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Current perspectives of nanoparticles in medical and dental biomaterials

The Journal of Biomedical Research 2012年第3期26卷 143-151页

作者： ibrahim Mohamed hamouda Department of Dental Biomaterials and Restorative Dentistry Faculty of Dentistry Mansoura University Mansoura Dakahleya 35516 Egypt

Nanotechnology is gaining tremendous impetus due to its capability of modulating metals into their nanosize, which drastically changes the chemical, physical and optical properties of metals. Nanoparticles have been intro- duced as materials with good potential to be extensively used in biological and medical applications. Nanoparticles are clusters of atoms in the size range of 1-100 nm. Inorganic nanoparticles and their nano-composites are applied as good antibacterial agents. Due to the outbreak of infectious diseases caused by different pathogenic bacteria and the development of antibiotic resistance, pharmaceutical companies and researchers are searching for new antibacterial agents. The metallic nanoparticles are the most promising as they show good antibacterial properties due to their large surface area to volume ratios, which draw growing interest from researchers due to increasing microbial resistance against metal ions, antibiotics and the development of resistant strains. Metallic nanoparticles can be used as effective growth inhibitors in various microorganisms and thereby are applicable to diverse medical devices. Nanotechnology discloses the use of elemental nanoparticles as active antibacterial ingredient for dental materials. In dentistry, both restorative materials and oral bacteria are believed to be responsible for restoration failure. Secondary caries is found to be the main reason to restoration failure. Secondary caries is primarily caused by invasion of plaque bacteria （acid-producing bacteria） such as Streptococcus mutans and lactobacilli in the presence of fermentable carbohydrates. To make long-lasting restorations, antibacterial materials should be made. The potential of nanoparticles to control the formation of biofilms within the oral cavity is also coming under in- creasing scrutiny. Possible uses of nanoparticles as topically applied agents within dental materials and the appli- cation of nanoparticles in the control of oral infection

关键词： nanoparticles nano-medicine nano-biomaterials nanotechnology antibacterial agent

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Maxillary denture flange and occlusal discrepancies of Vertex ThermoSens in comparison with conventional heat-cured denture base materials

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The Journal of Biomedical Research 2019年第2期33卷 139-144页

作者： Hanadi A.Lamfon ibrahim M.hamouda Maxillofacial and Oral Rehabilitation Department Umm Al-Qura University Conservative Dentistry Faculty of Dentistry Umm Al-Qura University Dental Biomaterials Faculty of Dentistry Mansoura University

This study was conducted to investigate the maxillary denture bases and occlusal discrepancies using the Vertex Thermosens in comparison with the conventional polymethyl-methacrylate materials. Twenty maxillary denture bases were prepared from the Vertex ThermoSens and a conventional heat-cured denture base materials. Acrylic maxillary second molars were arranged in their respective positions on the ridge. After curing of both types of denture bases, they were deflasked with their respective master casts. Reference points were prepared for measurements of the antero-posterior and cross-arch dimensions at the denture borders using caliper device. Furthermore, the teeth discrepancies were measured between reference points in the ligual aspect of the second maxillary molars. The recorded data was analyzed using SPSS statistical software version 20. The results showed initial shrinkage of both denture bases in the antero-posterior and cross-arch dimensions immediately after decasting. This contraction was compensated gradually during storage in water up to 2 weeks. Regarding the variable time, there was a significant difference between the tested materials. Moreover, the results revealed occlusal discrepancies and shifting of teeth inward immediately after decasting, followed by outward movement after storage in water for 2 weeks. Regarding the variables time and materials, there were significant differences. Both materials exhibited inward shrinkage in the antero-posterior and cross-arch dimensions immediately after decasting. Both denture bases showed inward shifting of teeth immediately after decasting, followed by outward movement after storage in water up to 2 weeks.

关键词： denture distortion flange discrepancy acrylic resin occlusal discrepancies denture base

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Fracture resistance of posterior teeth restored with modern restorative materials

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The Journal of Biomedical Research 2011年第6期25卷 418-424页

作者： ibrahim M. hamouda Salah H. Shehata Department of Biomaterials Mansoura University Al-Gomhoria St Mansoura 35516 Egypt Department of Conservative Dentistry Mansoura University Al-Gomhoria St Mansoura 35516 Egypt

We studied the fracture resistance of maxillary premolars restored with recent restorative materials. Fifty maxillary premolars were divided into five groups： Group 1 were unprepared teeth; Group 2 were teeth prepared without restoration; Group 3 were teeth restored with tetric ceram HB; Group 4 were teeth restored with InTen S; and Group 5 were teeth restored with Admira. The samples were tested using a universal testing machine. Peak loads at fracture were recorded. The teeth restored with Admira had the highest fracture resistance followed by those restored with InTen-S and tetric ceram HB. Prepared, unrestored teeth were the weakest group. There was a significant difference between the fracture resistance of intact teeth and the prepared, unrestored teeth. There was also a significant difference among the tested restorative materials. Teeth restored with Admira showed no significant difference when compared with the unprepared teeth. It was concluded that the teeth restored with Admira exhibited the highest fracture resistance.

