Effect of mineralized dentin matrix on the prognosis of bone defect and retained root after coronectomy.

OBJECTIVE: To investigate the impact of mineralized dentin matrix (MDM) on the prognosis on bone regeneration and migration of retained roots after coronectomy. MATERIALS AND METHODS: Patients were divided into three groups based on the type of bone graft after coronectomy: Group C (n = 20, collagen), Group T (n = 20, tricalcium phosphate (TCP) + collagen), and Group D (n = 20, MDM + collagen). CBCT scans, conducted immediately and 6 months after surgery, were analyzed using digital software. Primary outcomes, including changes in bone defect depth and retained root migration distance, were evaluated 6 months after surgery. RESULTS: After 6 months, both Groups D and T exhibited greater reduction of the bone defect and lesser retained root migration than Group C (p < 0.001). Group D had greater regenerated bone volume in the distal 2 mm (73 mm3 vs. 57 mm3, p = 0.011) and lesser root migration (2.18 mm vs. 2.96 mm, p < 0.001) than Group T. The proportion of completely bone embedded retained roots was also greater in Group D than in Group C (70.0% vs. 42.1%, p = 0.003). CONCLUSIONS: MDM is an appropriate graft material for improving bone defect healing and reducing retained root migration after coronectomy. CLINICAL RELEVANCE: MDM is an autogenous material prepared chairside, which can significantly improve bone healing and reduce the risk of retained root re-eruption. MDM holds promise as a routine bone substitute material after M3M coronectomy.

A biphasic calcium phosphate/acylated methacrylate gelatin composite hydrogel promotes osteogenesis and bone repair.

PURPOSE/AIM: Bone defects caused by trauma, tumors, congenital malformation, or inflammation are very common in orthopedics. In recent years, mimicking the composition and structure of natural bone tissue has become a hot topic in biomaterial research, with the aim of developing an ideal biomaterial for bone defect transplantation. Here, the feasibility of a biphasic calcium phosphate (BCP)/acylated methacrylate gelatin (GelMA) composite hydrogel to repair bone defects was evaluated in vitro and in rats. MATERIALS AND METHODS: The biocompatibility of a biphasic calcium phosphate (BCP)/acylated methacrylate gelatin (GelMA) composite hydrogel was evaluated by cytoskeleton staining, live/dead cell staining and cell proliferation assays. The in vitro osteogenic activities of the composite hydrogel were evaluated by alkaline phosphatase and alizarin red staining, as well as osteogenic gene expression analysis at both transcript and protein levels. The in vivo bone repair activities were evaluated using the rat skull defect model. RESULTS: The BCP/GelMA composite hydrogel displayed excellent biocompatibility and promoted osteogenesis of bone marrow mesenchymal stem cells in vitro. In addition, the BCP/GelMA composite hydrogel markedly promoted new bone formation in the rat skull-defect model. CONCLUSIONS: BCP/GelMA composite hydrogel may be an effective artificial material for bone tissue engineering.

Effects of Allogeneic Bone Substitute Configurations on Cell Adhesion Process In Vitro.

OBJECTIVE: To explore the potential effect of three allogenic bone substitute configurations on the viability, adhesion, and spreading of osteoblasts in vitro. METHODS: Freeze-dried cortical bone were ground and fractions were divided into three groups with different sizes and shapes, defined as bone fiber (0.1 mm × 0.1 mm × 3 mm), bone powder (0.45-0.9 mm), and bone granule group (3-6 mm). MC3T3-E1 cells were divided and co-cultured within groups to induce cell adhesion. The configuration of allogenic bone was captured by scanning electron microscopy and confocal laser scanning microscopy, and substrate roughness values were quantified. Cell adhesion rate was assessed using the hemocyte counting method, cell viability was determined by CCK-8 assay and live/dead staining, and cell morphology was visualized by Phalloidin and DAPI, and the mRNA expression of adhesion-related gene (vinculin) of different substitutes were determined with quantitative real-time polymerase chain reaction. RESULTS: The roughness values of bone fiber, bone powder, and bone granule group were 1.878 µm (1.578-2.415 µm), 5.066 µm (3.891-6.162 µm), and 0.860 µm (0.801-1.452 µm), respectively (bone powder group compared with bone granule group, H = 18.015, P < 0.001). Similar OD values of all groups in CCK-8 assay indicated good biocompatibility of these substitutes (bone fiber, 0.201 ± 0.004; bone powder, 0.206 ± 0.008; bone granule group, 0.197 ± 0.006; and the control group, 0.202 ± 0.016, F = 0.7152, P > 0.05). In addition, representative cell adhesion rates at 24 h showed significantly lower cell adhesion rate in bone fiber group (20.3 ± 1.6%) compared to bone powder (29.3 ± 4.4%) and bone granule group (27.3 ± 3.2%) (F = 10.51，P = 0.009 and P = 0.034, respectively), but there was no significant difference between the latter two groups (P > 0.05). Interestingly, the expression of vinculin mRNA steadily decreased in a time-dependent manner. The vinculin expression reached its peak at 6 h in each group, and the vinculin levels in bone fiber, bone powder, and bone granule group were 2.119 ± 0.052, 3.842 ± 0.108, and 3.585 ± 0.068 times higher than those in the control group, respectively (F = 733.643, all P < 0.001). Meanwhile, there was a significant difference in the expression of target gene between bone powder and bone granule group (P = 0.006). CONCLUSION: All allogenic bone substitutes presented an excellent cell viability. Moreover, bone powder and bone granule group were more likely to promote cell adhesion and spreading compared to bone fiber group.

