ABSTRACT
Objective: Repair of an indirect restoration is usually preferred over its replacement. This study aimed to evaluate the effect of silane in different surface preparation techniques on the bond strength of direct to indirect composite resin
Methods: For this in vitro experimental study, 48 indirect composite cubes were fabricated, divided into 4 groups of 12 and subjected to the following preparation techniques: Group 1. Sandblasting with 50micro aluminum oxide particles [SB], Group 2. Sandblasting+ silanization [SB+Sil], Group 3. Etching with 9.5% hydrofluoric [HF] acid, Group 4. Etching with 9.5% HF acid+ silanization [HF+Sil]. Before the restoration process, specimens were subjected to 500 thermal cycles and received surface preparations. Single Bond adhesive was applied to the surface in all groups. Specimens were restored with direct composite resin and stored in an incubator at 37[degree sign]C for 24h. Fracture was induced in the specimens by an Instron machine and the shear bond strength was measured. Data were converted to mega Pascal and analyzed using two-way ANOVA and Tukey's post hoc
Results: The highest shear bond strength was 13.85 [2.75] MPa and belonged to group 1; while the lowest bond strength was 8.43 [1.35] MPa and observed in group 2
Conclusion: Based on the obtained results, composite surface preparation by sandblasting yields more favorable results than HF acid etching and application of silane can also increase the bond strength
ABSTRACT
The ability of composite restorations to prevent microleakage needs desirable bonding material for proper sealing. The purpose of this study was to evaluate class V composite restorations microleakage in premolars with/without electric current while applying variant dentin bonding in vitro. 120 non-carious human premolars were used for this study and standardized class v cavities were prepared. The tooth roots were cut by discs at a distance of 5 mm from CEJ and pulp tissue was removed. The teeth were divided into six groups of 20. In the first group, electric current was applied, Single bond [3M ESPE, St Paul, MN, USA] with a broom motion attached to the cathode and a sponge containing bonding was used as anode. The used current was 15microA and the Single bond in the second group was used without electricity. Then two bondings PQ1 [Ultradent, Germany] and Optibond solo plus [Kerr, USA] were used with and without electricity. After adhesive application and curing the bonding agents, cavities were restored by a composite [Valux Plus]. The root ends were sealed by wax and all teeth surfaces, except 1 mm around the restorations were covered with a nail varnish. The specimens were thermocycled for 1000 cycles and placed in fushin for 24 hours and were then sectioned vertically and examined under a stereomicroscope. Data were scored on a 0-4 scale based on microleakage at the gingival margins and analyzed using Kruskal-Wallis and Mann-whitney test. Based on the results, the extent of microleakage in the groups of electric current was significantly less than the groups without using the electric current [P=0.05]. The lowest degree of microleakage was found in PQ1 group, and the greatest difference between the groups with and without electricity was also found in PQ1 group. Single bond and Optibond Solo Plus with electric current showed a lower degree of microleakge. The result showed that use of electric current during the application of dental adhesives could reduce the extent of microleakage
ABSTRACT
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. 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. The mean total color difference [Delta 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]. Rebonding with adhesive materials used in this study did not increase the color stability of composite restorations
Subject(s)
Color , Adhesives , Dental Bonding , SpectrophotometryABSTRACT
Objective: Shear bond strength is an important property inherent to the durability of tooth-colored restorative materials namely composite resins. It has been years that halogen light sources have been used for polymerization of composite resins. In recent years Light Emitting Diodes [LED] have been introduced for this purpose. With respect to their longer bulb life, needless of a filter and no heat production, the demand for their use has increased. This study aimed to compare three different LED curing-lights with conventional Quartz Tungsten Halogen [QTH] lights to assess their effects on shear bond strength of composite to dentin
Methods: In this laboratory study, 60sound caries-free premolar teeth, after disinfection with sodium hypochlorite and cleaning with a scaler, were divided into four groups of 15. After the specimens had their dentin surface exposed with a metal disc, the composite restoration was done
The restorations in each group were done using Single Bond bonding agent and cured with the QTH light curing units and three different LED curing devices. Next, the strength of each bond was measured with an Instron Machine. The results were analyzed with one-way ANOVA and Tukey's test
Results: Analysis of the data with one-way ANOVA revealed statistically significant differences between the groups [p<0.05]
The greatest bond strength related to the LED light in ramp mode with 114.68 Newtons [N] or 22.94megapascals [MPa].The lowest related to the pulsed-LED with a mean of 70.35N [14.70 MPa]. In pair wise comparison of the 4 groups with Tukey's test, all groups with the exception of QTH with a mean of 99 N [19.80 MPa] and the conventional LED with a mean of 86.78N [17.35 MPa], had a significant difference [p<0.05]
Conclusion: Our study showed that the use of LED light in ramp mode had better results compared to the QTH light source [control group] [p=0.38]. Conventional LED light was comparable to the QTH light as well [p=0.169]?
ABSTRACT
Although composite resin restorations have many advantages, they can lead to several clinical problems. The primary reason for these problems is microleakage. The aim of this study was to compare the rebonding effect on microleakage of class V composite restorations using two low viscosity resins. In this in vitro study, 60 class V composite restorations were performed in buccal and lingual surfaces of human extracted premolars with the occlusal margin in enamel and the gingival margin in dentin/cementum. The teeth were randomly divided into 3 groups: [I] restorations with no rebonding, [II] restoration margins rebonded with an enamel adhesive [Margin Bond], [III] restoration margins rebonded with a specific unfilled resin. The specimens were then thermocycled and immersed in 0.5% fuchsin dye solution. The samples were sectioned longitudinally and observed under a stereomicroscope for assessment of microleakage. The data were analyzed by Kruskal-Wallis, Wilcoxon and Mann-Whitney tests. P<0.05 was considered as the level of significance. Statistical analysis showed a significant difference in the microleakage of gingival margins [P<0.001], but not in enamel margins [P=0.148]. Microleakage at the gingival margins of group [III] was significantly less than that of group [II]. Group [I] showed the highest amount of microleakage. Rebonding by a low viscosity resin reduces microleakage at the gingival margins of class V composite restorations, but has no significant effect on the occlusal margins.
ABSTRACT
The use of electric current during application of etch-and-rinse adhesive systems has been recently introduced to decrease microleakage. This study investigated the effects of an electric field produced by an experimental device for the application of a two-step etch-and-rinse adhesive on moist dentin surface. Sixty freshly extracted human premolars were used for this study. In order to simulate real conditions, the pulpal pressure was set to 35 cm H[2]O for all the specimens. The teeth were divided into two groups: in group I, etch-and-rinse system [Single Bond] was applied with electric current while group II, etch-and-rinse system [Single Bond] was applied without electric current. Specimens were prepared for dye penetration test. The data were analyzed using Mann-Whitney U test. The results showed that group I had less microleakage scores compared to group II [P = 0.047]. Based on the result of this study, it could be concluded that using electric current for applying adhesive systems had a significant effect on reducing microleakage