关键词： fracture resistance composite resin adhesives mesio-occlusal-distal (MOD) cavities

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Cone-beam computed tomography analysis of curved root canals after mechanical preparation with three nickel-titanium rotary instruments

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The Journal of Biomedical Research 2013年第4期27卷 326-335页

作者： Samia M.Elsherief Mohamed K.Zayet ibrahim M.hamouda Department of Endodontics Faculty of Oral and Dental Medicine Cairo University Department of Endodontics Faculty of Dentistry Umm Al Qura University Lecturer of Radiology Faculty of Oral and Dental Medicine Cairo University Department of Dental Biomaterials Faculty of Dentistry Mansoura University Conservative Dentistry Department Faculty of Dentistry Umm Al Qura University

Cone beam computed tomography is a 3-dimensional high resolution imaging method. The purpose of this study was to compare the effects of 3 different NiTi rotary instruments used to prepare curved root canals on the final shape of the curved canals and total amount of root canal transportation by using cone-beam computed tomography. A total of 81 mesial root canals from 42 extracted human mandibular molars, with a curvature ranging from 15 to 45 degrees, were selected. Canals were randomly divided into 3 groups of 27 each. After preparation with Protaper, Revo-S and Hero Shaper, the amount of transportation and centering ability that occurred were assessed by using cone beam computed tomography. Utilizing preand post-instrumentation radiographs, straightening of the canal curvatures was determined with a computer image analysis program. Canals were metrically assessed for changes （surface area, changes in curvature and transportation） during canal preparation by using software SimPlant; instrument failures were also recorded. Mean total widths and outer and inner width measurements were determined on each central canal path and differences were statistically analyzed. The results showed that all instruments maintained the original canal curvature well with no significant differences between the different files （P=0.226）. During preparation there was failure of only one file （the protaper group）. In conclusion, under the conditions of this study, all instruments maintained the original canal curvature well and were safe to use. Areas of uninstrumented root canal wall were left in all regions using the various systems.

关键词： Rotary NiTi instrument canal curvature canal straightening

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Classifying rockburst with confidence:A novel conformal prediction approach

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International Journal of Mining Science and Technology 2024年第1期34卷 51-64页

作者： Bemah ibrahim Isaac Ahenkorah University of South Australia UniSA STEMSA 5000Australia

The scientific community recognizes the seriousness of rockbursts and the need for effective mitigation *** literature reports various successful applications of machine learning(ML)models for rockburst assessment;however,a significant question remains unanswered:How reliable are these models,and at what confidence level are classifications made?Typically,ML models output single rockburst grade even in the face of intricate and out-of-distribution samples,without any associated confidence *** the susceptibility of ML models to errors,it becomes imperative to quantify their uncertainty to prevent consequential *** address this issue,we propose a conformal prediction(CP)framework built on traditional ML models(extreme gradient boosting and random forest)to generate valid classifications of rockburst while producing a measure of confidence for its *** proposed framework guarantees marginal coverage and,in most cases,conditional coverage on the test *** CP was evaluated on a rockburst case in the Sanshandao Gold Mine in China,where it achieved high coverage and efficiency at applicable confidence ***,the CP identified several“confident”classifications from the traditional ML model as unreliable,necessitating expert verification for informed *** proposed framework improves the reliability and accuracy of rockburst assessments,with the potential to bolster user confidence.

关键词： Rockburst Machine learning Uncertainty quantification Conformal prediction

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Immediate and delayed micro-tensile bond strength of different luting resin cements to different regional dentin

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The Journal of Biomedical Research 2013年第2期27卷 151-158页

作者： Abdelraheem Mohamed Ali ibrahim Mohamed hamouda Mohamed Hamed Ghazy Manal Mohamed Abo-Madina Department of Conservative Dentistry Faculty of Dentistry Mansoura University Department of Dental Biomaterials Faculty of Dentistry Mansoura University Department of Conservative Dentistry Faculty of Dentistry Umm Al Qura University Crown & Bridge Department of Conservative Dentistry Faculty of Dentistry Mansoura University

We sought to evaluate immediate and delayed micro-tensile bond strength of Panavia F2.0 and Multilink Sprint resin cement to superficial, deep and cervical dentin. Thirty-six freshly extracted non-carious human molars were sectioned in the mesiodistal direction to expose three different dentin regions including superficial dentin （1 mm below the dentine-enamel junction）, deep dentin （1 mm above the highest pulp horn） and cervical dentin （0.5 mm above the cemento-enamel junction and 0.5 mm below the dentine-enamel junction）. Resin cements were applied on dentin surfaces and composite blocks were luted under constant seating pressure. Each group was divided into three subgroups according to time intervals. Specimens were sectioned to obtain sticks of 1 mm2 in diameter and subjected to microtensile bond strength testing at a cross head speed of 1 mrn/min. Both resin cements showed higher micro-tensile bond strength to superficial dentin than that to deep or cervical dentin （P 〈 0.001）. Micro-ten- sile bond strengths of Panavia F2.0 were higher than those of Multilink Sprint at different dentin regions （P 〈 0.001）. Immediate ＂micro-tensile bond strengths were higher than those of delayed micro-tensile bond strengths for both resin cements （P 〈 0.001）. It was concluded that resin cements with different chemical formulations and applications yield significantly different micro-tensile bond strengths to different dentin regions.

