Publications by authors named "Muhammad Kaleem"

24 Publications

  • Page 1 of 1

Chitosan capping of CuO nanoparticles: Facile chemical preparation, biological analysis, and applications in dentistry.

Int J Biol Macromol 2021 Jan 17;167:1452-1467. Epub 2020 Nov 17.

Department of Tissue Engineering, China Medical University, Shenyang 110122, China; Institute of Regulatory Science for Medical Device, National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, China.

This investigation is vital contribution to the healthcare system utilizing techniques of nanobiotechnology. It interestingly applies chitosan capped CuO nanoparticles in the field of medicine and restorative dentistry. The CuO nanoparticles and CuO-Chitosan nanoparticles are prepared by co-precipitation, and their characterization is performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray (EDX). The average crystallite size of these nanoparticles has been found to be in the dimensions of <40 nm and <35 nm, respectively. CuO-Chitosan nanoparticles show significant enhancement in in vitro antibacterial, antioxidant, cytotoxic, and antidiabetic activity as compared to CuO nanoparticles. In addition, the successful amalgamation of CuO nanoparticles and CuO-Chitosan nanoparticles into dentine bonding agents results in providing efficient remedy against secondary caries. CuO-Chitosan nanoparticles reinforced dental adhesive discs cause significant upsurge in reduction of Lactobacillus acidophillus and Streptococcus mutans. Also, the augmentation of mechanical properties, water sorption and solubility plus slow and sustained release profile and slight variation of shear bond strength is attained. Taken together, the chemically synthesized CuO nanoparticles and CuO-Chitosan nanoparticles have proven to be promising candidates having enormous potential to be utilized in drug delivery and nanotheranostics.
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http://dx.doi.org/10.1016/j.ijbiomac.2020.11.099DOI Listing
January 2021

Synthesis of an anti-cariogenic experimental dental composite containing novel drug-decorated copper particles.

Mater Sci Eng C Mater Biol Appl 2020 Sep 1;114:111040. Epub 2020 May 1.

Department of Dental Materials, National University of Medical Sciences (NUMS), Rawalpindi, Pakistan.

Secondary caries is one of the most major cause for re-placement of dental composite restorations. Targeting the survival of cariogenic bacteria residing on the restoration surface may reduce this problem. The present study aims to evaluate the antibacterial potential as well as assess the physical and chemical properties of experimental dental composites containing novel drug-decorated copper particles (DDCP) as adjunct antibacterial filler particles. These were incorporated at concentrations of 0%, 0.5%, 0.10%, 0.20%, and 0.25% (w/w) into experimental composite consisting of methacrylate monomers and silanized silica fillers. RESULTS: Direct contact test revealed that the anti-cariogenic potential of experimental composites was more than the control groups. The cell viability assay showed no toxic effect on MC3T3-E1 cell lines in the MTT assay. The microhardness of experimental composites increased as the percentage of DDCP increased, however, the degree of cure was increased only up till the concentration of 0.20%. The release kinetics of the composites reveals that even after 28 days there was a steady and slow release of copper particles signifying the sustained anti-cariogenic effect. CONCLUSION: The experimental composites have good anti-cariogenic potential, which was sustained for one month without any deleterious effect on the physical and chemical properties of resin dental composites.
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http://dx.doi.org/10.1016/j.msec.2020.111040DOI Listing
September 2020

Chitosan encapsulated ZnO nanocomposites: Fabrication, characterization, and functionalization of bio-dental approaches.

Mater Sci Eng C Mater Biol Appl 2020 Nov 11;116:111184. Epub 2020 Jun 11.

Department of Tissue Engineering, China Medical University, Shenyang 110122, China; Institute of Regulatory Science for Medical Device, National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, China. Electronic address:

Current report is paramount contribution via nanotechnology to the existing remedies of health diseases. The lag in application of capped metallic oxide nanoparticles in restorative dentistry exist which is covered by this promising study. The uncapped and chitosan encapsulated ZnO nanoparticles were fabricated by facile co-precipitation method, and characterized using various biophysical strategies including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Energy dispersive x-ray (EDX). ZnO nanoparticles and ZnO-Citosan nanoparticles were estimated to be <30 nm and <25 nm in size on respective basis. Significant in vitro antibacterial, antioxidant, cytotoxic and antidiabetic activity of ZnO nanoparticles has been elucidated that is enhanced by capping with chitosan polymer. 90% cytotoxicity against brine shrimps, 69.6% antidiabetic activity against α-amylase, and noteworthy antioxidation power by chitosan decorated ZnO nanoparticles has been effectively illustrated. Furthermore, the effective secondary caries remediation approach has been established by an amalgamation of ZnO nanoparticles and ZnO-Chitosan nanoparticles into dentine bonding agents. A remarkable reduction in Streptococcus mutans and Lactobacillus acidophillus strains has been observed, in-specific boosted by chitosan capped ZnO nanoparticles reinforced dental adhesive discs. Additionally, augmented mechanical properties, greater resistance to water sorption and solubility, notably high release profile, and slight variation of shear bond strength values have been obtained. In short, the prepared nanoparticles reported are detected to be auspicious theranostic agents for combating wide array of human pathogens in healthcare system.
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http://dx.doi.org/10.1016/j.msec.2020.111184DOI Listing
November 2020

Comparative Fluoride Release and Antimicrobial Analysis of Commercial and Experimental Bioactive Glass/Nano-Oxide-Based Dentifrices.

