Displaying publications 101 - 120 of 382 in total

Abstract:
Sort:
  1. Fulltext Degradation effects of dietary solvents on microhardness and inorganic elements of computer-aided design/computer-aided manufacturing dental composites
    Munusamy SM, Helen-Ng LC, Farook MS
    BMC Oral Health, 2024 Feb 01;24(1):162.
    PMID: 38302972 DOI: 10.1186/s12903-024-03905-7
    BACKGROUND: Computer-aided design/computer-aided manufacturing (CAD/CAM) dental composites were introduced with superior mechanical properties than conventional dental composites. However, little is known on effects of dietary solvents on microhardness or inorganic elemental composition of CAD/CAM composites.

    OBJECTIVES: The objectives of this study were to evaluate the degradation effects of each dietary solvent on the microhardness of the different CAD/CAM dental composites and to observe the degradation effects of dietary solvent on the inorganic elements of the dental composites investigated.

    METHODS: Fifty specimens with dimensions 12 mm x 14 mm x 1.5 mm were prepared for direct composite (Filtek Z350 XT [FZ]), indirect composite (Shofu Ceramage [CM]), and three CAD/CAM composites (Lava Ultimate [LU], Cerasmart [CS], and Vita Enamic [VE]). The specimens were randomly divided into 5 groups (n = 10) and conditioned for 1-week at 37°C in the following: air (control), distilled water, 0.02 N citric acid, 0.02 N lactic acid and 50% ethanol-water solution. Subsequently, the specimens were subjected to microhardness test (KHN) using Knoop hardness indenter. Air (control) and representative postconditioning specimens with the lowest mean KHN value for each material were analyzed using energy dispersive X-ray spectroscopy (EDX). Statistical analysis was done using one-way ANOVA and post hoc Bonferroni test at a significance level of p = 0.05.

    RESULTS: Mean KHN values ranged from 39.7 ± 2.7 kg/mm2 for FZ conditioned in 50% ethanol-water solution to 79.2 ± 3.4 kg/mm2 for VE conditioned in air (control). With exception to LU, significant differences were observed between materials and dietary solvents for other dental composites investigated. EDX showed stable peaks of the inorganic elements between air (control) and representative postconditioning specimens.

    CONCLUSIONS: The microhardness of dental composites was significantly affected by dietary solvents, except for one CAD/CAM composite [LU]. However, no changes were observed in the inorganic elemental composition of dental composites between air (control) and 1-week postconditioning.

    Matched MeSH terms: Materials Testing
  2. Degree of conversion and physicomechanical properties of newly developed flowable composite derived from rice husk using urethane dimethacrylate monomer
    Azlisham NAF, Johari Y, Mohamad D, Yhaya MF, Mahmood Z
    Proc Inst Mech Eng H, 2023 Dec;237(12):1339-1347.
    PMID: 38014749 DOI: 10.1177/09544119231208222
    This study evaluated the use of urethane dimethacrylate (UDMA) as a base monomer to prepare the newly developed flowable composite (FC) using nanohybrid silica derived from rice husk in comparison to bisphenol A-glycidyl methacrylate (Bis-GMA) on the degree of conversion and physicomechanical properties. The different loadings of base monomer to diluent monomer were used at the ratio of 40:60, 50:50, and 60:40. The bonding analysis confirmed the presence of nanohybrid silica in the newly developed FC. Independent t-test revealed a statistically significant increase in the degree of conversion, depth of cure and Vickers hardness of the UDMA-based FC, while surface roughness showed comparable results between the two base monomers. In conclusion, UDMA-based FC demonstrated superior performance with 60%-65% conversions, a significantly higher depth of cure exceeding 1 mm which complies with the Internal Standard of Organization 4049 (ISO 4049), and a substantial increase in Vickers hardness numbers compared to Bis-GMA-based FC, making UDMA a suitable alternative to Bis-GMA as a base monomer in the formulation of this newly developed FC derived from rice husk.
