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Article
The effect of storage time and disinfection method on the activity of some dental stone disinfectants

Authors: Enas M. Tarik ايناس طارق --- Shatha S. Al-Ameer شذى الامير
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2005 Volume: 17 Issue: 3 Pages: 8-12
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: It has been recommended that all materials returning from the laboratory be disinfected before placement in the patient’s mouth. Various adverse reactions have been reported when using disinfectant solutions with impression materials. Therefore, disinfection of dental cast may be effective in preventing cross infection. This study was carried out to evaluate the effect of storage time on the antimicrobial activity of chlorhexidine, sodium hypochlorite, and madacide-1 solutions and to test the effect of spray, immersion and incorporation techniques on their activities.Materials and Methods: Stone specimens were prepared in cylindrical blocks, under aseptic conditions, containing the three tested solutions applied by spray, immersion and incorporation methods. These specimens were stored for (1½h, 1 day, 3days, 7days, and 10days) and then tested by using disk-diffusion plate method to estimate the release of disinfectant solutions against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa,and Candida albicans. The zones of inhibition were measured with a ruler (in mm) after incubation, which was for 24h at 37°C aerobically.Results: The results showed that all microorganisms were sensitive to chlorhexidine and sodium hypochlorite while E.coli and P. aeruginosa were resistant to madacide. Also it was shown that chlorhexidine was more effective than madacide and sodium hypochlorite as a long acting disinfectant while sodium hypochlorite was the most effective as a short acting one.Conclusion: Immersion method had more inhibitory effect than the other methods representing (60 %) of all the tested specimens followed by incorporation method (25%) and the least percentage for spray method (15%).


Article
The effect of addition of calcium hypochlorite disinfectant on some physical and mechanical properties of dental stone

Authors: Shorouq M. Abass شروق عباس --- Ibrahim K. Ibrahim
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2012 Volume: 24 Issue: special issue 1 Pages: 36-43
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: The potentially damaging effects of the immersion technique, the difficulty in covering the entiresurface of the cast with the spray disinfecting solution, and the inability to assume that every impression presented tothe laboratory has been disinfected has led to the need for incorporating a disinfectant directly into the calciumsulfate hemihydrate. This study was designed to evaluate the effect of the addition of Calcium Hypochoritedisinfectant on some physical and mechanical properties of the dental stone.Materials and methods: Calcium Hypochlorite disinfectant in aqueous solution in different concentrations 0.5, 1.0, 1.5and 2.0% was added to type III dental stone. Setting time, setting expansion, reproduction of details, compatibilitywith impression materials and consistency are physical properties which were evaluated. The compressive strengthand surface hardness as mechanical properties were also determined.Results: The results of this study showed that the addition of 1 % of calcium hypochlorite improved some of thephysical and mechanical properties of dental stone (Setting Expansion, Compressive Strength and Surface Hardness)while its adversely affected the other properties (Setting Time)Conclusions: The 1 % of calcium hypochlorite disinfectant solution could be used to disinfect dental cast with theleast effect when compared with the other concentrations of calcium hypochlorite


Article
Evaluation of Some Physical Properties of Locally Prepared Alpha-calcium Sulfate Hemihydrate

Author: Lamia T Rejab
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2013 Volume: 13 Issue: 1 Pages: 14-20
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: Aim of the study is to evaluate some physical properties of locally prepared dental stone form natural gypsum by two different calcination methods with autoclave with and without adding crystal habit modifier during calcination procedure for different periods of time. Materials and methods: The values of some physical properties that include specific gravity, water/ powder ratio and linear setting expansion of the prepared dental stone with autoclave with and without adding crystal habit modifier during calcination procedure for different periods of time and compared with that of commercial den-tal stone. ANOVA and Duncan's multiple range test were performed to determine the significant differ-ence among the tested groups at p ≤ 0.05%. Results: Results showed that there were significant differ-ences of the values of the physical properties between the locally prepared dental stone with autoclave and the commercial one at p≤ 0.05 in specific gravity, water/ powder ratio and linear setting expansion. Conclusions :The results appeared the alpha- calcium sulfate hemihydrates dental stone that prepared in autoclave with adding crystal habit modifier has superior properties than of that prepared without modifier, but still not reach the properties of the commercial product. All values of the tested proper-ties were in accordance with ADA Specification