Eur J Dent 2020 Feb 4;14(1):38-44. Epub 2020 Feb 4.

Department of Restorative Dental Sciences, College of Dentistry, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia.

Objectives:  The objectives were to measure fluoride release and assess the antimicrobial behavior of fluoride-doped nano bioactive glass (F-nBG) and nano zinc oxide (ZnO)-enriched novel dentifrices.

Materials And Methods:  Experimental dentifrices were synthesized by incorporating ZnO nanoparticles and F-nBG (1.5 wt% and 4 wt%) as active ingredients. The fluoride release behavior of suspensions and elutes of samples were analyzed by ion selective electrode. Antimicrobial activity and minimum bactericidal concentration against and were evaluated. Microbial stability against contamination was also assessed by a challenge test.

Results:  The fluoride release behavior of experimental dentifrices was higher than that of commercial dentifrices and was dependent on filler loading. The fluoride release was more from suspensions than elutes. Zones of inhibition (ZOIs) and minimum bactericidal concentration values for novel dentifrices showed direct proportionality with filler loading, and effectiveness was exhibited against both strains. Experimental dentifrices exhibited effective antibacterial potential, which could possibly be due to release of sufficient fluoride and zinc ions in aqueous media from F-nBG and ZnO present in their formulations.

Conclusion:  Combination of F-nBG and ZnO may provide a multi-benefit approach for simultaneously treating early white spot lesions, reducing bacterial growth, and providing core plaque control.
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http://dx.doi.org/10.1055/s-0040-1701292DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7069735PMC
February 2020

The current use of anti-cariogenic agents and fluoride agents to cure write spot lesion: A systematic analysis.

J Pak Med Assoc 2019 Dec;69(12):1876-1882

Margalla Institute of Health Sciences, Rawalpindi.

To find the best option to treat White Spot Lesion in existing caries treatments, and to identify the selected articles discussing etiology of caries along with White spot lesion. Null hypothesis was that "Only anticariogenic agent can cure White Spot Lesion". PRISMA guidelines were used to conduct the systematic analysis. An electronic customized search was performed using mesh terminologies on PubMed database based on inclusion criteria that included studies with; any treatment option that can treat or prevent WSL; and minimally invasive treatment options that may be altered to treat WSL. While exclusion criteria comprised studies with treatment of rampant caries, severe early childhood caries and root caries. Inclusion criteria for etiological factors incorporated studies with factors that lead to white spot lesion or carious lesion. Finally, therapeutic agents of dental caries were analyzed. Only the use of anti-cariogenic agent cannot cure White Spot Lesion. Hence study fails to prove the null hypothesis. Although combination of anti-cariogenic agents with a re-mineralizing agent can provide additional options for the treatment or prevention of WSL.
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http://dx.doi.org/10.5455/JPMA.281716DOI Listing
December 2019

Electrochemical corrosion and bacterial adhesion study of Two Osteosynthetic Maxillofacial Bone Plates.

J Pak Med Assoc 2019 Apr;69(4):514-517

School of Chemical & Material Engineering, National University of Science and Technology (NUST), PAKISTAN.

Objective: To evaluate the novel locally manufactured osteosynthetic titanium bone mini plates used for mandibular fracture fixation, and to compare it with an international brand to have an alternative to expensive plates.

Methods: The study was conducted at National University of Science and Technology from Jan 2013 to June 2013. Local and German brands of osteosynthetic titanium bone mini plates were studied electrochemically through Tafel extrapolation curves using Gamry® electrochemical framework in modified simulated body fluid prepared with pH 7.4 at 37OC. For bacterial adhesion, staphylococcus aureus bacterial culture of 50 l was used with an OD600 of 1.0 corresponding to approximately 1.79×109 cells ml-1. Data was analysed using SPSS 20..

Results: Corrosion resistance behaviour of local and German plates was not significantly different (p>0.05), but in case of bacterial adhesion the local plates showed significantly low adhesion compared to the imported material (p<0.05). Overall, the biocompatible properties of local plates met international brand qualities.

Conclusions: Electrochemical corrosion and bacterial adhesion of local osteosynthetic maxillofacial bone plates matched the quality of an international brand.
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April 2019

Microwave-assisted synthesis and in vitro osteogenic analysis of novel bioactive glass fibers for biomedical and dental applications.

