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Rana, Muhammad H., Sharaz Shaik, Mohammad S. Hameed, Samar Al-Saleh, Eman M. AlHamdan, Abdullah Alshahrani, Abdulaziz Alqahtani, Ahmed Heji Albaqawi, Fahim Vohra, and Tariq Abduljabbar. "Influence of Dental Glass Fibers and Orthopedic Mesh on the Failure Loads of Polymethyl Methacrylate Denture Base Resin." Polymers 13, no. 16 (August 20, 2021): 2793. http://dx.doi.org/10.3390/polym13162793.
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The aim of the present study was to evaluate the fracture loads of polymethyl methacrylate (PMMA) complete denture bases reinforced with glass-fiber mesh and orthopedic casting tape (OCT) in comparison to conventional PMMA dentures under artificial aging. Dental fiberglass framework (Group 1) and OCT (Group 2 and 3) reinforced PMMA acrylic dentures were fabricated on the edentulous ridge. Ten PMMA dentures without reinforcement (Group 4) were included as controls. All specimens were placed in a chewing simulator chamber, and fatigue load was applied. To assess the fracture loads, static loads with a universal testing machine were applied. Fractured specimens in each group were evaluated under a scanning electron microscope. The data were statistically analyzed employing analysis of variance and Tukey post-hoc test. The association of denture weight and thickness on fracture load was assessed using Pearson and Spearman correlations. Dental fiberglass (Group 1) displayed the highest fracture load (692.33 ± 751.41 N), and Group 4 (control) exhibited the lowest fracture loads (281.41 ± 302.51 N). Dentures reinforced with fiberglass mesh framework exhibited intact fractures. In contrast, Group 2 and 3 specimens using OCT demonstrated ditching fractures. It was observed that the thickness and weight of all the reinforced specimens influenced the load required to fracture the dentures (p < 0.001). Denture specimens strengthened with OCT (Groups 2 and 3) exhibited failure loads lower than dental fiberglass (Group 1) specimens but higher than unreinforced controls.
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Van der Kolk - Bender, Celine A., Maarten J. Koudstaal, and Eppo B. Wolvius. "Treatment of Severely Atrophic Edentulous Mandible Fractures: Load-Bearing or Load-Sharing?" Craniomaxillofacial Trauma & Reconstruction Open 2, no. 1 (January 2018): s—0038–1667295. http://dx.doi.org/10.1055/s-0038-1667295.
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Several nonsurgical and surgical techniques have been employed to treat fractures of the severely atrophic mandible. The aim of this study was to analyze the repair outcome of these fractures. From 2010 to 2016, patients with fractures of the severely atrophic mandible were included. All files were retrospectively studied. Twelve patients (mean age: 76 years; female, n = 8) with a single ( n = 6) or multiple fracture(s) of the atrophic edentulous mandible (mean height was 10.1 mm) were identified. Fracture occurred following trauma ( n = 9), explantation of dental implants ( n = 2), and placing an overdenture bar ( n = 1). In seven cases, consolidation was successful following open reduction and internal fixation (ORIF) using a load-bearing reconstruction plate. In five cases, the initial treatment was different: conservative treatment, using gunning splint, and performing ORIF using miniplates. In all five cases, additional ORIF using a load-bearing reconstruction plate was needed. In four cases, short dental implants were placed several months following fracture repair. In case of a severely atrophic mandibular fracture, the authors advise ORIF with a load-bearing reconstruction plate. In selected cases, secondary oral rehabilitation with short dental implants and implant-supported prosthesis is feasible.
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Almas, Khalid, Esam Tashkandi, Philippe Aramouni, Elie Zebouni, and Salam Dib. "Fracture Resistance and Failure Location of Zirconium and Metallic Implant Abutments." Journal of Contemporary Dental Practice 9, no. 7 (2008): 41–48. http://dx.doi.org/10.5005/jcdp-9-7-41.
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Abstract Aim The purpose of this study was to evaluate the fracture resistance and failure location of single-tooth, implant-supported, all-ceramic restorations on different implant abutments subjected to a maximum load. Methods and Materials Forty Certain 3i implants and 20 ITI Straumann implants were used in this study in combination with 20 UCLA abutments, 20 ZiReal abutments, and 20 synOcta Ceramic Blanks to form three groups according to abutment type. All 60 abutments were prepared with standard measurements: a 1.0 mm deep chamfer, 2.0 mm of incisal reduction, and a total height of 7 mm. Sixty IPS Empress 2 full ceramic crowns were fabricated and cemented on each abutment with a resin cement. Static loading was simulated under maximum loading and fracture locations were noted. Results The mean load to failure data and standard deviations for the three groups were as follows: Group 1 (792.7 N ± 122.5) and Group 3 (793.6 ± 162.3) showed no significant difference in fracture resistance while the values for specimens in Group 2 (604 N ± 191.1) had the lowest mean value and were significantly lower. In Group 1, 16 crowns and four abutment fractures were reported, while in Group 3, 17 crowns and three abutments fractured. Group 2 actually showed three types of fractures. Two specimen fractures were located at the implant level, six with fractures occuring within the Empress 2 all-ceramic crown, and the remaining 12 failures were located at the abutment level. Conclusion Within the limitations of this laboratory study, the following conclusions were drawn: The mean load-to-failure values for all three groups were well above the reported normal maximal incisal load range. The load to failure for both the zirconium oxide (ZrO2) abutments (ZiReal on 3i Certain implants and synOcta Ceramic Blanks on SLA ITI Straumann implants) had mean fracture loads of 792.7 N (+122.6) and 604.2 N (+191.2), respectively. The zirconium oxide (ZrO2) ZiReal and titanium (UCLA) abutments on the 3i Certain implants had statistically significantly higher fracture loads (792.7 N and 703.7 N, respectively) than those recorded for the 3i Ceramic Blank abutments on the SLA ITI Straumann implant (604.2 N). The ITI Straumann Ceramic Blank abutments showed uniform fracture behavior. Fracture mainly emanated from the cervical buccal aspect of the abutment. Clinical Significance The three abutments tested showed they can withstand clinical loads above the normal range of mastication. Citation Aramouni P, Zebouni E, Tashkandi E, Dib S, Salameh Z, Almas K. Fracture Resistance and Failure Location of Zirconium and Metallic Implant Abutments. J Contemp Dent Pract 2008 November; (9)7:041-048.
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Kamgue Lenwoue, Arnaud, Jingen Deng, Yongcun Feng, Haitao Li, Adefarati Oloruntoba, Naomie Songwe Selabi, Micheal Marembo, and Yuanxiu Sun. "Numerical Investigation of the Influence of the Drill String Vibration Cyclic Loads on the Development of the Wellbore Natural Fracture." Energies 14, no. 7 (April 6, 2021): 2015. http://dx.doi.org/10.3390/en14072015.
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Wellbore instability is one of the most serious issues faced in the drilling process. During drilling operations, the cyclic loads applied on the fractured formation progressively modify the initial parameters (i.e., length and width) of the fractured formation, thus resulting into undesirable wellbore instability. In this paper, using a nonlinear finite element software (ABAQUS) as the numerical simulator, a poro-elasto-plastic model has been established which aimed at analyzing the influence of drill string vibration cyclic loads on the development of the wellbore natural fracture. The numerical results showed that the fracture width as a function of time profiles followed a sinusoidal behavior similar to the drill string vibration cyclic load profiles. For different cyclic load magnitudes with constant number of cyclic loads, the highest percentage increase of the fracture width after integration of cyclic loads was 64.77%. Interestingly, the fracture width increased with the fracture length in the near wellbore region while it globally decreased in the region far away from the wellbore. But for constant cyclic load magnitude with different number of cyclic loads, the biggest percentage increase of the fracture width after integration of cyclic loads was slightly lower representing 63.12% while the oscillating period of the fracture width increased with the number of cyclic loads. The parametric study revealed that the drill string vibration cyclic loads were relatively independent of the fracture length and the bottom hole pressure. However, the fracture width and the loss circulation rates were considerably impacted by the drill string vibration and the highest percentage increase of the loss circulation rate after integration of cyclic loads was 14.3%. This study provides an insight into the coupling of the fracture rock development and the continuous cyclic loads generated by drill string vibrations which is an aspect that has been rarely discussed in the literature.
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Gaintantzopoulou, Maria D., Eleftherios T. Farmakis, and George C. Eliades. "Effect of Load Cycling on the Fracture Strength/Mode of Teeth Restored with FRC Posts or a FRC Liner and a Resin Composite." BioMed Research International 2018 (August 14, 2018): 1–10. http://dx.doi.org/10.1155/2018/9054301.
