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Article
The Effect of the Thermopress Curing Technique on the Water Sorption and Solubility of the Cold and Heat–Cured Acrylic Resins

Author: Lamia T Rejab
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2008 Volume: 8 Issue: 11 Pages: 11-17
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: This study aims to evaluate the effect of the thermopress curing technique on the water sorption
and solubility of the cold–cured and heat–cured acrylic resins and compared this technique with the
bench curing technique used for the cold–cured resin and with the conventional water bath curing technique
for the heat–cured resin. Materials and Methods: they were to measure the water sorption and
solubility, the specimens were prepared as disks with a dimension according to the ADA Specification
No. 12. So specimens were divided into five groups depending on the type of the resin ( cold and heat–
cured ) methods of curing which were ( thermopress, conventional water bath and bench cure ) and the
time of curing cycle. Specimens were weighed before and after immersion in the distilled water and
after drying with silica gel using an electronic balance to measure the water sorption and solubility.
One way analysis of variance (ANOVA) followed by Duncan , s multiple range test was performed to
determined the significant different between the mean values among the tested groups at (p< 0.05)
level of significance. Results: There is a significant differences between the water sorption and solubility
of resin that cured by the different curing methods and different curing cycle times. The water
sorption and solubility of resin specimens that cured by thermopress have the higher values. Conclusions:
The water sorption and solubility of the cold and heat–cured acrylic resins is affected by the curing
method. The curing under higher pressure produces specimens with lower water sorption and solubility
values.


Article
Effect of Wax Burn-Out Heating Temperature on The Compressive Strength of Casting Dental Alloy Investment

Author: Lamia T Rejab
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2008 Volume: 8 Issue: 12 Pages: 197-204
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: To evaluate the effect of the burn-out heating on the compressive strength of investment materials.Materials and Methods: Three commercial investment materials were used in this study. Seventy two cylindrical shape specimens were prepared to evaluate the compressive strength of the investment materials at room temperature (cold strength) and at two different burn-out heating temperatures : 700 oC and 1000 oC (hot strength). Three groups were prepared according to tested investment materials, The specimens were then subdivided into three subgroups according to burn-out heating temperatures,eight specimens for each subgroup. The compressive strength (kg /cm2) was evaluated by using Instron testing machine. Mean values were compared statistically with one way analysis of variance (ANOVA),Duncan , s multiple range test and t-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 compressive strength among the three tested investment materials. The compressivestrength value significantly decreased with increasing burn-out heating temperature. Conclusion:The result of this study showed that the increase of burn-out heating had a significant decrease the compressive strength of the investment materials, and cold compressive strength gives an indicationof the hot strength .


Article
Digital analysis of the color of the heat-cured acrylic resin (using scanner)

Author: Lamia T Rejab
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2011 Volume: 11 Issue: 17 Pages: 88-95
Publisher: Mosul University جامعة الموصل

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Abstract

Aim: Using scanner image to digitally analyze the brightness and the effect of the type the of material, thickness and immersion of material in different solutions on the color change of the heat-cured acrylic resin denture base material. Materials and Methods: Two types of heat-cured acrylic resin denture base material were used. Totally 30 samples were prepared for uniform dimension for each color test. Sample scanner imaged and color metric is analyzed with software program Adob Photoshop 9.0. The CommissionInte´rnationale de l’E´ clairage for characterizing color ( CIE L*a*b*) color difference metrics were used for the performance analysis. Color change (&#916;E) value calculated to determine clini-cally acceptable color change. Statistically ANOVA, Student's t–test , Dunnett pairwise multiple com-parison t–test and Duncan's multiple range test were carried out to determine the significant differences at p&#8804; 0.05 . Results: The results appeared that there is a significant differences of the brightness value before and after polishing of the acrylic resin samples. And statistically there is a significant effect of type, thickness, and immersion in different solution on the color change of the tested materials which is clinically not acceptable . Conclusion : The result appeared that scanner gives an accurate image to digitally evaluate brightness and color change of dental materials with CIE L*a*b*color system.

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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
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: 21 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
Evaluation the Effect of Different Methods of Disinfection on Tensile Strength and Bond Strength of Soft Denture Lining Ma-terials

Author: Lamia T Rejab
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2013 Volume: 13 Issue: 21 Pages: 58-65
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: Aim of the study to evaluate the effect of two different disinfection methods for two periods of time on tensile strength and bond strength of soft denture lining materials (Vertex and Molloplast-B). Materials and methods : The effect of two disinfection methods ,first chemical disinfection method (which include artificial saliva , saturated salt and vinegar solution), and second microwave method on two physical properties the tensile and bond strength of soft denture lining materials for two periods of times (14 and 30 days) was evaluated, two hundred samples were prepared, one hundred samples to each property test . ANOVA and Duncan's multiple range test were performed to determine the signifi-cant difference among the tested groups at p ≤ 0.05% . Results: The result showed that the highest val-ue of tensile and bond strength of Vertex after 14 and 30 days were achieved with the microwave group, while for Molloplast -B highest value achieved with the control distilled water group. The low-est value was achieved after immersion in vinegar group for both soft lining material. A significant difference between the two soft lining materials among all disinfection methods at p≤ 0.05.Conclusions : The results appeared that the chemical disinfection and microwave disinfection methods have a significant effect on the tensile strength and bond strength of both vertex and Mol-loplast –B soft ling materials for two periods of time. Microwave disinfection has less effect than the chemical disinfection on the properties. The effect of disinfection increase significantly with increas-ing period of time .


