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Showing 8 results for Resin Composite
Fracture toughness of Ideal Macoo resin composite compared with standard ones
T. Hooshmand , A. Keshvad ,
Volume 18, Issue 2 (5-2005)
Abstract

Statement of Problem: Evaluation of fracture properties is a basic principle for true assessment of brittle materials’ properties. Resin–based composite materials are being used extensively in today’s dentistry. Fracture toughness is considered an important parameter for providing useful information about material’s nature, properties and its resistance to fracture.

Purpose: The purpose of this study was to evaluate the fracture toughness of a resin composite produced in the country and to compare it with that of other standard materials.

Materials and Methods: Four types of resin composite materials were used as follow to prepare 60 specimens (n=15 for each group), A) Tetric Ceram (Ivoclar–Vivadent) B) Brilliant (Coltene-Whaledent) C) SpectrumTPH (Dentsply) and D) Ideal Macoo (Ideal Macoo, Iran). Specimens of 5 mm diameter ( 0.1 mm) and 2 mm depth (±0.1 mm) were prepared in a central notch (90 notch angle) PTFE mold. Then specimens were light cured with two applications of overlapping exposures for a total of 120 s and were stored in distilled water at 37ºC for 48 hours, A cylindrical roller of 3 mm diameter was seated inside the V sections and fracture was accomplished in a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed by one–way ANOVA and post-hoc paired Tukey HSD test with P<0.05 as the limit of significance.

Results: The mean KIC and torque to fracture (T) values for each material tested were A) 3.080.42, 16.992.34, B) 2.880.63, 16.041.98 C) 3.400.53, 18.752.93 and D) 2.870.46, 15.782.57 MN/m3/2SD and N/mmSD, respectively. Group C showed significantly the highest mean KIC and T values among groups tested which was significantly higher than that of group B and D (P<0.05). The mean KIC and T values for groups A, B, and D were not significantly different (P>0.05).

Conclusion: From evaluating the fracture properties of materials tested in this study it was concluded that the mean fracture toughness value for SpectrumTPH (Dentsply) was significantly higher than that of Ideal Macoo resin composite material (Ideal Macoo, Iran). The F.T value for Ideal Macoo was considered acceptable as it was not significantly different from that of other resin composite materials tested.


Influence of ZOE and formocressol on the shear bond strength of composite to dentin of primary teeth
Aa. Soleymani, Z. Bahrololoomi, S. Parkam,
Volume 24, Issue 1 (3-2011)
Abstract

Background and Aims: Dentin contamination with different materials used in pediatrics is effective on the bond strength of adhesives to primary teeth. Therefore, the purpose of this in vitro study was to evaluate the effect of zinc oxide-eugenol and formocresol on the shear bond strength (SBS) of resin composite to the dentin in primary teeth.

Materials and Methods: A total of 72 extracted second morals were selected and mounted in acrylic resin. Buccal and lingual dentin surface were prepared and randomly allocated into 4 groups of 18 specimens each. Groups were subjected to different treatments as follows: group A, the surfaces were received no pretreatment and served as control group B, the surfaces were covered with a paste of ZOE (Zoliran) group C, the surfaces were covered with a paste of ZOE (Kemdent) group D, specimens were placed on gauze soaked in formocresol. The specimens were covered with tinfoil and stored in distilled water at 37oC for 7 days. The temporary restorations were removed after one week. The dentin surfaces were treated with single bond adhesive resin 3M (ESPE/USA) according to manufacturer’s instructions and light cured for 20 seconds. Composite P60 columns (4 mm internal diameter and 3 mm height) were applied on the prepared surfaces and light cured for 40 seconds. Shear bond testing were carried out after 24 hours with a cross head speed of 0.5 mm/min. Statistical analysis was conducted using one- way ANOVA and Tukey Post-hoc test.

Results: The mean shear bond strengths were 17.52±3 MPa for group A, 15.41±3.3 MPa for group B, 15.63±3.2 MPa for group C, and 18.57±3.8 MPa for group D. There was no significant difference between the shear bond strength of group A compared with those of groups B, C, and D (P>0.05).

Conclusion: The bond strength of composite to dentin in primary teeth was not influenced by the zinc-oxide eugenol (Zoliran & Kemdent) or formocreosol.