Biomed Mater 2018 10 31;14(1):015005. Epub 2018 Oct 31.

Interdisciplinary Research Centre in Biomedical Materials, COMSATS University Islamabad, Lahore Campus, Lahore 54000, Pakistan.

Glass fiber-based materials have gained interest for use in biomedical and dental applications. The aim of this study was to make E-glass fiber bioactive by a novel method using the microwave irradiation technique. Industrial E-glass fibers were used after surface activation with the hydrolysis method. The ratio of calcium and phosphorous precursors was set at 1.67. After maintaining the pH of the calcium solution, E-glass fibers in two ratios, i.e. 30% (nHA/E30) and 50% (nHA/E50) wt/wt, were added. The phosphorous precursor was added later and the solution was irradiated in a microwave to obtain nano-hydroxyapatite (nHA) particles on E-glass fibers. The structural, physical and in vitro biocompatibility analyses of the resulting materials were conducted. The expression of osteopontin (OPN) and collagen (Col) type 1 was measured by reverse transcription polymerase chain reaction (RT-PCR) and comparison was made between all the groups. Fourier transform infrared spectroscopy and x-ray diffraction showed characteristic peaks of nHA, and a change in the peak intensities was observed with an increase in the concentration of E-glass fibers. Scanning electron microscopic (SEM) images confirmed the homogenous adhesion of nHA spherical particles all over the fibers. Cell viability with mesenchymal stem cells showed growth, proliferation, and adhesion. All the materials were able to upregulate the expression of the OPN and Col, where gene expression was highest in nHA followed by nHA/E30 and nHA/E50. The bioactive glass fibers were synthesized in the shortest time and showed osteogenic properties. These materials have the potential for use in bone tissue engineering, dental prosthesis, and tooth restoration.
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http://dx.doi.org/10.1088/1748-605X/aae3f0DOI Listing
October 2018

Advances in functional magnetic resonance imaging data analysis methods using Empirical Mode Decomposition to investigate temporal changes in early Parkinson's disease.

Alzheimers Dement (N Y) 2018 14;4:372-386. Epub 2018 Jun 14.

Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas, NV, USA.

Introduction: Previous neuroimaging studies of Parkinson's disease (PD) patients have shown changes in whole-brain functional connectivity networks. Whether connectivity changes can be detected in the early stages (first 3 years) of PD by resting-state functional magnetic resonance imaging (fMRI) remains elusive. Research infrastructure including MRI and analytic capabilities is required to investigate this issue. The National Institutes of Health/National Institute of General Medical Sciences Center for Biomedical Research Excellence awards support infrastructure to advance research goals.

Methods: Static and dynamic functional connectivity analyses were conducted on early stage never-medicated PD subjects (N = 18) and matched healthy controls (N = 18) from the Parkinson's Progression Markers Initiative.

Results: Altered static and altered dynamic functional connectivity patterns were found in early PD resting-state fMRI data. Most static networks (with the exception of the default mode network) had a reduction in frequency and energy in specific low-frequency bands. Changes in dynamic networks in PD were associated with a decreased switching rate of brain states.

Discussion: This study demonstrates that in early PD, resting-state fMRI networks show spatial and temporal differences of fMRI signal characteristics. However, the default mode network was not associated with any measurable changes. Furthermore, by incorporating an optimum window size in a dynamic functional connectivity analysis, we found altered whole-brain temporal features in early PD, showing that PD subjects spend significantly more time than healthy controls in a specific brain state. These findings may help in improving diagnosis of early never-medicated PD patients. These key observations emerged in a Center for Biomedical Research Excellence-supported research environment.
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http://dx.doi.org/10.1016/j.trci.2018.04.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6115608PMC
June 2018

Effect of nano-bioceramics on monomer leaching and degree of conversion of resin-based composites.

Dent Mater J 2018 Nov 23;37(6):940-949. Epub 2018 Aug 23.

Department of Restorative Dental Sciences, College of Dentistry, Imam Abdulrahman Bin Faisal University.

The aim of this laboratory study was to evaluate the monomer leaching and degree of conversion (DC) from experimental bioactive resin composites (RBCs) and to do comparison with commercial bulkfill and packable resin composites. Experimental dimethacrylatebased resin composites were reinforced with silanated nano-hydroxyapatite (30 and 45 wt%). The ion leaching and DC of these resin composites were compared and contrasted with SDR™ and Filtek P60™ by using the high performance liquid chromatography (HPLC) and Fourier transform infrared spectroscopy (FTIR), respectively. A significant difference was found in elution of monomer between the resin composites. SDR™ showed significantly high monomer elution and structural changes compared to other resin composites. The DC of bioactive RBCs showed the highest conversion rate after polymerization. Resin composite with nano-hydroxyapatite with the presence of a bioactive component might provide biomimetic approach for the material. Moreover, a low concentration of nanohydroxyapatite nano-fillers have shown better properties than micro-fillers based resin composites.
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http://dx.doi.org/10.4012/dmj.2017-338DOI Listing
November 2018

Patient-specific seizure detection in long-term EEG using signal-derived empirical mode decomposition (EMD)-based dictionary approach.

