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Article
Effect of different metal surface treatments and thermocycling on shear bond strength and microleakage of the flexible acrylic at Co/Cr interface

Authors: Ghazwan AA --- Nabeel AH نبيل عبد الفتاح هاطور
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2011 Volume: 23 Issue: special issue Pages: 10-14
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Optimum bond strength at the valplast nylon (V.N.)-Co/Cr interface of a prosthesis is essential for thesuccess of that prosthesis. The junction between metal alloy and resin is an area of clinical concern. The aim of studyevaluation of the effect of different metal surface treatments and thermocycling on the shear bond strength andmicroleakage at the V.N.-Co/Cr interface.Material and method: A total No. of 140 samples were prepared and divided into two main groups according to thetype of test carried out. Group {A} referred to the metal samples of microleakage test which consists of 60 metalsamples, which were then subdivided into two groups; each one consists of 30 metal samples, according to thenumber of thermal cycles: (A1 subjected for 1000 thermal cycles and A2 for 3000 thermal cycles). Samples of eachgroup were then subdivided into three subgroups; each one consists of 10 metal samples, according to the type ofsurface treatment that was applied. Each group either had an air abrasion (A1a and A2a) or application of metalbonding agent (Metal Primer) (A1P and A2P) or combination of air abrasion and Metal Primer application (A1C andA2C). Each metal sample was divided into experimental half which received one type of surface treatment andcontrols half which was kept untreated. Group {B} referred to the metal samples of shear bond test which consists of80 metal samples. The samples of this group were then subdivided into two groups; each one consists of 40 metalsamples, according to the thermocycling: (B1 subjected for group without thermocycling and B2 for thermocycledgroup with 1000 cycles). Samples of each group were then subdivided into four subgroups; each one consists of 10metal samples, according to the type of surface treatment that was applied. Each group was either untreated (B1Uand B2U) or had an air abrasion (B1a and B2a) or application of metal bonding agent (Metal Primer) (B1P and B2P) orcombination of air abrasion and Metal Primer application (B1C and B2C). Before thermocycling the valplast nylon wasapplied to the metal samples.Result: The results showed that the metal samples treated with metal primer II had the highest value of shear bondand lowest value of microleakage followed by the metal samples treated with metal primer II combined with airabrasion. The metal samples treated with air abrasion only had the lowest value of shear bond and highest value ofmicroleakage The results of present study showed that specimens had a reduced shear bond in comparison withthe specimens of the same treatments after different thermocycling period


Article
Effect of different denture cleanser solutions on some mechanical and physical properties of nylon and acrylic denture base materials

Authors: Mohamad Salman مهند سلمان --- Shatha Saleem شذى سليم
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2011 Volume: 23 Issue: special issue Pages: 19-24
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Thermoplastic non –metal clasp denture became recently the most attractive option for patients dueto its esthetic outcome and many other advantages. The chemical immersed denture cleanser is the most widelyused method by the patients to maintain clean and healthy denture , but the use of such cleanser may haveharmful effect on the denture base materials .This study aimed to evaluate some physical and mechanicalproperties of one of the thermoplastic denture base materials which is (nylon) compared with those belong toconventional heat cured acrylic and to observe the effect of two prepared denture cleansers ( 4% oxalic acid ,4%tartaric acid ) in addition to one commercial denture cleanser (lacalut dent) on the indentation hardness , flexuralstrength , flexibility , surface roughness and color stability of nylon and conventional heat cured acrylic.Materials and method: Two hundred and sixty specimens (130 nylon and 130 acrylic) were prepared ,60 specimens(30 nylon ,30 acrylic ) were used to test each of the properties mentioned above except an 80 specimens were used(40 nylon ,40 acrylic ) to test flexural strength and flexibility.Results: The result obtained in the present study showed high significant difference between nylon and conventionalheat cured acrylic in four properties which were: indentation hardness , flexural strength , flexibility and color stability,with no difference in the surface roughness .Furthermore oxalic acid and tartaric acid cleansers significantlydecrease the indentation hardness and flexural strength of conventional heat cured acrylic while lacalut dent didn’tsignificantly affect those properties of acrylic, also all the three cleansers didn’t affect the indentation hardness andflexural strength of nylon .oxalic acid and tartaric acid cleansers significantly decreased the flexibility of nylon whilelacalut dent didn’t significantly changed this property. All the three cleanser had no effect on the flexibility ofacrylic. All the three cleanser had no effect on the surface roughness or color stability of nylon and acrylic.Conclusions: It can be concluded that nylon had better flexibility and translucency than conventional heat curedacrylic while conventional heat cured acrylic had better indentation hardness and flexural strength than nylon.Regarding surface roughness the two polymers show no significant difference between them.There were an adverse effect of the prepared denture cleansers which contain isopropyl alcohol on indentationhardness and flexural strength of conventional heat cured acrylic , it decreased both those properties , so it isadvised not to use solution containing alcohol as acrylic denture cleanser also it is advised not to use it withnylon denture because it decreased its flexibility. Lacalut dent which is an oxygenating commercial denturecleanser, had no adverse effects on both polymers used in the study, so it can be used safely with them


