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Article
Shear Strength of Acrylic Resin Base to Nickel Chromium Minor Connector of Removable Partial Denture

Author: Ahmed A Al-Ali
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2010 Volume: 10 Issue: 16 Pages: 366-375
Publisher: Mosul University جامعة الموصل

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Abstract

AIMS: To test the shear strength and type of failure between the latticework and mesh minor connec-tors on one side, and cold–, thermopress–, light–, and heat–cured acrylic resin base on the other. MA-TERIALS AND METHODS: Two types of minor connectors for metallic removable partial denture, latticework and mesh are casted from nickel–chromium alloy; Different types of acrylic resin(cold–, thermopress–, light–, and heat– cured) are used to test the shear strength. The type of failure was also investigated. ANOVA, Duncan multiple rang test in addition to T–test were carried out to determine the significant difference at P<0.05. RESULTS: There is significant difference between the four acryl-ic resin variables in relation to shear strength with each of the latticework and mesh type minor connec-tors. In each group of acrylic resin, except the thermopress–cured group, there is a significant differ-ence between the latticework and mesh types of minor connectors. CONCLUSIONS: The shear strength between the acrylic resin base and the nickel–chromium minor connector differ in the differ-ent types of acrylic resin and differ in the different types of minor connectors.

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Article
The Effect of Different Denture Cleansers on Different Color Properties of Permanent Soft Liner

Author: Ahmed A Al–Ali
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2011 Volume: 11 Issue: 17 Pages: 78-87
Publisher: Mosul University جامعة الموصل

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Abstract

AIMS: To determine the effect of different denture cleansers on hue, value, and chroma of permanent silicone soft liner at different immersion periods. MATERIALS AND METHODS: Soft liner speci-mens were immersed in four denture cleansers (“citric acid + soda”, salt, “apple vinegar + soda”, and alum) for periods of 1, 3, 7, and 14 days. A digital spectrophotometer was used to access color differ-ences of soft liner before and after each storage period in each solution. RESULTS: The citric acid and salt cleansers decrease the value, chroma, and hue. The apple vinegar cleanser does not affect signifi-cantly any color property. The alum cleanser decrease value and chroma, but does not affect hue of soft liner. CONCLUSIONS: The effects of different denture cleansers tested on different color properties of soft liner were different. The effect of the immersion period on the different color properties tested was different for each denture cleanser.

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Article
Evaluation of macrohardness of recast-ed Cobalt–chromium alloy

Author: Ahmed A Al–Ali
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2007 Volume: 7 Issue: 9 Pages: 111-117
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: To study the effect of recasting on the macrohardness of cobalt chromium (Co–Cr)alloy, and to evaluate the effect of finishing and polishing on it. Materials and methods: Two brand of Co–Cr alloys were used, divided into three groups, the specimens of the first group were casted from new materials, the second were casted from previously casted material without the addition of any new material (100% recast), the third were casted by combination 50% new material and 50% used material. Half of the specimens just finished and the other half were finished and polished , hardness for all of them were measured. Results: Showed that recasting, both 100% and 50%, significantly increase the macrohardness of Co–Cr alloys and no significant effect of finishing and polishing on it. Conclusion: Recasting may affect properties of Co–Cr alloy and new material should be used rather than recasted material.


Article
Evaluation of compressive strength for refractory casts made from different investment materials

Author: Ahmed A Al–Ali
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2007 Volume: 7 Issue: 10 Pages: 166-172
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: To compare the compressive strength of refractory casts made from investments for cobalt–chromium and investment for titanium and to study the effect of mixing fluid on compressive strength.Materials and Methods: Three types of investments were used, one for titanium and two for cobalt–chromium, each one is mixed with three types of mixing fluids; tap water, distilled water and special liquid,to produce refractory casts. Compressive strength test was carried out using compression testing machine.Results: Showed significant differences in compressive strength between the types of investments, withtitanium investment mixed with special liquid showed the highest value. There were significant differencesbetween subgroups of the same type by changing mixing fluid type. Conclusions: Refractory casts madefrom titanium investment showed significantly higher compressive strength than refractory casts madefrom Co–Cr investments, and there was a difference between the two special liquids used, and tap water inwhich it produced casts with higher compressive strength than distilled water in two out of the threeinvestment materials tested.


