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Objective: The aim of this study was to evaluate the effect of decontamination methods on shear bond strength of resin cement to translucent monolithic zirconia. Material and Methods: Eighty 4-mol yttria-stabilized tetragonal zirconia polycrystal specimens were fabricated. All specimens were subjected to saliva contamination and divided into four groups (n = 20) according to the decontamination methods: 70% isopropanol (AL); zirclean (ZC); 5.25% sodium hypochlorite (NaOCL); and no cleaning (NC). All specimens were bonded by using self-adhesive resin cement. Half of the specimens in each group (n = 10) were subjected to aging. All specimens were subjected to shear bond strength test in a universal testing machine. Failure modes were evaluated by using a scanning electron microscope (SEM). The data obtained were statistically analyzed by using one-way ANOVA followed by the HSD Tukey test (p < 0.05). Results: ANOVA test revealed a significant difference among the different decontamination methods (p < 0.05). No significant differences were found among NaOCL, ZC, and AL groups as revealed by the HSD Tukey test (p > 0.05). The effect of aging was significantly different in all groups (p < 0.05); whereas, no significant difference was found in group ZC (p > 0.05). The (SEM) analysis showed mixed failures in all groups, except in group NC where only adhesive failure was observed. Conclusion: Saliva contamination during clinical evaluation significantly decreases the shear bond strength between self-adhesive resin cement and translucent monolithic zirconia. The cleaning methods have an impact on improving the bond strength between resin cement and translucent monolithic zirconia (AU)
Objetivo: O objetivo deste estudo foi avaliar o efeito dos métodos de descontaminação na resistência ao cisalhamento entre cimento resinoso e zircônia monolítica translúcida. Material e métodos: Foram fabricados oitenta espécimes policristalinos de zircônia tetragonal estabilizada com ítria a 4 mol. Todas as amostras foram submetidas à contaminação salivar e divididas em quatro grupos (n = 20) de acordo com os métodos de descontaminação: isopropanol a 70% (AL); zircleano (ZC); Hipoclorito de sódio a 5,25% (NaOCL); e sem limpeza (NC). Todas as amostras foram cimentadas utilizando um cimento resinoso autoadesivo. Metade das amostras de cada grupo(n = 10) foram submetidas ao envelhecimento. Todas as amostras foram submetidas ao teste de resistência ao cisalhamento em uma máquina de teste universal. Os módulos de falha foram avaliados usando um microscópio eletrônico de varredura (MEV). Os dados obtidos foram analisados estatisticamente utilizando ANOVA de uma via, seguida pelo teste de HSD Tukey (p < 0,05). Resultados: O teste ANOVA revelou diferença significativa entre os diferentes métodos de descontaminação (p < 0,05). Não foram encontradas diferenças significativas entre os grupos NaOCl, ZC e AL, conforme revelado pelo teste HSD Tukey (p> 0,05). O efeito do envelhecimento foi significativamente diferente em todos os grupos (p < 0,05); enquanto nenhuma diferença significativa foi encontrada no grupo ZC (p > 0,05). A análise (SEM) mostrou falhas mistas em todos os grupos, exceto no grupo NC, onde apenas foi observada falha adesiva. Conclusão: A contaminação por saliva durante a avaliação clínica diminui significativamente a resistência ao cisalhamento entre o cimento resinoso autoadesivo e a zircônia monolítica translúcida. Os métodos de limpeza têm um impacto na melhoria da resistência da união entre o cimento resinoso e a zircônia monolítica translúcida. (AU)
Subject(s)
Sodium Hypochlorite , Decontamination , Resin Cements , 2-Propanol , Shear StrengthABSTRACT
As an effective implant for bone fracture, bone screws are widely used in clinic. Based on the clinical application of bone screws, this study summarized different kinds of bone screws according to their structures and materials, analyzed 3 kinds of common screw failure (loosening, breaking, corrosion) and the influencing factors. The common testing methods of screws were summarized, especially the key points and difficulties during the testing process for bone screws were analyzed, which was important for improving the design of product, selection of materials and development of in vitro testing technology. The development trend for testing method of bone screws was prospected as well.