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The aim of the study was to comparatively evaluate the fracture strength and mode of root canal treated teeth restored with resin composites with and without posts. The lingual cusps of root canal treated first upper premolars (n = 10/group) were removed down to cervical enamel and restored with the following: group A: glass-fiber post (Glassix) followed by a particulate-filled composite resin (PFC, G-aenial posterior, 3 × 2 mm layers); group B: glass-fiber reinforced composite bulk fill liner (EverX posterior, 4 mm layer) with the PFC (2 mm layer). Specimens were immersed in H2O (1 w/37°C), then subjected to load cycling (50 N/0.2 Hz/200k cycles), and fractured under compressive loading. Failure mode was characterized by stereomicroscopy. Statistical analysis was performed by Mann-Whitney (load) and Chi-square (mode) at a = 0.05. No statistically significant differences (p = 0.273) were found in fracture load between median values of groups A (860 N) and B (1059 N). In group A, 60% of the specimens demonstrated catastrophic root fractures and 40% mixed crown fractures (tooth cusp and restoration), whereas in group B, no root fractures were found, and the failure modes were equally distributed between mixed fractures as above and fracture of the buccal cusp. These differences were statistically significant (p = 0.004). The combination of the glass-FRC bulk fill liner with the PFC diminished the catastrophic root fractures induced by FRC posts, at a similar or higher fracture load.
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Guo, Baohua, and Hangyu Dong. "Shear failure modes and AE characteristics of sandstone and marble fractures." Open Geosciences 11, no. 1 (June 12, 2019): 249–62. http://dx.doi.org/10.1515/geo-2019-0020.
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Abstract To study the shear failure modes of rock fractures with different morphologies, rock types and test conditions, direct shear tests were conducted with the aid of an acoustic emission test system to obtain the characteristics of acoustic emissions in the shear process. The test results indicated that sandstone fractures experienced brittle shear failure under higher constant normal loads (15-30 kN) and plastic shear failure under lower normal loads (5 kN and 10 kN), while the marble fracture experienced plastic shear failure under each normal load. Dropping of shear stress, sharp change from shear dilatation to shear shrinkage and sudden release of high AE energy could be found when brittle shear failure occurred in sandstone fracture under a higher normal load. Thus, combining the location evolution characteristics of acoustic emission, it can be concluded that the entire shear dislocation of sandstone fracture in brittle shear failure mode happened just after the peak under higher normal loads. However, the entire shear dislocation of sandstone fracture under lower normal loads and marble fracture under all normal loads occurred just at the beginning of the shear process.
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Ti, Zhengyi, Jiazhen Li, Meng Wang, Kang Wang, Zhupeng Jin, and Caiwang Tai. "Fracture Mechanism in Overlying Strata during Longwall Mining." Shock and Vibration 2021 (June 21, 2021): 1–15. http://dx.doi.org/10.1155/2021/4764732.
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We used the key stratum theory to establish a more realistic thin-plate mechanical model of elastic foundation clamped boundary and study the fracture mechanism of overlying strata during longwall mining. We analyzed the fracture characteristics and factors affecting fracture of the key stratum combined with the Mohr–Coulomb yield criterion. Besides, we used numerical simulation methods to verify the evolution pattern of the overlying strata fracture. The results show that the fracture mechanisms of the elastic foundation clamped structure’s key stratum varied depending on the position under longwall mining. The advanced coal wall area of the upper surface is a compressive-shear fracture. The center area of the lower surface is a tensile fracture. With the increase of the excavation length and the load of the key stratum, the central area and the advanced coal wall area of the long side are fractured before the advanced coal wall area of the short side. With the increase of flexural rigidity of the key stratum, the advanced coal wall area of the long side fractures before the central area and the advanced coal wall area of the short side. With the increase of the foundation modulus and the advanced load of the key stratum, the central area fractures before the surrounding advanced coal wall area. The advanced influence distance was positively correlated with the key stratum’s flexural rigidity and advanced load and negatively correlated with the foundation modulus and excavation length. The advanced influence distance was not affected by the load of the key stratum. The numerical simulation results show that, with the increase of the mining area, the fracture trace of overlying strata in goaf extended to the coal wall’s interior. The fracture range of overlying strata is larger than that of the miningd: area. This study has a practical value for water disasters, gas outbursts, and rock strata control.
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Hadad, Henrique, Luara Teixiera Colombo, Laís Kawamata de Jesus, Ana Flávia Piquera Santos, Paulo Sérgio Perri de Carvalho, Francisley Ávila Souza, and Ana Paula Farnezi Bassi. "Rehabilitation of atrophic mandible with implants. Strategy and case report of fracture complication." Research, Society and Development 9, no. 10 (September 26, 2020): e2899108588. http://dx.doi.org/10.33448/rsd-v9i10.8588.
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Rehabilitation through implant-supported prosthesis on atrophic jaws presents great deal of difficulty. Mandible fractures related to implants is not a common complication, however when it occurs, it represents serious damage. The aim of this paper was to report a clinical case of a 63-year-old patient with mandibular fracture after implant installation, treated through a buccal access and load-shearing plate system to stabilize the fractured bone and reduce the discomfort. The use of load shearing plate presented good results in this case, stabilizing the bone fracture, and helping with the repairing process, enabling subsequent rehabilitation of the patient, with a 3-year follow-up.
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Fahim, Daniel K., Kay Sun, Wafa Tawackoli, Ehud Mendel, Laurence D. Rhines, Allen W. Burton, Daniel H. Kim, Bruce L. Ehni, and Michael A. K. Liebschner. "Premature Adjacent Vertebral Fracture After Vertebroplasty: A Biomechanical Study." Neurosurgery 69, no. 3 (April 14, 2011): 733–44. http://dx.doi.org/10.1227/neu.0b013e31821cc499.
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Abstract BACKGROUND: There is an increased incidence of fractures in untreated adjacent vertebrae after vertebroplasty. OBJECTIVE: To introduce unconstrained 6 degrees of freedom biomechanical testing to investigate whether vertebroplasty lowered the fracture strength of adjacent untreated vertebrae under physiological loading conditions and to describe the observed fracture pattern. METHODS: Three-level spinal segments (T10-12 and L1–3) from 6 spines were tested under unconstrained axial compression in which shear forces and torque were minimized using a 6-degrees of freedom robotic arm. Fracture initiation loads and ultimate failure loads of lumbar segments were predicted from the corresponding thoracic segments by assuming constant fracture stress along the spinal column. The predicted values were compared with postvertebroplasty experimental values of the lumbar spine segments. Plain radiographs were taken at 600-N increments to record the developing fracture pattern. RESULTS: All 6 vertebroplasty group specimens experienced reductions in fracture strengths ranging from 27.4% to 47.6% with an average decrease of 32.6% (P < .002) and reductions in ultimate failure load ranging from 1.6% to 47.3%, with an average decrease of 34.7% (P < .003) compared with predicted values from the nonvertebroplasty group. In all vertebroplasty group specimens, the superior and inferior endplates of the untreated middle vertebral body (L2) were deflected, whereas 5 of the 6 nonvertebroplasty group specimens did not show any evidence of endplate deflection. CONCLUSION: Vertebroplasty altered the load transfer along the anterior spinal column, thereby statistically significantly increasing fracture risk and ultimate failure load of the untreated adjacent vertebrae. The radiographic findings support the endplate deflection fracture mechanism as the cause of adjacent fractures after vertebroplasty.
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Eggermont, F., L. C. Derikx, N. Verdonschot, I. C. M. van der Geest, M. A. A. de Jong, A. Snyers, Y. M. van der Linden, and E. Tanck. "Can patient-specific finite element models better predict fractures in metastatic bone disease than experienced clinicians?" Bone & Joint Research 7, no. 6 (June 2018): 430–39. http://dx.doi.org/10.1302/2046-3758.76.bjr-2017-0325.r2.
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Objectives In this prospective cohort study, we investigated whether patient-specific finite element (FE) models can identify patients at risk of a pathological femoral fracture resulting from metastatic bone disease, and compared these FE predictions with clinical assessments by experienced clinicians. Methods A total of 39 patients with non-fractured femoral metastatic lesions who were irradiated for pain were included from three radiotherapy institutes. During follow-up, nine pathological fractures occurred in seven patients. Quantitative CT-based FE models were generated for all patients. Femoral failure load was calculated and compared between the fractured and non-fractured femurs. Due to inter-scanner differences, patients were analyzed separately for the three institutes. In addition, the FE-based predictions were compared with fracture risk assessments by experienced clinicians. Results In institute 1, median failure load was significantly lower for patients who sustained a fracture than for patients with no fractures. In institutes 2 and 3, the number of patients with a fracture was too low to make a clear distinction. Fracture locations were well predicted by the FE model when compared with post-fracture radiographs. The FE model was more accurate in identifying patients with a high fracture risk compared with experienced clinicians, with a sensitivity of 89% versus 0% to 33% for clinical assessments. Specificity was 79% for the FE models versus 84% to 95% for clinical assessments. Conclusion FE models can be a valuable tool to improve clinical fracture risk predictions in metastatic bone disease. Future work in a larger patient population should confirm the higher predictive power of FE models compared with current clinical guidelines. Cite this article: F. Eggermont, L. C. Derikx, N. Verdonschot, I. C. M. van der Geest, M. A. A. de Jong, A. Snyers, Y. M. van der Linden, E. Tanck. Can patient-specific finite element models better predict fractures in metastatic bone disease than experienced clinicians? Towards computational modelling in daily clinical practice. Bone Joint Res 2018;7:430–439. DOI: 10.1302/2046-3758.76.BJR-2017-0325.R2.
