ABSTRACT
Statement of the Problem: The clinical success of ceramic depends on the quality of the bond between the zirconia and resin cement
Purpose: In the present study, the effects of universal and conventional MDP-containing primers were evaluated on the shear bond strength of zirconia ceramic and nanofilled composite resin
Materials and Method: Thirty blocks of zirconia ceramic [6mm×2mm] were prepared. Then the inner surfaces were air-abraded and divided into three groups [n= 10] as follows: untreated with primer [control group, I]; All- Bond Universal [group II] and Z-Prime Plus [group III]. The specimens in each group were bonded with Variolink N cement to cylinders of composite resin Z350XT. After 24 hour water storage, the shear bond strength test was performed with a universal testing machine at a crosshead speed of 1mm/ min and bond strength values [MPa] were calculated and analyzed with one-way ANOVA and post hoc Tukey tests [p< 0.05]. The failure mode of each specimen was evaluated under a stereomicroscope and representative specimens were analyzed by scanning electron microscopy [SEM]
Results: The mean shear bond strength values [MPa] were 7.58 +/- 1.62, 17.51 +/- 1.34 and 22.45 +/- 3.60 in groups I, II and III, respectively. These results indicated that the shear bond strength were significantly higher in groups II and III compared to the control group [p< 0.001]. Chemical pre-treatment of zirconia with Z- Prime Plus revealed significantly higher bond strength than the All-Bond Universal adhesive [p< 0.002]. All the failure modes were adhesive in the control group [I] and when using primer treatment, mixed failures occurred in 40% and 50% of specimens in groups II and III, respectively
Conclusion: Treatment with both primers resulted in higher bond strength values compared to the control group. The use of Z-Prime Plus treatment in combination with air-abrasion procedure resulted in the highest bond strength
ABSTRACT
Statement of the Problem: The bond strength of composites with different adhesive systems with dentin is an important factor in long term durability of composite restorations. The effect of titanium tetrafluoride [TiF4] as anti caries agent and sodium hypo-chlorite [NaOCl] as disinfectant on the shear bond of nanofilled and silorane based composite resins have not been investigated in previous studies
Purpose: This study was conducted to determine bond strength between dentin and two composite systems, by means of shear bond test using TiF4 and NaOCl
Materials and Method: Middle dentin of 60 intact extracted maxillary premolar teeth were exposed by sectioning the crowns at a depth of 2mm from central groove and parallel to the occlusal surface. Standardized smear layer was created using a 600-grit silicon carbide paper and then samples were embedded in acrylic resin blocks. Then the samples were randomly divided into 6 groups summarized as Group I: Z350, Group II: Z350+ NaOCl, Group III: Z350+ TiF4, Group IV: P90, Group V: P90+ NaOCl, Group VI: P90+ TiF4 according to manufacturer's instruction. Then samples were subjected to shear bond strength [SBS] test using universal testing machine and data were analyzed using ANOVA and Tukey tests [p< 0.05]
Results: Application of 5% NaOCl caused a significant decrease in SBS of nanofilled composite resin [p= 0.004], and also silorane based composite resin [p= 0.006]. Appli-cation of 4% TiF4 caused a significant increase in SBS of silorane based composite resin [p= 0.001]. The effect of TiF4 on nanofilled composite was not statistically significant
Conclusion: Using TiF4 has a positive effect on increasing the shear bond while NaOCl has negative effect on bond strength
ABSTRACT
Statement of the Problem: The adhesion of resin-modified glass-ionomer [RMGI] to composite resin has a very important role in the durability of sandwich restorations. Hydroxyapatite is an excellent candidate as a filler material for improving the mechanical properties of glass ionomer cement
Purpose: The aim of this study was to assess the effect of adding micro- and nano-hydroxyapatite [HA] powder to RMGI on the shear bond strength [SBS] of nanofilled and silorane-based composite resins bonded to RMGI containing micro- and nano-HA
Materials and Method: Sixty cylindrical acrylic blocks containing a hole of 5.5×2.5 mm [diameter × height] were prepared and randomly divided into 6 groups as Group 1 with RMGI [Fuji II LC] plus Adper Single Bond/Z350 composite resin [5.5×3.5 mm diameter × height]; Group 2 with RMGI containing 25 wt% of micro-HA plus Adper Single Bond/Z350 composite resin; Group3 with RMGI containing 25 wt% of nano-HA plus Adper Single Bond/Z350 composite resin; Group 4 with RMGI plus P90 System Adhesive/P90 Filtek composite resin [5.5×3.5 mm diameter × height]; Group 5 with RMGI containing 25 wt% of micro-HA plus P90 System Adhesive/P90Filtek composite resin; and Group 6 with RMGI containing 25 wt% of nano-HA plus P90 System Adhesive/P90 Filtek composite resin. The specimens were stored in water [37 degree C, 1 week] and subjected to 1000 thermal cycles [5 degree C/55 degree C]. SBS test was performed by using a universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed by two-way ANOVA and Tukey test [p< 0.05]