Spherical center and rotating platform hinged knee prosthesis: Finite-element model establishment, verification and contact analysis.

BACKGROUND: Biomechanical study is fundamental for the preclinical evaluation of knee prostheses. However, there are few reports on the contact characteristic investigation in the hinged knee prosthesis. The purpose of this study was to investigate the contact characteristics of a novel hinged knee prosthesis. METHODS: All of the component models were designed and assembled using Solidworks. A comparison of the contact area and ultra-high-molecular-weight polyethylene (UHMWPE) deformation using the experimental method (EM) and finite-element analysis (FEA) under 3000 N with the prosthesis at different flexions was performed. The peak contact pressure and von Mises stress on tibial insert and bushing were investigated under nine specific samples that were extracted from a gait cycle using FEA (according to ISO 14243-1: 2009). RESULTS: The largest contact area and UHMWPE deformation were 100.78 ± 8.71 mm2 and 0.085 ± 0.015 mm in the EM, and 96.68 mm2 and 0.096 mm in FEA. The peak contact pressure and von Mises stress on the tibial insert were 26.3071 MPa and 10.5115 MPa at 13% of the gait cycle and on bushing were consistently 0 MPa. The contact pressures were distributed at the posterior of the insert. CONCLUSION: The finite-element model was validated to be applicable for predicting the real prosthesis behavior based on the good correlation of the results using the EM and FEA. The model can help to identify contact characteristics and be can used in optimization studies of this novel prosthesis during the design phase.

Epidermal growth factor receptor-targeted immune magnetic liposomes capture circulating colorectal tumor cells efficiently.

AIM: To compare the capacity of newly developed epidermal growth factor receptor (EGFR)-targeted immune magnetic liposomes (EILs) vs epithelial cell adhesion molecule (EpCAM) immunomagnetic beads to capture colorectal circulating tumor cells (CTCs). METHODS: EILs were prepared using a two-step method, and the magnetic and surface characteristics were confirmed. The efficiency of capturing colorectal CTCs as well as the specificity were compared between EILs and EpCAM magnetic beads. RESULTS: The obtained EILs had a lipid nanoparticle structure similar to cell membrane. Improved binding with cancer cells was seen in EILs compared with the method of coupling nano/microspheres with antibody. The binding increased as the contact time extended. Compared with EpCAM immunomagnetic beads, EILs captured more CTCs in peripheral blood from colorectal cancer patients. The captured cells showed consistency with clinical diagnosis and pathology. Mutation analysis showed same results between captured CTCs and cancer tissues. CONCLUSION: EGFR antibody-coated magnetic liposomes show high efficiency and specificity in capturing colorectal CTCs.

[Tissue engineering study on chitosan-gelatin/hydroxyapatite composite scaffolds--osteoblasts culture].

OBJECTIVE: To investigate the behavior of rat calvarial osteoblasts cultured on chitosan-gelatin/hydroxyapatite (CS-Gel/HA) composite scaffolds. METHODS: The rat calvarial osteoblasts (the 3rd passage) were seeded at a density of 1.01 x 10(6) cells/ml onto the CS-Gel/HA composite scaffolds having porosity 85.20%, 90.40% and 95.80%. Cell number was counted after cultured for 3 days, 1 week, 2 weeks and 3 weeks. Cell proliferation, bone-like tissue formation, and mineralization were separately detected by HE, von Kossa histological staining techniques. RESULTS: The CS-Gel/HA composite scaffolds supported the attachment of seeded rat calvarial osteoblasts. Cells proliferated faster in scaffold with higher porosity 90.40% and 95.80% than scaffold with lower porosity 85.20%. The osteoblasts/scaffold constructs were feasible for mineral deposition, and bone-like tissue formation in 3 weeks. CONCLUSION: This study suggests the feasibility of using CS-Gel/HA composite scaffolds for bone tissue engineering.