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Zhang, Zhongke, Yang Yu, Huaxia Zhao, and Hui Tong. "Effect of Loading Methods on the Fatigue Properties of Dissimilar Al/Steel Keyhole-Free FSSW Joints." Materials 13, no. 19 (September 23, 2020): 4247. http://dx.doi.org/10.3390/ma13194247.
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The energy evolution, fatigue life and failure behaviour of dissimilar Al/steel keyhole-free Friction stir spot welding (FSSW) joints were studied under different fatigue loads. The absorption energy of fatigue fracture, the fracture mechanism and the sensitivity of the fatigue limits to the fatigue load parameters were analysed. It was found that the stress ratio R determines the fatigue limit Ff, while the fatigue limit Ff is not sensitive to the loading frequency. The high-frequency fatigue load will increase the displacement deformation μ and fatigue fracture absorption energy Ea of the spot-welded joint, which are larger under asymmetric fatigue loading than those under symmetrical fatigue loading. At the same time, the symmetrical fatigue load can form the steady-state hysteresis loop, while asymmetric fatigue loading cannot, but asymmetric fatigue loading exhibits the displacement increment of fatigue softening. The fracture failure of spot-welded joints is a multiple crack source and the mixed-mode of ductile and brittle fracture mechanism, which exhibits typical fatigue striations in the fatigue fractures.
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Liu, Shu Jun, Zhu Xin Li, and Yi Su. "Metal Magnetic Memory Testing of X60 Pipeline Steel under Tension Load and Fatigue Load." Applied Mechanics and Materials 148-149 (December 2011): 1404–7. http://dx.doi.org/10.4028/www.scientific.net/amm.148-149.1404.
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To study the relation between stress and the Metal Magnetic Memory Testing (MMMT) signal Hp(y) of ferromagnetic structure, a material mechanics experiment using X60 pipeline steel specimens under tension load and fatigue load is performed. The results show: The value of MMMT signal in elastic stage is small under tension load, while the value of MMMT signal in plastic stage is large. In the process of static tension, the zero crossing point (ZCP) of initial MMMT signal curves shift to the fracture position, and there is only one ZCP of MMMT signal curve at the position of fracture area. In the process of low-load fatigue, the shape and distribution of MMMT signal curves are similar under different cycle numbers of fatigue load. The value of MMMT signal increases a little with the increase of cycle number of fatigue load, and then increases sharply when the specimen is to be fractured. There is only one ZCP of MMMT signal curve at the position of fracture area in the process of fatigue loading.
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Fu, Lu, Hong Wei Zhao, Yu Xiang Zhu, Qing Zou, Chun Yang Geng, Bo Zhao, and Chang Sheng Liu. "The Effect of Load Direction on the Structure Capacity of Human Proximal Femur during Falling." Applied Mechanics and Materials 137 (October 2011): 7–11. http://dx.doi.org/10.4028/www.scientific.net/amm.137.7.
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The annual occurrence of hip fracture increases very rapidly, which cause a heavy public health burden. From a biomechanical perspective, hip fractures are thought to be caused by different directions of load. Fifteen different load conditions were studied here to simulate various falling configurations, the directions of which were defined by angle γ, δ. The purpose of the current study was to clarify the influence of load direction on strength and fracture site of the proximal femur using FE method to determine the load direction under which the proximal femur is most vulnerable to fracture.
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Samsami, Shabnam, Robert Pätzold, Martin Winkler, Sven Herrmann, and Peter Augat. "The effect of coronal splits on the structural stability of bi-condylar tibial plateau fractures: a biomechanical investigation." Archives of Orthopaedic and Trauma Surgery 140, no. 11 (March 26, 2020): 1719–30. http://dx.doi.org/10.1007/s00402-020-03412-8.
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Abstract Introduction Surgical treatment of bi-condylar tibial plateau fractures is still challenging due to the complexity of the fracture and the difficult surgical approach. Coronal fracture lines are associated with a high risk of fixation failure. However, previous biomechanical studies and fracture classifications have disregarded coronal fracture lines. Materials and methods This study aimed to develop a clinically relevant fracture model (Fracture C) and compare its mechanical behavior with the traditional Horwitz model (Fracture H). Twelve samples of fourth-generation tibia Sawbones were utilized to realize two fracture models with (Fracture C) or without (Fracture H) a coronal fracture line and both fixed with lateral locking plates. Loading of the tibial plateau was introduced through artificial femur condyles to cyclically load the fracture constructs until failure. Stiffness, fracture gap movements, failure loads as well as relative displacements and rotations of fracture fragments were measured. Results The presence of a coronal fracture line reduced fracture construct stiffness by 43% (p = 0.013) and decreased the failure load by 38% from 593 ± 159 to 368 ± 63 N (p = 0.016). Largest displacements were observed at the medial aspect between the tibial plateau and the tibial shaft in the longitudinal direction. Again, the presence of the coronal fracture line reduced the stability of the fragments and created increased joint incongruities. Conclusions Coronal articular fracture lines substantially affect the mechanical response of tibia implant structures specifically on the medial side. With this in mind, utilizing a clinically relevant fracture model for biomechanical evaluations regarding bi-condylar tibial plateau fractures is strongly recommended.
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Patel, Samik, Juan Giugale, Nathan Tiedeken, Richard E. Debski, and John R. Fowler. "Impact of Screw Length on Proximal Scaphoid Fracture Biomechanics." Journal of Wrist Surgery 08, no. 05 (April 22, 2019): 360–65. http://dx.doi.org/10.1055/s-0039-1685514.
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Background Proximal scaphoid fractures display high nonunion rates and increased revision cases. Waist fracture fixation involves maximizing screw length within the cortex; however, the optimal screw length for proximal scaphoid fractures remains unknown. Purpose The main purpose of this article is to compare stiffness and ultimate load for proximal scaphoid fracture fixation of various headless compression screw lengths. Methods Eighteen scaphoids underwent an osteotomy simulating a 7 mm oblique proximal fracture. Screws of three lengths (10, 18, and 24 mm) were randomly assigned for fixation. Each specimen underwent cyclic loading with stiffness calculated during the last loading cycle. Specimens that withstood cyclic loading were loaded to failure. Results No significant difference in stiffness between screw lengths was found. Ultimate load was significantly impacted by the screw length. A significant difference in ultimate load between a 10 and 24 mm screw was found; however, no significant difference occurred in ultimate load between an 18 and 24 mm screw. Conclusions No significant difference in stiffness between all groups could be due to similarities in purchase in the proximal aspect. The 10 mm screw withstanding less ultimate load compared to the 24 mm screw could be due to the 10 mm screw gaining less purchase on either side of the fracture site compared to the 24 mm screw. Lack of significant difference in ultimate load between the 18 and 24 mm screw could be occurring because the fracture site is closer to the 18 mm screw midpoint, as distal threads are engaged closer to the fracture. Clinical Relevance Maximizing screw length may not provide superior fixation biomechanically compared with fixation utilizing a 6 mm shorter screw for proximal scaphoid fractures.
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Yang, K. H., K. L. Shen, C. K. Demetropoulos, A. I. King, P. Kolodziej, R. S. Levine, and R. H. Fitzgerald. "The Relationship Between Loading Conditions and Fracture Patterns of the Proximal Femur." Journal of Biomechanical Engineering 118, no. 4 (November 1, 1996): 575–78. http://dx.doi.org/10.1115/1.2796045.
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In an attempt to test the hypothesis of spontaneous hip fracture, seven pairs of femurs, with ages ranging from 59 to 90, were tested under two loading conditions designed to simulate muscular contraction. Simulated iliopsoas contraction produced femoral neck fractures at an average normalized ultimate load of 5.2 ± 0.8 times body weight. Simulated gluteus medius contraction produced sub-/inter-trochanteric fractures at an average normalized ultimate load of 4.1 ± 0.6 times body weight. The average ultimate load for all specimens was 3040 ± 720 N. Fracture patterns produced by both loading conditions were clinically relevant. The results from this study suggest that abnormal contraction produced by major rotator muscles could induce hip fracture.
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Zhang, Yanzhong, T. B. Bini, Zheng Ming Huang, and S. Ramakrishna. "Fracture Characteristics of Knitted Fabric Composites under Tensile Load." Advanced Composites Letters 9, no. 2 (March 2000): 096369350000900. http://dx.doi.org/10.1177/096369350000900205.