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PURPOSE: The purpose of this study was to evaluate the effect of the zirconia surface architecturing technique (ZSAT) on the bond strength between veneering porcelain and zirconia ceramic. MATERIALS AND METHODS: 20 sintered zirconia ceramic specimens were used to determine the optimal surface treatment time, and were randomly divided into 4 groups based on treatment times of 0, 1, 2, and 3 hours. After etching with a special solution, the surface was observed under scanning electron microscope, and then the porcelain was veneered for scratch testing. Sixty 3 mol% yttria-stabilized tetragonal zirconia polycrystal ceramic blocks were used for tensile strength testing; 30 of these blocks were surface treated and the rest were not. Statistical analysis was performed using ANOVA, the Tukey post-hoc test, and independent t-test, and the level of significance was set at α=.05. RESULTS: The surface treatment of the zirconia using ZSAT increased the surface roughness, and tensile strength test results showed that the ZSAT group significantly increased the bond strength between zirconia and veneering porcelain compared to the untreated group (36 MPa vs. 30 MPa). Optimal etching time was determined to be 2 hours based on the scratch test results. CONCLUSION: ZSAT increases the surface roughness of zirconia, and this might contribute to the increased interfacial bond strength between zirconia and veneering porcelain.
Subject(s)
Ceramics , Dental Porcelain , Tensile StrengthABSTRACT
Introduction: Hypertension is one of the leading disorders contributing to significant morbidity and mortality in the world today. Today’s stressful life and modern life styles including the food habits have increased the incidence, acquiring a status of modern day epidemic along with diabetes mellitus. The onset and severity of complication in a system is said to be dependent on the duration of hypertension and the degree of its control. Autonomic dysfunction is drawing more and more attention of the medical fraternity for its supposed role in sudden deaths observed in hypertensive and diabetics. Aim of the study: Our aim is to Hand grip test and Cold presser test in normotensive and moderately hypertensive patients. Materials and methods: A comparative study of cardiovascular autonomic function tests in hypertensive and normotensive individuals was conducted in the Department of Physiology, Department of Community Medicine, RMMCH-Urban Health Centre, Chidambaram on 25 hypertensive patients in the age group of 30-40 years and age matched control group of 25 normotensive individuals. The study was programmed to assess sympathetic nerve functions based on cardiovascular parameters like blood pressure and heart rate measurement. Among the autonomic function tests discussed in the review of literature. Results: In HGT this is an indicator for sympathetic insufficiency. Rise in DBP of > 16 mmHg is taken as normal. In autonomic disorder the rise is < 10 mmHg.
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Introduction: The challenge of restoring patient's function that presented some loss of an organ or tissue encourages the Tissue Engineering and Biotechnology to develop materials that promote bone regeneration. Poly(lactic-co-glycolic acid) (PLGA) copolymer is among of the most biomaterials used. Objective: To evaluate the tensile strength of PLGA membranes at different conditions of humidity and temperature. Material and methods: PLGA membranes were hourglass-shape cut and prepared at three different conditions of temperature and humidity (n = 10): (I) dry membrane at environment temperature of about 20ºC (control group), (II) moist membrane plasticized at 55ºC, (III) moist membrane plasticized at 55ºC, which subsequently underwent cooling. Subsequently, the membranes were subjected to tensile tests in a universal testing machine (DL-2000, EMIC) at 1.0 mm/min. Data was submitted to ANOVA and Tukey's test (p < 0.05). Results: Group I showed the highest tensile strength mean (16.7 ± 1.9a MPa, p = 0.0022). There was no statistically significant difference between the means of groups II (14.6 ± 1.4 MPab) and III (13.9 ± 1.7 MPab). Conclusion: The dried PLGA membranes showed higher tensile strength than the membranes that were only either plasticized or cooled.
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@#Objective To study the test-retest reliability of grip strength assessment in the bed-ridden elders above 80 years old. Methods The left and right grip strength of 20 patients who were bed-ridden for more than 1 year, older than 80 years were measured on the lying position with the JAMAR Hand Dynamometer, and they were measured again in the same way by the same conner a week later. Results The intraclass correlation coefficient were 0.985 and 0.970 in the grip strength of left and right hands, respectively. Conclusion The assessment of grip strength showed good test-retest reliability in the bed-ridden elders above 80.
