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Article
The Effect of Microwave Disinfection on the Dimensional Change of Acrylic Resins.

Authors: Luay N Abbood --- Lamia T Rejab --- Ahmad M Hussen
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2008 Volume: 8 Issue: 11 Pages: 38-43
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: To evaluate the effect of the microwave disinfection on the dimensional changes of the heat–
cured acrylic resin. Materials and Methods: Heat–cured acrylic resin was used in this study. Thirty
two disk–shaped specimens with reference points were prepared to evaluate the linear dimensional
changes of the heat–cured acrylic resin that sterilized by microwave irradiation and by chemical
solutions chlorhexidine and sodium hypochlorite. The specimens were divided into four tested groups,
eight specimens for each group. Group I as control group and other groups divided according to the
sterilization method. The dimensional change was evaluated with an Electronic Digital Caliper. Mean
values wear compared statistically with: One–way Analysis of Variance (ANOVA), followed by
Duncan's Multiple Range Test to determine the significant different among the tested groups at
(p≤0.05) level of significance. Results: They showed that there was a highly significant difference of
the means values of the linear dimensional change among the four tested groups. Specimens sterilized
by microwave irradiation have a higher value than that sterilized by the chemical solutions.
Conclusions: The results of this study appeared that sterilization by the microwave irradiation produce
a significant effect on the dimensional stability of the heat–cured acrylic resin, while sterilization by
chemical solution produce no significant difference.


Article
Effect of Organic Acid Solutions on Color Change of Acrylic Resin Facing For Fixed Crowns and Bridges

Author: Lamia T Rejab
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2008 Volume: 8 Issue: 12 Pages: 128-135
Publisher: Mosul University جامعة الموصل

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Abstract

Aim: To evaluate the effect of the organic acid solution on color stability of the facing heat-cured acrylic resin. Materials and methods: Two heat-cured facing acrylic resins were used in this study.Sixty four rectangular shape specimens were prepared to evaluate the color changes of the heat-cured acrylic resin after immersion in three organic acids (acetic, citric and lactic acids). The specimens weredivided into two groups according to tested resin materials, and then subdivided into four tested groups according to immersion solution, eight specimens for each subgroup. The assessment of color property(opacity) done by using ultra-violet visible spectrophotometer at wavelength 345 nm. Mean values were compared statistically with one way analysis of variance (ANOVA) followed by Duncan , s multiplerange test to determine the significant difference among the tested groups at (p<0.05) level of significance.Results: The results showed that there is a significant difference of the means value of the color change among the four tested groups for both tested materials for two different immersion periods,but there is no significant difference of color change between tested materials. Specimens immersed in acetic acid have a higher value than that immersed in other organic acids. Conclusion: The result of this study show that immersion in organic acids for different immersion periods had a significant effect on color stability of the facing heat-cured acrylic resin cured acrylic resin .


Article
The Effect Of Different Curing Times on The Hardness, Fracture Resistance And Color Change of Visible Light Cured Denture Base Resin

Author: Mohammed M Sadoon
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2009 Volume: 9 Issue: 13 Pages: 66-70
Publisher: Mosul University جامعة الموصل

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Abstract

Aim: To evaluate the effect of the organic acid solution on color stability of the facing heat-cured acrylic resin. Materials and methods: Two heat-cured facing acrylic resins were used in this study.Sixty four rectangular shape specimens were prepared to evaluate the color changes of the heat-cured acrylic resin after immersion in three organic acids (acetic, citric and lactic acids). The specimens weredivided into two groups according to tested resin materials, and then subdivided into four tested groups according to immersion solution, eight specimens for each subgroup. The assessment of color property(opacity) done by using ultra-violet visible spectrophotometer at wavelength 345 nm. Mean values were compared statistically with one way analysis of variance (ANOVA) followed by Duncan , s multiplerange test to determine the significant difference among the tested groups at (p<0.05) level of significance.Results: The results showed that there is a significant difference of the means value of the color change among the four tested groups for both tested materials for two different immersion periods,but there is no significant difference of color change between tested materials. Specimens immersed in acetic acid have a higher value than that immersed in other organic acids. Conclusion: The result of this study show that immersion in organic acids for different immersion periods had a significant effect on color stability of the facing heat-cured acrylic resin cured acrylic resin .


Article
The Effect of Incorporation of Two Different Fibers on Some Mechanical Properties of Heat Cure Acrylic Resin Dr. Abdalbasit A Fatihallah BDS, MSc, PhD

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Abstract

To evaluate the effect of addition of different fibers on some mechanicalproperties of heat cured acrylic resin (flexural strength, impact strength and hardness).210 specimens were used in the study.70 specimens were used for flexuralstrength with measurements (65mm*10mm*2.5mm) length, width and thicknessrespectively. The specimens were divided into seven test groups (n=10). The firstgroup is the Control one and it was without fiber reinforcement, second groupreinforced with 2mm polyester fibers, third group reinforced with 4mm polyesterfibers, fourth group reinforced with 2mm Polypropylene fibers, fifth group reinforcedwith 4mm Polypropylene fibers, sixth group reinforced with 2mm of both fibers(polyester and Polypropylene), and seventh group reinforced with 4mm of both fibers(polyester and Polypropylene). 70 specimens were used for impact strength in sevengroup (n=10) with measurements (80mm*10mm*4mm) length, width and thicknessrespectively. 70 specimens were used for hardness test in seven groups (n=10) withmeasurements (65mm*10mm*2.5mm) length, width and thickness respectively.The Results Show that there are highly significant differences between all groupsexcept for a significant differences between control and combination 2 mm fiberlength (mean differences=33.45). For the hardness test the comparisons show thatthere is no significant differences between groups except for a significant differencesbetween control and combination of both fibers with 2mm length (mean differences=-1.34). For impact strength; there are highly significant differences between all groupsexcept for a significant differences between Polyester fiber of 2mm length andcombination of the two fiber of 2 mm length (mean differences=-3.1).In conclusion, the addition of different fibers (polyester and Polypropylene) toacrylic resin gives it more resistance to break and more resistance to bend.