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This paper reports tensile properties of single layer and multilayer knitted glass fabric reinforced epoxy composites. The single layer composite was subjected to tensile load in off-axis angles of 0°, 30°, 45°, 60° and 90°. The multilayer laminates stacked as configurations of [0°]4, [07±4570°], [0°/90°/90°/0°] and [90°]4 were tested under a uniaxial tensile load. Emphasis was on the fracture characteristics of these composites. A ‘matrix digestion and layer peeling’ method was used to visualize the fracture modes of all the layers in a fractured laminate on a lamina level. It was found that the fracture mode of an angle-plied lamina in the laminate is different from that of a single layer composite under an off-axial tensile load.
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Sukegawa, Shintaro, Norio Yamamoto, Keisuke Nakano, Kiyofumi Takabatake, Hotaka Kawai, Takahiro Kanno, Hitoshi Nagatsuka, and Yoshihiko Furuki. "Biomechanical Loading Comparison between Titanium and Bioactive Resorbable Screw Systems for Fixation of Intracapsular Condylar Head Fractures." Materials 13, no. 14 (July 15, 2020): 3153. http://dx.doi.org/10.3390/ma13143153.
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Osteosynthesis resorbable materials made of uncalcined and unsintered hydroxyapatite (u-HA) particles, poly-L-lactide (PLLA), are bioresorbable, and these materials have feasible bioactive/osteoconductive capacities. However, their strength and stability for fixation in mandibular condylar head fractures remain unclear. This in vitro study aimed to assess the biomechanical strength of u-HA/PLLA screws after the internal fixation of condylar head fractures. To evaluate their biomechanical behavior, 32 hemimandible replicas were divided into eight groups, each consisting of single-screw and double-screw fixations with titanium or u-HA/PLLA screws. A linear load was applied as vertical and horizontal load to each group to simulate the muscular forces in condylar head fractures. Samples were examined for 0.5, 1, 2, and 3-mm displacement loads. Two screws were needed for stable fixation of the mandibular condylar head fracture during biomechanical evaluation. After screw fixation for condylar head fractures, the titanium screws model was slightly more resistant to vertical and horizontal movement with a load for a small displacement than the u-HA/PLLA screws model. There was no statistically significant difference with load for large displacements. The u-HA/PLLA screw has a low mechanical resistance under small displacement loading compared with titanium within the limits of the mandibular head fracture model study.
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Keyak, Joyce H. "Relationships between femoral fracture loads for two load configurations." Journal of Biomechanics 33, no. 4 (April 2000): 499–502. http://dx.doi.org/10.1016/s0021-9290(99)00202-x.
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Torg, Joseph S., Helene Pavlov, Mary Jane O'Neill, Claude E. Nichols, and Brian Sennett. "The axial load teardrop fracture." American Journal of Sports Medicine 19, no. 4 (July 1991): 355–64. http://dx.doi.org/10.1177/036354659101900406.
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Wang, Dan, Yuan Zhi Xu, Cheng Lin Lu, Qi Xiang Yang, Dong Sheng Zhang, Long Quan Shao, and Rao Rao Wang. "Comparison of Fracture Strength and Fracture Modes of Zirconia Dental Ceramics Manufactured by Four Different CAD/CAM Systems." Key Engineering Materials 492 (September 2011): 30–34. http://dx.doi.org/10.4028/www.scientific.net/kem.492.30.
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Four sorts of zirconia dental ceramic systems including Cercon smart, Lava, Porcera, and CEREC 3 were studied to analyze fracture mechanism of different CAD/CAM zirconia ceramic. In each system, 12 sectioned specimens were prepared, 6 specimens were taken as controlled group, 6 as experimental group. Quasi-statistic loading before and after cyclic loading was applied at the veneer surface of the specimen. Deformation and crack initiation were monitored with camera in order to carry out digital image correlation (DIC) analysis. The results showed that median cracks were observed under the yielding zone. Specimens fractured along the core/veneer interface with the crack growth. No cone crack was confirmed and fracture only existed in veneer layer. After cyclic loading there were no significant differences for the four ceramic systems in terms of the critical load, while significant differences existed in terms of the fracture load. Both critical load and fracture load were lowered after cyclic loading. After cycling loading, the 4 tested zirconia CAD/CAM ceramic possess high fracture strength to meet the requirement for oral functions. The fracture modes of the four zirconia ceramic systems indicate that the strength of the veneer should be enhanced.
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AlAmar, Mohammed, and Fawaz Alqahtani. "Effect of Different Implant-Abutment Connection Materials on the Fracture Resistance of Zirconia Abutments." Journal of Oral Implantology 46, no. 2 (January 7, 2020): 88–92. http://dx.doi.org/10.1563/aaid-joi-d-19-00192.
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The aim of the present in vitro study was to assess the modes of failures under static load among titanium (Ti) and 1- and 2-piece zirconia abutments. The 1- and 2-piece zirconia abutment specimens were fabricated from prescanned Ti abutments. Twenty-one implant abutments and 21 implant replicas were equally divided into 3 groups as follows: (a) Group 1 (Titanium group); (b) Group 2 (1-piece zirconia abutment group); and (c) Group 3: 2-piece zirconia abutment group). A 250 000-cycle linear fatigue load ranging between 10 N and 210 N was applied to all specimens using an all-electric dynamic test instrument. The specimens were loaded until they fractured. In all groups, assessment of mode of fracture was done on visual assessment by a trained and calibrated investigator. Prior sample-size estimation was performed; and sample distribution was assessed using the Kolmogorov and Shapiro tests. Screw fracture (n = 7) and abutment bending at the apical part (n = 7) occurred in the Ti group. In the 1-piece zirconia group, screw and abutment fractures occurred in 7 and 7 cases, respectively. In the 2-piece zirconia screw fracture (n = 7) above the Ti zirconia junction (transgingival segment) and abutment fracture (n = 7) were determined as the failure modes. In vitro, the 1-piece zirconia abutments are more fracture resistant than titanium and 2-piece zirconia abutments. From a clinical perspective, further studies are needed to determine the minimum static load value required to induce fracture of the 1- and 2-piece zirconia abutments.
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Yin, Qian, Hongwen Jing, Richeng Liu, Guowei Ma, Liyuan Yu, and Haijian Su. "Experimental Study on Stress-Dependent Nonlinear Flow Behavior and Normalized Transmissivity of Real Rock Fracture Networks." Geofluids 2018 (2018): 1–16. http://dx.doi.org/10.1155/2018/8217921.
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The mechanism and quantitative descriptions of nonlinear fluid flow through rock fractures are difficult issues of high concern in underground engineering fields. In order to study the effects of fracture geometry and loading conditions on nonlinear flow properties and normalized transmissivity through fracture networks, stress-dependent fluid flow tests were conducted on real rock fracture networks with different number of intersections (1, 4, 7, and 12) and subjected to various applied boundary loads (7, 14, 21, 28, and 35 kN). For all cases, the inlet hydraulic pressures ranged from 0 to 0.6 MPa. The test results show that Forchheimer’s law provides an excellent description of the nonlinear fluid flow in fracture networks. The linear coefficient a and nonlinear coefficient b in Forchheimer’s law J=aQ+bQ2 generally decrease with the number of intersections but increase with the boundary load. The relationships between a and b can be well fitted with a power function. A nonlinear effect factor E=bQ2/(aQ+bQ2) was used to quantitatively characterize the nonlinear behaviors of fluid flow through fracture networks. By defining a critical value of E = 10%, the critical hydraulic gradient was calculated. The critical hydraulic gradient decreases with the number of intersections due to richer flowing paths but increases with the boundary load due to fracture closure. The transmissivity of fracture networks decreases with the hydraulic gradient, and the variation process can be estimated using an exponential function. A mathematical expression T/T0=1-exp(-αJ-0.45) for decreased normalized transmissivity T/T0 against the hydraulic gradient J was established. When the hydraulic gradient is small, T/T0 holds a constant value of 1.0. With increasing hydraulic gradient, the reduction rate of T/T0 first increases and then decreases. The equivalent permeability of fracture networks decreases with the applied boundary load, and permeability changes at low load levels are more sensitive.
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SATO, Kiyoshi, Hisato YAMAMOTO, and Takeshi YAMANOUCHI. "Fracture Mechanis. Fracture of Notched Wood under Impact Load." Journal of the Society of Materials Science, Japan 49, no. 8 (2000): 836–38. http://dx.doi.org/10.2472/jsms.49.836.
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Luo, Jin, Michael A. Adams, and Patricia Dolan. "Vertebroplasty and Kyphoplasty Can Restore Normal Spine Mechanics following Osteoporotic Vertebral Fracture." Journal of Osteoporosis 2010 (2010): 1–9. http://dx.doi.org/10.4061/2010/729257.