Article
The Effect of Disinfectant on the Microstructure of Dental Stone at Different Time Intervals

Author: Dr. Shorouq Majid Abass B.D.S., M.Sc.* د. شروق ماجد
Journal: MUSTANSIRIA DENTAL JOURNAL مجلة المستنصرية لطب الاسنان ISSN: 18138500 Year: 2007 Volume: 4 Issue: 2 Pages: 199-205
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

Gypsum products have been considered to be among the most widely used model and die materials. Modifications of these materials by adding chemicals or salts result in a change in their structure. This study was designed to evaluate the effect of the addition of Calcium Hypochlorite disinfectant on the microstructure of dental stone.Calcium Hypochlorite disinfectant in aqueous solution in different concentrations (0.5, 1.0, 1.5 and 2.0%) was added to type III dental stone. The microstructure of the dental stone samples was examined under the microscope and then photo scoped, pictures were taken at different time intervals (immediately, after 10, 30 min., 1and 2 hours) for all the test groups.The results of this study showed that at different time intervals, from the beginning of mixing of dental stone with Calcium Hypochlorite disinfectant solution, deformation in the microstructure was produced (calcium sulfate dihydrate crystals).Microscopically appearance of dental stone samples mixed with Calcium Hypochlorite disinfectant solution revealed a deformation in size and shape of the calcium sulfate dihydrate crystals when compared with the control group.


Article
The effects of drying techniques on the compr-essive strength of gypsum products

Authors: Radhwan H Hasan --- Kasim A Mohammad
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2005 Volume: 5 Issue: 1 Pages: 63-68
Publisher: Mosul University جامعة الموصل

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Abstract

Excess water in set dental stone decreases its strength.So different methods were used to expel excess water but thecompressive strength may be affected by drying technique.The purpose of this study was to evaluate the compressive strengthof two types of set dental stone after air, conventionaloven and microwave drying techniques.A total of 60 stone specimens (30 specimens made fromSilky Rock stone and 30 Zeta stone) were prepared by the aidof an acrylic split mold according to ADA Specification No.25. Specimens were divided into six groups of 10 identicalspecimens for each. Then groups were either dried by air,conventional oven or microwave oven. Using UnconfinedCompression Machine, the specimens were loaded by a crosshead speed of 1 mm/minute till the specimen being fractured.The load required to fracture the stone specimens was recordedand analyzed using analysis of variance followed by Duncan’sMultiple Range Test for the statistical comparisons betweendrying techniques at a significance level of p< 0.05, andStudent’s t–test was used to compare between the two stonetypes.The results revealed that high significant differenceswere present between the different drying techniques(p<0.0001) with air dried specimens were significantly strongerthan others and microwave dried specimens were significantlystronger than conventional oven dried specimens. SilkyRock (type IV) stone was significantly stronger than Zeta(type III) stone (p<0.001).From this study, it could be concluded that the highestcompressive strength can be obtained by air drying of the stonefor 24 hours, while microwave drying technique give betterresults than conventional oven drying technique with theadvantage of time saving over the two other drying techniques.


Article
The effect of SOLO and sodium hypochlorite disinfectant on some properties of different types of dental stone

Authors: Aseel M. Al-khafaji اسيل الخفاجي --- Shorouq M. Abass شروق عباس --- Bayan S. Khalaf بيان خلف
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2013 Volume: 25 Issue: 2 Pages: 8-17
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Dental casts come into direct contact with impression materials and other items that are contaminatedby saliva and blood from a patient's mouth, leaving the casts susceptible to cross-contamination. The disinfectantsolutions of the impression materials cause various adverse reactions. Therefore, disinfection of dental casts may beeffective in preventing cross infection. This study was carried out to evaluate the surface hardness, dimensionalaccuracy, reproduction of details and surface porosity of type III, type IV and type IV extra hard dental stone afterimmersion in and spray by using SOLO and Sodium hypochlorite disinfectant solutions.Materials and methods: 240 Stone samples were prepared in rubber rings, A total of 60 test block were prepared foreach test (surface hardness, dimensional accuracy, reproduction of details and surface porosity).the samples weredivided into three groups (20 for each type of stone) type (III, IV, IV extra hard); SOLO and Sodium hypochloritedisinfectant by 2 methods (immersion and spray) were used in each test.Results: the results of dimensional accuracy, reproduction of details, surface hardness and surface porosity revealedno significant difference for all types of tested stone samples after immersion or spraying in SOLO and NaOCl exceptthe surface hardness of type IV extra hard showed significant difference after spray with SOLO and the surfaceporosity of type IV extra hard showed significant difference after immersed in both SOLO and NaOCl solutions.Conclusions: Based on the results of this study immersion in and spray by using SOLO and NaOCl disinfectant solutionsproduced no adverse effect on dimensional accuracy, reproduction of details, surface hardness and surfaceporosity for type III, type IV dental stone and for type IV extra hard dental stone except for the surface hardness fortype IV extra hard when sprayed with SOLO and the surface porosity when type IV extra hard stone immersed in theSOLO and NaOCl solutions