    Matched MeSH terms: Materials Testing
  3. A technique for evaluating the oil/heavy-oil viscosity changes under ultrasound in a simulated porous medium
    Hamidi H, Mohammadian E, Junin R, Rafati R, Manan M, Azdarpour A, et al.
    Ultrasonics, 2014 Feb;54(2):655-62.
    PMID: 24075416 DOI: 10.1016/j.ultras.2013.09.006
    Theoretically, Ultrasound method is an economical and environmentally friendly or "green" technology, which has been of interest for more than six decades for the purpose of enhancement of oil/heavy-oil production. However, in spite of many studies, questions about the effective mechanisms causing increase in oil recovery still existed. In addition, the majority of the mechanisms mentioned in the previous studies are theoretical or speculative. One of the changes that could be recognized in the fluid properties is viscosity reduction due to radiation of ultrasound waves. In this study, a technique was developed to investigate directly the effect of ultrasonic waves (different frequencies of 25, 40, 68 kHz and powers of 100, 250, 500 W) on viscosity changes of three types of oil (Paraffin oil, Synthetic oil, and Kerosene) and a Brine sample. The viscosity calculations in the smooth capillary tube were based on the mathematical models developed from the Poiseuille's equation. The experiments were carried out for uncontrolled and controlled temperature conditions. It was observed that the viscosity of all the liquids was decreased under ultrasound in all the experiments. This reduction was more significant for uncontrolled temperature condition cases. However, the reduction in viscosity under ultrasound was higher for lighter liquids compare to heavier ones. Pressure difference was diminished by decreasing in the fluid viscosity in all the cases which increases fluid flow ability, which in turn aids to higher oil recovery in enhanced oil recovery (EOR) operations. Higher ultrasound power showed higher liquid viscosity reduction in all the cases. Higher ultrasound frequency revealed higher and lower viscosity reduction for uncontrolled and controlled temperature condition experiments, respectively. In other words, the reduction in viscosity was inversely proportional to increasing the frequency in temperature controlled experiments. It was concluded that cavitation, heat generation, and viscosity reduction are three of the promising mechanisms causing increase in oil recovery under ultrasound.
    Matched MeSH terms: Materials Testing/methods*
  4. Process of prototyping coronary stents from biodegradable Fe-Mn alloys
    Hermawan H, Mantovani D
    Acta Biomater, 2013 Nov;9(10):8585-92.
    PMID: 23665503 DOI: 10.1016/j.actbio.2013.04.027
    Biodegradable stents are considered to be a recent innovation, and their feasibility and applicability have been proven in recent years. Research in this area has focused on materials development and biological studies, rather than on how to transform the developed biodegradable materials into the stent itself. Currently available stent technology, the laser cutting-based process, might be adapted to fabricate biodegradable stents. In this work, the fabrication, characterization and testing of biodegradable Fe-Mn stents are described. A standard process for fabricating and testing stainless steel 316L stents was referred to. The influence of process parameters on the physical, metallurgical and mechanical properties of the stents, and the quality of the produced stents, were investigated. It was found that some steps of the standard process such as laser cutting can be directly applied, but changes to parameters are needed for annealing, and alternatives are needed to replace electropolishing.
    Matched MeSH terms: Materials Testing/methods*
  5. New bioactive glass-ceramic: synthesis and application in PMMA bone cement composites
    Abd Samad H, Jaafar M, Othman R, Kawashita M, Abdul Razak NH
    Biomed Mater Eng, 2011;21(4):247-58.