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Osteoporotic vertebral fractures often lead to pain and disability. They can be successfully treated, and possibly prevented, by injecting cement into the vertebral body, a procedure known as vertebroplasty. Kyphoplasty is similar, except that an inflatable balloon is used to restore vertebral body height before cement is injected. These techniques are growing rapidly in popularity, and a great deal of recent research, reviewed in this paper, has examined their ability to restore normal mechanical function to fractured vertebrae. Fracture reduces the height and stiffness of a vertebral body, causing the spine to assume a kyphotic deformity, and transferring load bearing to the neural arch. Vertebroplasty and kyphoplasty are equally able to restore vertebral stiffness, and restore load sharing towards normal values, although kyphoplasty is better at restoring vertebral body height. Future research should optimise these techniques to individual patients in order to maximise their beneficial effects, while minimising the problems of cement leakage and adjacent level fracture.
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Witek, Lucjan. "Fracture Problem of the Valve of Piston Engine." Solid State Phenomena 250 (April 2016): 255–62. http://dx.doi.org/10.4028/www.scientific.net/ssp.250.255.
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In this paper the fracture problem of exhaust valve of the piston engine was investigated. Visual inspection showed that on the fractured surface of the valve the beach marks, typical for fatigue failure were observed. The crack origin was not covered by corrosion products or material defects. In order to explain the reasons of damage of the valve, the non-linear finite element method was utilized. The numerical model composed of the poppet valve, the guide and the seat face was defined. In the analysis both the mechanical load resulting from the valve spring and also the thermal load arising from a non-uniform temperature field were defined. The loads were at first defined separately in order to check which load component has a dominant influence on the stress level. In third load case (which represents the operational thermo-mechanical engine conditions) the mentioned loads were defined simultaneously. The results of performed computations showed that the operational dynamic stress (in the critical zone of the valve where the crack appeared) is more than 12 times lower than the yield stress of the material. It means that the premature fatigue fracture of the valve was probably caused by any phenomenon concerned with the increase of the operational stress in the valve. The additional observation of the second (non-damaged) valve from the same engine head showed that the carbon deposit was located on the valve face. The results of the stress analysis of the valve with additional carbon particle showed, that in the valve stem a high bending stress was observed.
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Vogel, Danny, Martin Liebelt, Florian Kalkowsky, Thomas Oberbach, Daniel Delfosse, and Rainer Bader. "Mechanical and numerical characterization of ceramic femoral components for hip resurfacing arthroplasty." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 233, no. 9 (June 18, 2019): 883–91. http://dx.doi.org/10.1177/0954411919855296.
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Hip resurfacing arthroplasty may have distinct advantages for young and active patients, but large metal-on-metal bearings can be associated with increased wear, adverse tissue reactions and higher rate of implant loosening. Ceramic wear couples are a commonly used alternative to metals and therefore might be an alternative for hip resurfacing arthroplastys. The aim of this study was to evaluate the mechanical strength of femoral components made of an alumina-toughened zirconia composite by means of experimental testing and finite element analysis. For the mechanical characterization, ceramic femoral components (Ø: 48 mm) were tested under compression loading experimentally until fracture occurred or a maximum load of 85 kN was obtained. The femoral components were either loaded against a ceramic cup or a copper ring (outer diameter Ø: 7.0 mm). In addition, the complex geometry of the ceramic femoral component was simplified, and only the stem was loaded in a cantilever test until fracture. In addition, the fracture tests were numerically simulated to investigate the influence of additional loading conditions and geometric parameters, which were not experimentally tested. The experimental data were used for validation of the finite element analysis. None of the tested ceramic femoral components fractured at a compression load of 85 kN when they were loaded against a ceramic cup at an inclination angle of 45°. When the femoral components were loaded against a copper ring, the femoral components fractured at 29.9 kN at a testing angle of 45°. The fracture load was reduced when an angle of 30° and increased when an angle of 60° was simulated. Using an experimental cantilever test, the stem of the femoral component fractured at 1124.0 N. When the stem length was increased or the diameter was reduced by 10% in the finite element analysis, the fracture load was reduced. Decreasing the length or increasing the diameter led to an increase of the fracture load. The strongest influence was found for the reduction of the transition radius of the stem, with a decrease of the fracture load up to 27.2%. The analyzed femoral components made of alumina-toughened zirconia (ATZ) showed sufficient mechanical capability to withstand high loadings during unfavorable loading conditions. However, further biomechanical and tribological investigations are required before clinical application.
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Tsutsumi, Mitsuyoshi, and Nagatoshi Okabe. "OS08W0290 The fracture model of porous ceramics subjected to mechanical load." Abstracts of ATEM : International Conference on Advanced Technology in Experimental Mechanics : Asian Conference on Experimental Mechanics 2003.2 (2003): _OS08W0290. http://dx.doi.org/10.1299/jsmeatem.2003.2._os08w0290.
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Jung, Dal Woo, and Nak Sam Choi. "Fracture Characteristics of a Hybrid Composite Joint Beam for the Tilting Car Body under Static and Fatigue Transverse Loads." Key Engineering Materials 353-358 (September 2007): 2681–84. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.2681.
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Fatigue fracture behavior of a hybrid joint beam for the tilting car body was evaluated in comparison to the case of static fracture. Specimen beams of the hybrid joint part attached in the real tilting car body were fabricated for the bending test. Characteristic fracture behaviors of hybrid joint beam specimens under cyclic transverse loads were very different from the case under static loads. Static transverse load caused shear deformation and fracture in the honeycomb core region, while cyclic transverse load brought about delamination along the interface between composite skin and honeycomb core layers as well as fracture of the welded joint. Fracture characteristics obtained by the transverse fatigue tests were reflected for improving the hybrid joint structure in the real tilting car body.
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Abedin, Mohammad, and Armin B. Mehrabi. "Effect of Cross-Frames on Load Distribution of Steel Bridges with Fractured Girder." Infrastructures 5, no. 4 (April 1, 2020): 32. http://dx.doi.org/10.3390/infrastructures5040032.
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In steel girder bridges, fracture of one girder may occur without noticeable bridge profile changes. It is critical to ensure that the bridge will have adequate capacity to prevent collapse until the next cycle of inspection discovers the damage. It is realized that once one of the bridge girders is fractured, vertical loads need to be distributed through an alternative path to the intact girder(s). In this case, cross-frames can play an important role in transferring the loads and preventing from sudden collapse. This paper investigates the impact of cross-frames on load distribution after a fracture is occurred in one girder. Bridge configurations with different cross-frame spacing were studied using finite element modeling and simulation of the bridge behavior with a fractured steel plate girder. Nonlinear and dynamic solution methods were used for these analyses. Results of this investigation demonstrated the important role cross-frames can play in providing some reserved capacity for the bridge with fractured girder to enhance the bridge redundancy. The contribution of the cross-frames and the behavior of the bridge after fracture in one girder however depends on the configuration of the bridge. A study of the variation of the effect of cross-frames with respect to the number of girders is also included in this paper.
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Rodríguez, Verónica, Celia Tobar, Carlos López-Suárez, Jesús Peláez, and María J. Suárez. "Fracture Load of Metal, Zirconia and Polyetheretherketone Posterior CAD-CAM Milled Fixed Partial Denture Frameworks." Materials 14, no. 4 (February 18, 2021): 959. http://dx.doi.org/10.3390/ma14040959.
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The aim of this study was to investigate the load to fracture and fracture pattern of prosthetic frameworks for tooth-supported fixed partial dentures (FPDs) fabricated with different subtractive computer-aided design and computer-aided manufacturing (CAD-CAM) materials. Materials and Methods: Thirty standardized specimens with two abutments were fabricated to receive three-unit posterior FDP frameworks with an intermediate pontic. Specimens were randomly divided into three groups (n = 10 each) according to the material: group 1 (MM)—milled metal; group 2 (L)—zirconia; and group 3 (P)—Polyetheretherketone (PEEK). The specimens were thermo-cycled and subjected to a three-point bending test until fracture using a universal testing machine (cross-head speed: 1 mm/min). Axial compressive loads were applied at the central fossa of the pontics. Data analysis was made using one-way analysis of variance, Tamhane post hoc test, and Weibull statistics (α = 0.05). Results: Significant differences were observed among the groups for the fracture load (p < 0.0001). MM frameworks showed the highest fracture load values. The PEEK group registered higher fracture load values than zirconia samples. The Weibull statistics corroborated these results. The fracture pattern was different among the groups. Conclusions: Milled metal provided the highest fracture load values, followed by PEEK, and zirconia. However, all tested groups demonstrated clinically acceptable fracture load values higher than 1000 N. PEEK might be considered a promising alternative for posterior FPDs.
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Baek, Seung, Jae Mean Koo, and Chang Sung Seok. "Fracture Characteristic of Single Crystalline Silicon Using Nano-Indentation and Finite Element Analysis." Key Engineering Materials 306-308 (March 2006): 601–6. http://dx.doi.org/10.4028/www.scientific.net/kem.306-308.601.