Article
Effects of Different Disinfectant Additives on Compressive Strength of Dental Stone

Authors: Qasim A. Mohammad --- Radhwan H. Hasan --- Sadi Sh. Thiab
Journal: Journal of University of Babylon مجلة جامعة بابل ISSN: 19920652 23128135 Year: 2014 Volume: 22 Issue: 5 Pages: 1686-1695
Publisher: Babylon University جامعة بابل

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Abstract

Purpose: The aim of this study was to analyze the compressive strength of dental stone after incorporating different disinfectant solutions during stone models preparation. Materials and methods: A one hundred eighty die stone type IV cylindrical specimens were prepared with dimensions of 20mm diameter and 40 mm height by adding different disinfectants (Sodium hypochlorite 1% and 0.5%, Chlorhexidine 2% and 1%, glutaraldehyde 2% and 1%, Iodine 4% and 2% and a control group without additives) divided into 18 groups, 10 specimens per each group (each two groups identical of same disinfectant and same concentration). Then one of each two identical groups was tested to evaluate its compressive strength after air drying for 24 hours while the other group tested after 48 hours.Results: Chlorhexidine and glutaraldehyde in both concentrations and drying time as well as sodium hypochlorite 0.5% showed no significant difference in compressive strength compared to control group, and they showed higher values compared to sodium hypochlorite 1%. While Iodine groups in both concentrations and drying times showed the least values among all groups.Conclusions: According to the results of this study, Chlorhexidine and glutaraldehyde 1-2% as well as 0.5% sodium hypochlorite can be added to disinfect die stone casts without affecting their compressive strength, while both sodium hypochlorite at a higher concentration and iodine at any concentration are not recommended to be used for this purpose .

الهدف من هذه الدراسة هو دراسة تأثير اضافة مواد معقمة الى قوالب حجر الأسنان على قوة الكبس لهذه القوالب. تم تحضير نماذج اسطوانية من حجر الأسنان قطر القاعدة 20 ملم وارتفاع 40 ملم وبإضافة ماء كمادة قياسية او مواد معقمة بتراكيز مختلفة (كلورهيكسيدين 2% و 1% ، كلوتارالديهايد 2% و 1% ، هايبوكلوريد الصوديوم 1% و 0.5%، يود 4% و 2%) كان المجموع الكلي للنماذج المستخدمة 180 نموذج وتم توزيعها الى 18 مجموعة بواقع 10 نماذج لكل مجموعة (كل مجموعتين متماثلتين بمادة التعقيم ونسبته المئوية)، ثم تم فحص قوة كبس المجموعة الاولى من كل مجموعتين متماثلتين بعد 24 ساعة تجفيف بتركه معرض للهواء وفحص المجموعة الاخرى بعد 48 ساعة. واظهرت النتائج ان كل من الكلورهيكسيدين وكلوتارالديهايد وكذلك هايبوكلوريد الصوديوم بتركيز 0.5% ليس لها تأثير سلبي على قوة الكبس لحجر الأسنان مقارنة مع المجموعة القياسية بدون المواد المعقمة، وجميعها كانت اقوى من مجموعة هايبوكلوريد الصوديوم 1%. في حين كانت مجموعات اليود وبكلا التركيزين و بأي زمن تجفيف هي الادنى وبشكل معنوي مقارنة بجميع باقي المجموعات. يمكن الاستنتاج من هذه الدراسة انه بالإمكان استخدام الكلورهيكسيدين وكلوتارالديهايد 1-2% وكذلك هايبوكلوريد الصوديوم بتركيز منخفض 0.5% لتعقيم قوالب حجر الأسنان، في حين لا يمكن استخدام هايبوكلوريد الصوديوم بتراكيز اعلى وكذلك اليود بأي تركيز كان لهذا الغرض بسبب تأثيرهم السلبي على قوة الكبس لحجر الاسنان.