Article
Effect of silica layer on bonding strength of thermoplastic nylon to cold cure acrylic resin

Author: Israa M. Hummoudi
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2013 Volume: 25 Issue: 3 Pages: 24-27
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: The combination of thermoplastic nylon resin materials and auto polymerizing resin is necessary in somesituation for repair and adjustment. This study evaluated shear bond strength between thermoplastic nylon material(flexible) and auto polymerizing acrylic resin subjected to holes and silica coated layer.Materials and Method: Forty five (45) specimens were prepared from flexible acrylic bonded to auto-polymerizingacrylic resin and divided into three groups according to the surface treatments as follows:Group A: 15 specimens of flexible acrylic bonded with cold-cure acrylic by holes.Group B: 15 specimens of flexible acrylic bonded with cold-cure acrylic by silica coated layer.Group C: 15 specimens of flexible acrylic bonded with cold-cure acrylic by combination of holes and silica coatedlayer. All specimens were analyzed by using Instron testing machine.Results: The result of this study showed that high mean values were obtained from group C (combination) while lowmean values were obtained from B (silica coated layer).Conclusion: It can be concluded that combination of mechanical surface treatment resulted in significantimprovement in shear bond strength of flexible acrylic bonded with cold cure acrylic

Keywords

Thermoplastic nylon --- silica --- shear bond --- hole


Article
The Effect of Two Types of Separating Medium and Investment Materials on Some Physical Properties of Acrylic and Nylon Denture Base Materials

Authors: Suad Jafar Alnakash --- Nagham Bahjat Kamil --- Farah Nabeel Mohammed Tahir Al-Khayyat
Journal: Karbala Journal of Medicine مجلة كربلاء الطبية ISSN: 19905483 Year: 2013 Volume: 6 Issue: 2 Pages: 1675-1683
Publisher: Kerbala University جامعة كربلاء

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Abstract

background: The relatively rough surface of gypsum mould may be penetrated byacrylic denture base resin and adhere to it, to prevent this, a separating medium mustbe employed.Objectives: The aim of this study is to evaluate the effect of separating medium substituteand investment materials on Surface roughness, Water sorption and solubility of acrylic andnylon denture base materials.Material and method: Two types of separating medium were chosen (Cold mold seal andglycerin). 160 specimens were prepared from heat cure and Valplast resins. Each main groupwas subdivided into four subdivisions according to the type of investment material andseparating medium used; each group of them contains 10 specimens for each test.After processing of both resins, some physical properties such as water sorption, solubilityand surface roughness have been evaluated according to investment material and comparedwith those processed using cold mold seal and glycerin.Result: In this study, the surface roughness and water solubility of both base materials aresignificantly higher when using cold mold seal than glycerin. Mean value of heat-cure acrylicresin shows high water sorption than that of Valplast. When compared by ANOVA test, thereis no significant difference between groups in both investment materials.Conclusion: The use of glycerin as a separating medium leads to smoother surfaces of bothdenture base materials, while for water sorption, neither the separating medium nor theinvestment material has an effect on it. Cold mold seal leads to higher water solubility of bothbase materials regardless of the type of investment material.


