Comparison of Three Attachments in Implant-Tissue Supported Overdentures: An In Vitro Study

Objective: Retention and resistance of the implant-tissue supported overdenture may be affected by the type of attachment. The aim of this research was to compare the retention and resistance of Nobel Biocare Ball (NBB), Nobel Biocare Bar and Clip (NBBC) andSterngold ERA Red (ERAR) attachments on an implant-tissue supported overdenture model.Materials and Methods: The attachment samples were divided into 3 groups of NBB,NBBC, and ERAR (5 samples in each group). Two parallel Nobel Biocare Branemark implants were placed symmetrically at the symphysis region of a mandibular test model. A metallic overdenture was fabricated precisely adapted to the model and attached to aZwick testing machine (crosshead speed of 51 mm/min). Dislodging tensile forces were applied in three vertical, oblique, anterior-posterior directions and two situations, at the beginning and after 100 times of insertion/removal of the overdenture, for each sample.The maximum dislodging force was measured. A One-way ANOVA test was employed followed by Tukey’s test.Results: ERAR was the most retentive and resistant in both situations. NBB and NBBC showed the same anterior-posterior resistance at the beginning. All test groups representeda large amount of retention and resistance loss after the insertion/removal of the overdenture,while NBBC showed a higher loss of anterior-posterior resistance than NB.Conclusion: A highest level of retention and resistance was seen in ERAR. The retention and resistance were affected by the wear of attachments

Comparison of the effect of ball and bar attachment designs on retention and stability of mandibular implant-supported overdentures

Objectives The present study evaluated the effect of bar and ball attachment designs on retention and stability of a mandibular overdenture supported by four implants.Methods An edentulous mandibular acrylic resin model with four implants in the anterior part of the ridge (A, B, D and E) was fabricated. A metal framework simulating the overdenture was also fabricated. Totally, 30 overdentures were divided into three groups based on the attachment design; BL: Four ball attachments in A, B, D and E positions; BB: One bar attachment between B and D positions and two ball attachments at positions A and E; BR: Bar attachments between the positions A, B, D and E with two posterior extensions. To evaluate the retention and stability of the overdenture, tensile dislodging forces were applied in three directions of vertical, oblique and anterior- posterior by a universal testing machine. One-way ANOVA and Tukey’s HSD test were performed to analyze the data. All tests were carried out at 0.05 level of significance.Results There were statistically significant differences between the groups in the peak load (P < 0.001). The peak load values for vertical, oblique and anterior-posterior dislodging forces were the highest for BL with 49.38 ± 2.19 N, 52.19 ± 1.44 N, and 49.03 ± 5.89 N, respectively, while these values were the lowest for BR with 29.78 ± 2.52 N, 12.10 ± 0.45 N, and 6.26 ± 0.45 N, respectively.Conclusion The attachment designs affected the retention and stability of mandibular implant-supported overdentures

The Prevalence of Temporomandibular Disorders in Patients Referred to the Prosthodontics Department of Shahid Beheshti Dental School in Fall 2010

Objective: Temporomandibular disorders (TMDs) are among the most common disorders of the maxillofacial region and are often characterized by pain and dysfunction of the temporomandibular joint(TMJ) and muscles of mastication. Due to the presence of several diagnostic criteria for such disorders, the reported prevalence rates for TMDs have been variable in different communities. The aim of this study was to determine the prevalence of TMDs in patients presenting to the Prosthodontics Department of Shahid Beheshti Dental School (SBDS) in fall 2010.Methods: In this descriptive study, 150 patients presenting to the Prosthodontics Department of SBDS (86 females and 64 males) were randomly selected and evaluated by using a questionnaire (subjectively) and clinical examinations (objectively). Presence and prevalence of various symptoms of TMDs such as clicking and tenderness on palpation in the muscles of mastication and the TMJ were evaluated in patients. Statistical comparisons were carried out using chi-square test.Results: Clicking, masticatory muscle and joint tenderness, TMDs, and limitation of mouth opening were found in 21.3%, 18.7%, 5.3%, 18.7% and 1.3% of patients, respectively. Despite the higher prevalence of TMDs in females, the difference in this regard between males and females was not statistically significant (39.3% in men versus 60.7% in women).Conclusion: Based on the obtained results, the prevalence of TMDs and its related symptoms was 18.7% in patients presenting to the Prosthodontics Department of SBDS in fall 2010. This value was lower than the rates reported in the literature

