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Showing 4 results for Resin Cements
Comparison of shear bond strength of stainless steel brackets bonded with three light- cured adhesives
Zahra Minaei Basharik, Manouchehr Rahmati Kamel, Pouyan Amini Shakib, Maysam Mirzaie, Ali Bijani,
Volume 4, Issue 2 (9-2015)
Abstract

Introduction: The bonding process of the brackets to enamel has been a critical issue in orthodontic research. The purpose of this study was to evaluate the shear bond strength of 3 light-cured adhesives (transbond XT, Z250, light bond).

Materials &Methods: In this study sixty extracted human premolars were collected and randomly divided into 3 test groups. All teeth were etched by 37% phosphoric acid. In first group brackets were bonded by Transbond XT adhesive, in group two brackets were bonded by Light bond adhesive and in third group were bonded by filtek Z250 composite. All of them were cured with Ortholux xt for 40 seconds.24 hours after thermocycling, Shear Bond Strength (SBS) values of these brackets were recorded using a Universal Testing Machine. Adhesive Remnant Index (ARI) scores were determined after the failure of the brackets, using Stereo Microscope the data were analyzed using ANOVA and Chi-square tests.

Results: Mean shear bond strength of Transbond XT, light bond and Z250 were 28.9±2.25 MPa, 25.06±1.98 MPa and 26.8±2.57 MPa, respectively. No significant difference was observed in the SBS among the groups and a clinically acceptable SBS was found for the three adhesives. ARI scores were not significantly different between the various groups (P>0.05).

Conclusion: This study showed that the Z250 can be used as light bond and transbond xt to bond orthodontic brackets and ARI and SBS scores were not significantly different.


Effect of different surface treatments on microtensile bond strength of two types of composite substructures with ceramic by resin cements
Negin Tabari, Seyedkamal Seyedmajidi, Toloo Jafari, Soraya Khafri, Homayoon Alaghehmand,
Volume 10, Issue 2 (9-2021)
Abstract
Introduction: The aim of this study was to investigate the effect of different surface treatments on the microtensile bond strength (µTBS) of two types of composite substructures with Vita Mark II ceramics by resin cement.
Materials & Methods: Sixty-four substructure specimens were molded from two dual-cure composites Core.it and Build-it, equally, and cured by LED light. The specimens of each group were randomly divided into 4 subgroups (n=8) treated by one of HF acid 10%, air abrasion, Er: YAG laser, and one group without any treatment (control group), and then the specimens of each group were bonded to Vita Mark II CAD/CAM ceramic blocks using two Duo-Link and Panavia F 2.0 resin (n=4 and 20 slice in any group). Each final specimen was thermocycled between 5 °C and 55 °C for 2500 cycles and then cut by a slow speed saw to obtain 5 sticks with cross-section dimensions of about 1×1 mm². The µTBS test was done at a speed of 0.5 mm/min by Universal Testing Machine. The fracture pattern was then determined using a stereomicroscope. Statistical differences between groups were determined by one-way ANOVA using Tukey's multiple comparison tests.
Results: Among all 16 groups, the highest µTBS was observed in the group with Core.it substructure composite and Duo-link resin cement without any surface treatment and after that in the second step in build-it substructure composite group and Panavia resin cement without surface treatment. The most common fracture pattern in all groups was cohesive in resin cement (P value<0.05).
Conclusion: According to this study, composite substructure surface treatment by hydrofloridric acid, laser and air abrasion reduced µTBS between substructure- ceramic and so  is not recommended.

The effect of dentin pretreatment using silver nanoparticles on shear bond strength of one self-etch and one etch-and-rinse resin cements
Farzaneh Mohammadi, Fatemeh Koohpeima, Mohammad Javad Mokhtari,
Volume 11, Issue 1 (3-2022)
Abstract
Introduction: Metal nanoparticles may apply to the cavity walls as acceptable antibacterial agents. The present work was conducted to assess the effect of silver nanoparticles (NPs) on the resin cements Shear Bond Strength (SBS) using one self-etch and one etch and rinse resin cement.
Materials & Methods: Sixty intact noncarious extracted, human third molars were selected. All teeth were cut out in the middle of dentin thickness. Resin cement samples were randomly assigned to five groups: (A) Duolink cement without any further surface treatment; (B) Duolink cement with silver NPs (0.5%) dentin surface treatment after acid etching and before the One Step Plus (OSP) adhesive system; (C) Duolink cement with silver NPs (0.5%) dentin surface treatment before acid etching and OSP; (D) Panavia F2.0 cement without any further surface treatment; and (E) Panavia F2.0 cement with silver NPs (0.5%) dentin surface treatment. SBS was assessed by using universal testing machine. Then, human gingival fibroblasts (HGF) cells were treated with tested materials. The biocompatibility of resin cement was evaluated by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl-2H-tetrazolium bromide (MTT) assay.
Results: The maximum and minimum of the SBS at the presence of silver NPs were observed in group E (15.81±0.91, P-value<0.01) and group B (12.01±0.15, P-value <0.05), respectively. In comparison with the controls, the resin cements incorporated  with 0, 0.2% and 0.5% silver NPs, 20.34%, 22.00% and 22.67% for Panavia F2.0 and 36.84%, 37.34% and 38.17% for Duolink flow - decreased in total cell number, respectively (P-value<0.01).
Conclusion: These findings demonstrated that Panavia F2.0 cement with silver NPs dentin surface treatment showed satisfactory result in the SBS compared to Panavia F2.0 cement without any further surface treatment.

Effect of concentration of hydrofluoric acid and etching time on microtensile bond strength of Zirconia-reinforced lithium silicate ceramics
Morteza Rostami, Faraneh Mokhtarpour, Homayoon Alaghehmand,
Volume 11, Issue 2 (9-2022)
Abstract
Introduction: Etching the internal surface of ceramic restorations with hydrofluoric (HF) acid and silane is a well-accepted technique to enhance the bond strength. The aim of this study was to assess the effect of concentration of hydrofluoric acid and etching time on microtensile bond strength (µTBS) of zirconia-reinforced lithium silicate (ZLS) ceramics in 2021.
Materials & Methods: This in vitro study was conducted on 8 Celtra-Duo ceramic blocks size 14 measuring 12×14×18 mm. Each ceramic block was divided into three equal pieces by a cutting machine to obtain a total of 24 specimens. The specimens were randomly divided into 6 groups for etching with 5% and 10% HF acid for 30, 60, and120 seconds. Silane (Clearfil porcelain activator) and bonding agent (Clearfil SE Bond) were applied to the etched specimens. Panavia F2 resin cement was applied on the surfaces and light-cured. The mTBS of resin cement to porcelain was measured by a universal testing machine. The mode of failure was determined under a stereomicroscope at x40 magnification. Data were analyzed by one- and two-way ANOVA (P<0.05).
Results: The mean mTBS of Celtra-Duo ceramics subjected to etching for 30, 60, and 120 seconds was not significantly different in the use of 5% and 10% HF acid concentrations (P>0.05). Two-way ANOVA showed that the effects of HF acid concentration and etching time, and their interaction effect were not significant on µTBS of CAD/CAM Celtra-Duo ceramics (P>0.05). The mode of failure was dominantly adhesive in both concentrations of 5% and 10% HF acid. No mixed failure occurred in both concentrations. 
Conclusion: Considering the non-significant difference in µTBS of ceramics subjected to different concentrations of HF acid for different times, the application of HF acid with lower concentration for a shorter period is recommended to prevent possible adverse effects on ceramic strength.

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