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This study investigated the hypothesis that the dentin bond strength of self-etching adhesive (SEA) might be improved by applying additional layer of bonding resin that might alleviate the pH difference between the SEA and the restorative composite resin. Two SEAs were used in this study; Experimental SEA (Exp, pH: 1.96) and Adper Prompt (AP, 3M ESPE, USA, pH: 1.0). In the control groups, they were applied with two sequential coats. In the experimental groups, after applying the first coat of assigned SEAs, the D/E bonding resin of All-Bond 2 (Bisco Inc., USA, pH: 6.9) was applied as the intermediate adhesive. Z-250 (3M ESPE, USA) composite resin was built-up in order to prepare hourglass-shaped specimens. The microtensile bond strength (MTBS) was measured and the effect of the intermediate layer on the bond strength was analyzed for each SEA using t-test. The fracture mode of each specimen was inspected using stereomicroscope and Field Emission Scanning Electron Microscope (FE-SEM). When D/E bonding resin was applied as the second coat, MTBS was significantly higher than that of the control groups. The incidence of the failure between the adhesive and the composite or between the adhesive and dentin decreased and that of the failure within the adhesive layer increased. According to the results, applying the bonding resin of neutral pH can increase the bond strength of SEAs by alleviating the difference in acidity between the SEA and restorative composite resin.
Subject(s)
Adhesives , Dentin , Hydrogen-Ion Concentration , Incidence , Oceans and SeasABSTRACT
Objective To explore the correlation between the strength of trunk flexors and extensors obtained by isometric and isokinetic concentric tests. Methods The strength of trunk extensors and flexors were measured by isometric and isokinetic concentric tests during trunk flexion and extension in 50 healthy subjects, and the peak torque of flexion and extension (FPT and EPT) and the ratios of FPT/EPT were analyzed with correlation and regression analysis. Results The FPT and EPT of trunk flexors and extensors were positively correlated (r_F=0.827,P0.05, respectively), the regression equations of FPT and EPT were y
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Anastomosis of rat common carotid artery was performed by applying four crossed-fixing sutures and by mantling with human fibrinogen-thrombin glue. There was a 97% patency rate 24 hours after surgery, and the anastomosed vessels were still patent on the 7th and 30th postoperative days. Aneurysm formation was absent but stenotic change was seen to 1 case of 8 angiographic studies. Histopathological studies of microvascular anastomosis showed that this surgical technique of anastomosis has certain advantages, namely that it reduces the number of sutures needed, is less traumatic to the vascular wall, ensures elastic vascular junction, and the glue used possess high biological inertness that provides a better physiological connection of vessels than conventional suturing. The duration of the clipping and the operation is significantly reduced. A tensile strength test 24 hours following operation and 1 week later showed that this anastomosis was significantly better than that achieved with the usual manual suture method. The author therefore concludes that this new surgical technique of microvascular anastomosis may be valuable in microvascular neurosurgery.
Subject(s)
Animals , Humans , Rats , Adhesives , Aneurysm , Carotid Artery, Common , Fibrin Tissue Adhesive , Fibrin , Neurosurgery , Sutures , Tensile StrengthABSTRACT
Boys and girls of elementary school (1 st, 3 rd and 6 th-grades), junior high school (2 nd-grade) and senior high school (2 nd-grade) were tested for 2 days to examine the reliability of grip strength, back strength, arm strength and leg strength.<BR>The following results were obtained:<BR>1. When elementary school boys performed three trials of these four items, over half boys recorded maximal value up to the second trial.<BR>2. The reliability of tests applied to the left and right sides (grip strength, arm strength and leg strength) was not different each other.<BR>3. In boys and girls attending elementary, junior- and senior high schools the reliability of grip strength was highest and the next was back strength.<BR>4. Grip strength had statistically significant relationship to the other three items. Thus grip strength is considered to be the representative of four strength tests for growing boys and girls.