Governmental origin: why NTBFs grow in a transitional economy

The NTBFs have attracted growing interest from most of the transitional economies as they are seen as an important source of greater value added creation while being characterised with higher rate of return on capital. Shedding light on the growth determinants of new technology-based firms not only helps managers to accomplish organisational goals but also assists policymakers in devising effective strategies. The role of individual, organisational as well as environmental factors in the development of the new technology-based firms has been separately addressed by many researchers. The simultaneity of these factors leads to diverse configurations, each of which envisaging different growth paths for the firm. The aim of this paper is to identify the growth paths for the new technology-based firms. To this end, Some interviews were conducted with the managers of the developed new technology-based firms in Iran (as a transitional economy) and the key themes governing the growth pattern of this group of firms have been identified using the thematic analysis, while possible growth paths for these firms were established by means of qualitative comparative analysis. The designed questionnaires were distributed among 22 developed firms and 8 underdeveloped firms for the period 2013–2015 and the obtained data were analysed using the FSQCA software, which led us to the development of dominant growth path for new technology-based firms. Based on the findings of this paper and factors affecting the growth of firms, two growth paths are suggested for the new technology-based firms, of which the one with greater role for government is more likely to take place. Communication with government officials and lobbying groups in the field of science and technology as the key customer in transitional economies is critical to the corporate growth, which has been identified as a sufficient condition for this research

Improving recombinant protein solubility in Escherichia coli: Identification of best chaperone combination which assists folding of human basic fibroblast growth factor

Manipulating the cytoplasmic folding environment by increasing the intracellular concentration of folding modulators, such as chaperone molecules, causes the convenient production of heterologous proteins. Wrong selection of chaperones will negatively affect the host cells physiology and the production of heterologous proteins. Due to this reason, type and combination of chaperone molecules are crucial to produce more soluble and active form of target protein. In the current study, the cooverproduction of five different combinations of 6 chaperones, comprising "DnaK/DnaJ /GrpE/GroES/ GroEL", "GroES/GroEL", "DnaK/DnaJ/GrpE", "GroES/GroEL/TF" and "TF" along with recombinant human basic fibroblast growth factor (rhbFGF) were studied. As a result, we proved that none of these combinations was able to completely prevent the formation of inclusion  bodies, but co-overexpression of the bacterial chaperone system TF along with rhbFGF could significantly enhance the yield of soluble protein. Recombinant soluble hbFGF that co-expressed with TF was then purified from the cells and was found to be identical to the active rhbFGF expressed alone with respect to size and spectral properties.Key words: Human basic fibroblast growth factor (hbFGF), chaperone co-expression, chaperone combination, inclusion body, protein folding

Attenuation of influenza virus infectivity with herbal-marine compound (HESA-A): an in vitro study in MDCK cells