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
Clinical determination of the occlusal plane and its relation with orofacial measurements

Authors: Zeina M Ahmad --- Inas A Jawad --- Ahmed A Al–Ali
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2007 Volume: 7 Issue: 9 Pages: 101-110
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: To determine the level and angulation of the occlusal plane of the artificial dental arch by measuring the level and angulation of the occlusal plane of completely dentulous subjects and to find the relation of these measurements to some of the vertical facial and intra oral dimensions. Materials and Methods: The sample of the study consisted from 54 completely dentulous adult subjects (24 female and 30 male) with class 1 normal occlusion aged 19–24 years. Dental casts were taken for each subject, the level and angulation of the occlusal plane, vertical facial, and intra oral dimensions were measured using digital vernier caliper and protractor. The data were analyzed with statistical package for social science program. Results: Sexual differences were found in the intra and extraoral measurements. Most of the measurements dealing with the occlusal plane level and angulation were correlated with each other and with facial measurements. Conclusions: The level and angulation of the occlusal plane of the maxillary and mandibular dental arches as measured on the dental casts are higher in maxilla than in mandible and the intra and extraoral vertical facial measurements are greater in male than female.


Article
Water absorption and solubility of coated and non–coated silicone–based permanent soft liner

Authors: Zeina M Ahmad --- Ahmed A Al–Ali --- Munther N Kazanji
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2010 Volume: 10 Issue: 15 Pages: 162-168
Publisher: Mosul University جامعة الموصل

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Abstract

AIMS: To determine the period of time that a new generation of silicone–based, chairside, permanent soft liner resist absorption and solubility and determine the effect of coating material. MAERIALS AND MEHODS: Specimens of (Mucopren soft) soft liner were prepared, stored in water, and tested after 1 , 2 , 3 , and 8 months. Half of the specimens were coated with coating material supplied by manufacturer and the other half remained uncoated. Silica gel was used for drying and sensitive elec-tronic balance was used for weighing specimens. Universal formulas were used for calculating water absorption and solubility. T–test and ANOVA followed by Duncan multiple range test were used to determine the significant difference at P<0.05 level. RESULS: There was no statistically significant difference between coated and non–coated soft liner in relation to water absorption and solubility. There was no statistically significant difference in water absorption and solubility when comparing it among the periods of testing from the first month to the eighth months. Coating the soft liner decrease the percentage absorption and solubility of the silicone soft liner but this effect is statistically not sig-nificant. CONCLUSIONS: Mucopren soft– lining material has proved excellent resistance to solubili-ty for a long period (8 months). Water absorption is limited and are clinically accepted. Coating (Mu-copren soft) soft liner with coating material slightly improve the resistance to water absorption and solubility.


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.


Article
Dimensional Changes of Record Base for Complete Denture

Authors: Ahmed MA Hussain --- Ahmed A Al–Ali --- Zeina M Ahmad
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2007 Volume: 7 Issue: SpIss Pages: S5-S9
Publisher: Mosul University جامعة الموصل

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Abstract

The aims of this study are to compare the dimensional changes of record base from heat and cold cured acrylic resin, with the latter cured by two techniques, and to study the regions vulnerable to dimensional changes. Materials and Methods: The adaptation of the record base on edentulous maxillary casts were tested by sectioning the record base–stone casts sets transversely and measuring the gaps with travelling microscope. The gaps represent the crest of the ridge, midline, and the deepest points of buccal sulcus. Results: Record base made from cold cured acrylic resin showed significantly higher dimensional changes than that from heat curd acrylic resin. There were no significant difference between the bench–curd and thermopress curing for cold cured acrylic resin. No significant differences found between the ridge crest and midline , but both show significantly less dimensional changes than the buccal vestibules. Conclusions: Curing cold cured acrylic resin by thermopress machine would not improve dimensional stability. And to improve the dimensional stability, the denture base that is made from heat cured acrylic resin may be used as a record base

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