Mechanical properties of trabecular bone were major particulars to understand a bone's quality and a information of osteoporotic patients. In a measurement of trabecular bone's properties, however, it was very difficult to extract and prepare it's specimen. Thus the goal of this study was to estimate the validity for indentation test which widely used as a non-destructive test of porous materials such as a trabecular bone using a FE analysis. We composed the FE model based on uniaxial compression test and clinical observation. It was able to extend for the simulation of indentation test. In addition to that, this FE model well imitated a behavior of a trabecular bone. We obtained a load-displacement curve by the indentation simulation and calculated the elastic modulus using Pharr's hypothesis. We estimated the validity of the indentation test by comparing compression simulation and indentation simulation. When indenter diameter was five times of pore size, the result of indentation simulation converged on compression simulation. If indentation depth was insufficient, the result of indentation simulation made serious errors. Therefore, to obtain the appropriate result of the indentation test, indenter diameter have to be five times of pore size and indentation depth should be about 8% of indenter diameter at least.
Elastic Modulus ; Humans

PURPOSE: The aim of this study was to evaluate the biaxial flexural strength (BFS) of one zirconia-based ceramic used with various veneering ceramics. MATERIALS AND METHODS: Zirconia core material (Katana) and five veneering ceramics (Cerabien ZR; CZR, Lava Ceram; LV, Cercon Ceram Kiss; CC, IPS e.max Ceram; EM and VITA VM9; VT) were selected. Using the powder/liquid layering technique, bilayered disk specimens (diameter: 12.50 mm, thickness: 1.50 mm) were prepared to follow ISO standard 6872:2008 into five groups according to veneering ceramics as follows; Katana zirconia veneering with CZR (K/CZR), Katana zirconia veneering with LV (K/LV), Katana zirconia veneering with CC (K/CC), Katana zirconia veneering with EM (K/EM) and Katana zirconia veneering with VT (K/VT). After 20,000 thermocycling, load tests were conducted using a universal testing machine (Instron). The BFS were calculated and analyzed with one-way ANOVA and Tukey HSD (alpha=0.05). The Weibull analysis was performed for reliability of strength. The mode of fracture and fractured surface were observed by SEM. RESULTS: It showed that K/CC had significantly the highest BFS, followed by K/LV. BFS of K/CZR, K/EM and K/VT were not significantly different from each other, but were significantly lower than the other two groups. Weibull distribution reported the same trend of reliability as the BFS results. CONCLUSION: From the result of this study, the BFS of the bilayered zirconia/veneer composite did not only depend on the Young's modulus value of the materials. Further studies regarding interfacial strength and sintering factors are necessary to achieve the optimal strength.
Ceramics* ; Elastic Modulus

This study was to compare the tensile bond strength and flexibility of four different soft liners(Coe Soft, Soft Relining, Soft Liner, Dura Base Soft) before & after thermocycling. Each soft liner was bonded to denture base resin block, and measured the tensile bond strength and modulus of elasticity using Universal testing machine. The mean value of tensile bond strength and modulus of elasticity for each experimental groups were statistically processed by SPSS(Statistical Package of Social Sience). The obtained results were as follows : 1. Dura Base Soft had the highest tensile bond strength and Coe Soft had the lowest tensile bond strength. 2. Coe Soft had the lowest modulus of elasticity, and Dura Base Soft had the highest modulus of elasticity of all the soft liners. 3. Thermocycling \ no effects on the tensile bond strength and modulus of elasticity of all the soft liners. 4. The failure modes of Coe Soft, Soft Relining, Soft Liner were mainly cohesive failure and that of Dura Base Soft were mainly adhesive failure.
Adhesives ; Denture Bases ; Dentures* ; Elastic Modulus* ; Pliability

