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Article
Shear Bond Strength of Chemical and Light Cured Glass Ionomer Cements Bonded to Resin Composite

Authors: Sabah A. Ismail صباح عبد الوهاب اسماعيل --- Shaymaa SH. Hassan شيماء شاكر حسن
Journal: Tikrit Journal for Dental Sciences مجلة تكريت لعلوم طب الاسنان ISSN: 20731213 Year: 2012 Volume: 1 Issue: 2 Pages: 27-32
Publisher: Tikrit University جامعة تكريت

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Abstract

The purpose of this study was to compare the shear bond strength of chemically cured (Conventional) glass ionomer cement and light cured (Resin modified) glass ionomer cement to resin composite and to evaluate the effect of acid etching of the glass ionomer cements on the shear bond strength.Forty acrylic molds were prepared, a hole (6×2) mm was prepared in each mold to retain the glass ionomer cements (GICs). The samples were divided into two main groups. The first group were filled with Conventional GIC and the second group were filled with Resin modified glass ionomer cement (RMGIC), then each group were subdivided into two subgroups, the first subgroup were acid etched and the second subgroup were left without etching. The bonding agent applied to the demarcated bond area on the GIC surface, the composite resin cylinders were built up over the GIC base. The samples were stored for one week in deionized water then thermocycled. The samples then tested for shear bond strength (SBS) using universal testing machine.The result shows that Independent samples T-test used for statistical analysis. The result showed that RMGIC significantly had higher SBS than conventional GIC. No statistical difference was shown in SBS between subgroup etched and without etching for RMGIC, but the conventional GIC showed significantly higher SBS in subgroup without etching than with etching.This study Conclude that the SBS of RMGIC to resin composite was significantly higher than that of conventional GIC. Acid etching the GIC surface did not improve the SBS of GICs to resin composite.


Article
Flowable Composite for Orthodontic Bracket Bonding (in vitro study)

Author: Bahn G. Agha بان غانم اغا
Journal: Tikrit Journal for Dental Sciences مجلة تكريت لعلوم طب الاسنان ISSN: 20731213 Year: 2012 Volume: 1 Issue: 2 Pages: 44-50
Publisher: Tikrit University جامعة تكريت

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Abstract

Flowable resin composites have been recommended for many clinical uses and have been formulated in a variety of compositions and viscosities to meet various uses. The aim of this study was to determine if flowable composite with or without resins could be used as orthodontic bracket bonding. Sixty noncarious human premolars were divided into three equal groups. Metal brackets were bonded to etched enamel using a composite resin control (Resilience® orthodontic adhesive) and flowable composite with and without sealant resin (Resilience® flowable composite). After 72 hours of incubation in deionized water at 37 C°, debonding was performed with a shearing force. The shear bond strength (SBS) and the mode of bond failure were examined. High significant difference was observed in the SBS between control and flowable groups. Clinically acceptable SBS was found for the two flowable adhesives with bond failures occurred mostly in the bracket–adhesive interface. No significant differences between flowable groups. In conclusion, the use of flowable composite with and without sealant resin is advocated for orthodontic bracket bonding.


Article
Effect of glass fiber reinforcement surface treatment on the soft liner retention and longevity

Authors: Inas Abdul-Sattar ايناس عبد الستار --- Nabeel Abdul-Fattah نبيل عبد الفتاح هاطور
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2012 Volume: 24 Issue: 3 Pages: 8-12
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Denture liners have been used in dentistry for many years. Soft denture liner is one of the denture linerswhich used to enhance the fit of poor fitting dentures and prevent trauma to sensitive mucosa. One of thedisadvantages of the soft denture liner is the frequent debonding from the denture during clinical use thus reducingthe longevity of such prosthesis. Glass fibers integrated at or on the fitting surface of the denture used to improve thebonding of the silicone soft liner to the acrylic surface.Materials and methods: the shear bond strength calculated to evaluate the effect of the glass fiber surfacetreatment on the bonding between the acrylic surface and the silicon soft liner. 120 samples were prepared anddivided into 3 major groups: Group I for the conventional heat cure acrylic, Group II for the pour acrylic and Group IIIfor the light cure acrylic. Each one of these major groups divided into 2 subgroups, the first one for the Mollosil siliconsoft liner and the second one is for the Molloplast-B silicon soft liner. Each one of these sub groups consist of 2 types ofthe acrylic surface: smooth (control) and glass fiber net surface treatment.Results: this study revealed that some types of the surface treatment exhibited a highly significant improvement in thebonding between the acrylic surface and the soft liner.Conclusion: glass fiber surface treatment could improve the bonding between the acrylic surface and the soft liner


Article
Effect of different metal surface treatments and thermocycling on shear bond strength of heat cure and light cure at Co/Cr and Ni/Cr interface

Authors: Ali M. Khursheed علي خورشيد --- Salah A. Mohammed صلاح محمد
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2012 Volume: 24 Issue: 2 Pages: 1-5
Publisher: Baghdad University جامعة بغداد

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Abstract

Background Optimum bond strength at the metal – resin interface of prosthesis is essential for the success of thatprosthesis. The junction between metal alloy and acrylic resin is an area of clinical concern .Failure of a R.P.D. maybe linked to this interface. The main objective of this study were to determine the effect of different metal surfacetreatment and thermocycling on the shear bond strength of Co/Cr alloy and Ni/Cr alloy to heat cure acrylic resinand light cure acrylic resin.Materials and methods: 120 metal samples were prepared, 60 Co/Cr samples and 60 Ni/Cr of square flat plate (30mm x 30mm x 2 mm) that incorporated a central area (8mmx 12mm) of a large retentive mesh to simulate dentureframework. The samples were cleaned, finished and electropolished. Sixty samples of each type of metals weredivided into two groups according to the type of acrylic resin received each one 30 samples (A and group C) forheat cure, B and group D for light cure) which were furtherly subdivided according to the type of surface treatmentinto 3 subgroups each one 10 samples(A1 ,B1 ,C1and D1 )for no surface treatment, no thermocycling as a controlgroup (A2, B2 ,C2 and D2 )for Metal Prime II application with thermocycling (A3, B3 ,C3 and D3) for combination ofAir Abrasion and Metal Primer II application with thermocycling. The acrylic block were then prepared as arectangular block(12mm length ,8 mm width ,6 mm high )that was placed on a central area of metal plates, theacrylic was fabricated in the same conventional way of denture construction. All the sample were mounted onspecially test fixture that would hold them rigid at a 90-degree angle from the horizontal plane of the crosshead ofthe Instron machine .A tangent shear force was created by applying vertical load to the specimen .All of thespecimen were tested with Instron machine using stainless steel chisel shaped road at a constant crosshead speed of5 mm min until failure of the bond occurred The specimen were stressed to failure .The force of bond failure wasrecorded in Newton, which was divide by the surface of the bonded area (96 mm2 )to obtain the shear bondstrength calculated in Mpa.Result: The results showed that the subgroup that received no surface treatment and without thermocycling for bothtwo type of resins heat cure and light cure (A1, B1, C1and D1) had the highest shear bond values, followed bysubgroups that received Air Abrasion + Metal Primer II surface treatments and thermocycling (A3, B3, C3,D3).Subgroups that received Metal Primer II alone (A2, B2, C2 and D2) showed the least shear bond value than theother subgroups.Conclusion: All metal samples of Co/Cr and Ni/Cr with heat cure acrylic resin showed higher SBS mean values thanthat light cure resin whether with surface treatment and thermocycling or without thermocycling concluded higherbinding of heat cure acrylic resin with the metal surface

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