Article
The Effect of Some Disinfectants on Some Mechanical Properties of Nylon (Valplast) Denture Base Material

Author: Ilham H. Al-Abdulla
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2015 Volume: 15 Issue: 26 Pages: 374-380
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: To evaluate the effect of two disinfecting solutions (povidone iodine 10%, ethanol alcohol 100%) on the surface roughness and surface hardness of nylon denture base material. Materials and Method: 40 sample of valplast material were constructed with dimensions of (65mm,10mm,2.5mm) length ,width and thickness respectively. (10) samples were used to measure the surface roughness before and after soaking in (ethanol material 100%) for 5 min., (10) samples were used to measure the surface hardness before and after soaking in (ethanol alcohol 100%) for 5 min., other 20 samples have been used in the same way as the 1st 20 but with iodine disinfectant. Results: Descriptive statistics for indentation hardness of valplast in ethanol and iodine indicate there is no significant difference for each one (P=0.3, P=0.7 respectively).T-test indicate there is no significant difference between them (P=0.3).Descriptive statistics for surface roughness in ethanol indicate there is an increase but it is not significant (P=0.2), while for iodine there is a decrease also it is not significant (P=0.1).T-test indicate no significant difference between them(P=0.07). Conclusion: Hardness of nylon denture base material increased by immersing in each of the ethanol and iodine but their increase is not significant (within 5 min.). Surface Roughness of nylon denture base material increases by immersing in ethanol alcohol while it decreases by immersing in iodine, this increase or decrease is not significant (within 5 min.).


Article
The influence of different pH of saliva and thermal cycling on the adaptation of different denture base materials

Authors: Yasir A. Hussein ياسر حسين --- Shatha S. Al-Ameer شذى الامير
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2012 Volume: 24 Issue: 3 Pages: 47-53
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: The difference in the adaptation of denture bases processed from heat cure acrylic, light cure acrylicand nylon materials and the effect of artificial accelerated aging (thermal cycling and pH) on the adaptation wasstudied.Materials and methods: One hundred eighty stone cast were prepared and assigned into 3 main groups accordingto the denture base material that processed on them(heat cure, light cure, nylon), each denture base and its castwas sectioned at posterior palatal border and the gap between the denture base and the cast was measured usingdigital microscope. Half of each group exposed to thermal cycling (2000 cycle) between (5 C-55 C ) 30 second ineach bath then the adaptation was evaluated again. All denture bases were stored in artificial saliva of different pH(5.7, 7,8.3) at 37 C for 30 days, then the adaptation was measured again.Results and discussions: The results showed that the adaptation of heat cure acrylic was better than light cure andnylon before and after aging process. The nylon showed the poorest adaptation. Thermal cycling decreases theadaptation of all denture bases. Variation of pH effected the adaptation of heat cure and light cure denture basesand did not affect the adaptation of nylon


Article
Evaluation of the tensile bond strengths of heat cure acrylic and Valplast with silicone self cure soft liner

Author: Ali J. Abdulsahib علي عبد الصاحب
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2012 Volume: 24 Issue: special issue 2 Pages: 5-9
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Soft lining materials have a key role in modern prosthodontics because of their capability of restoringhealth of inflamed and distorted mucosa. Gradual changes of oral tissues require that complete or partial denturesbe relined to improve their adaptation to the supporting tissue. This study aimed to evaluate the tensile bondstrength of heat cure acrylic and Valplast denture base materials to silicone self-cure soft lining material stored inartificial saliva.Materials and method: Two types of self cured silicone soft lining material (one with prime the other without prime oradhesive) applied to polymethylmethacrylate and injection-molded nylon denture base materials for tensile bondstrength testing using Instron machine.Results: The comparison between all test groups after (48) hours immersion in artificial saliva were highly significantly different fromeach other except for the comparison between groups PSP and VSP in which theirmeans were non-significant. After (12) weeks,the comparison between all test groupswere highly significantly different fromeach otherwhen compared statistically.Conclusion: This study indicated that prime (adhesive) increase the bond strength of the silicone soft lining materialswith denture base materials. Silicone soft lining materials are affected by artificial saliva storage


Article
Investigation of Addition Different Fibers on the Performance of Cement Mortar

Authors: Aya A. Shaher --- Hussein A. Jaber --- Ahmed M. Al-Ghaban
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2018 Volume: 36 Issue: 9 Part (A) Engineering Pages: 957-965
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