We intended to evaluate the Young's modulus of trabecular bone and apparent density from Computed Tomography(CT) and Spherical Indentation test and to quantify relation ship between them. The distal femurs(31 age, male, left and right) were prepared for exprimentatin and were embedded with repect to anatomical orientation. Then the specimens were scnned at 1 mm intervals on GE9800 CT scanner and the Hounsfield Units(HU, or CT number) were extracted from each CT image. After scanning, the bones were sectioned with diamond saw, producing 8 mm cubes of trabecular bone(72 eachs) from the metaphyseal region of both distal femur. The cubes were mechanically tested in inferior-superior(IS), anteriorposterior(AP), and medial-lateral(ML) direction with custom-made device, Spherical Indentatin Tester. After testing, the real apparent density of specimens were measured. The results of this study showed that the IS modulus was singificantly greater than both the AP and ML modulus and the AP modulus was also greater than ML modulus significantly(p<0.01). A linear relation ship between HU and real apparent density was found to be significant(R2=0.68) and significant power relationship between the apparent density and the tangent moduli(either by CT or physical measures) was also found.
Diamond ; Elastic Modulus* ; Femur ; Humans* ; Male ; Ships

The post core system has been used for reconstructon of severely damaged crown by caries or trauma.But problems such as crown exfoliation,post core fracture and root fracture have been reported. Ideal mechanical properties of the post require high fracture strength,high elastic limit and high resistance against fatigue and corrosion.Modulus of elasticity of the post should be similar with that of dentine.Low hardness is also required for the convenience of post removal in failure.Furthermore, the post itself must be translucent for the esthetical purpose.Several types of the post have been developed to satisfy the criteria above mentioned. The purpose of this study was to find out the mechanical properties of quartz fiber post by comparing with those of gold post and zirconia post. The results of this study were as follows : 1.Maximal fracture strength and stiffness of quartz fiber post were similar with those of gold post and zirconia post. 2.Young's modulus and hardness of quartz fiber post were lower than those of gold post and zirconia post. Mechanical property of quartz fiber post against post fracture was similar with that of gold post and zirconia post.Mechanical property of quartz fiber post against root fracture was higher than that of gold post and zirconia post.Quartz fiber post could be removed easily due to low hardness.
Crowns ; Elastic Modulus ; Elasticity ; Fatigue ; Hardness ; Quartz*

PURPOSE: Direct splinting material should have high flexural strength to withstand force during mastication and low modulus of elasticity to provide some movement while force applied for relief of stress. The purpose of this study was to compare flexural strength and modulus of elasticity of several resinous splinting materials. MATERIALS AND METHODS: Four materials; Super-Bond C&B, G-FIX, G-aenial Universal Flo, FiltekTM Z350 XT; were used in this study. Fifteen rectangular bar specimens of each material were prepared. Three-point bending test were performed to determine physical properties. Maximum load at fracture was recorded and flexural strength and modulus of elasticity were calculated. One-way analysis of variance (ANOVA) and Scheffe's tests at a 0.05 level of significance were conducted on all test results. RESULTS: Statistical analysis reveals that Super-Bond C&B had significant low mean value for flexible strength and the other three materials showed no significant difference. For modulus of elasticity, Super-Bond C&B exhibited statistically lower modulus of elasticity. G-FIX presented intermediate result, showing statistically higher modulus of elasticity than Super-Bond C&B but lower than G-aenial Universal Flo and FiltekTM Z350 XT. There was no significant difference on modulus of elasticity between G-aenial Universal Flo and FiltekTM Z350 XT. CONCLUSION: Using a G-FIX, the newly commercially available splinting material, which shows higher fracture resistance properties comparable to flowable and restorative composite resin and a relatively flexible nature might be a beneficial for stabilizing teeth mobility.
Elastic Modulus* ; Mastication ; Splints* ; Tooth Mobility ; Tooth*

PURPOSE: To evaluate the relationship between morphometric analysis of bone microstructure from digital radiographic image and trabecular bone strength. MATERIALS AND METHODS: One hundred eleven bone specimens with 5 mm thickness were obtained from the mandibles of 5 pigs. Digital images of specimens were taken using a direct digital intraoral radiographic system. After selection of ROI (100x100 pixel) within the trabecular bone, mean gray level and standard deviation were obtained. Fractal dimension and the variants of morphometric analysis (trabecular area, periphery, length of skeletonized trabeculae, number of terminal point, number of branch point) were obtained from ROI. Punch sheer strength analysis was performed using Instron (model 4465, Instron Corp., USA). The loading force (loading speed 1 mm/min) was applied to ROI of bone specimen by a 2 mm diameter punch. Stress-deformation curve was obtained from the punch sheer strength analysis and maximum stress, yield stress, Young's modulus were measured. RESULTS: Maximum stress had a negative linear correlation with mean gray level and fractal dimension significantly (p< 0.05). Yield stress had a negative linear correlation with mean gray level, periphery, fractal dimension and the length of skeletonized trabeculae significantly (p< 0.05). Young's modulus had a negative linear correlation with mean gray level and fractal dimension significantly (p< 0.05). CONCLUSIONS: The strength of cancellous bone exhibited a significantly linear relationship between mean gray level, fractal dimension and morphometric analysis. The methods described above can be easily used to evaluate bone quality clinically.
Elastic Modulus ; Fractals ; Mandible ; Radiography ; Skeleton ; Swine

