OBJECTIVE: To explore the influence of the thickness of mixed cardboard on the compressive strength of glass ionomer cement and the associated factors. METHODS: Three different types of glass ionomer cements were mixed on the top of 60, 40, 20 and 1 pieces of paper (P60, P40, P20 and P1), respectively. The compressive strength of the materials was tested after solidification, and the bubble rate was calculated with the assistance of scanning electron microscope. RESULTS: (1) Compressive strength: ① ChemFil Superior glass ionomer (CF): The average compressive strength of P1 group was the highest, which was significantly different from that of P40 and P60 groups (P values were 0.041 and 0.032 respectively); ② To Fuji IX GP glass ionomer (IX): The average compressive strength of P1 group was the highest, which was statistically different from that of P40 and P60 groups (P values were 0.042 and 0.038 respectively); ③ Glaslonomer FX-Ⅱ glass ionomer cement (FX): The average compressive strength of P1 group was the highest, which was statistically different from that of P20, P40 and P60 groups (P values were 0.031, 0.040 and 0.041 respectively), but there was no statistical difference among the other groups. All the three materials showed that the compressive strength of glass ions gradually increased with the decrease of the thickness of the blended paperboard, and the two materials had a highly linear negative correlation, the correlation coefficients of which were CF-0.927, IX-0.989, FX-0.892, respectively. (2) Scanning electron microscope: P1 group had the least bubbles among the three materials. CONCLUSION It indicates that the thickness of mixed cardboard has a negative correlation with the compressive strength of glass ions. The thicker the mixed cardboard is, the greater the elasticity is. Excessive elasticity will accelerate the mixing speed when the grinding glass ions. Studies have shown that the faster the speed of artificial mixing is, the more bubbles is produced.The thicker ther mixed cardboard is, the more bubblesn are generated by glass ionomer cement, and the higher the compressive strength is. Using one piece of paper board to mix glass ionomer cement has the least bubbles and can obtain higher compressive strength.
Compressive Strength ; Materials Testing ; Glass Ionomer Cements ; Silicon Dioxide

BACKGROUND: Three-dimensional (3D) printed bone tissue engineering scaffolds have been widely used in research and clinical applications. β-TCP is a biomaterial commonly used in bone tissue engineering to treat bone defects, and its multifunctionality can be achieved by co-doping different metal ions. Magnesium doping in biomaterials has been shown to alter physicochemical properties of cells and enhance osteogenesis. METHODS: A series of Mg-doped TCP scaffolds were manufactured by using cryogenic 3D printing technology and sintering. The characteristics of the porous scaffolds, such as microstructure, chemical composition, mechanical properties, apparent porosity, etc., were examined. To further study the role of magnesium ions in simultaneously inducing osteogenesis and angiogenesis, human bone marrow mesenchymal stem cells (hBMSCs) and human umblical vein endothelial cells (HUVECs) were cultured in scaffold extracts to investigate cell proliferation, viability, and expression of osteogenic and angiogenic genes. RESULTS: The results showed that Mg-doped TCP scaffolds have the advantages of precise design, interconnected porous structure, and similar compressive strength to natural cancellous bone. hBMSCs and HUVECs exhibit high proliferation rate, cell morphology and viability in a certain amount of Mg²⁺. In addition, this concentration of magnesium can also increase the expression levels of osteogenic and angiogenic biomarkers. CONCLUSION: A certain concentration of magnesium ions plays an important role in new bone regeneration and reconstruction. It can be used as a simple and effective method to enhance the osteogenesis and angiogenesis of bioceramic scaffolds, and support the development of biomaterials and bone tissue engineering scaffolds.
Biocompatible Materials ; Biomarkers ; Bone and Bones ; Bone Marrow ; Bone Regeneration ; Cell Proliferation ; Compressive Strength ; Endothelial Cells ; Humans ; In Vitro Techniques ; Ions ; Magnesium ; Mesenchymal Stromal Cells ; Methods ; Osteogenesis ; Porosity ; Printing, Three-Dimensional ; Veins

The pH of the oral cavity can dynamically change due to diverse foods and beverages served. The purpose of the present study was to evaluate flexural and compressive properties of composite resins after immersion in solutions of different pHs. Four composite resins were cured and immersed in test solutions of different pHs (3, 7.1, and 9) for 2 weeks. Flexural and compressive properties (strength and modulus) were evaluated using universal test machine. After immersion, initial flexural and compressive strength significantly changed to 1.5–30.0% and 0.3–19.6%, respectively; flexural and compressive modulus significantly changed to 4.4–29.0% and 3.5–21.5%, respectively. However, the values obtained from solutions of different pHs were not significantly and consistently different to each other.
Beverages ; Composite Resins ; Compressive Strength ; Hydrogen-Ion Concentration ; Immersion ; Mouth