<p>Abstract</p> <p>Background</p> <p>The influenza virus is still one of the most important respiratory risks affecting humans which require effective treatments. In this case, traditional medications are of interest. HESA-A is an active natural biological compound from herbal-marine origin. Previous studies have reported that the therapeutic properties of HESA-A are able to treat psoriasis vulgaris and cancers. However, no antiviral properties have been reported.</p> <p>Methods</p> <p>This study was designed to investigate the potential antiviral properties of HESA-A and its effects in modulating TNF-α and IL-6 cytokine levels. HESA-A was prepared in normal saline as a stock solution (0.8 mg/ml, pH = 7.4). Percentages of cell survival when exposed to different concentrations of HESA-A at different time intervals was determined by MTT assay. To study the potential antiviral activity of HESA-A, Madin-Darby Canine Kidney (MDCK) cells were treated with the effective concentration (EC₅₀) of HESA-A (0.025 mg/ml) and 100 TCID₅₀/0.1 ml of virus sample under different types of exposure.</p> <p>Results</p> <p>Based on the MTT method and hemagglutination assay (HA), HESA-A is capable of improving cell viability to 31% and decreasing HA titre to almost 99% in co-penetration exposures. In addition, based on quantitative real-time PCR (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA), it was found that HESA-A causes decrements in TNF-α and IL-6 cytokine expressions, which was significant for TNF-α (<it>p </it>≤ 0.05) but not for IL-6.</p> <p>Conclusion</p> <p>In conclusion, HESA-A was effective against influenza infection through suppressing cytokine expression.</p

Fast neutron transmission and tomography simulation using Monte Carlo techniques for the examination of large industrial and biological objects.

Elemental analysis of substances made of heavy elements and detection of light elements in heavy matrices are difficult by means of photon transmission techniques. Neutrons have been used in this work, taking unique advantage of their absorption and scattering properties, to detect the structure of industrial and biological objects made of strongly-neutron scattering or absorbing materials, or to study objects combining of high and low neutron cross section materials. The most convenient matrices and impurities amenable to neutron inspection were searched by obtaining expressions for minimum detectable mass and length fraction of elements in an object. Formulae to calculate the minimum required number of neutrons to detect an impurity in a matrix have also been developed. The optimum sample thickness to be investigated with a minimum number of neutrons is likewise derived. Calculations have been carried out for the minimum detectable mass fraction of hydrogen in a number of sample matrices of industrial interest and of elements in a water matrix highlighting the differences with photon attenuation measurements. Results are presented for three neutron energies cold (0.001 eV), thermal (0.025 eV), and fast (14 MeV); concentrations in the parts per million range are demonstrated. Fast neutrons were used because of their high penetration ability, in order to study bulk industrial and biological samples and for their adequacy in detection of light elements such as H, C, N and O in large objects. An attempt to simulate fast neutron transmission tomographs of biological samples was made using the MORSE-CGA Monte-Carlo code. The code was used to calculate transmission of multienergetic U-235 fast fission neutron source in a complex geometry for industrial and biological applications. A fast neutron collimator for radiography, a collimator for brain tomography and a tomography chamber were simulated to design a technique to estimate the effect of scattered neutrons in practical tomography. The macroscopic cross section and mean free path of neutrons for the media of the heterogeneous matrices were also obtained by using microscopic cross sections of elements from the DLC-100G package. Using a multienergetic source provided an opportunity to determine the optimum neutron energy for examination of objects. The analysis required establishing a technique to calculate the fraction of neutrons in each energy group for the 100 group structure of the DLC-100G package. Finally the simulated neutron tomographic images were reconstructed by using the neutron transmission data for different angles of the object, and reconstructing them by the filtered back projection technique. In non-destructive evaluation of medical organs by fast neutron simulation tomography the simulated tomography of prototype biological objects were able to distinguish brain in skull, bone-marrow in bone and bone in soft tissue with good contrast up to 0.42. These results are valuable to identify developing cystic lesions and daughter cyst within the marrow vascular spaces, solid bony tumors, aberrant masses in the facial bone, tumor in spine or other bone marrow abnormalities. In studying component characterisation of industrial objects non-destructively by fast neutron tomography a 3mm diameter duct containing engine-oil was detected at 40 cm depth inside an aluminium combustion engine with a remarkable contrast of 0.35. The minimum detectable mass of oil in aluminium for an optimum neutron energy was 0.1mg/g with a similar result for iron

Fast neutron transmission and tomography simulation using Monte Carlo techniques for the examination of large industrial and biological objects

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