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Nano-indentation test is used widely to determine the fracture toughness of brittle materials and to provide information on important material properties such as the Young’s modulus and hardness. In this study, using nano-indentation testing, atomic force microscope (AFM), and finite element method (FEM), we performed the indentation fracture toughness and fracture strength measurement for a (100) single crystalline silicon at different load states. In addition, the loads of the phase transformation events during unloading were estimated by the load-depth curves. The phase transformation load and micro-crack propagation events at pop-out during the unloading process depended on the maximum applied indentation load.
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Song, Seung-rye, Kyeong-Mee Park, and Bock-Young Jung. "Fracture strength analysis of titanium insert-reinforced zirconia abutments according to the axial height of the titanium insert with an internal connection." PLOS ONE 16, no. 4 (April 1, 2021): e0249208. http://dx.doi.org/10.1371/journal.pone.0249208.
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This study aimed to analyze fracture strength in vitro by varying the axial height of the titanium insert and the labial height of the zirconia abutment in an internal connection implant to identify the titanium insert axial height with optimal mechanical stability. Sixty implants with an internal connection system were used. Two-piece zirconia abutments were used with the titanium inserts. Combinations of different titanium insert axial heights (mm) and zirconia abutment labial heights (mm) constituted five groups: Gr1 (1–3), Gr2 (3–3), Gr3 (3–5), Gr4 (5–3), and Gr5 (5–5). After thermocycling, a fracture load test was performed with a universal testing machine. The initial deformation load and the fracture load were measured and analyzed. The fractured surface and cross-section of the specimens were examined by scanning electron microscopy (SEM). The groups of titanium inserts with axial heights of 3 mm and 5 mm showed significantly greater initial deformation load and fracture load than the group with an axial height of 1 mm (p < 0.05), but there was no significant difference between the two groups with axial heights of 3 mm and 5 mm. The labial height of the zirconia abutment had no significant influence on the initial deformation load and fracture load. In some specimens in Gr4 and Gr5, cracking or bending of the titanium insert and abutment screw was observed on SEM. The axial height of the titanium insert should be designed to not be less than 3 mm to increase the fracture strength and promote the long-term stability of implants.
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Zakiev, Islam, George A. Gogotsi, Michael Storchak, and Vadim Zakiev. "Glass Fracture during Micro-Scratching." Surfaces 3, no. 2 (June 10, 2020): 211–24. http://dx.doi.org/10.3390/surfaces3020016.
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The regularity of glass surface fracture and resistance to destruction were investigated by the methods of progressive and static microscratching with the Berkovich indenter. The research hardware was the original nanoindentation/microscratching devices and a non-contact interference profilometer for studying the morphology of the formed microscratches. The regularities of the fracture stages and the cracks growth along the microscratch were established depending on the indenter applied load. Based on analysis of the microcracks profile formed at various loads on the indenter immediately after the process of applying these scratches and after several hours of rest, it was found that the process of crack propagation along the scratch continues for a long time. Taking into account this established fact, a discrete-statistical method of the cracks formation for a long time is proposed. In accordance with this method, scratching is carried out with a constant load on short and separated tracks. The load on the indenter in each track increases discretely with a certain step. The influence of the medium on the scratching process is analyzed. The breaking mechanism in the glasses scratching process is formulated as the load on the indenter increases, and a model of the glass fracture stages is proposed.
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Sims, John E., Derek Elsworth, and John A. Cherry. "Stress-dependent flow through fractured clay till: a laboratory study." Canadian Geotechnical Journal 33, no. 3 (July 2, 1996): 449–57. http://dx.doi.org/10.1139/t96-066.
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Stress-dependent hydraulic conductivities of weathered fractured clay till were measured in a flexible-wall permeameter. Measured conductivities were in the range 107 to 108 cm/s, of the same order as the clay matrix (108 cm/s), and representing equivalent hydraulic apertures in the range 05 μm. In general, the isolated fractures exhibited strongly nonlinear closure characteristics and hysteric behaviour under stress reversal. Some fracture samples exhibited only weak stress dependency, representing observable features of only nominal conductivity. Results of the investigations suggest fractures are closed to residuel aperture for an overburden load of the order of 12 m, this defining an effective closure depth and the degree of maximum useful compactive effort that might be applied to "seal" fractures and reduce fluid migration. Key words: fracture permeability, till, stress permeability, landfills.
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SRIPADA, S., D. I. ROWLEY, M. SAITO, K. SHIMADA, T. NAKASHIMA, and C. A. WIGDEROWITZ. "Biomechanical Testing of the Fractured Distal Radius Treated with A New Bone Cement–Is it Strong Enough?" Journal of Hand Surgery 31, no. 4 (August 2006): 385–89. http://dx.doi.org/10.1016/j.jhsb.2006.04.005.
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This study evaluates the in vitro ability of CAP, a bone graft substitute with osteointegration and osteoconductive properties, to restore the anatomy and strength of fractured distal radii. Ten pairs of cadaveric radii were imaged and tested to failure, simulating a fracture. The radii were reconstructed using CAP and were re-fractured and sequentially imaged. The deformities of the bones were determined through computerised evaluation of the radiographs. Radiographic analysis showed that CAP is capable of restoring the anatomy of the distal radius. The load and work required to fracture intact radii were compared to those required to fracture the reconstructed radii. The load to fracture was similar in the two situations. The work to fracture, however, was higher with reconstructed radii, suggesting that these are stronger than the original bones. Our study supports the hypothesis that CAP is capable of restoring the original anatomy and dimensions of the distal radius and re-establishing its mechanical strength.
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Huang, Xiao Hui, Wen Guang Liu, Guo Qun Zhao, and Xin Hai Zhao. "An Investigation into the Fracture Mechanical Behavior of Bone Cement: Simulation Using Cohesive Zone Models (CZMs)." Advanced Materials Research 156-157 (October 2010): 1658–64. http://dx.doi.org/10.4028/www.scientific.net/amr.156-157.1658.
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In this investigation, we propose a new concept to embed cohesive zone into the continuum structure of bone cement, an example of brittle material, in investigating the mechanical behavior and fracture mechanism and to predict the fracture which elastic fracture mechanics (EFM) is unable to. Four finite element (FE) models with embedded cohesive zones for the simulations of tensile, compression, double shear and 3-point bending tests have been implemented. Cohesive zones (CZ) are embedded at high risks of fracture with orientations determined by fracture mode. A bilinear cohesive traction-separation law (TSL) is applied. The fracture parameters in traction-separation curve are validated and justified in the simulations to agree well with the force-displacement curves in the four practical tests. Apart from the maximum load, the perpetual safe working load (SWL) in theory also can be predicted by tracing the history of the stiffness degradation of fractured cohesive zone by means of simulation. A distinct advantage of our numerical model is that it is able to extend to investigate the mechanical behavior and fracture mechanism of other brittle materials. The proposed method with embedded cohesive zones in FE models can be introduced to predict the fracture and to forecast the maximum load and safe working load (SWL) of the continuum structure in more complicated loading conditions.
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Freitag, Tobias, Karl Philipp Kutzner, Ralf Bieger, Heiko Reichel, Anita Ignatius, and Lutz Dürselen. "Biomechanics of a cemented short stem: a comparative in vitro study regarding primary stability and maximum fracture load." Archives of Orthopaedic and Trauma Surgery 141, no. 10 (March 23, 2021): 1797–806. http://dx.doi.org/10.1007/s00402-021-03843-x.
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Abstract Purpose In total hip arthroplasty, uncemented short stems have been used more and more frequently in recent years. Especially for short and curved femoral implants, bone-preserving and soft tissue-sparing properties are postulated. However, indication is limited to sufficient bone quality. At present, there are no curved short stems available which are based on cemented fixation. Methods In this in vitro study, primary stability and maximum fracture load of a newly developed cemented short-stem implant was evaluated in comparison to an already well-established cemented conventional straight stem using six pairs of human cadaver femurs with minor bone quality. Primary stability, including reversible micromotion and irreversible migration, was assessed in a dynamic material-testing machine. Furthermore, a subsequent load-to-failure test revealed the periprosthetic fracture characteristics. Results Reversible and irreversible micromotions showed no statistical difference between the two investigated stems. All short stems fractured under maximum load according to Vancouver type B3, whereas 4 out of 6 conventional stems suffered a periprosthetic fracture according to Vancouver type C. Mean fracture load of the short stems was 3062 N versus 3160 N for the conventional stems (p = 0.84). Conclusion Primary stability of the cemented short stem was not negatively influenced compared to the cemented conventional stem and no significant difference in fracture load was observed. However, a clear difference in the fracture pattern has been identified.