    PMID: 22182792 DOI: 10.3233/BME-2011-0673
    In present study, a new composition of glass-ceramic was synthesized based on the Na2O-CaO-SiO2-P2O5 glass system. Heat treatment of glass powder was carried out in 2 stages: 600 °C as the nucleation temperature and different temperature on crystallization at 850, 950 and 1000 °C. The glass-ceramic heat-treated at 950 °C was selected as bioactive filler in commercial PMMA bone cement; (PALACOS® LV) due to its ability to form 2 high crystallization phases in comparison with 850 and 1000 °C. The results of this newly glass-ceramic filled PMMA bone cement at 0-16 wt% of filler loading were compared with those of hydroxyapatite (HA). The effect of different filler loading on the setting properties was evaluated. The peak temperature during the polymerization of bone cement decreased when the liquid to powder (L/P) ratio was reduced. The setting time, however, did not show any trend when filler loading was increased. In contrast, dough time was observed to decrease with increased filler loading. Apatite morphology was observed on the surface of the glass-ceramic and selected cement after bioactivity test.
    Matched MeSH terms: Materials Testing/methods
  6. Some flexural properties of a nylon denture base polymer
    Yunus N, Rashid AA, Azmi LL, Abu-Hassan MI
    J Oral Rehabil, 2005 Jan;32(1):65-71.
    PMID: 15634304
    Nylon denture base material could be a useful alternative to poly (methyl methacrylate) (PMMA) in special circumstances such as patient allergy to the monomer. The aim of this study was to evaluate the flexural properties of a nylon denture base material (Lucitone FRS), a conventional compression-moulded heat-polymerized (Meliodent), a compression-moulded microwave-polymerized (Acron MC) and an injection-moulded microwave-polymerized (Lucitone 199) PMMA polymers. The effect of aldehyde-free, oxygen releasing disinfectant solution (Perform) on these properties was also investigated. The flexural modulus and the flexural strength were assessed with a three-point bending test. Specimens were stored in water at a temperature of 37 degrees C for 30 days. For each material, half of the prepared specimens were randomly selected and immersed in the disinfectant 24 h prior to testing. Results were compared statistically at a confidence level of 95%. The result showed that in both the control and disinfected groups, the flexural modulus of nylon was significantly lower than the three PMMA polymers. The flexural strength of nylon was significantly lower than those of Meliodent and Acron MC but was comparable with Lucitone 199. A 24-h immersion in the disinfecting solution increased the rigidity of nylon denture base material.
    Matched MeSH terms: Materials Testing/methods
  7. The use of freeze-dry bovine pericardium (FDBP) in diaphragmatic herniorrhaphy in dogs
    Loqman MY, Wong CM, Hair-Bejo M, Zuki AB, Hafeez YM
    Med J Malaysia, 2004 May;59 Suppl B:113-4.
    PMID: 15468844
    A study was conducted to investigate the effectiveness of freeze-dried bovine pericardium (FDBP) as a biomaterial in diaphragmatic herniorrhapy in dogs. Eight adult dogs were randomly selected and divided into two equal groups. In FDBP group, a diaphragmatic defect was induced and repaired with an identical size of FDBP. In the control group, a diaphragmatic wall was incised at three-side border creating a flap and sutured. Grossly, only mild intrathoracic adhesion was observed for most of the animals, and no herniation occured. Microscopically, the biomaterial incorporated into the host's tissue by ingrowth of young muscle fiber and massive new blood vessel formation in between the fibrous tissue.
    Matched MeSH terms: Materials Testing*
  8. In vivo study of CORAGRAF: a preliminary results
    Rosdan S, Al-Salihi KA, Suzina AH, Samsudin AR
    Med J Malaysia, 2004 May;59 Suppl B:111-2.
    PMID: 15468843
    The main objective of the study was to determine the biodegradability, resorption and osteoconductivity potency of coral implant. Coral blocks (CORAGRAF) were prepared from sea coral Porites species. The blocks were implanted in the right mandible of rabbit model. Implants were harvested at 2 and 4 weeks intervals and subjected for light and scanning electron microscopy. Dense hydroxyapatite (DHA) was implanted in the left mandible as a control. The results of this study demonstrated that CORAGRAF is a good implant material that can accelerates bone healing and be resorbed in an acceptable time. The mechanisms of the resorption seemed to be the same (crumbling process), a first step where the edge of the coral become powdery then a second step which could be phagocytosis and dissolution in extracellular fluid.
