CMC-Na) by oral gavage daily for two weeks. A sham group received no further intervention, while the other groups had titanium particles implanted. Tissues were collected and analyzed by measurements such as micro-computed tomography (micro-CT) analyses, histology, immunofluorescence stainings, cell viability assays, assays for resorption pit formation, Reverse Transcription-Polymerase Chain Reactions (RT-PCRs), and Western blots were conducted. The study demonstrated a significant upregulation of EGFR in response to titanium particle exposure. Inhibition of EGFR phosphorylation with gefitinib effectively reduced bone degradation at osteolytic sites in a murine model. Gefitinib treatment led to a notable reduction in M1 macrophage polarization, as indicated by immunofluorescence staining and Western blot analysis of macrophage markers. Mechanistically, selective EGFR inhibitors mitigate osteoclastogenesis and osteoclast resorption by inhibiting the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) and nuclear factor-κB (NF-κB) signaling pathways. Our findings provide compelling evidence of the essential role of EGFR-related pathways in M1 polarization, osteoclast activation, and ensuing periprosthetic osteolysis. Overall, EGFR presents a novel target for addressing bone resorption-associated conditions triggered by particles or modulated by macrophages and osteoclasts.

Catalpol Enhances Osteogenic Differentiation of Human Periodontal Stem Cells and Modulates Periodontal Tissue Remodeling in an Orthodontic Tooth Movement Rat Model.

This study examines the effects and mechanisms of catalpol (CAT) on the proliferation and osteogenic differentiation of cultured human periodontal ligament stem cells (hPDLSCs) in vitro and assesses the impact of CAT on periodontal remodeling in vivo using an orthodontic tooth movement (OTM) model in rats. hPDLSCs were cultured in a laboratory setting, and their proliferation and osteogenic differentiation were assessed using the Cell-counting Kit-8 (CCK-8), Alizarin Red Staining (ARS), quantitative calcium assay, alkaline phosphatase (ALP) staining and activity assay, and immunofluorescence assay. Additionally, the expression of collagen type 1 (COL-1), ALP, and runt-related transcription factor-2 (RUNX-2) was evaluated through qRT-PCR and Western blot analysis. To verify the function of the estrogen receptor-α (ER-α)-mediated phosphatidylinositol-3-kinase-protein kinase B (PI3K/AKT) pathway in this mechanism, LY294002 (a PI3K signaling pathway inhibitor) and the ER-α specific inhibitor methyl-piperidine-pyrazole (MPP) were used. The osteogenic markers ER-α, AKT, and p-AKT (phosphoprotein kinase B) were identified through Western blot analysis. Eighteen male Sprague-Dawley rats were assigned to two groups randomly: a CAT group receiving CAT and a control group receiving an equivalent volume of saline. Micro-computed tomography (micro-CT) analysis was employed to evaluate tooth movement and changes in alveolar bone structure. Morphological changes in the periodontal tissues between the roots were investigated using hematoxylin and eosin (HE) staining and tartaric-resistant acid phosphatase (TRAP) staining. The expression of COL-1, RUNX-2, and nuclear factor-κB (NF-κB) ligand (RANKL) was assessed through immunohistochemical staining (IHC) to evaluate periodontal tissue remodeling. Tests were analyzed using GraphPad Prism 8 software. Differences among more than two groups were analyzed by one-way or two-way analysis of variance (ANOVA) followed by the Tukey's test. Values of p < 0.05 were regarded as statistically significant. In vitro experiments demonstrated that 10μM CAT significantly promoted the proliferation, ALP activity, and calcium nodule formation of hPDLSCs, with a notable increase in the expression of COL-1, ALP, RUNX-2, ER-α, and p-AKT. The PI3K/AKT pathway was inhibited by LY294002, and further analysis using MPP suggested that ER-α mediated this effect. In vivo, experiments indicated that CAT enhanced the expression of COL-1 and RUNX-2 on the tension side of rat tooth roots, reduced the number of osteoclasts on the compression side, inhibited RANKL expression, and suppressed OTM. CAT can promote hPDLSCs proliferation and osteogenic differentiation in vitro through the ER-α/PI3K/AKT pathway and enhance periodontal tissue remodeling in vivo using OTM models. These findings suggest the potential for the clinical application of catalpol in preventing relapse following OTM.