J Neural Eng 2018 10 25;15(5):056004. Epub 2018 Jun 25.

Department of Electrical Engineering, University of Management and Technology, Lahore, Pakistan.

Objective: The objective of the work described in this paper is the development of a computationally efficient methodology for patient-specific automatic seizure detection in long-term multi-channel EEG recordings.

Approach: A novel patient-specific seizure detection approach based on a signal-derived empirical mode decomposition (EMD)-based dictionary approach is proposed. For this purpose, we use an empirical framework for EMD-based dictionary creation and learning, inspired by traditional dictionary learning methods, in which the EMD-based dictionary is learned from the multi-channel EEG data being analyzed for automatic seizure detection. We present the algorithm for dictionary creation and learning, whose purpose is to learn dictionaries with a small number of atoms. Using training signals belonging to seizure and non-seizure classes, an initial dictionary, termed as the raw dictionary, is formed. The atoms of the raw dictionary are composed of intrinsic mode functions obtained after decomposition of the training signals using the empirical mode decomposition algorithm. The raw dictionary is then trained using a learning algorithm, resulting in a substantial decrease in the number of atoms in the trained dictionary. The trained dictionary is then used for automatic seizure detection, such that coefficients of orthogonal projections of test signals against the trained dictionary form the features used for classification of test signals into seizure and non-seizure classes. Thus no hand-engineered features have to be extracted from the data as in traditional seizure detection approaches.

Main Results: The performance of the proposed approach is validated using the CHB-MIT benchmark database, and averaged accuracy, sensitivity and specificity values of 92.9%, 94.3% and 91.5%, respectively, are obtained using support vector machine classifier and five-fold cross-validation method. These results are compared with other approaches using the same database, and the suitability of the approach for seizure detection in long-term multi-channel EEG recordings is discussed.

Significance: The proposed approach describes a computationally efficient method for automatic seizure detection in long-term multi-channel EEG recordings. The method does not rely on hand-engineered features, as are required in traditional approaches. Furthermore, the approach is suitable for scenarios where the dictionary once formed and trained can be used for automatic seizure detection of newly recorded data, making the approach suitable for long-term multi-channel EEG recordings.
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http://dx.doi.org/10.1088/1741-2552/aaceb1DOI Listing
October 2018

Microwave-assisted synthesis and evaluation of type 1 collagen-apatite composites for dental tissue regeneration.

J Biomater Appl 2018 07 2;33(1):103-115. Epub 2018 May 2.

4 Imam Abdulrahman Bin Faisal University College of Dentistry, Dammam, Saudi Arabia.

The aim was to develop an economical and biocompatible collagen-based bioactive composite for tooth regeneration. Acid-soluble collagen was extracted and purified from fish scales. The design was innovated to molecularly tailor the surface charge sites of the nano-apatite providing chemical bonds with the collagen matrix via microwave irradiation technique. The obtained collagen was identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis. The composites were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis/differential scanning calorimetry, and scanning electron microscopy. MC3T3-E1 cell lines were used to assess the biological effects of these materials by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetra zolium bromide (MTT) assay. Indirect contact test was performed by extracting representative elutes in cell culture media and sulforhodamine B analysis was performed. Chorioallantoic membrane assay was conducted to define the new vessels formation behavior. The purity of collagen extracts was determined and showed two α-chains, i.e. the characteristic of type I collagen. Fourier transform infrared spectroscopy showed the characteristic peaks for amide I, I, III, and phosphate for collagen and composites. Scanning electron microscopy images showed three-dimensional mesh of collagen/apatite nano-fibers. Nontoxic behavior of composites was observed and there were graded and dose-related effects on experimental compounds. The angiogenesis and vessels formation behavior were observed in bioactive collagen composite. The obtained composites have potential to be used for tooth structure regeneration.
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http://dx.doi.org/10.1177/0885328218773220DOI Listing
July 2018

Comparative abrasive wear resistance and surface analysis of dental resin-based materials.

Eur J Dent 2018 Jan-Mar;12(1):57-66

Department of Restorative Dental Sciences, College of Dentistry, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia.

Objective: The objective of this study was to assess the surface properties (microhardness and wear resistance) of various composites and compomer materials. In addition, the methodologies used for assessing wear resistance were compared.