    Matched MeSH terms: Materials Testing*
  9. In vitro cytotoxicity testing on valued added hydroxyapatite as bone replacement material
    Shaari R, Samsudin AR
    Med J Malaysia, 2004 May;59 Suppl B:109-10.
    PMID: 15468842
    The present in vitro evaluation indicated that the value added hydroxyapatite (HA) was more toxic than pure HA but the toxicity of value added HA was slight compared to the positive control. In this testing, the conclusion can be made that value added HA is less biocompatible than commercialized pure HA. This toxicity may be caused by both the particle size and degradation (leaching). Further studies should be carried out to determine whether there is particle size effect or leaching effect when using powder as compared to the block materials. The in vivo evaluation should be done to assess the reaction to this value added HA as compared to the pure HA.
    Matched MeSH terms: Materials Testing*
  10. Endothelialisation of poly (carbonate-siloxane-urea) urethane
    Kannan RY, Sales KM, Salacinski HJ, Butler PE, Seifalian AM
    Med J Malaysia, 2004 May;59 Suppl B:107-8.
    PMID: 15468841
    Matched MeSH terms: Materials Testing*
  11. Mechanical properties of HDPE/UHMWPE blends: effect of filler loading and filler treatment
    Lai KL, Roziyanna A, Ogunniyi DS, Zainal AM, Azlan AA
    Med J Malaysia, 2004 May;59 Suppl B:61-2.
    PMID: 15468819
    Various blend ratios of high-density polyethylene (HDPE) and ultra high molecular weight polyethylene (UHMWPE) were prepared with the objective of determining their suitability as biomaterials. In the unfilled state, a blend of 50/50 (HDPE/UHMWPE) ratio by weight was found to yield optimum properties in terms of processability and mechanical properties. Hydroxyapatite (HA) was compounded with the optimum blend ratio. The effects of HA loading, varied from 0 to 50wt% for both filled and unfilled blends were tested for mechanical properties. It was found that the inclusion of HA in the blend led to a remarkable improvement of mechanical properties compared to the unfilled blend. In order to improve the bonding between the polymer blend and the filler, the HA used was chemically treated with a coupling agent known as 3-(trimethoxysiyl) propyl methacrylate and the treated HA was mixed into the blend. The effect of mixing the blend with silane-treated HA also led to an overall improvement of mechanical properties.
    Matched MeSH terms: Materials Testing*
  12. HAp physical investigation--the effect of sintering temperature
    Azran YM, Idris B, Rusnah M, Rohaida CH
    Med J Malaysia, 2004 May;59 Suppl B:79-80.
    PMID: 15468828
    The paper presents the effect of sintering temperature on the physical properties of porous hydroxyapatite (HAp In this study, the HAp was prepared using polymeric sponge techniques with different binder concentrations. The sintering process was carried out in air for temperature ranging from 1200 degrees C to 1600 degrees C. Different physical properties namely density and porosity were observed at different sintering temperatures. The HAp prepared with higher PVP binder showed a slightly decreased in apparent density with increasing sintering temperature, while those HAp prepared with lower PVP showed a slightly increase in apparent density with increasing sintering temperature. The total porosity was found to be approximately constant in the whole sintering temperature range. However, closed porosity decreases with increasing sintering temperature for HAp prepared by lower binder concentration. On the other hand, the HAp prepared by higher binder concentrations showed increasing closed porosity with increasing sintering temperature. Other features such as the influence of sintering temperatures on grain and strut would also be presented in this paper.
    Matched MeSH terms: Materials Testing*
  13. Comparison of hydroxyapatite powders derived from different resources
    Hee SL, Nik Intan NI, Fazan F
    Med J Malaysia, 2004 May;59 Suppl B:77-8.