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Prechtel, Alexander, Bogna Stawarczyk, Reinhard Hickel, Daniel Edelhoff, and Marcel Reymus. "Fracture load of 3D printed PEEK inlays compared with milled ones, direct resin composite fillings, and sound teeth." Clinical Oral Investigations 24, no. 10 (January 27, 2020): 3457–66. http://dx.doi.org/10.1007/s00784-020-03216-5.
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Abstract Objective The objective of this in vitro study was to investigate fracture load, fracture types, and impact of chewing simulation of human molars restored with 3D printed indirect polyetheretherketone (PEEK) inlays and compare these with milled indirect PEEK inlays, direct resin composite fillings, and sound teeth. Materials and methods A total of 112 molars with form congruent class I cavities were restored with (n = 16/group) 3D printed indirect PEEK inlays via fused layer manufacturing (FLM): (1) Essentium PEEK (ESS), (2) KetaSpire PEEK MS-NT1 (KET), (3) VESTAKEEP i4 G (VES), (4) VICTREX PEEK 450G (VIC), (5) milled indirect PEEK inlays JUVORA Dental Disc 2 (JUV), and (6) direct resin composite fillings out of Tetric EvoCeram (TET). Sound teeth (7) acted as positive control group. Half of the specimens of each group (n = 8) were treated in a chewing simulator combined with thermal cycling (1.2 million × 50 N; 12,000 × 5 °C/55 °C). Fracture load and fracture types of all molars were determined. Statistical analyses using Kolmogorov-Smirnov test and two-way ANOVA with partial eta squared (ηp2) followed by Scheffé post hoc test, chi square test and Weibull modulus m with 95% confidence interval were computed (p < 0.05). Results ESS and TET demonstrated the lowest fracture load with a minimum of 956 N, whereas sound molars showed the highest values of up to 2981 N. Chewing simulation indicated no impact (p = 0.132). With regard to Weibull modulus, KET presented a lower value after chewing simulation than JUV, whereas TET had the highest value without chewing simulation. All indirect restorations revealed a tooth fracture (75–100%), direct resin composite fillings showed a restoration fracture (87.5%), and 50% of the sound teeth fractured completely or had cusp fractures. Conclusions All 3D printed and milled indirect PEEK inlays as well as the direct resin composite fillings presented a higher fracture load than the expected physiological and maximum chewing forces. Clinical relevance 3D printing of inlays out of PEEK via FLM provided promising results in mechanics, but improvements in terms of precision and esthetics will be required to be practicable in vivo to represent an alternative dental material.
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Fernlund, G., M. Papini, D. McCammond, and J. K. Spelt. "Fracture load predictions for adhesive joints." Composites Science and Technology 51, no. 4 (January 1994): 587–600. http://dx.doi.org/10.1016/0266-3538(94)90091-4.
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Ravindrarajah, R. Sri, and R. N. Swamy. "Load effects on fracture of concrete." Materials and Structures 22, no. 1 (January 1989): 15–22. http://dx.doi.org/10.1007/bf02472690.
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Oliver, Rema, G. Yee, Y. Yu, J. B. Matthews, E. Ingham, and W. R. Walsh. "Fracture Healing in the Presence of Polyethylene Wear Debris and Oestrogen Deficiency." Key Engineering Materials 353-358 (September 2007): 831–34. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.831.
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The number of peri-prosthetic femoral fractures in todays aging population is increasing. Fractures of the femur may occur intra-operatively or post-operatively, either at the tip of the femoral stem or in areas where cortical thinning has occurred. This is further enhanced if the patient is osteoporotic. These fractures can be difficult to treat due to the complexity of the mechanical status and further complicated biologically by the presence of ultra high molecular weight polyethylene (UHMWPE) wear debris that can migrate from the articulating surface of the prosthesis to the fracture site. In this study, the effect of PE wear debris on the healing of osteoporotic fractures was investigated using a rodent ovariectomised (OVX) model. One hundred female Sprague Dawley rats were subjected to either bilateral OVX or Sham surgery at 10 weeks of age. Three months later, a closed fracture was created in the right femur using a 3-point bending device and an intramedullary k-wire for fixation. Animals were divided into 4 groups (n=3-8). A 0.2ml suspension of Ceridust (PE wear debris), hyaluronic acid & saline was injected directly into the fracture site at the time of surgery into half the animals. Control animals received comparable injections excluding the Ceridust. Animals were sacrificed at 1, 3 and 6 weeks. The OVX animals had a greater body weight compared to the Sham animals (p<0.05). DEXA analysis revealed that the presence of PE wear debris had no effect on the BMD within the fracture callus at either time-point. Mechanical analysis revealed an increase in bone strength with time. The presence of PE had no statistical effect upon the ultimate peak load or stiffness, however there was a trend towards increased peak load in the PE groups at 3 and 6 weeks following 3-months oestrogen deficiency. Histological analysis showed that the control OVX fractures had more cartilage development than the Sham group at 3 weeks and delayed remodeling at 6 weeks. The PE treated OVX group showed more fibrous tissue at the fracture gap and inside the diaphysis tunnel showing further delayed healing compared to the Sham group with PE. In this study after 3-months of oestrogen deficiency, no differences in mechanical or BMD was found in the fractured limbs between the PE –treated and non-PE treated fractures. However, histologically, PE wear debris induced fibrous tissue at the fracture site which further delayed the healing process. More care should be taken with aged patients receiving revision surgery, as these patients become harder to manage when fractured due to the influence of both osteoporosis and PE wear debris.
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Hollensteiner, Marianne, Sabrina Sandriesser, Emily Bliven, Christian von Rüden, and Peter Augat. "Biomechanics of Osteoporotic Fracture Fixation." Current Osteoporosis Reports 17, no. 6 (November 21, 2019): 363–74. http://dx.doi.org/10.1007/s11914-019-00535-9.
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Abstract Purpose of Review Fractures of osteoporotic bone in elderly individuals need special attention. This manuscript reviews the current strategies to provide sufficient fracture fixation stability with a particular focus on fractures that frequently occur in elderly individuals with osteoporosis and require full load-bearing capacity, i.e., pelvis, hip, ankle, and peri-implant fractures. Recent Findings Elderly individuals benefit immensely from immediate mobilization after fracture and thus require stable fracture fixation that allows immediate post-operative weight-bearing. However, osteoporotic bone has decreased holding capacity for metallic implants and is thus associated with a considerable fracture fixation failure rate both short term and long term. Modern implant technologies with dedicated modifications provide sufficient mechanical stability to allow immediate weight-bearing for elderly individuals. Depending on fracture location and fracture severity, various options are available to reinforce or augment standard fracture fixation systems. Summary Correct application of the basic principles of fracture fixation and the use of modern implant technologies enables mechanically stable fracture fixation that allows early weight-bearing and results in timely fracture healing even in patients with osteoporosis.
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Kanchanomai, Chaosuan, Panurungsit Muanjan, and Vajara Phiphobmongkol. "Stiffness and Endurance of a Locking Compression Plate Fixed on Fractured Femur." Journal of Applied Biomechanics 26, no. 1 (February 2010): 10–16. http://dx.doi.org/10.1123/jab.26.1.10.
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The effects of locking screw position (long column fixation—long distance between the nearest screws to the fracture—and short column fixation—short distance between the nearest screws to the fracture) and fracture gap size (1-mm and 8-mm transverse fracture gap) on stiffness and fatigue of fractured femur fixed with a locking compression plate (LCP) were biomechanically evaluated. The stiffness of 1-mm fracture gap models and that of intact femoral model were in the range of 270–284 N/mm, while those of 8-mm fracture gap models were significantly lower (155–170 N/mm). After 1,000,000 cycles of loading, no fracture of LCP of 1-mm fracture gap models fixed in either long column or short column fashions occurred. On the other hand, the complete fractures of LCPs of 8-mm fracture gap models fixed in long column and short column fashions occurred after 51,500 and 42,000 cycles of loading, respectively. These results suggest that the full weight loading may be allowed for the patient with 1-mm transverse femoral fracture fixed with an LCP. On the other hand, the full load of walking should be avoided for the patient with 8-mm transverse femoral fracture fixed with an LCP before adequate healing.
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Sathar, S., H. J. Reeves, R. J. Cuss, and J. F. Harrington. "The role of stress history on the flow of fluids through fractures." Mineralogical Magazine 76, no. 8 (December 2012): 3165–77. http://dx.doi.org/10.1180/minmag.2012.076.8.30.