Results: There were significant differences between groups 1 and 4 [RMGI groups, p= 0.025], and groups 3 and 6 [RMGI+ nano-HA groups, p= 0.012]. However, among Z350 and P90 specimens, no statistically significant difference was detected in the SBS values [p= 0.19, p= 0.083, respectively]
Conclusion: RMGI containing HA can improve the bond strength to methacrylate-based in comparison to silorane-based composite resins. Meanwhile, RMGI without HA has the best bond strength to silorane-based composite resins
ABSTRACT
Statement of the Problem: Composite bond to dentin is crucial in many clinical conditions particularly in deep cavities without enamel margins due to insufficient penetration of adhesive into demineralized dentin
Purpose: The aim of this study was to assess the shear bond strength [SBS] of a methacrylate-based and a silorane-based composite resin to surface and deep dentin after pretreatment with dimethyl sulfoxide [DMSO]
Materials and Method: Eighty extracted human premolars were randomly divided into two groups of flat occlusal dentin with different cuts as A: surface group [sections just below the dentinoenamel junction [DEJ] and B: deep group [2 mm below DEJ]. Each group was randomly assigned to 4 subgroups and their samples were restored with Adper Single bond [ASB] and Filtek Z350 or Silorane system Adhesive [SA] and Filtek P90 composite resins, using a 3×3mm cylindrical plastic mold. following these steps, the subgroups were assigned as SubgroupA1: surface dentin+ Silorane System Primer [SSP]+ Silorane System Bonding [SSB]+ P90; Subgroup A2: surface dentin+ 37% etchant [E37%] + Adper Single Bond [ASB]+ Z350; Subgroup A3: surface dentin+ DMSO+ SSP+ SSB+ P90; Subgroup A4: surface dentin+ E37%+ DMSO+ ASB+ Z350; Subgroup B1: deep dentin+ SSP+ SSB+ P90; Subgroup B2: deep dentin+ E37%+ ASB+ Z350; Subgroup B3: deep dentin+ DMSO+ SSP+ SSB+ P90; Subgroup B4:dentin +E37% +DMSO +ASB +Z350. The specimens were thermocycled at 5 +/- 2/55 +/- 2[degree]C for 1000 cycles and then tested for SBS
Results: Using DMSO as dentin conditioner increased SBS of ASB to deep dentin [p<0.001] and SBS of SA to surface dentin [p= 0.003] but had no effect on SBS of SA to deep dentin [p= 1.00]
Conclusion: The ability of DMSO to increase SBS of ASB to deep dentin provides a basis for improving bonding of this composite resin in deep cavities
ABSTRACT
Statement of the Problem: Hemostatic agents may influence the bond strength of different bonding agents. Also, chlorhexidine has shown positive effects on bond strength values and their combination effect has not been reported yet
Purpose: The aim of this study was to evaluate the effect of contamination with a hemostatic agent on shear bond strength [SBS] of total- and self-etching adhesive systems and the effect of chlorhexidine application after removal of the hemostatic agent
Materials and Method: In this experimental study, the occlusal enamel of each sixty caries-free mandibular molars was removed and their midcoronal dentin was exposed. The specimens were then mounted in auto-polymerizing resin 1mm apical to CEJ. Then, the specimens were divided into 6 groups [n=10] based on contamination with a hemostatic agent [H], application of chlorhexidine [CHX] and the adhesive system used; and then were classified as Group 1: Adper Single Bond [ASB]; Group 2: H+ASB; Group 3: H+0.2% CHX+ASB; Group 4: Clearfil SE Bond [CSB]; Group 5: H+CSB; Group 6: H+0.2% CHX+CSB. Then, composite resin rods [4×2 mm] were built up on the dentin surfaces and after thermocycling, the SBS [MPa] was evaluated. Statistical analysis was performed using two-way ANOVA and post hoc Tukey tests [p< 0.05]
Results: There were statistically significant differences between bond strength values of group 1 [ASB] and group 2 [H+ASB] [p< 0.001] and group 1 [ASB] and group 3 [H+CHX+ASB] [p< 0.001]. Similarly, significant differences were seen between group 4 [CSB] and group 5 [H+CSB] [p< 0.001] and between group 4 [CSB] and group 6 [H+CHX+CSB] [p< 0.001]
Conclusion: Contamination with hemostatic agent reduced the SBS of both totaland self-etching adhesive systems. In addition, application of chlorhexidine after the removal of hemostatic agent had a negative effect on SBS of total- and self-etching adhesive systems
ABSTRACT
Statement of the Problem: Composite resin may be used in different temperatures; it is crucial to determine the effect of temperature on mechanical properties of nanohybrid and silorane-based composite
Purpose: This in vitro study compared the flexural strength and modulus of elasticity of nanohybrid and silorane-based resin composite, at 4[degree]C, room temperature [25[degree]C], and 45[degree]C