Materials And Methods: This study was conducted using restorative material (Filtek Z250, Filtek Z350, QuiXfil, SureFil SDR, and Dyract XP) to assess wear resistance. A custom-made toothbrush simulator was employed for wear testing. Before and after wear resistance, structural, surface, and physical properties were assessed using various techniques.

Results: Structural changes and mass loss were observed after treatment, whereas no significant difference in terms of microhardness was observed. The correlation between atomic force microscopy (AFM) and profilometer and between wear resistance and filler volume was highly significant. The correlation between wear resistance and microhardness were insignificant.

Conclusions: The AFM presented higher precision compared to optical profilometers at a nanoscale level, but both methods can be used in tandem for a more detailed and precise roughness analysis.
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http://dx.doi.org/10.4103/ejd.ejd_380_17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5883477PMC
April 2018

Compressively sampled MR image reconstruction using generalized thresholding iterative algorithm.

J Magn Reson 2018 01 21;286:91-98. Epub 2017 Nov 21.

Department of Electrical Engineering, COMSATS Institute of Information Technology, Islamabad, Pakistan.

Compressed sensing (CS) is an emerging area of interest in Magnetic Resonance Imaging (MRI). CS is used for the reconstruction of the images from a very limited number of samples in k-space. This significantly reduces the MRI data acquisition time. One important requirement for signal recovery in CS is the use of an appropriate non-linear reconstruction algorithm. It is a challenging task to choose a reconstruction algorithm that would accurately reconstruct the MR images from the under-sampled k-space data. Various algorithms have been used to solve the system of non-linear equations for better image quality and reconstruction speed in CS. In the recent past, iterative soft thresholding algorithm (ISTA) has been introduced in CS-MRI. This algorithm directly cancels the incoherent artifacts produced because of the undersampling in k-space. This paper introduces an improved iterative algorithm based on p-thresholding technique for CS-MRI image reconstruction. The use of p-thresholding function promotes sparsity in the image which is a key factor for CS based image reconstruction. The p-thresholding based iterative algorithm is a modification of ISTA, and minimizes non-convex functions. It has been shown that the proposed p-thresholding iterative algorithm can be used effectively to recover fully sampled image from the under-sampled data in MRI. The performance of the proposed method is verified using simulated and actual MRI data taken at St. Mary's Hospital, London. The quality of the reconstructed images is measured in terms of peak signal-to-noise ratio (PSNR), artifact power (AP), and structural similarity index measure (SSIM). The proposed approach shows improved performance when compared to other iterative algorithms based on log thresholding, soft thresholding and hard thresholding techniques at different reduction factors.
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http://dx.doi.org/10.1016/j.jmr.2017.11.008DOI Listing
January 2018

Oral assessment of children with autism spectrum disorder in Rawalpindi, Pakistan.

Autism 2019 01 27;23(1):81-86. Epub 2017 Oct 27.

Army Medical College, National University of Medical Sciences, Pakistan.

Comparison of oral health status, dental needs and dietary habits of children with autism and their healthy siblings. In this cross-sectional study, oral hygiene measures, sugar consumption and dental examination of 58 Pakistani children with autism spectrum disorder were assessed and compared to 27 of their siblings without autism spectrum disorder. Questionnaires were distributed to their parents regarding oral hygiene measures, dietary habits and past dental experiences. Clinical examination for the presence of dental caries, periodontal disease or parafunctional habits was carried out and findings were associated with the mother's education. Children with autism had a higher incidence of caries (50%) as compared to their healthy siblings (22.2%). Significant differences were observed between the groups regarding frequency of brushing and independent brushing. Dental plaque was observed on anterior teeth in 24% children with autism spectrum disorder as compared to 14% in the control group. Trauma due to self-injurious behaviour and bruxism was also recorded and compliance during clinical examination was noted in children with autism spectrum disorder. There was no significant difference in sugar consumption between children with autism spectrum disorder and their healthy siblings. Children with autism had greater dental needs and were more prone to developing dental problems as compared to their healthy siblings.
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http://dx.doi.org/10.1177/1362361317730299DOI Listing
January 2019

Effect of filler particles morphology of resin-composites on cavity packing force for repeated condensation.

Dent Mater J 2017 May 29;36(3):340-347. Epub 2017 Mar 29.

School of Dentistry, JR Moore Building, University of Manchester.

Effect of variation in morphology and size of filler particles, temperature and increase in condensation speed on packability of resincomposites was investigated. Eight experimental light-cured resin-composites (RZDn series) were tested. Each material was placed in a cylindrical mould at 26 or 32ºC. A flat-ended stainless-steel probe (φ=6 mm) was mechanically lowered with two different speeds 2 and 8 mm/s onto and into at the surface of the unset sample until a compressive force of 1 N was reached. This was repeated for five cycles, and from each cycle F was calculated. All spherical and irregular filler particle resin-composites showed a decrease in F with increase in number of compressions. Increase in temperature also decreased F, but this effect was not very prominent in the case of irregular filler resin-composites. Filler particle morphology, increase in temperature and compression cycle speed has a prominent effect on packability of resin-composites.
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http://dx.doi.org/10.4012/dmj.2016-215DOI Listing
May 2017

Stiffness of uncured resin-composites assessed via cavity-packing forces.