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AbstractUnderstanding flow along fractures and faults is of importance to the performance assessment (PA) of a geological disposal facility (GDF) for radioactive waste. Flow can occur along pre-existing fractures in the host-rock or along fractures created during the construction of the GDF within the excavation damage zone (EDZ). The complex fracture network will have a range of orientations and will exist within a complex stress regime. Critical stress theory suggests that fractures close to localized shear failure are critically stressed and therefore most conductive to fluid flow. Analysis of fault geometry and stress conditions at Sellafield has revealed that no features were found to be, or even close to being, classified as critically stressed, despite some being conductive. In order to understand the underlying reasons why non-critically stressed fractures were conductive a series of laboratory experiments were performed. A bespoke angled shear rig (ASR) was built in order to study the relationship between fluid flow (water and gas) through a fracture surface as a function of normal load. Fluid flow reduced with an increase in normal load, as expected. During unloading considerable hysteresis was seen in flow and shear stress. Fracture flow was only partially recovered for water injection, whereas gas flow increased remarkably during unloading. The ratio of shear stress to normal stress seems to control the fluid flow properties during the unloading stage of the experiment demonstrating its significance in fracture flow. The exhumation of the Sellafield area during the Palaeogene–Neogene resulted in considerable stress relaxation and in fractures becoming non-critically stressed. The hysteresis in shear stress during uplift has resulted in faults remaining, or becoming, conductive. The field and laboratory observations illustrate that understanding the stress-history of a fractured rock mass is essential, and a mere understanding of the current stress regime is insufficient to estimate the flow characteristics of present-day fractures.
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Basankin, Igor, Vladimir Porkhanov, Karapet Takhmazyan, Asker Afaunov, Dmitrii Ptashnikov, Olga Ponkina, Marina Tomina, Sergey Malakhov, and Vladimir Shapovalov. "PROPHYLACTIC OF STRESS FRACTURES OF VERTEBRAE ADJACENT TO TRANSPEDICULAR SCREW FIXATION FOR OSTEOPOROSIS." Coluna/Columna 18, no. 4 (December 2019): 313–17. http://dx.doi.org/10.1590/s1808-185120191804225726.
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ABSTRACT Objective: To assess the efficacy and use of vertebroplasty as a prophylactic measure to prevent stress fractures of vertebrae adjacent to transpedicular screw fixation with augmentation for osteoporosis. Methods: An experimental cadaveric study was performed to assess the overall strength of 10 cadaveric blocks of T10-L4 vertebral segments with simulation of L1 fracture and T12-L2 transpedicular 4-screw system with augmentation. T11 and L2 vertebroplasty cranial and caudal to the transpedicular system was performed in 5 blocks in the main group. Stress testing of the blocks was performed by placing them under a vertically directed load until destruction. Results: Vertically directed load on the blocks in the main group (0.84 ± 0.39831 kN) resulted in T11 vertebrae fractures. Vertebrae with augmentation were resistant to the load in the main group. T10 vertebrae fractures in the blocks of the main group occurred at a load of 1.91 ± 0.40566 kN. Conclusion: 1. The adjacent T11 vertebra is the weakest vertebra in the anatomical blocks of T10-L4 vertebral segments with simulation of L1 fracture (type A according to the AO/Magerl classification) and the T12-L2 4-screw transpedicular system with augmentation. 2. Bone cement injection into the T11 cranial vertebra adjacent to the level of fixation increases the overall strength of the blocks 3. Vertebroplasty of the overlying vertebra is an effective way to prevent its fracture and in case of osteoporosis. 4. Prophylactic vertebroplasty of the vertebra caudal to the level of fixation is unnecessary due to the insignificant risk of a fracture. Level of Evidence III; Experimental – Quasi experiments
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Jung, Dal Woo, and Nak Sam Choi. "Static and Fatigue Analysis of a Hybrid Joint Part for the Tilting Car Body." Key Engineering Materials 353-358 (September 2007): 2860–63. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.2860.
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Fatigue fracture behavior of a hybrid joint part for the tilting car body was evaluated in comparison to the case of static fracture. The specimens of hybrid joint part applied in the real tilting car body were fabricated for the bending test. Characteristic fracture behaviors of hybrid joint part specimens under cyclic loads were obviously different from the case under static loads. Static bending load caused the shear deformation and fracture in the honeycomb core region, while cyclic bending load did the delamination along the interface between composite skin and honeycomb core layers as well as the fracture of welded joint part. Experimental results obtained by static and fatigue tests were reflected in modifications of design parameters of the hybrid joint structure in the real tilting car body.
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Zhao, Yong, Shen Hua Yang, and Qi Feng Zheng. "The Effect of Notch Processing on Fracture of High-Carbon Steel (C70S6)." Advanced Materials Research 217-218 (March 2011): 1283–88. http://dx.doi.org/10.4028/www.scientific.net/amr.217-218.1283.
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The effect of starting notch machining methods on fracture splitting of connecting rod was studied by axial tensile tests with single edge notch. The axial tensile specimens were made of the high carbon microalloyed steel (C70S6) which is now most widely used by the connecting rod of fracture splitting. The single edge notch of axial tensile specimens were respectively machined by laser notch、wire cut electrical discharge and broaching. The notch tip plastic deformation of specimens was compared by the fractography. The experimental results indicate that the specimens with laser notch can be fractured by the smallest axial tensile load which is respectively about 20% and 30% smaller than the fracture load of the specimens by wire cut electrical discharge and broaching. Considering the rich micro-local crack transformation hardened zones around the notch by laser the paper present the equivalent critical stress intensity factor KIcL which can be used to calculate the fracture load with laser notch.
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Majidinia, Sara, Marjaneh Ghavamnasiri, Hila Hajizadeh, Mohammad Sadegh Namazikhah, and Mohammad Javad Moghaddas. "Effect of Posts on the Fracture Resistance of Load-cycled Endodontically-treated Premolars Restored with Direct Composite Resin." Journal of Contemporary Dental Practice 10, no. 3 (2009): 10–17. http://dx.doi.org/10.5005/jcdp-10-3-10.
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Abstract Aim The aim of this study was to investigate the fracture resistance and failure mode of premolars restored with composite resin using various prefabricated posts. Methods and Materials Sixty sound maxillary premolars were divided into four equal sized groups. All but the control group received endodontic treatment followed by placement of mesiodistocclusal (MOD) composite restorations (Tetric Ceram) as follows: Group T = no post, Group DT = fiber reinforced composite (FRC) post (DT Light), Group FL = prefabricated metal post (Filpost). The control group (C) had no cavities prepared. After thermal and load cycling, static load was applied at a 30° angle until fracture. Failure modes were categorized as restorable and non-restorable. Data were analyzed using the analysis of variance (ANOVA) and Duncan tests (α = 0.05). Results The mean values of fracture loads (N) for all groups were: C (880±258); T (691±239); DT (865±269); and FL (388±167). Statistically significant differences (P<0.05) were observed for all groups except between groups C and DT. The Chi Square test showed failure modes in groups C and DT were mostly restorable. The most non-restorable fractures were observed in group FT. Conclusion Intact teeth and the teeth restored with composite and quartz fiber posts had a similar fracture resistance and the failure modes were mostly restorable. The lowest fracture resistance and the most nonrestorable failures were observed in conjunction with metal posts. Clinical Significance The results of this in vitro study suggest the use of a quartz fiber post used in conjunction with an MOD composite resin restoration improves fracture resistance in an endodontically treated premolar. Citation Hajizadeh H, Namazikhah MS, Moghaddas MJ, Ghavamnasiri M, Majidinia S. Effect of Posts on the Fracture Resistance of Load-cycled Endodontically-treated Premolars Restored with Direct Composite Resin. J Contemp Dent Pract 2009 May; (10)3:010-017.
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Taha, NA, JE Palamara, and HH Messer. "Fracture Strength and Fracture Patterns of Root-filled Teeth Restored With Direct Resin Composite Restorations Under Static and Fatigue Loading." Operative Dentistry 39, no. 2 (March 1, 2014): 181–88. http://dx.doi.org/10.2341/13-006-l.
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SUMMARY Aim To assess fracture strength and fracture patterns of root-filled teeth with direct resin composite restorations under static and fatigue loading. Methodology MOD cavities plus endodontic access were prepared in 48 premolars. Teeth were root filled and divided into three restorative groups, as follows 1) resin composite; 2) glass ionomer cement (GIC) core and resin composite; and 3) open laminate technique with GIC and resin composite. Teeth were loaded in a servohydraulic material test system. Eight samples in each group were subjected to stepped fatigue loading: a preconditioning load of 100 N (5000 cycles) followed by 30,000 cycles each at 200 N and higher loads in 50-N increments until fracture. Noncycled teeth were subjected to a ramped load. Fracture load, number of cycles, and fracture patterns were recorded. Data were analyzed using two-way analysis of variance and Bonferroni tests. Results Fatigue cycling reduced fracture strength significantly (p<0.001). Teeth restored with a GIC core and a laminate technique were significantly weaker than the composite group (379±56 N, 352±67 N vs 490±78 N, p=0.001). Initial debonding occurred before the tooth underwent fracture. All failures were predominantly adhesive, with subcrestal fracture of the buccal cusp. Conclusions Resin composite restorations had significantly higher fracture strength than did other restorations. Fatigue cycled teeth failed at lower load than did noncycled teeth.