Browsing by Subject "Tensile Strength"
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Item A calculation of stress distribution in metal-porcelain crowns by using three-dimensional finite element method(2002) Aykul H.; Toparli M.; Dalkiz M.The objective of this study was to calculate stress distribution in a maxillary second premolar tooth which occurred by the mastication force. The tooth model was crowned with Au-Pd alloy, Ni-Cr alloy and porcelain. A load of 450 N, at an angle of 45° to the longitudinal axis was applied on the occlusal margin of the crown tooth. The tooth was assumed isotropic, homogenous, elastic and unsymmetrical. This numerical study was carried out using three-dimensional finite element models and calculation programs were prepared by the authors using FORTRAN 77. The distribution of compressive, tensile and shear stress were plotted for the dentine, dentine-metal and metal-porcelain interfaces. The highest stress values were observed when Ni-Cr alloy and porcelain was used. © 2002 Blackwell Science Ltd.Item The use of titanium clips in septal surgery for correction and strengthening(2012) Manavbaş Y.I.; Kerem H.; Erdem A.Permanent correction of septal deformities is one of the most difficult and controversial subjects in aesthetic nasal surgery. The main reasons for failure in most of the corrective procedures are either not to weaken the septal cartilage enough to straighten it, or to treat the septum too radically causing iatrogenic deformities or predisposing it to new deformities postoperatively. Our approach to correct septal deformities relies on the principle of strengthening/reinforcing the septal cartilage (with or without some weakening maneuvers to correct the deformities beforehand) with application of titanium hemoclips at some critical locations in septum. Eighty-seven patients operated on between 2007 and 2009 are included in this study. Thirty-six of these patients had combined septo-nasal deformities while the remaining 51 had solely septal deformities. In 30 patients with septo-nasal deformity the technique was proven to be successful. The remaining 6 patients of this group had axial nasal deformity (rather than intrinsic septal problems) and did not respond to our technique successfully. Within four years of follow up, we did not encounter any recurrences, infections, ulcerations or exposure in the mucosa covering the titanium clips. None of the titanium clips were required to be removed for any reasons. © 2011 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.Item Role of a combination dietary supplement containing mucopolysaccharides, vitamin C, and collagen on tendon healing in rats(Turkish Association of Orthopaedics and Traumatology, 2018) Gemalmaz H.C.; Sarıyılmaz K.; Ozkunt O.; Gurgen S.G.; Silay S.Objective: The aim of this study was to investigate the effect of mucopolysaccharide, vitamin C, and collagen supplementation on the healing of Achilles tendon in rats. Methods: Sixteen rats were separated into 2 groups. Both Achilles tendons of all rats were transected 5 mm above the insertion and repaired using a Kessler suture. After the surgical repair, the study group received the daily recommended amount of the supplement by gastric gavage, while the control group received a placebo. At the end of the third week, the animals were sacrificed. The biomechanical properties of the groups were compared with ultimate tensile strength and stiffness tests. The biological properties of the 2 groups were assessed with a histomorphometric comparison to determine the amount of collagen type I (COL1), proliferating cell nuclear antigen (PCNA), and transforming growth factor β1 (TGF-β1) expression in 3 different tissue subgroups (collagen matrix, tenocytes, and endotenon fibroblasts). Results: Analysis of histomorphometric results revealed that the rats receiving dietary supplements demonstrated a significant increase in PCNA (mean value of 86 in the control group and 168.85 in the trial group; p < 0.05) and TGF-β1 (mean value of 87.57 in the control group and 161.85 in the trial group; p < 0.05) in the endotenon fibroblasts of the repair site. However, there was no difference between the groups in PCNA or TGF-β1 when the collagen matrix and the tenocytes of the repair site were examined. Furthermore, no significant difference could be found between groups in COL1 in any of the 3 tissue subgroups (collagen matrix, tenocytes, and endotenon fibroblasts). The statistical analysis also indicated that the rats receiving supplements did not demonstrate a significant increase in the ultimate tendon tensile strength or stiffness. Conclusion: The results of this study revealed no advantage to the oral administration of the trial supplement in collagen synthesis or biomechanical properties in rats after 3 weeks using the presented study design. However, the increased expression of PCNA and TGFβ1 seen in the endotenon fibroblasts of the repair site might play a role in the continuum of tendon healing. © 2018 Turkish Association of Orthopaedics and TraumatologyItem Methyl cellulose/okra mucilage composite films, functionalized with Hypericum perforatum oil and gentamicin, as a potential wound dressing(Elsevier B.V., 2024) Coban S.N.; Polatoglu I.; Eroglu E.There is a growing demand for the development of functional wound dressings enriched with bioactive natural compounds to improve the quality of life of the population by accelerating the healing process of chronic wounds. In this regard, a functional composite film of okra mucilage (OM) and methylcellulose (MC) incorporated with Hypericum perforatum oil (Hp) and gentamicin (G) was prepared and characterized as a wound dressing. Increasing Hp resulted in improved film properties with a more porous structure, higher WVTR, and lower surface hydrophobicity. Furthermore, incorporating Hp into OM:MC films led to increased elongation at the break while reducing the tensile strength of the films. The highest values of total antioxidant capacity (1.09–1.16 mM trolox equivalent) and total phenolic content (13.76–16.94 μg GA equivalent mL−1) were measured in the composite films containing the highest Hp concentration (1.5 %). In addition, OM:MC/HpG composite films exhibited significant antibacterial activity against both E. coli and S. aureus and prevented the transmission of these bacteria through the films. Hp incorporation reduced the cytotoxic effects of OM:MC films on BJ cells and increased the wound closure rate in vitro. In conclusion, the developed OM:MC/HpG composite film can be a promising candidate as a novel wound dressing with its superior properties. © 2023