Dent Mater 2016 09 27;32(9):e199-203. Epub 2016 Jun 27.

School of Dentistry, JR Moore Building, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom.

Objectives: To evaluate the stiffness and packability of unset resin-composites at different temperatures, taking into account the cavity wall effect.

Materials And Methods: Six representative commercial resin-composites were selected. Each material was placed in mould of different sizes for example (φ=7, depth=5mm; or φ=3, depth=5mm) held at 26 or 37°C. Maximum packing force (Fp) of the resin-composite was measured. A flat-ended stainless-steel probe with a diameter of either 6mm or 3mm was mechanically lowered onto and into the surface of each unset sample with a speed of 0.50mm/s to a depth of 2mm, which was held constant for 10s. The compressive force produced on the probe by the unset resin-composites was plotted against time and the maximum value was identified (Fp). Peak stress Sp was calculated by dividing the Fp by area of the probe used. Data were analyzed by univariate ANOVA and multiple pair wise comparisons were performed using a Tukey post-hoc test to establish homogenous subsets (at p=0.05).

Results: Sp was taken as potential measure of stiffness. It ranged from 0.12 to 4.21MPa and from 0.07 to 3.08MPa at 26 and 37°C, respectively. Univariate ANOVA showed significant influence of the plunger cavity ratios, temperature and materials on Sp (p<0.001). A strong interaction was also found between plunger cavity ratios, temperature and materials for Sp (p<0.05).

Conclusion: Peak stress Sp is a useful parameter for characterizing the stiffness of uncured resin-composite materials, additionally resin-composite formulation, temperature and wall effect did effect the packability of resin-composite.
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http://dx.doi.org/10.1016/j.dental.2016.06.004DOI Listing
September 2016

Chemical and morphological characteristics of mineral trioxide aggregate and Portland cements.

Dent Mater J 2016 ;35(1):112-7

Department of Dental Materials, Army Medical College, National University of Sciences and Technology.

The purpose of this study was to investigate the chemical composition and particle morphology of white mineral trioxide aggregate (WMTA) and two white Portland cements (CEM 1 and CEM 2). Compositional analysis was performed by energy dispersive X-ray spectroscopy, X-ray fluorescence spectrometry and X-ray diffraction whereas, morphological characteristics were analyzed by scanning electron microscope and Laser scattering particle size distribution analyzer. The elemental composition of WMTA, CEM 1 and CEM 2 were similar except for the presence of higher amounts of bismuth in WMTA. Calcium oxide and silicon oxide constitute the major portion of the three materials whereas, tricalcium silicate was detected as the major mineral phase. The particle size distribution and morphology of WMTA was finer compared to CEM 1 and CEM 2. The three tested materials had relatively similar chemical composition and irregular particle morphologies.
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http://dx.doi.org/10.4012/dmj.2015-117DOI Listing
July 2017

Cardio-protective and anti-cancer therapeutic potential of Nigella sativa.

Iran J Basic Med Sci 2014 Dec;17(12):967-79

Department of Food Technology, PMAS Arid Agriculture University Rawalpindi, 43600 Pakistan.

Nigella sativa is the miraculous plant having a lot of nutritional and medicinal benefits, and attracts large number of nutrition and pharmacological researchers. N. sativa seed composition shows that it is the blessing of nature and it contains and many bioactive compounds like thymoquinone, α-hederin, alkaloids, flavonoids, antioxidants, fatty acids many other compounds that have positive effects on curing of different diseases. Several medicinal properties of N. sativa like its anti-cancer, anti-inflammatory, anti-diabetic, antioxidant activities and many others are well acknowledged. However, this article focuses on activity of N. sativa against cardiovascular diseases and cancer. For gathering required data the authors went through vast number of articles using search engines like Science direct, ELSEVIER, Pub Med, Willey on Line Library and Google scholar and the findings were classified on the basis of relevance of the topic and were reviewed in the article. N. sativa is rich source of different biologically active compounds and is found effective in controlling number of cardiovascular diseases and various cancers both in vivo and in vitro studies.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4387232PMC
December 2014

Pathological speech signal analysis and classification using empirical mode decomposition.

Med Biol Eng Comput 2013 Jul 5;51(7):811-21. Epub 2013 Mar 5.

Department of Electrical and Computer Engineering, Ryerson University, Toronto, Canada.