Article
Efficacy of Three Denture Cleansers on Candida-Related Denture Stomatitis

Author: Lamia T Rejab
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2013 Volume: 13 Issue: 22 Pages: 235-240
Publisher: Mosul University جامعة الموصل

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Abstract

Aim: The aim of the study is to evaluate the efficacy of three dentures cleanser on Candida related denture stomatitis through assessing their ability to reduce the number of colony forming unit (CFU) of Candida on palate of the patient for different times. Materials and methods: Group of 12 patients who have denture stomatitis were divided into four groups according to the type of denture cleaners (Protefix, sodium hypochlorite solution 0.02%, saturated sodium chloride salt solution and control wa-ter). The microbiological examination was done to determine the efficacy of the cleansers that used by assessing the number of (CFU) at different times (day before treatment and after 14, 28days of treat-ment). The data were statistically analyzed, (ANOVA) followed by Duncan's multiple Range test to assess the significant difference between the groups at P≤0.05. Results: The results showed that there was a significant effect of three cleansers on reducing number of (CFU) of Candida species in the treatment of denture stomatitis after 14 and 28 days of treatment, but it was not significant for control water group. Sodium hypochlorite showed the highest efficacy. Conclusions: Result showed that there was no significant difference in the efficacy between the three cleansers indicating that all cleansers are effective in the treatment of denture stomatitis .


Article
The Relation of Bruxism with Teeth Attri-tion and Condylar Asymmetry (Clinical and Radiological Assay)

Authors: Rand Sh Al-Ani --- Lamia T Rejab
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2011 Volume: 11 Issue: 18 Pages: 265-274
Publisher: Mosul University جامعة الموصل

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Abstract

Aim : The paper aims to evaluate the effect of teeth wear severity associated with bruxism on the con-dylar height asymmetry index among different gender using panoramic radiograph viewing technique. Materials and methods: One hundred fifty subjects were participate in this study. Seventy five were bruxers and seventy five were non-bruxers. Degree of tooth wear severity was graded using Smith and Knight method. The panoramic radiographs were taken for each patient using a panoramic apparatus to determine vertical mandibular height asymmetry indices by a method developed by Habets et al. Mann-Whitney U test, Kruskal-Wallis test and Pearson Chi-Square test were used to determine the possible statistically significant differences between groups set at (P &#8804; 0.05).Results: The results showed there are significant differences between the vertical mandibular height asymmetry indices of the bruxers and non-bruxers subjects. The female bruxer subjects had the higher condylar index value than that of the male but statistically , there is no significant difference, while the severity of tooth wear had a signifi-cant different affect on the condylar indices. Conclusions: The results showed that the vertical man-dibular asymmetry indices were affected by the tooth wear associated with bruxer subjects. The bruxer subjects had the higher value than the non-buxer subjects and there is no significant difference of the condylar index of bruxer subjects among different genders. While , condylar index value increased significantly as the tooth wear severity grade increased.

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Article
Evaluation the Effect of Different Methods of Disinfection on Surface Roughness of Soft Denture Lining Materials

Authors: Lamia T Rejab --- Ihssan F Al-Takai
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2013 Volume: 13 Issue: 22 Pages: 296-304
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: Aim of the study to evaluate the effect of two different disinfection methods for two periods of time on surface roughness of soft denture lining materials (Vertex and Molloplast-B). Materials and methods : The effect of two disinfection methods ,first chemical disinfection method (which include artificial saliva with saturated salt and artificial saliva with vinegar solution), and second microwave method on the surface roughness of soft denture lining materials for two periods of times (14 and 30 days) was evaluated, One hundred samples were prepared. ANOVA and Duncan,s multiple range test were performed to determine the significant difference among the tested groups at p ≤ 0.05% .Results: The results showed that the lowest value of surface roughness (Ra)value after 14 and 30 days for Vertex soft denture lining material was achieved with the microwave group, while the lowest value of surface roughness (Ra)value after 14 and 30 days for Molloplast-B was achieved with the distilled water. The highest value of surface roughness (Ra) for Vertex soft denture lining material was achieved with vinegar after 14 and 30 days., while for Molloplast-B was achieved with vinegar group after 14 days and with salt group after 30 days. Conclusion : The results of T-test Table showed that there were no statistically significant differences in surface roughness(Ra) value between Vertex and Molloplast -B soft denture lining materials after 14 and 30 days except for microwave group after 14 days at P value ≤ 0.05. Distilled water disinfection has less effect on the property than other chemical disinfection and microwave regimen. The effect of disinfection increase significantly with increasing period of time.


Article
Examination of the particle’s shape, size and distribution of the commercial dental gypsum products

Authors: Lamia T Rejab --- Sawsan H Al–Jubori
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2003 Volume: 3 Issue: 2 Pages: 103-107
Publisher: Mosul University جامعة الموصل

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Abstract

Gypsum products used in dentistry are in the form of α and β calcium sulfate hemihydrate as dental stone and plaster. The aim of the study is examination of the particle’s shape, size and distribution of the different commercial dental gypsum products. The particle’s shape was examined microscopically with transmitted light microscope instead of reflected light microscope or electron microscope. Analysis of the particle’s size distribution and the measurement of the powder particle’s fineness was performed by sieving procedure using sieving machine. The data was collected and calculated and then compared with the ADA Specification No. 25 for gypsum products. The results showed that the microscopical examination with transmitted light microscope give clear accurate and precise image about the different shapes of the stone and plaster. The results of the analysis for particle’s size distribution showed that there is a difference in the distribution between the different tested commercial dental gypsum products and also showed that all products have particle’s size larger than the ADA Specification No. 25.

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