OBJECTIVE: To analyze the influence of different mixing pads on the physical and mechanical properties of glass ionomer cement. METHODS: Three different glass ionomer base cements were mixed with a plastic spatula on three different mixing pads including paper pad, glass pad and silicon pad whose HS were 40, 60 and 80. The GIC was packed into stainless steel molds to get specimens. Surface roughness, surface hardness and compressive strength were evaluated. RESULTS: As for compressive strength, CF: There was the highest mean compressive strength that was significantly higher than those of silicon pad 60 group, paper 60 group and paper 20 group in silicon pad 40 group, the differences P values were 0.002, 0.027, and 0.036, statistically significant difference between the above groups (P<0.05). IX: there was the highest mean compressive strength that was significantly higher than those of silicon pad 60 group in paper pad 20 group,the differences P value was 0.008, statistically significant (P<0.05). FX: there was the highest mean compressive strength that was no significantly higher than those of paper pad 20 group in silicon pad 40 group, but was significantly higher than those of the other groups. As for surface hardness, CF: there was the highest mean surface hardness that was significantly higher than those of silicon pad 60 and 80 group, paper 60 group in silicon pad 40 group, the differences P value was 0.021, 0.001, 0.032, 0.008 and 0.016, statistically significant difference between the above groups (P<0.05). IX and FX: there was no statistical significance between any two groups in surface hardness. As for surface roughness, CF: there was no statistical significance between any two groups in surface roughness. IX: there was the lowest mean surface roughness that was significantly lower than those of paper pad 40 and 60 group in glass pad group, the differences P values were 0.003 and 0.027, statistically significant difference between the above groups (P<0.05). FX: there was the lowest mean surface roughness that was significantly lower than those of paper pad 60 group in glass pad group, the differences P value was 0.018, showing a statistical difference (P<0.05). CONCLUSION Mixing glass ionomer cement on silicon pad 40 results in higher compressive strength and lower surface roughness, worthy of clinical popularization.
Compressive Strength ; Glass Ionomer Cements ; Hardness ; Materials Testing ; Surface Properties

In maxillofacial surgery, there is a significant need for the design and fabrication of porous scaffolds with customizable bionic structures and mechanical properties suitable for bone tissue engineering. In this paper, we characterize the porous Ti6Al4V implant, which is one of the most promising and attractive biomedical applications due to the similarity of its modulus to human bones. We describe the mechanical properties of this implant, which we suggest is capable of providing important biological functions for bone tissue regeneration. We characterize a novel bionic design and fabrication process for porous implants. A design concept of "reducing dimensions and designing layer by layer" was used to construct layered slice and rod-connected mesh structure (LSRCMS) implants. Porous LSRCMS implants with different parameters and porosities were fabricated by selective laser melting (SLM). Printed samples were evaluated by microstructure characterization, specific mechanical properties were analyzed by mechanical tests, and finite element analysis was used to digitally calculate the stress characteristics of the LSRCMS under loading forces. Our results show that the samples fabricated by SLM had good structure printing quality with reasonable pore sizes. The porosity, pore size, and strut thickness of manufactured samples ranged from (60.95± 0.27)% to (81.23±0.32)%, (480±28) to (685±31) μm, and (263±28) to (265±28) μm, respectively. The compression results show that the Young's modulus and the yield strength ranged from (2.23±0.03) to (6.36±0.06) GPa and (21.36±0.42) to (122.85±3.85) MPa, respectively. We also show that the Young's modulus and yield strength of the LSRCMS samples can be predicted by the Gibson-Ashby model. Further, we prove the structural stability of our novel design by finite element analysis. Our results illustrate that our novel SLM-fabricated porous Ti6Al4V scaffolds based on an LSRCMS are a promising material for bone implants, and are potentially applicable to the field of bone defect repair.
Alloys ; Bionics ; Bone Substitutes/chemistry* ; Bone and Bones/pathology* ; Compressive Strength ; Elastic Modulus ; Finite Element Analysis ; Humans ; Lasers ; Materials Testing ; Maxillofacial Prosthesis Implantation ; Porosity ; Pressure ; Printing, Three-Dimensional ; Prostheses and Implants ; Prosthesis Design ; Stress, Mechanical ; Surgery, Oral/instrumentation* ; Tissue Engineering/methods* ; Titanium/chemistry*