Materials and Method: In this experimental study, 60 specimens were prepared in a metal split mold [2×2×25mm]. Two different resin composites, Filtek Z250 XT [3M/ ESPE] and Filtek P90 [3M/ESPE], were evaluated. The material were inserted into split molds at room temperature, 4[degree]C or 45[degree]C and cured with LED [1200 mW/cm2] for 20 seconds in four points [n=10]. Then, a three-point bending test was performed using a universal testing machine at a crosshead speed of 0.5 mm/min for measuring the flexural strength and flexural modulus of samples. The data were analyzed by the two-way ANOVA and Tukey test [p< 0.05]
Results: The mean highest flexural strength was observed at 45[degree]C, showing statistically significant difference with flexural strength at 4[degree]C [p= 0.0001] and 25[degree]C [p= 0.003] regardless of the type of resin composite. The flexural modulus at 45[degree]C was highest, showing the statistically significant difference with flexural modulus at 4[degree]C [p= 0.0001] and 25[degree]C [p= 0.002]. The flexural modulus was statistically different between nanohybrid and silorane-based resin composite [p= 0.01] in 25[degree]C and 45[degree]C, but there were no statistically significant differences between flexural strength of Filtek Z250 XT and Filtek P90 regardless of the temperatures [p= 0.062]. Conclusion: Preheating the resin composite at 45[degree]C improves flexural strength and modulus of nanohybrid and silorane-based resin composite. However, flexural strength and modulus of the tested materials were not affected by precooling. The flexural modulus of nanohybrid resin composite was significantly higher than siloranebased resin composite in 25[degree]C and 45[degree]C temperatures
ABSTRACT
Statement of the Problem: Monomer viscosity and solvent evaporation can be affected by the adhesive system temperature. Higher temperature can elevate the vapor pressure in solution and penetration of adhesive in smear layer. Bonding mechanism may be influenced by the adhesive temperature
Purpose: This study aimed to evaluate the effect of pre-heating on shear bond strength of etch-and-rinse and self-etching adhesives to ground bovine dentin surfaces, at temperatures of 4[degree sign], 25[degree sign] and 40[degree sign]
Materials and Method: In this experimental study, 60 maxillary bovine incisors were randomly divided into 6 groups [n=10]. The central part of labial dentin surfaces was exposed with a diamond bur and standardized smear layer was created by using silicon carbide paper [600 grit] under water-coolant while the specimens were mounted in acrylic resin. Two adhesive systems, an etch-and-rinse [Adper single bond] and a self-etch [Clearfil SE Bond] were stored at temperatures of 4[degree sign], 25[degree sign] and 40[degree sign] for 30 minutes and were then applied on the prepared labial surface according to the manufacturer's instructions. The composite resin [Z350] was packed in Teflon mold [5 mm in diameter] on this surface and was cured. The shear bond strength [MPa] was evaluated by universal testing machine [Zwick/Roell Z020, Germany] at cross head speed of 1mm/min. The results were statistically analyzed by using ANOVA and Tukey tests [p< 0.05]
Results: No significant difference was found between the shear bond strength of Clearfil SE Bond adhesive in different temperature and single Bond adhesive system at 25[degree sign] and 40[degree sign]. However, there were significant differences between 4[degree sign] of Adper single bond in comparison with 25[degree sign] and 40[degree sign] [p= 0.0001]
Conclusion: Pre-heating did not affect the shear bond strength of SE Bond, but could promote the shear bond strength of Adper Single Bond
ABSTRACT
Statement of the Problem: Immediate application of bonding agent to homebleached enamel leads to significant reduction in the shear bond strength of composite resin due to the residual oxygen. Different antioxidant agents may overcome this problem
Purpose: This study aimed to assess the effect of different antioxidants on the shear bond strength of composite resin to home-bleached
Materials and Method: Sixty extracted intact human incisors were embedded in cylindrical acrylic resin blocks [2.5×1.5 cm], with the coronal portion left out of the block. After bleaching the labial enamel surface with 15% carbamide peroxide, they were randomly divided into 6 groups [n=10]. Before performing composite resin restoration by using a cylindrical Teflon mold [5×2 mm], each group was treated with one of the following antioxidants: 10% sodium ascorbate solution, 10% pomegranate peel solution, 10% grape seed extract, 5% green tea extract, and aloe vera leaf gel. One group was left untreated as the control. The shear bond strength of samples was tested under a universal testing machine [ZwickRoell Z020]. The shear bond strength data were analyzed by one-way ANOVA and post hoc Tukey tests [p< 0.05]
Results: No significant difference existed between the control and experimental groups. Moreover, there was no statistically significant difference between the effects of different antioxidants on the shear bond strength of bleached enamel
Conclusion: Different antioxidants used in this study had the same effect on the shear bond strength of home-bleached enamel, and none of them caused a statistically significant increase in its value