Article
Effect of Conventional Polishing Procedure in Water Sorption of Cold and Heat Cured Acrylic Denture Base Material

Author: Azad Mohammed Ridha Al-Muthaffer
Journal: Medical Journal of Babylon مجلة بابل الطبية ISSN: 1812156X 23126760 Year: 2016 Volume: 13 Issue: 2 Pages: 481 -488
Publisher: Babylon University جامعة بابل

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Abstract

Acrylic resin is almost universally for partial or complete denture base construction due to its favorable properties. Unfortunately some disadvantages such as water sorption have been reported which causes dimensional changes that may subject the acrylic denture base to internal stresses, so the water sorption is a physical property of importance. Forty square shaped specimens (twenty specimens for heat and cold cured acrylic material) were prepared. Ten specimens from heat cured acrylic (HP) and cold cured acrylic (CP) material were polished, and ten specimens from heat cured acrylic (Hx) and cold cured acrylic (Cx) were not polished as control group. At room temperature, all specimens were weighed; this weight value was considered the initial weight of the specimen (W0). All specimens were kept in distilled water bath for 24 hours, and then specimens were weighed(W1)then the specimens were kept out of water bath for 24 hours to dry to (W0), and all samples return back to water bath for 24 hours to weigh again (W2). This manner was repeated till (W4).There is a significant difference (p=0.018) between (CP) and (Cx) and a significant difference (p=0.047) between (HP) and (Hx) and no significant difference between cold and heat cured acrylic before (p=0.699) and after polishing (p=0.52) at (p ≤0.05).


Article
Effect of the Curing Methods on the Surface Hardness of Different Thickness on Heat–Cured Acrylic Resin

Authors: Luay N Abood --- Lamia T Rejab --- Ahmad M Ali
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2007 Volume: 7 Issue: SpIss Pages: S1-S4
Publisher: Mosul University جامعة الموصل

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Abstract

To evaluate the surface hardness of the heat–cured acrylic resins with two different thicknesses cured by two curing methods conventional water bath and microwave energy. Materials and Methods: Heat–cured acrylic resin was used in this study. Rectangular specimens were prepared with two different thicknesses (3 and 6mm) and cured by two different curing methods, conventional water bath and microwave energy methods. The specimens were divided into two groups according to the curing method and specimens thickness. Forty specimens were prepared, ten specimens for each group. The surface hardness was evaluated with Rock well hardness tester. Mean values wear compared statistically with one way analysis of variance (ANOVA) followed by Duncan' s multiple range test to determine the significant different among the groups at (p<0.05) level of significance. Results: The results showed that there is a highly significant difference of the means value of the surface hardness among the four tested groups. Specimens cured by conventional water bath with 3mm thickness have the highest value in relation to 6mm thickness of specimens cured by microwave energy. Conclusions: The curing method, and specimens thicknesses have a significant effect on the specimens surface hardness value. The specimens that cured by the conventional water bath method have a higher values than that cured by the microwave energy curing method and the thicker specimens have a lower values than the thinner one in both curing methods


Article
A Study the Effect of Addition of Silanized Zirconium Oxide Nanoparticles on Some Properties of High-Impact Heat-Cured Acrylic Resin

Authors: Soodad A. Al-Hiloh سوداد الحلو --- Intisar J. Ismail انتصار جميل اسماعيل
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2016 Volume: 28 Issue: 2 Pages: 19-25
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: The incorporation of rubber has not been entirely successful because it can have detrimental effectson the transverse Strength and hence the rigidity of the denture base.Materials and methods: Zirconium oxide nanoparticales were coated with a layer oftrimethoxysilylpropylmethacrylate (TMSPM) before sonication in monomer (MMA) with the percentages 3% byweight then mixed with powder using conventional procedure.(100) samples were prepared and divided into fivegroups according to the test performed ,Each group consisted of 20 specimens and these were subdivided into 2groupsGroup (A): control group (10 specimens of high impact acrylic resin without zirconium oxide) and Group(B):zirconium oxide group(10 specimens of high impact acrylic resin with 3% wt zirconium oxide).The testsconducted were impact strength, transverse strength, indentation hardness(shore D), surface roughness, watersorption and solubility. The results were statistically analyzed using Dunntt t-test.Results: Highly significant increase in impact strength and transverse strength occurred with the incorporation of 3%wt Zirconium oxide nanofiller. A highly significant increase in surface hardness, but the water sorption and solubilitywere significantly decreased with the addition of silanized (ZrO2) Nano particles compared with the control group.nosignificant statistical difference in surface roughness.Conclusions: The addition of silanized ZrO2 Nano particles to high impact heat cure acrylic resin material improves theimpact strength, transverse strength and surface hardness of high-impact heat-cure acrylic resin at the same timethis addition decreases water sorption and solubility. On the other hand there was no change in surface roughnesswith the addition of 3% wt of silanized ZrO2Nano particles

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