This work presents an investigation of possibility incorporate of synthetic fibers (glass, nylon and carbon) at two states (short: 1cm, long: 5cm) effects on the mechanical properties of mortars (cement: sand composition (1:3)). Fibers materials used at different weight percentages ranged of (0, 0.4, 0.8, and 1.2) wt%. Density, water absorption, porosity, thermal conductivity, compressive strength and flexural strength experimentally investigated for mortar specimens after curing for (28 days). The results showed that the incorporation of these fiber materials improvement mechanical and physical tests for all reinforced samples with short and long fibers, and that the highest value of the mechanical and physical properties obtained from long fiber (5cm) reinforced cement samples with (1.2%Nylon), reaching the rate of increase in values of compressive strength by (17.74%), flexural strength by (52.8%), and water absorption by (4.54%), while reaching the rate of decrease in values of density by (5.32%). The higher values for short fiber (1cm) reinforced samples reaching the rate of increase in values of compressive strength by (10.92%), flexural strength by (40.65%), and water absorption by (6.65%), while reaching the rate of decrease in values of density by (8.91%). Results of thermal conductivity test showed decrease in values conductivity for all mortar samples with long short synthetic fibers and that the minimum value of conductivity obtained with (1.2%Carbon), reaching the rate of increase in values of thermal conductivity by (41.84%) for long fiber reinforced samples, while the lowest value for conductivity by (75.98%) for short fiber reinforced samples.


Article
FUNCTIONALIZED TITANIUM DIOXIDE NANOPARTICLES - NYLON 6 NANOCOMPOSITE MEMBRANE FOR IMPROVED SALT REJECTION UNDER LOW PRESSURE WATER NANOFILTRATION
غشاء متراكب نانوي ثاني أكسيد التيتانيوم - نايلون 6 لتحسين طرد الاملاح تحت ضغط منخفض للترشيح النانوي للماء

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In this paper, (Nylon-6) spider-net containing (dioxide titanium) nanoparticles were electro spun to produce nanofiber membrane with (TiO2 NPs). Characterization of the nanofiber membrane containing (TiO2 NPs) were done by (SEM) and (EDX) analyses. Pure (Nylon-6) nanofibers with an average diameter of (139 nm) were produced while (TiO2) additive gives membrane (Nylon/TiO2) with an average nanofibers diameter of (123 nm). (TiO2 NPs) with small amounts in (Nylon-6) solution were found which improve the hydrophilicity (antifouling effect) with water contact angle (5.7º), pure water flux (4800.45 Lm-2h-1) and mechanical strength (7.075 MPa). It was concluded that (Nylon-6/TiO2) antimicrobial (spider-net) which considered as a composite membrane with antifouling effect can be used in water filter applications. An improvement in the produced membrane mechanical strength was reached, also, rejection test of salt was achieved with rejection percentage of (76) and (71) for (Pb(NO3)2) and (NaCl) respectively.

في البحث الحالي ، تم اجراء عملية برم كهربائي لمادة (نايلون6) الحاوية على (اوكيسد تيتانيوم النانوي) لتحضير غشاء ذو شبكة عنكبوتية من الالياف النانوية . تم توصيف الغشاء الحاوي على الالياف النانوية الناتج من عملية البرم الكهربائي (نايلون/ اوكسيد التيتانيوم النانوي) بواسطة (طيف الاشعه المتشتتة - EDX) و (المجهر الالكتروني الماسح - SEM) ، غشاء النايلون النقي اعطى الياف نانوية بمعدل قطر (139 نانومتر) بينما الغشاء (نايلون/ اوكسيد التيتانيوم) انتج الياف بمعدل قطر (123 نانومتر). كمية صغيرة من دقائق اوكسيد التيتانيوم النانوية في الاغشية حسنت قياس زاوية التماس الماء حيث انخفضت الى (5.7º) وبذلك تحسنت خاصية البلل للغشاء كمرشح (hydrophilicity). معدل تدفق المياه النقية وصل الى (4800.045 لتر/ م2 ساعة) . اظهرت الخواص الميكانيكية اجهاد شد وصل الى (7.075 ميجا باسكال). تم فحص خواص الغشاء المضاده للبكتريا وامكانية استخدامه في تنقية معالجة المياة. بلغت نسبة طرد الاملاح للغشاء (76% و 71%) لكل من نترات الرصاص وكلويد الصوديوم ، على التوالي .

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