Article
Some Mechanical Properties of Dental Stone Specimens after Disinfections by 70% Hospital Sprit
بعض الخواص الميكانيكية لعينات حجرية الأسنان بعد التطهير بنسبة 70٪ من كحول المستشفى

Author: Amera Kamal
Journal: Zanco Journal of Medical Sciences مجلة زانكو للعلوم الطبية ISSN: 19955588/19955596 Year: 2009 Volume: 13 Issue: 1 Pages: 49-54
Publisher: Hawler Medical Univeristy جامعة هولير الطبية

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Abstract

Background and objectives: The transmission of oral pathogens to impression and subsequently on to gypsum casts had been demonstrated. The aim of the study to investigate the effect of disinfections of type III dental stone casts by spraying and immersion in 70% hospital sprit (ethanol) on the compressive strength and surface roughness at two different time intervals (24 and 48) hours.Materials and methods: Forty eight cylindrical stone specimens (12 for each group), were prepared for compressive strength and surface roughness testing. Six specimens of each group were tested after (24) hours and the other six after (48) hours.Results: The study showed no significant differences in values of compressive strength and surface roughness between the control and sprayed groups at (24 and 48) hours, this could be due to the fact that the sprayed specimens absorbs fewer amounts of disinfectants than the immersed groups.Conclusions: The immersion of the specimens in (70%) ethanol for (10) seconds and (30) minutes decrease the compressive strength and increase the surface roughness.


Article
The effect of glycerin-painted wax pattern on surface quality of dental stone mold

Author: Dr. Arshad F. Jassem Al-Kaabi. * د. ارشد فيصل جاسم
Journal: MUSTANSIRIA DENTAL JOURNAL مجلة المستنصرية لطب الاسنان ISSN: 18138500 Year: 2016 Volume: 13 Issue: 1 Pages: 52-56
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

Aim: The aim of this study was to examine the effects of glycerin-coated wax patternon dental stone surface quality in terms of surface roughness and micro airbubble formation.Method: In this study, a total of 20 modeling wax samples were used for thehydrophilicity test (the contact angle test) divided into 2 groups (control andglycerin-painted). A total of 20 dental stone samples were also prepared forvisual and microscopic analysis divided into 2 groups (control and glycerinpainted).Results and conclusion: The contact angle data showed a significant decrease insurface hydrophilicity for the glycerin-painted group (P-value < 0.05). However,the visual and microscopical analysis did not show a prominent distinction insurface quality between the two groups, so there is no noticeable effect on dentalstone surface caused by glycerin-modified wax pattern.


Article
The antibacterial activity of certain disinfectant solutions incorporated into stone mixture

Author: Dr. Basima Mohammed Ali Hussein.* د. باسمة محمد
Journal: MUSTANSIRIA DENTAL JOURNAL مجلة المستنصرية لطب الاسنان ISSN: 18138500 Year: 2008 Volume: 5 Issue: 2 Pages: 200-204
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

Cross infection control is a way of life and it was realized that a radical changes inthe way of work in the dental clinic and laboratories would detect considerable revisesof traditional working patterns. Disinfection of dental stone cast by incorporation ofChlorhexidine gluconate CHX, Sodium hypochlorite and Madacide 11 separately in aconcentration of (0.5 , 0.5 , full strength) respectively according to the manufacturerinstructions and testing their activity against S.aureus,  -haemolytic streptococcuspneumonia, pseudomonas aeruginosa and E. coli was performed. 5 trials were donefor each disinfectant solution and control (distilled water).The result showed that all the disinfectant solutions showed significant reductionof microbial growth in comparison with the control. Sodium hypochlorite sterilizedental stone cast followed by CHX.Sodium hypochlorite gave negative result for allthe tested microorganisms in all the trials followed by chlorhoxidine gluconatesolutions .Disinfection of stone cast is among recommended methods in infectioncontrol.Sodium hypochlorite was the best among the tested disinfected solutions.

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