Degree of conversion of micro-hybrid, nano-hybrid and Ormocer composites using LED and QTH light-curing units
Tahereh Sadat Jafarzadeh Kashi, Mohammad Erfan, Akbar Fazel Najafabadi, Seied Mostafa Fatemi, Marjan Behroozibakhsh, Haleh Hali, Hosein Bagheri Gorgani,
Volume 25, Issue 2 (4-2012)
Abstract

Background and Aims: The aim of this study was to measure the degree of conversion (DC) of three types of composite resins (micro-hybrid, nano-hybrid and Ormocer) with different light curing units (LED LCU and QTH LCU) in two depths.

Materials and Methods: Three commercially available dental resin composites were used in this study: (Tetric Ceram, Ivoclar Vivadent, Liechtenstein-A2 shade), (Tetric Evoceram, Ivoclar Vivadent, Liechtenstein-A2 shade), (Ceram X, Dentsply, Germany-M2 shade). Specimens were divided into two groups, 5 specimens were photo-activated by QTH unit (Coltolux 75-Colten) and the other five specimens were cured by LED (Demi-Kerr). Then each specimen was sectioned at the top surface and at 2-mm depth. The DC was measured by FT-IR
(Bruker-tensor 27). The data were analyzed by 3-way ANOVA test.

Results: There was significant difference between tested composite resins (P<0.001). The results of top surfaces were significantly different from those observed at 2-mm depth (P<0.001). The type of curing unit affected the polymerization of Ceram X resin composite.

Conclusion: This study showed a significant difference in the degree of conversion in different thicknesses within three groups of resin composites.


Laboratorial comparison of color stability of resin composites after rebonding with two different adhesive materials
Azita Kaviani, Asadoallah Ahmadzadeh, Maryam Zarei,
Volume 26, Issue 1 (3-2013)
Abstract

Background and Aims: Discoloration of resin composites is considered to be the major factor in esthetic restoration failures. The aim of this study was to evaluate the color stability of resin composites after rebonding with two different adhesive materials.

Materials and Methods: Forty five composite disc samples were divided into three groups (n=15). The surface of specimens was finished by polishing disc and rubber. In group 1, any additional phase was not performed. In group 2, composite discs were etched by %37 orthophosphoric acid, then Margin- bond was used for rebonding. In group 3, the etching procedure was in the same manner used for group 2, but Permaseal was used after etching. After the first phase of spectrophotometric measurement, the specimens were dipped in coffee mix for 3 weeks for aging the specimens. Then the second phase of spectrophotometric evaluation was performed. Collected data was analyzed using one-way ANOVA test followed by Tukey test. P<0.05 was considered as the level of significance.

Results: The mean total color difference (∆E) observed in groups 1 to 3 were 1.4±0.34, 5.24±1.51, and 7.44±1.34, respectively. Statistical significant differences were shown between the groups (P<0.001).

Conclusion: Rebonding with adhesive materials used in this study did not increase the color stability of composite restorations.


The effect of fluoride containing materials (mouthrinse and toothpaste) on color stability of resin composites
Ladan Ranjbar Omrani, Masumeh Hasani Tabatabaei, Soma Faridi, Elham Ahmad,
Volume 30, Issue 3 (10-2017)
Abstract
Background and Aims: The aim of this study was to evaluate the effects of two fluoride containing mouth rinses on the color stability of two different resin composites.
Materials and Methods: 27 specimens (2×4×5 mm) were prepared from each of the following materials: a micro filled composite (Gradia, GC) and nanohybrid (Grandio). The specimens were polished by Soflex fine and superfine disks and then incubated in artificial saliva at 37°C for 24 h. The baseline color values (L, a, b) of each specimen were measured using an Easyshade spectrophotometer according to the CIELab color scale. The specimens were immersed in 20 mL of each mouth rinse and stored in an incubator at 37°C for 12 h. After incubation, the color values of all specimens were measured again, and the color change value (ΔE) was calculated. Data were analyzed by a 2-way analysis of variance at a significance level of 0.05.
Results: None of the mouth rinses created clinical significant color changes in the samples. There was no statistically significant difference among color susceptibility between resin composites (P=0.330). The interaction between the effect of mouth rinses and type of restorative materials was not statistically significant (P>0.05).
Conclusion: Accordance to the results of this study, the fluoride containing mouth rinses does not create color change in resin composites.