The purpose of this study was to evaluate the shock absorbing effect of 4 restorative materials and intramobile connector. The damping effect of four restorative materials used to veneer test crown rigidly connected to IMZ implant and subjected to an impact force was measured. These materials included a gold alloy(stabilor G) : a noble metal ceramic alloy(Degudent H) : porcelain(Duceram) : composite resin(Dentacolor). In addition, this study compared damping effect of same restoretive materials after using polyoxymethylene intramobile connector(POM IMC). The result of this study suggest that : *In case of using metal IMC 1. Veneered composite resin(group IV) reduced the impact force by 75%, when compared to an equivalent thickness of porcelain(group III). Group IV reduced the impact force by 87% and 89%, respectively, when compared to Stabilor G(group I) and Degudent H(group II). 2. The impact force recorded was higher for the alloy with the higher elastic modulus.(Stabilor G, group I, Young's modulus 107 Gpa, versus Degudent H, Group II, Young's modulus 95 Gpa) 3. It took the longest time for composite resin veneered group(IV) to reach to peak force when compared group I, II, III. *In case of using POM IMC 4. The mean impact force recorded were reduced by 79%(group I), 78%(group II), 69%(group III), 84%(group IV), respectively, when compared to using metal IMC. 5. The time required to reach the peak force were increased by 78%(group I, II) 87% (group III), 34% (group IV), respectively, when compared to using metal IMC
Alloys ; Ceramics ; Crowns ; Elastic Modulus ; Shock

OBJECTIVE: The aim of this systematic multiscale analysis was to evaluate the effects of thermoforming on the physical and mechanical properties of thermoplastic materials used to fabricate transparent orthodontic aligners (TOAs). METHODS: Specimens were fabricated using four types of thermoplastic materials with different thicknesses under a thermal vacuum. Transparency, water absorption and solubility, surface hardness, and the results of three-point bending and tensile tests were evaluated before and after thermoforming. Data were analyzed using one-way analysis of variance and Student's t-test. RESULTS: After thermoforming, the transparency of Duran and Essix A+ decreased, while the water absorption ability of all materials; the water solubility of Duran, Essix A+, and Essix ACE; and the surface hardness of Duran and Essix A+ increased. The flexure modulus for the 0.5-mm-thick Duran, Essix A+, and eCligner specimens increased, whereas that for the 0.75-/1.0-mm-thick Duran and eClginer specimens decreased. In addition, the elastic modulus increased for the 0.5-mm-thick Essix A+ specimens and decreased for the 0.75-mm-thick Duran and Essix ACE and the 1.0-mm-thick Essix ACE specimens. CONCLUSIONS: Our findings suggest that the physical and mechanical properties of thermoplastic materials used for the fabrication of TOAs should be evaluated after thermoforming in order to characterize their properties for clinical application.
Elastic Modulus ; Hardness ; Solubility ; Vacuum ; Water

The aim of this study was to examine that thick dentin bonding agent application or low modulus composite restoration could reduce stresses on dentin bonding agent layer. A mandibular first premolar with abfraction lesion was modeled by finite element method. The lesion was restored by different composite resins with variable dentin bonding agent thickness (50microm, 100microm, 150microm). 170N of occlusal loading was applied buccally or lingually. Von Mises stress on dentin bonding agent layer were measured. When thickness of dentin bonding agent was increased von Mises stresses at dentin bonding agent were decreased in both composites. Lower elastic modulus composite restoration showed decreased von Mises stresses. On root dentin margin more stresses were generated than enamel margin. For occlusal stress relief at dentin boning agent layer to applicate thick dentin bonding agent or to choose low elastic modulus composite is recommended.
Bicuspid ; Composite Resins ; Dental Enamel ; Dentin ; Elastic Modulus