关键词： immediate and delayed micro-tensile bond strength luting resin cements regional dentin

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New insights into astrocyte diversity from the lens of transcriptional regulation and their implications for neurodegenerative disease treatments

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Neural Regeneration Research 2024年第11期19卷 2335-2336页

作者： ibrahim Olabayode Saliu Guoyan Zhao Department of Genetics Washington University School of MedicineSt.LouisMOUSA Department of Neurology Department of Pathology and ImmunologyWashington University School of MedicineSt.LouisMOUSA

Astrocytes are a major glial cell type in the central nervous system,and they provide trophic and metabolic support to *** addition to these roles,they play crucial roles in modulating synaptic functions,development,and pruning(Brandebura et al.,2023).Astrocytes become reactive(activated)by undergoing morphological,molecular,and functional alterations in response to neuropathology such as in injuries and neurodegenerative diseases(NDs)(Escartin et al.,2021).

关键词： degenerative injuries

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Enteric neuropathy in diabetes:Implications for gastrointestinal function

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World Journal of Gastroenterology 2024年第22期30卷 2852-2865页

作者： Mona Mohamed ibrahim Abdalla Department of Human Biology School of MedicineInternational Medical UniversityBukit Jalil 57000Kuala LumpurMalaysia

Diabetes,commonly known for its metabolic effects,also critically affects the enteric nervous system(ENS),which is essential in regulating gastrointestinal(GI)motility,secretion,and *** development of diabetes-induced enteric neuropathy can lead to various GI dysfunctions,such as gastroparesis and irregular bowel habits,primarily due to disruptions in the function of neuronal and glial cells within the ENS,as well as oxidative stress and *** editorial explores the pathophysiological mechanisms underlying the development of enteric neuropathy in diabetic ***,it discusses the latest advances in diagnostic approaches,emphasizing the need for early detection and intervention to mitigate GI complications in diabetic *** editorial also reviews current and emerging therapeutic strategies,focusing on pharmacological treatments,dietary management,and potential neuromodulatory ***,this editorial highlights the necessity of a multidisciplinary approach in managing enteric neuropathy in diabetes,aiming to enhance patient quality of life and address a frequently overlooked complication of this widespread disease.

关键词： Diabetic neuropathy Gastrointestinal Insulin resistance Diabetes Enteric nervous system Enteric neuropathy

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Evaluation the Mechanical Properties of Nanofilled Composite Resin Restorative Material

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Journal of Biomaterials and Nanobiotechnology 2012年第2期3卷 238-242页

作者： ibrahim M. hamouda Hagag Abd Elkader Dental Biomaterials Faculty of Dentistry Mansoura and Umm Al Qura Universities Egypt.

This study was designed to evaluate the wear resistance, fracture toughness and flexural strength of a nanofilled composite resin restorative material in comparison with a conventional hybrid composite resin. A total of 60 specimens were prepared from both types composite resins. Specimens were cured with a light curing device according to the manufacturer’s instructions. Wear resistance was evaluated through subjecting the specimens to wear testing at 0.1 bar wet pressure against carbide abrasive counter-body using wear testing machine under water as lubricant. The test conditions were;speed = 265 rpm, load = 0.1 bar, time = 5 min. Flexural strength and fracture toughness were tested using three-point bending test in universal testing machine at a cross head speed of 2 mm/min until failure occurred. The nanofilled composite resin material exhibited higher wear resistance than the hybrid composite resin material. On the other hand, there were no significant differences between the two materials in values of flexural strength and fracture toughness. It was concluded that the nanofilled composite resin was harder but it does not stronger than the conventional hybrid composite resin.

关键词： Nanofilled Wear Flexural Strength Toughness Composite Resin

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Microleakage of Nanofilled Composite Resin Restorative Material

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Journal of Biomaterials and Nanobiotechnology 2011年第3期2卷 329-334页

作者： ibrahim hamouda Hagag abd Elkader Manal F. Badawi 不详

The role of nanofillers in reducing the microleakage of dental composite resins has not been previously investigated. So this study was designed to evaluate microleakage of nanofilled composite resin in comparison to the conventional hybrid composite. Twenty extracted sound molars were selected. Class II cavities were prepared. All cavities were etched (enamel and dentin) with 37% phosphoric acid. Dentin bonding agents were applied to etched tooth surfaces and restored with nanofilled and hybrid composite restorative materials. The restored teeth were thermocycled. Specimens were immersed in 2% methylene blue dye, sectioned along the mesio-distal direction;dye penetration of occlusal and gingival margins of each section was evaluated using a stereo-microscope. No significant difference was found between the microleakage of nanofilled and hybrid composite restorations at occlusal / enamel and at gingival / dentin margins. Also, there were no significant differences for nanofilled composite restorations at occlusal / enamel margins and gingival / dentin margins. On the other hand, there were a significant differences for hybrid composite restorations at occlusal / enamel margins and gingival / dentin margins.

关键词： Microleakage Nanofilled composite resin Hybrid composite resin

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