    PMID: 15468827
    There is a great demand of Hydroxyapatite (HA) material in Orthopaedics and Dental applications due to its similarity to human bone. However, the lack of availability and due to high import cost of this material in Malaysia, research in producing synthetic HA locally is therefore timely. The use of local resources as the raw materials for the production of HA is also desirable in reducing the overall cost of HA. In this study, two HA materials were synthesised from different starting precursors, i.e. commercial pure Ca(OH)2 (HAS) and Ca(OH)2 directly from a local natural limestone deposit (HAL). Whereas a commercially available HA "Captal 60" (HAC) was used as reference. The synthesised powders obtained were fired at 1000 degrees C and at 1250 degrees C. Characterisation evaluations on bulk properties were carried out using XRD, SEM-EDX, ICP and FTIR. The results indicate that both HAS and HAL are comparable to HAC even at 1000 degrees C. Thus, the local natural limestone can be used to form HA. However, the overall appearance of these materials are quite different (HAC - blue, HAS - greenish and HAL - light green). The reasons for this and the subsequent mechanical and bioactive effects of these materials are currently being investigated.
    Matched MeSH terms: Materials Testing*
  14. Biomimetic structures for implants and tissue engineering scaffolds
    Ambrosio L, Battista S, Borzacchiello A, Borselli C, Causa F, De Santis R, et al.
    Med J Malaysia, 2004 May;59 Suppl B:71-2.
    PMID: 15468824
    Matched MeSH terms: Materials Testing*
  15. Cytotoxicity analysis of poly (carbonate-siloxane-urea) urethane
    Kannan RY, Sales KM, Salacinski HJ, Butler PE, Seifalian AM
    Med J Malaysia, 2004 May;59 Suppl B:99-100.
    PMID: 15468837
    Matched MeSH terms: Materials Testing*
  16. Lactic acid-based bioresorbable polymers: properties and traps
    Vert M
    Med J Malaysia, 2004 May;59 Suppl B:73-4.
    PMID: 15468825
    Matched MeSH terms: Materials Testing*
  17. Characterization of collagen/chitosan films for skin regenerating scaffold
    Ismarul IN, Ishak Y, Ismail Z, Mohd Shalihuddin WM
    Med J Malaysia, 2004 May;59 Suppl B:57-8.
    PMID: 15468817
    Various proportions of chitosan/collagen films (70/30% to 95/05%) w/w were prepared and evaluated for its suitability as skin regenerating scaffold. Interactions between chitosan and collagen were studied using Fourier Transform Infrared spectroscopy (FTIR) and Differential Scanning Colorimetry (DSC). Scanning Electron Microscope (SEM) was used to investigate the morphology of the blend. Mechanical properties were evaluated using a Universal Testing Machine (UTM). The chitosan/collagen films were found to swell proportionally with time until it reaches equilibrium. FTIR spectroscopy indicated no chemical interaction between the components of the blends. DSC data indicated only one peak proving that these two materials are compatible at all proportions investigated. SEM micrographs also indicated good homogeneity between these two materials.
    Matched MeSH terms: Materials Testing*
  18. Medicinal and cosmetics soap production from Jatropha oil
    Shahinuzzaman M, Yaakob Z, Moniruzzaman M
    J Cosmet Dermatol, 2016 Jun;15(2):185-93.
    PMID: 26777540 DOI: 10.1111/jocd.12209
    Soap is the most useful things which we use our everyday life in various cleansing and cosmetics purposes. Jatropha oil is nonedible oil which has more benefits to soap making. It has also cosmetics and medicinal properties. But the presence of toxic Phorbol esters in Jatropha oil is the main constrains to use it. So it is necessary to search a more suitable method for detoxifying the Jatropha oil before the use as the main ingredient of soap production. This review implies a more suitable method for removing phorbol esters from Jatropha oil. Several parameters such as the % yield of pure Jatropha oil soap, TFM value of soap, total alkali content, free caustic alkalinity content, pH, the antimicrobial activity, and CMC value of general soap should be taken into consideration for soap from detoxified Jatropha oil.