Flowable resins can be used as a base material during the restoration of deep tooth cavity. The purpose of the present study was to evaluate the mechanical properties of the layered specimens which have flowable resin as a base material. For the study, two composite resins and five flowable resins were chosen for the overlying and base materials, respectively. Flexural and compressive properties of each bulk and ten layered specimens were measured. Layered specimens showed high flexural strength (FS) and flexural modulus (FM) if bulk state FS and FM of the base flowable resin are high. However, compressive strength (CS) was not that case. CS of the layered specimen was not high (251.4~295.3 MPa) whether CS of the bulk state is high or not (259.8~439.8 MPa). FM showed high linear correlation with CM. After all mechanical properties of the layered specimens were not consistently influenced by the mechanical properties of the base flowable resins regardless of the overlying composite resins.
Composite Resins ; Compressive Strength ; Tooth

A rapid freezing/lyophilizing/reinforcing process is suggested to fabricate reinforced keratin/hydroxyapatite (HA) scaffold with improved mechanical property and biocompatibility for tissue engineering. The keratin, extracted from human hair, and HA mixture were rapidly frozen with liquid nitrogen and then lyophilized to prepare keratin/HA laminar scaffold. The scaffold was then immersed in PBS for reinforcement treatment, and followed by a second lyophilization to prepare the reinforced keratin/HA scaffold. The morphology, mechanical, chemical, crystal and thermal property of the keratin/HA scaffold were investigated by SEM, FTIR, XRD, DSC, respectively. The results showed that the keratin/HA scaffold had a high porosity of 76.17 ± 3%. The maximum compressive strength and compressive modulus of the reinforced scaffold is 0.778 and 3.3 MPa respectively. Subcutaneous implantation studies in mice showed that in vivo the scaffold was biocompatible since the foreign body reaction seen around the implanted scaffold samples was moderate and became minimal upon increasing implantation time. These results demonstrate that the keratin/HA reinforced scaffold prepared here is promising for biomedical utilization.
Animals ; Compressive Strength ; Durapatite ; Foreign-Body Reaction ; Freeze Drying ; Hair ; Humans ; Mice ; Nitrogen ; Porosity ; Spectroscopy, Fourier Transform Infrared ; Tissue Engineering

BACKGROUND: Type 2 diabetes mellitus is associated with an increased risk of osteoporotic fracture despite relatively preserved bone mineral density (BMD). Although this paradox might be attributed to the influence of insulin resistance (IR) on bone structure and material properties, the association of IR with femur bone geometry and strength indices remains unclear. METHODS: Using data from the Cardiovascular and Metabolic Disease Etiology Research Center cohort study, we conducted a cross-sectional analysis among nondiabetic postmenopausal women. IR was estimated using the homeostasis model assessment of IR (HOMA-IR). Compartment-specific volumetric BMD (vBMD) and bone volume of proximal femur were measured using quantitative computed tomography. The compressive strength index (CSI), section modulus (Z), and buckling ratio of the femoral neck were calculated as bone strength indices. RESULTS: Among 1,008 subjects (mean age, 57.3 years; body mass index [BMI], 23.6 kg/m²), BMI, waist circumference, and vBMD of the femoral neck and total hip increased in a linear trend from the lowest ( < 1.37) to highest (≥2.27) HOMA-IR quartile (P < 0.05 for all). The HOMA-IR showed an independent negative association with total bone volume (standardized β=−0.12), cortical volume (β=−0.05), CSI (β=−0.013), and Z (β=−0.017; P < 0.05 for all) of the femoral neck after adjustment for age, weight, height, physical activity, and vitamin D and high-sensitivity C-reactive protein levels. However, the association between HOMA-IR and vBMD was attenuated in the adjusted model (femoral neck, β=0.94; P=0.548). CONCLUSIONS: Elevated HOMA-IR was associated with lower cortical bone volume and bone strength indices in nondiabetic postmenopausal women, independent of age and body size.
Body Mass Index ; Body Size ; Bone Density ; C-Reactive Protein ; Cohort Studies ; Compressive Strength ; Cross-Sectional Studies ; Diabetes Mellitus, Type 2 ; Female ; Femur Neck ; Femur* ; Hip ; Homeostasis ; Humans ; Insulin Resistance* ; Insulin* ; Metabolic Diseases ; Motor Activity ; Neck ; Osteoporosis ; Osteoporotic Fractures ; Postmenopause ; Vitamin D ; Waist Circumference