Comparison the effect of two types of light curing units with different modes on microleakage of composite filling in Cl II restorations
Esmail Yassini, Mansoureh Mirzaei, Bahar Safaei Yazdi, Zohreh Moradi,
Volume 30, Issue 3 (10-2017)
Abstract
Background and Aims: One of the main disadvantages of light cured composite resin materials is polymerization shrinkage upon curing. This leads to the microleakage of restoration and finally failure of the restoration. The purpose of this study was to investigate the effect of two types of light curing devices with different modes on the microleakage of posterior composite filling in Cl II restorations.
Materials and Methods: In this experimental study, 30 extracted sound molar human teeth were collected. All specimens were randomly divided into 3 groups of ten: Standard LED irradiation, pulse curing LED irradiation and QTH irradiation. All samples were prepared with mesial and distal boxes and composite fillings were done with three different light curing patterns for 20 s. After thermocycling, the specimens were kept in 2% methylene Blue solution for 24 h for microleakage test. After sectioning, the samples were evaluated by a stereomicroscope. For data analysis one-way ANOVA and Kolmogorov-Smirnov were used. P<0.05 was considered statistically significant.
Results: The quantitative tests showed that there were no statistical difference between study groups (P>0.05).
Conclusion: The results showed that both light curing devices were effective and no significant difference between different modes of LED light curing device on microleakage of class II composite restorations was found.

Invitro evaluation of the effect of some of the common carbonated beverages in Iran on the microhardness of two resin composites
Abdolrahim Davari, Alireza Danesh Kazemi, Mehrrnaz Fallah Tafti,
Volume 30, Issue 4 (1-2018)
Abstract
Background and Aims: A suitable restorative material must have acceptable mechanical properties. The aim of this study was to evaluate the effect of conventional acidic drinks on the micro-hardness of two dental resins.
Materials and Methods: 48 samples of each of P60 and G-aenial composites were prepared and randomly divided into six groups: Coca-Cola, Fanta, yoghurt drinks, soft beer, Sprites and control groups. The study was in 3 steps: after one day in distilled water and after one day and one week of immersion in beverages per day
(6 hours). The Vickers micro-hardness was then evaluated. Finally, data were analyzed by, t-tests, ANOVA and Tukey tests.
Resultes: Comparing the results between the two groups, a significant difference between the two composite was found. After one day in the water, the average micro-hardness for P60 was of 27.12 (kgf/mm2) and 16.51 (kgf/mm2) for G-aenial amount and these differences were found statistically significant (P=0.0001). For the
6-hour maintenance interval, the average micro-hardness between P60 and G-aenial was statistically significant (P=0.0001). For 42 hours, the average micro-hardness ranged between P60 and G-aenial that were statistically significant (P=0.0004). The stiffness of the P60 composite after 42 hours’ storage in soft beer significantly decreased compared with the control group (P=0.03). G-aenial composite hardness after 42 hours of soaking in the Coca-Cola was reduced significantly compared to yogurt drinks (P=0.02).
Conclusion: As a result, the hardness of P60 composite was higher than that of G-aenial. The hardness of both composites reduced in acidic drinks after one week.

Fracture toughness and color change of Nanohybrid resin composites in dry and wet conditions up to 60 days
Seyyede Fateme Basri, Rafat Bagheri, Maryam Sadat Tavangar,
Volume 31, Issue 1 (6-2018)
Abstract
Background and Aims: Fracture and color change are among the most common causes of clinical failure of resin composite restorations. Therefore, this study aimed to examine the fracture toughness and color changes of 3 Nano-hybrid resin composites in dry and wet conditions.
Materials and Methods: Three resin composites were studied. A total of 36 rectangular specimens were prepared for each material, randomly divided into 2 groups, and stored at 37°C dry or soaked in distilled water. In each group, the specimens were subdivided into three groups (n=6) and stored for 1, 7, and 60 days. After each time interval, the specimens were tested for the fracture toughness and loaded at a cross-head speed of 0.5mm/min using a universal testing machine. The baseline and final color measurement was recorded for each specimen using a spectrophotometer. The collected data was analyzed using ANOVA and Kruskal-Wallis tests.
Results: After 60 days, the mean value of fracture toughness was lower in the wet condition compared to that of dry condition. However, it was not significantly different except for aura Bulkfil (P=0.001). Color change was significantly different for Tetric Evoceram and aura with a greater value in the wet condition compared to that of dry (P=0.004). The greatest color stability was found for aura and the least for Tetric Evoceram.
Conclusion: In this study, most of the materials stored in a dry condition showed a greater fracture toughness and color change.

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