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Article
Effect of Dry Pressure Heat Curing Technique on Water Sorption and Color of Heat Cured Acrylic Resin

Author: Omar Z. AL-Tahho
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2014 Volume: 14 Issue: 2 Pages: 294-301
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: The purpose of this study was to evaluate the effect of dry pressure curing technique after immersion in distilled water for 1 ,4 and 12 weeks on the water sorption, solubility, and color change of heat cured acrylic resin as compared with conventional curing technique, also to evaluate the effect of immersion period on these properties. Materials and methods: Sixty specimens of vertex regular heat cured acrylic resin denture base material were used in this study, curing by two different technique, conventional curing technique and dry pressure curing technique, then immersed in distilled water for 1,4, and 12 week . The water sorption and solubility test were measured by means of mass change in the materials after water saturation and dehydration. While the color change test was measured by the samples converted to digital images on computer by using digital scanner, then the digital images were prepared with dimension 760 pixels*960 pixels for each samples by software program Adob Photoshop 9.0, by MATLAB 2010 program the image was analyzed to the basic primary colors RGB, then converted to (CIE L*a*b*) system by Photoshop 9.0 program, the CIE L*a*b* color difference metric were used to perform color change test. Mean values were compared statistically with T-test, one way analysis of variance and by Duncan's multiple range test to determined the significant different among the groups at p<0.05 level of significance. Results: In comparisons between curing techniques, that there was significant difference at p≤ 0.05 in water sorption and solubility, while in color change that there was no significant difference at P> 0.05 in different times immersion (1,4,and 12 weeks). In comparisons between immersion time that there was significant difference at p≤ 0.05 in water sorption, solubility, and color change test for both curing techniques. Conclusion: The dry pressure curing technique has an effect on the water sorption and solubility ratios but no effect on color change of heat cured acrylic resin, while the immersion period have an effect on the water sorption, solubility, and color change.


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: 2 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: 1 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
Effect of 38%hydrogen peroxide agent on color change of composite resins stained with tea and coffee beverages (An in vitro study)

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Abstract

Background: The esthetic application of bleaching materials has gained popularity,with consequences for teeth and restorative materials. The purpose of this an invitro study was to investigate the effect of in-office bleaching agent (38%hydrogen peroxide) on the color change of three composite resins after stainingwith tea and coffee beverages.Materials and Methods: Sixty disc-shaped samples from three different compositeresins (Tetric Ceram, Tetric Flow and Tetric Evo Ceram) were used in this study.The samples of each group were randomly divided into two subgroups accordingto type of beverages (tea and coffee) used for staining of samples. After stainingof composite resins the total color change (ΔE1 ) was calculated usingspectrophotometer, then the samples immersed in WHITEsmile® office bleachingagent for 15 min x 3 times with a 7 days interval followed by ΔE2 calculation.Data were subjected to the ANOVA, LSD and student t-test at 0.05 significancelevel.Results: The results revealed that, there was clinically significant color change ΔE>3.3 with a statistically highly significant differences (P=0.000) for all the groups.Coffee causes more discoloration than tea. After bleaching, the samples becamewhiter in color and only appreciable by skillful operator but considered clinicallyacceptable ΔE1 - ΔE2 < 3.3.Conclusion: Tea and coffee beverages causes discoloration in composite but thiseffect was depended on the type of beverages and composite resins. The most ofcolor change occurred with Tetric Flow composite resin after immersion in coffeebeverage. The bleaching agent (38% hydrogen peroxide) can remove the stainingof composite resins and make its color clinically acceptable.


Article
The effect of accelerated artificial aging on color change of three different types of composite (in vitro study)

Author: Dr. Zainab Shaker Al-Taii, B.D.S, M.Sc.* د. زينب شاكر
Journal: MUSTANSIRIA DENTAL JOURNAL مجلة المستنصرية لطب الاسنان ISSN: 18138500 Year: 2018 Volume: 15 Issue: 1 Pages: 9-17
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

The greater demand for esthetic in the modern life with the simplified bondingsteps for composite filling increase its universal use but their gradual change incolor over time make their replacement very important, the aim of this study is thecomparison among different type of composite to see which type is the best colorstability in the clinical work .Material and method :30 samples of three different materials have been made ,thefirst group is 10 samples fabricated from Filtek z250 ,the second group is 10samples fabricated from Filtek z250xt and the third group is 10 samples fabricatedfrom z350xt .All the samples color parameters were measured before placing inaccelerated weathering tester (time 0)then all the samples were placed in theaccelerated weathering tester for 150 h and 300h then the color parameters weremeasured from which the change in color had been measured. Statistical analysiswas performed by using ANOVA repeated measure test to see if there were anysignificant difference among the ΔE of experimental groupsResults : the results show that the z250 have the highest color stability as comparedwith other types of composite used in this study while the z350xt results show thelowest color stability also the result show that there's high significant differenceamong all groups among different time interval used in the studyConclusion: the change in color above the clinically acceptable threshold (3.3) wasseen in all types of composite used in this study and that the z 250xt shows theleast change in color.

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