OBJECTIVES: This study evaluated the effects of a bleaching agent on the composition, mechanical properties, and surface topography of 6 conventional glass-ionomer cements (GICs) and one resin-modified GIC. MATERIALS AND METHODS: For 3 days, the specimens were subjected to three 20-minute applications of a 37% H2O2-based bleaching agent and evaluated for water uptake (WTK), weight loss (WL), compressive strength (CS), and Knoop hardness number (KHN). Changes in surface topography and chemical element distribution were also analyzed by energy-dispersive X-ray spectroscopy and scanning electron microscopy. For statistical evaluation, the Kruskal-Wallis and Wilcoxon paired tests (a = 0.05) were used to evaluate WTK and WL. CS specimens were subjected to 2-way analysis of variance (ANOVA) and the Tukey post hoc test (α = 0.05), and KH was evaluated by one-way ANOVA, the Holm-Sidak post hoc test (a = 0.05), and the t-test for independent samples (a = 0.05). RESULTS: The bleaching agent increased the WTK of Maxxion R, but did not affect the WL of any GICs. It had various effects on the CS, KHN, surface topography, and the chemical element distribution of the GICs. CONCLUSIONS: The bleaching agent with 37% H2O2 affected the mechanical and surface properties of GICs. The extent of the changes seemed to be dependent on exposure time and cement composition.
Compressive Strength ; Dental Materials ; Glass Ionomer Cements ; Hardness ; Microscopy, Electron, Scanning ; Spectrum Analysis ; Surface Properties ; Tooth Bleaching Agents ; Water ; Weight Loss

OBJECTIVE: To investigate the physical and chemical properties of pulp capping materials based on bioactive glass (BG). METHODS: Novel BG pulp capping materials were composed of powder and fluid. The powder was BG (82.36% SiO₂, 15.36% CaO, and 2.28% P₂O₅) synthesized by using the sol-gel method combined with template technology. Two kinds of fluid were provided: (1) phosphate buffer (PB) solution and (2) phosphate buffer solution with 1% sodium alginate (SA) addition. After mixing the powder and fluid, BG-PB and BG-PB-SA were prepared. Setting time and compressive strength of the BG pulp capping materials were tested by setting time loading system and mechanical testing machine. Statistical analysis was performed using the independent sample t-test, with the significance set at 0.05. pH meters was used to test the pH of the BG pulp capping materials and mineral trioxide aggregate (MTA). The sealing ability of the BG pulp capping materials and MTA was tested by methylene blue dye leakage model. Statistical analysis was performed using one-way ANOVA analysis and LSD multiple comparison, with the significance set at 0.05. RESULTS: (1) Setting time: the initial and final setting time of BG-PB were (7.2±0.3) min and (12.7±0.9) min, respectively. And the initial and final setting time of BG-PB-SA was (7.5±0.3) min and (13.6±1.6) min. There was no significant difference between BG-PB and BG-PB-SA groups (P>0.05). (2) Compressive strength: the compressive strength of BG-PB was (16.5±1.8) MPa at 1 day and (14.1±3.7) MPa at the end of 28 days. However, the compressive strength of BG-PB-SA was (26.6±6.3) MPa on day 1 and (21.6±5.6) MPa on day 28, which was significantly higher than that of BG-PB (P<0.05). (3) pH: the pH of BG pulp capping materials' bulk immersed in simulated body fluid (SBF) went up to 8.06, and the highest pH of MTA was 8.47. Significant difference was observed between the BG pulp capping materials and MTA (P<0.05). (4) Sealing ability: the optical density (D) in positive control group was significantly higher than ln BG-PB, BG-PB-SA and MTA groups (P<0.05). And BG-PB and BG-PB-SA showed the similar favorable sealing ability with MTA, and no significant difference was observed among the three groups (P>0.05). CONCLUSION The novel BG pulp capping materials showed good physical properties, especially BG's setting time was short; BG pulp capping materials are promising.
Aluminum Compounds ; Calcium Compounds ; Compressive Strength ; Dental Pulp Capping ; Glass ; Materials Testing ; Oxides ; Silicates ; Silicon Dioxide