Automated classification of normal and pathological speech signals can provide an objective and accurate mechanism for pathological speech diagnosis, and is an active area of research. A large part of this research is based on analysis of acoustic measures extracted from sustained vowels. However, sustained vowels do not reflect real-world attributes of voice as effectively as continuous speech, which can take into account important attributes of speech such as rapid voice onset and termination, changes in voice frequency and amplitude, and sudden discontinuities in speech. This paper presents a methodology based on empirical mode decomposition (EMD) for classification of continuous normal and pathological speech signals obtained from a well-known database. EMD is used to decompose randomly chosen portions of speech signals into intrinsic mode functions, which are then analyzed to extract meaningful temporal and spectral features, including true instantaneous features which can capture discriminative information in signals hidden at local time-scales. A total of six features are extracted, and a linear classifier is used with the feature vector to classify continuous speech portions obtained from a database consisting of 51 normal and 161 pathological speakers. A classification accuracy of 95.7 % is obtained, thus demonstrating the effectiveness of the methodology.
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http://dx.doi.org/10.1007/s11517-013-1051-8DOI Listing
July 2013

Creep of experimental short fiber-reinforced composite resin.

Dent Mater J 2012 ;31(5):737-41

Department of Biomaterials Science and BioCity Turku Biomaterials Research Program, Institute of Dentistry, University of Turku.

The purpose of this study was to investigate the reinforcing effect of short E-glass fiber fillers oriented in different directions on composite resin under static and dynamic loading. Experimental short fiber-reinforced composite resin (FC) was prepared by mixing 22.5 wt% of short E-glass fibers, 22.5 wt% of resin, and 55 wt% of silane-treated silica fillers. Three groups of specimens (n=5) were tested: FC with isotropic fiber orientation, FC with anisotropic fiber orientation, and particulate-filled composite resin (PFC) as a control. Time-dependent creep and recovery were recorded. ANOVA revealed that after secondary curing in a vacuum oven and after storage in dry condition for 30 days, FC with isotropic fiber orientation (1.73%) exhibited significantly lower static creep value (p<0.05) than PFC (2.54%). For the different curing methods and storage conditions evaluated in this study, FC achieved acceptable static and dynamic creep values when compared to PFC.
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http://dx.doi.org/10.4012/dmj.2011-247DOI Listing
December 2013

Effect of filler size and morphology on viscoelastic stability of resin-composites under dynamic loading.

J Mater Sci Mater Med 2012 Mar;23(3):623-7

Dental Materials Department, Army Medical College, National University of Science and Technology, Rawalpindi, Pakistan.

Effect of variation in filler particle size, morphology and wet conditioning on the viscoelastic stability of resin-composites under dynamic loading was investigated. Eight experimental light cured resin-composites were selected. For each of the eight resin-composites, ten cylindrical specimens (4 × 6 mm), divided into two subgroups (n = 5) were prepared. Group 1 and 2 were loaded dynamically after 1 day of dry storage and 1 week of wet storage, respectively. A cyclic load between 1 and 50 MPa was applied for both groups at a frequency of 0.25 Hz for 30 min to obtain the 'dynamic' creep strain (%). Data was analysed by univariate ANOVA. Unimodal spherical and irregular resin-composites showed a significant influence of particle size and shape on dynamic creep under dry condition, but not for wet conditions. Irregular filler particles in both unimodal and multimodal resin-composites were more resistant to dynamic creep under wet conditions and showed higher stiffness.
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http://dx.doi.org/10.1007/s10856-011-4540-zDOI Listing
March 2012

Viscoelastic stability of resin-composites under static and dynamic loading.

Dent Mater 2012 Feb 27;28(2):e15-8. Epub 2011 Dec 27.

Biomaterials Research Group, School of Dentistry, University of Manchester, Manchester, UK. dr

Objectives: To compare the viscoelastic behavior (creep) of dental resin-composites under both static and cyclic loading in compression.

Methods: Ten cylindrical specimens (4 mm × 6 mm), divided into two subgroups (n = 5) were prepared from each of four commercial resin-composites, using a divisible stainless steel mold. They were thoroughly cured from all sides. Groups 1 and 2 were loaded statically and dynamically respectively after 1d of fabrication and dry storage. Group 1 was loaded with a constant static load of 35 MPa and it was applied for 2 h followed by 2 h of strain recovery to obtain the static creep (%) and permanent set (%) respectively. To Group 2 a cyclic load between 1 MPa and 50 MPa was applied at a frequency of 0.25 Hz for 30 min to obtain the "dynamic" creep strain (%). Regression and correlation analysis (α = 0.05) was performed to examine possible correlations between static and "dynamic" creep.

