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Article
Effect of Microwave and Ultrasonic Disinfecting Techniques on the color of Artificial Teeth: A Comparative Study

Author: Omar A. Sheet
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2011 Volume: 11 Issue: SpIss Pages: S1-S11
Publisher: Mosul University جامعة الموصل

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Abstract

ABSTRACT Aims of the Study: To evaluate the influence of disinfection by microwave and ultrasonic cleaning techniques on the color parameters of different types of artificial teeth used in prosthodontic treatment. MATERIALS & METHODS: Three types of artificial teeth were used: Porcelain teeth, RMH acrylic teeth (double cross linked) and Seif acrylic teeth (cross linked). Samples were immersed in distilled water for 48 hours at 37ºC before taking measurements. The color parameters (hue, chroma and value) of study samples were measured by Easy shade device before treatment, after disinfection by microwave (800 watt for 6 minutes), and lastly after cycle in ultrasonic cleaner (15minutes with effervescent tablet). Data were statistically analyzed by Analysis of Variance (ANOVA) followed by Duncan Multiple Analysis Range Test to determine the level of significance. RESULTS: Color of acrylic teeth was affected more than that of porcelain teeth. Results showed significant differences (P<0.05) in chroma and value color parameters before and after disinfection for Acrylic teeth but not for hue parameter. CONCLUSIONS: Seif teeth colors changed during disinfection more than RMH teeth, while Porcelain teeth the least. Microwave disinfection technique do not affect significantly the color of denture teeth


Article
The Effect of Additional Microwave Curing Cycle on Residual Monomer Release from Different Acrylic Resin Materials.

Authors: Ahmed A Al-Ali --- Anas M Almukhtar --- Omar A Sheet
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2011 Volume: 11 Issue: 18 Pages: 397-403
Publisher: Mosul University جامعة الموصل

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Abstract

AIMS: to evaluate the effect of microwave post-treatment in the reduction of residual monomer of different types of acrylic resin and evaluate the effect of microwave treatment time. MAERIALS AND MEHODS: three different types of acrylic resin materials are used; heat cured, light cured, and or-thocryl. Specimens are subjected to additional curing with microwave and compared their residual monomer with the control group. ANOVA followed by Duncan multiple range test were used to de-termine the significant difference at P<0.05 level. RESULS: there was a significant difference (p<0.0001) in the amount of residual monomer released from the three tested materials. No statistical difference were seen between 5 and 10 minute microwave treatment for the heat cured and orthocryl acrylic resin but there is significant difference between 5 and 10 minute treatment for the light cured acrylic resin. CONCLUSIONS: There are different levels of residual monomer when comparing the tested materials with each other. Additional treatment with microwave after curing decrease the residu-al monomer of all the tested acrylic resin materials.

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Article
Linear Dimensional Change and Accu-racy of Fit of Positive Pressure Thermo–Formed Prosthodontic Materials

Authors: Zeina M Ahmad --- Ahmed A Al–Ali --- Omar A Sheet
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2012 Volume: 12 Issue: 20 Pages: 206-217
Publisher: Mosul University جامعة الموصل

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Abstract

To determine the dimensional accuracy of thermoformed dental base plates. Materials and methods: Six different types of thermoformed materials were used. The circumference of the triangle formed between the index marks on standard maxillary edentulous metal model and measurements of the surface area of the gap between the posterior margin of base plate and the metal model were cap-tured with digital camera and measured with AutoCAD program. Measurements were made after 1 day after processing and then 2, 3 and 7 days. ANOVA and Duncan multiple range test were used to statistical analysis of the data. Results: The linear dimensional shrinkage and inaccuracy of fitness were significant for all of the thermoformed materials. The change after 7 days was not significantly different from that occurred after 1 day. Conclusions: All thermoformed materials exhibited dimen-sional instability, the Duran(hard material) and Durasoft(flexible material) were the most dimensional-ly stable and accurately fitted thermoformed materials.


Article
The Effect of Different Curing Techniques on the Degree of Bond Conversion for Different Types of Acrylic Resin Materials

Authors: Ahmed A Al–Ali --- Omar A Sheet --- Amer A Taqa
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2013 Volume: 13 Issue: 22 Pages: 351-357
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: To evaluate the effect of different types of curing techniques on the degree of bond conversion of methyl methycrylate to poly methyl methacrylate for different types of acrylic resin materials. Materials and methods: Three different types of acrylic resin materials are used; heat, cold and light cured resin, with four different curing techniques (auto, heat, microwave and light curing).The degree of bond conversion of these materials(taking the mean of three samples) were determined by fourier transform infrared device (FTIR). Independent t-test and ANOVA followed by Duncan Multiple Range Test were used to determine the significant difference at p<0.05 level. Results: There was a significant difference (p<0.0001) in the degree of bond conversion yielded from the three tested materials. Degree of bond conversion higher in light and heat cure acrylic than that of cold cure acrylic resin. Conclusions: Degree of bond conversion increased when curing done under high temperature as in microwave or heat curing method. However, light cure resin showed the highest degree of bond conversion.

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