Maxillary sinus floor augmentation using sponge- and cotton-like graft materials in a rabbit model

ObjectivesBone graft materials commonly used for maxillary sinus floor augmentation (MSFA), including hydroxyapatite (HAp) and β-tricalcium phosphate (β-TCP), are mostly granular and have poor handleability. HAp/collagen composite material (HAp/Col) and β-tricalcium phosphate (β-TCP)/poly(L-lactide-co-glycolide) (PLGA) have shown promise but their application in MSFA as bone graft materials remains unclear. Here, we investigated the bone-forming behavior of HAp/Col and β-TCP/PLGA in an MSFA rabbit model. MethodsMale Japanese white rabbits were used. HAP/Col or β-TCP/PLGA was randomly applied to the MSFA model. The specimens were harvested at 4 weeks (W), 8W, 16W, and 24W after surgery, and the augmented regions were evaluated using micro-computed tomography and histological analyses. ResultsThe graft materials were retained up to 16W in the HAp/Col group and 24W in the β-TCP/PLGA group. The augmented volume detected in the HAp/Col group at 4W was substantially reduced at subsequent time points. However, in the β-TCP/PLGA group, the volume observed at 4W was maintained up to 24W. In the HAp/Col group, the bone mineral content (BMC) at 4W was significantly lower than that at 8W (p=0.03716), and this elevated BMC was significantly decreased at 16W (p=0.00185) and 24W (p=0.00236). In the β-TCP/PLGA group, the BMC tended to increase from 4W to 16W and then decreased. ConclusionsBoth HAp/Col and β-TCP/PLGA are useful for MSFA because of their ability to form new bone and good handleability. The appropriate graft material should be selected depending on the application needs while understanding the properties of the newly formed bone.

Exploring the impact of blood and bone debris at the implant-abutment interface on peak removal torque: Bridging clinical observations with laboratory evidence

Three months after implant placement, difficulty was encountered in unscrewing the healing abutment within the normal torque range (<35 Ncm), resulting in the removal of the implant. Despite all attempts, the implant could not then be separated from the healing abutment. Retrospective analysis of intraoperative photographs revealed the presence of blood or bone debris within the implant before the healing abutment was placed; this was considered to be the likely cause of this phenomenon. The purpose of the study was to explore the impact of blood or bone debris within the implant during surgical placement on the torque required for unscrewing the healing abutment. A total of 27 implants were divided into 3 groups based on whether blood, blood and bone debris, or nothing was added. An electronic torque wrench was used to uniformly tighten the implants and healing abutments to 10 Ncm. These implants were then stored in a constant-temperature environment in physiological saline. After 1, 2, and 3 months, 3 implants from each group were randomly selected for microcomputed tomography analysis. Subsequently, an opening torque test was conducted to measure the maximum torque required to unscrew the healing abutment. The study data were compiled using Microsoft Excel 2019 and statistically analyzed with a statistical software package. One-way ANOVA was used to determine significant differences among groups, specifically by comparing and analyzing the bone volume fraction and maximum removal torque (RTQ) within the microgap between implants and healing abutments (α=.05). The in vitro simulated experiment revealed that the presence of blood mixed with bone debris led to an increase in high-density images within the microgap. Significant differences in the maximum removal torque were observed among the 3 groups 1, 2, and 3 months after in vitro placement (P<.05), indicating that blood and bone debris affected the torque required to unscrew the healing abutment. The presence of blood or bone debris in the microgap should be avoided to prevent an increase in the unscrewing torque.