    Matched MeSH terms: Materials Testing/methods
  19. Mechanical and physical behavior of newly developed functionally graded materials and composites of stainless steel 316L with calcium silicate and hydroxyapatite
    Ataollahi Oshkour A, Pramanik S, Mehrali M, Yau YH, Tarlochan F, Abu Osman NA
    J Mech Behav Biomed Mater, 2015 Sep;49:321-31.
    PMID: 26072197 DOI: 10.1016/j.jmbbm.2015.05.020
    This study aimed to investigate the structural, physical and mechanical behavior of composites and functionally graded materials (FGMs) made of stainless steel (SS-316L)/hydroxyapatite (HA) and SS-316L/calcium silicate (CS) employing powder metallurgical solid state sintering. The structural analysis using X-ray diffraction showed that the sintering at high temperature led to the reaction between compounds of the SS-316L and HA, while SS-316L and CS remained intact during the sintering process in composites of SS-316L/CS. A dimensional expansion was found in the composites made of 40 and 50 wt% HA. The minimum shrinkage was emerged in 50 wt% CS composite, while the maximum shrinkage was revealed in samples with pure SS-316L, HA and CS. Compressive mechanical properties of SS-316L/HA decreased sharply with increasing of HA content up to 20 wt% and gradually with CS content up to 50 wt% for SS-316L/CS composites. The mechanical properties of the FGM of SS-316L/HA dropped with increase in temperature, while it was improved for the FGM of SS-316L/CS with temperature enhancement. It has been found that the FGMs emerged a better compressive mechanical properties compared to both the composite systems. Therefore, the SS-316L/CS composites and their FGMs have superior compressive mechanical properties to the SS-316L/HA composites and their FGMs and also the newly developed FGMs of SS-316L/CS with improved mechanical and enhanced gradation in physical and structural properties can potentially be utilized in the components with load-bearing application.
    Matched MeSH terms: Materials Testing*
  20. Blood compatibility of human amniotic membrane compared with heparin-coated ePTFE for vascular tissue engineering
    Kakavand M, Yazdanpanah G, Ahmadiani A, Niknejad H
    J Tissue Eng Regen Med, 2017 06;11(6):1701-1709.
    PMID: 26190586 DOI: 10.1002/term.2064
    Amniotic membrane (AM), a placenta-derived natural biomaterial, has several characteristics which make it a potential substitute for blood vessels. However, there are no reports on the effects of the AM on blood components. The aim of this study was to evaluate the blood compatibility of the epithelial and mesenchymal surfaces of the amnion for potential use in vascular tissue engineering. The activation of intrinsic and extrinsic pathways of the clotting system, haemolysis and platelet adhesion were studied and the results were compared with heparin-coated expanded polytetrafluoroethylene (ePTFE) as a standard synthetic vascular graft. Prothrombin time (PT), activated partial thromboplastin time (aPTT), clotting time (CT) and haemolysis (%) tests showed that both the epithelial and mesenchymal sides of the AM are haemocompatible. Platelet aggregation and P-selectin production from the platelets showed that the epithelial surface of the AM has less induction of platelet activation than ePTFE. The results of scanning electron microscopy (SEM) demonstrated that platelets in contact with ePTFE had a higher rate of adhesion than with the epithelial and mesenchymal surfaces of the AM. Moreover, the morphological distribution of the platelets showed that the majority of platelets were round, while a large number of cells on ePTFE were dendritic. These results suggest that the AM which contains epithelial and mesenchymal stem cells has appropriate haemocompatibility to be employed in vascular tissue engineering, especially as a vein substitute. Copyright © 2015 John Wiley & Sons, Ltd.
    Matched MeSH terms: Materials Testing*
Related Terms
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links