Results: For the resin-composite investigated, a good correlation was found between "dynamic" creep strain (%) and maximum static creep strain (%) (r = 0.92) and a strong correlation was also found between "dynamic" creep strain (%) and permanent set (%) (r = 0.97), SIGNIFICANCE: Maximum static creep was significantly higher than "dynamic" creep. A direct numerical equivalence was not expected between static and "dynamic" creep values, as in the case of "dynamic" creep, loading was cyclic and was applied for a shorter overall period. Nevertheless a strong correlation was found between the static and dynamic creep measurement.
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http://dx.doi.org/10.1016/j.dental.2011.11.026DOI Listing
February 2012

A method for assessing force/work parameters for stickiness of unset resin-composites.

Dent Mater 2011 Aug 20;27(8):805-10. Epub 2011 May 20.

Army Medical College, National University of Science and Technology, Rawalpindi, Pakistan. dr

Objectives: To evaluate the stickiness of unset resin-composites, at different speeds and temperatures, in terms of maximum probe separation-force (F(max)) and work-of-separation (W(s)).

Materials And Methods: Eight commercial light-cured resin-composites were selected. Each material was placed in a cylindrical mold (φ=7 mm × 5 mm depth) held at 25 °C or 37 °C. The maximum force (F(max), N) and work probe separation (W(s), N mm) were measured by using a texture analyzer to register force/displacement. A flat-ended stainless-steel probe (φ=6mm) was mechanically lowered onto and into the surface of the unset sample. When a 'trigger' compressive force of 0.05 N was registered, data-acquisition commenced. Descent continued until a compressive force of 1N was reached, which was held constant for 1s. Then the probe was moved vertically upward at constant speed. This was varied over the range 2, 4, 6 and 8mm/s. The tensile force produced on the probe by the sticky resin-composite was plotted against displacement and the maximum value was identified (F(max)). W(s) was obtained as the integrated area. Data was analyzed by multivariate ANOVA and multiple pair wise comparisons was done by using a Tukey post hoc test to establish homogenous subsets (at p=0.05).

Results: F(max) and W(s) were taken as potential measures of stickiness. They ranged from 0.47 to 3.68 N and from 0.11 to 2.84 N mm, respectively. Multivariate ANOVA showed a strong interaction of withdrawal speed, temperature and materials on both F(max) and W(s) (p<0.001).

Conclusion: F(max) and W(s) are useful parameters for characterizing the handling-stickiness of resin-composite materials, additional to previously reported stickiness-strain or 'peak-height'. The resin-composites investigated could be differentiated, mostly showing increases in F(max) and W(s) stickiness with increased temperature and probe-withdrawal speed.
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http://dx.doi.org/10.1016/j.dental.2011.04.005DOI Listing
August 2011

Effect of filler particle size and morphology on force/work parameters for stickiness of unset resin-composites.

Dent Mater 2009 Dec 9;25(12):1585-92. Epub 2009 Sep 9.

School of Dentistry, University of Manchester, Manchester, UK. dr

Objectives: To investigate the effect of variation in filler particle size and morphology within an unset model series of resin-composites on two stickiness parameters: (1) maximum probe separation-force and (2) work-of-separation. This study was to complement previously reported measurements of composite stickiness in terms of a strain-parameter, 'peak-height'.

Materials And Methods: Eleven experimental light cured resin-composites were selected. All had the same matrix (Bis-GMA, UDMA and TEGDMA, with 0.33% camphoroquinone) and the same filler volume fraction-56.7%, however filler particles varied in size and shape and were either unimodal or multimodal in size-distribution. Each material was placed in a cylindrical mould (phi=7mmx5mm depth) held at 26 or 37 degrees C. The maximum force (F(max), N) and work of probe-separation (W(s), Nmm) were measured. A flat-ended stainless-steel probe (phi=6mm) was mechanically lowered onto and into the surface of the unset sample, until a compressive force of 1N was reached, which was held constant for 1s. Then the probe was moved vertically upward at a constant speed; either 2 or 8mm/s. The tensile force produced on the probe by the sticky composite was plotted against displacement and the maximum value was identified (F(max)). W(s) was obtained as the integrated area. Data was analyzed by multivariate ANOVA and multiple pair-wise comparisons using a Tukey post hoc test to establish homogenous subsets (at p=0.05) for F(max) and a Games-Howell was used for W(s).

Results: As potential measures of stickiness, F(max) and W(s) showed more coherent trends with fillersize when measured at the lower of the two probe speeds, 2mm/s. For unimodal resin-composite F(max) ranged from 1.04 to 5.11N and W(s) from 0.48 to 11.12Nmm. For the multimodal resin-composite they ranged from 1.64 to 4.13N and from 2.32 to 8.34Nmm respectively. Temperature increase tended to slightly reduce F(max), although this trend was not consistent. W(s) generally increased with temperature.

Conclusion: Filler particle size and morphology influences F(max) and W(s) of uncured resin-composite which partly express the handling behaviors of resin-composites.
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http://dx.doi.org/10.1016/j.dental.2009.08.002DOI Listing
December 2009