Effect of metal type and surface treatment on in vitro tensile strength of copings cemented to minimally retentive preparations

Evaluation of Bond Strength of Resin and Non-resin Cements to Different Alloys

BACKGROUND

 A strong metal-cement bond is one of the many factors that contribute to the clinical success of a fixed prosthesis. Even though it is crucial to create ideal resistance and retention forms during tooth preparation, dental cement must be strong enough to hold the restoration in place in the mouth. The present study set out to evaluate and compare the binding strength of resin modified glass ionomer cement, resin cement, and glass ionomer cement to four different metal alloys: titanium alloy, cobalt-chromium (Co-Cr) alloy, nickel-chromium (Ni-Cr) alloy, and noble metal alloys (silver palladium based).

METHODS

 Two hundred and forty metal alloy specimens were created; these were fashioned from (i) a noble metal alloy (silver-palladium based), (ii) a titanium alloy, (iii) a cobalt-chromium alloy, and (iv) a nickel-chromium alloy. A universal testing machine was used to perform the shear test, and statistical analysis of the result was done using a two-way analysis of variance (ANOVA) test and Bonferroni test.  Results: The Co-Cr alloy among the cement under investigation had the highest mean value of shear bond strength of 8.06 MPa, whereas a noble metal alloy had the lowest shear strength with a mean value of 5.36 MPa. The resin cement demonstrated the highest shear strength with a mean value that was higher than the other two types of cement. The shear bond strength of the examined samples was significantly affected by the interaction of the alloy and cement, according to the two-way ANOVA test (p=0.001).

CONCLUSION

 The results demonstrate that resin cement offers a stronger bond, followed by resin-modified GIC and GIC. The Co-Cr alloy had the highest shear bond strength, followed by Ni-Cr, titanium, and noble metal alloy which showed significantly lower shear strength than the other three alloys.

Comparison of Bond Strength in the Different Class of Resin Cements to Cast and CAD/CAM Co-Cr Alloys

Objectives

Despite the widespread use of resin cements in cementing dental restorations, their bond strength to CAD/CAM base metal alloys is not widely studied. This study aimed to evaluate the microshear bond strength (μSBS) between cobalt-chrome (Co-Cr) alloys fabricated using casting or CAD/CAM methods with three types of resin cements.

Materials and Methods

Fifty Co-Cr blocks were prepared with CAD/CAM or casting technique. Specimens were divided using primer or not and bonded to three types of resin cements: Panavia F2, RelyX Unicem, and Duo-Link. The differences between the mean μSBS values were analyzed using the two-way ANOVA test and Tukey analysis (α = 0.05). The mode of failure was evaluated using a stereomicroscope. In addition, the specimens were examined by scanning electron microscopy (SEM) based on two received signals: backscattered electrons (SEB) and secondary electrons (SEs). One intact alloy specimen in each group was analyzed by energy-dispersive X-ray spectroscopy (EDX).

Results

Most of the specimens in the no-primer group were prematurely debonded. Statistical analyses showed that the interaction between the alloy substrate and cement type was significant (p=0.001). The bond strength of Panavia F2 was significantly higher than Duo-Link in the CAD/CAM group (p=0.001). SEM evaluation confirmed the difference in grain structures, while EDX showed no remarkable difference in the chemical composition of the alloy substrates.

Conclusion

Alloy fabrication technique may influence the bond strength of resin cements. In the CAD/CAM group, cement containing MDP molecules exhibited higher strength than the etch-and-rinse one.

Influence of Different Surface Treatments on the Shear Bond Strength of Resin Cement to Base Metal Alloys

Introduction: This study aimed to investigate the effect of different surface treatments on the bond strength of resin cement to nickel-chrome (Ni-Cr) alloy. Methods: Forty disk-shaped specimens of Ni-Cr alloy were prepared and divided into 4 groups. In the first group, the specimens' surface was sandblasted with 50 µ Al2 O3 particles. In the second group, the specimens were prepared with the Er:YAG laser. In the third group, the specimens were prepared using the Er:YAG laser after sandblasting. In the fourth group, the specimens' surface was covered with a thin layer of MKZ metal primer after sandblasting. Then the cylinders of composite resin were bonded to the treated metal surfaces using Panavia F2.0 resin cement. All of the samples were subjected to 2000 thermal cycles. The shear bond strength was tested using a universal testing machine at the crosshead speed of 0.5 mm/min. The failure mode was also observed by a stereomicroscope. Data were analyzed using the one-way ANOVA and the Tukey HSD test at a significance level of 0.05. Results: The shear bond strength from the highest to the lowest were as follows: the Er:YAG laser group, the sandblast and MKZ primer combination group, the sandblast group, and the sandblast and Er:YAG laser combination group. The mean differences of shear bond strength between the Er:YAG laser group and the sandblast group (P=0.047) and also between the Er:YAG laser group and the sandblast and Er:YAG laser combination group (P=0.015) were statistically significant. Conclusion: Among the different surface treatments employed in this study, Er:YAG laser treatment increased the shear bond strength between the metal alloy and the resin cement (Pavnavia F2).

Airborne-particle abrasion; searching the right parameter

Background/purpose

Air-particle abrasion process used to increase surface roughness in order to increase metal-ceramic bond strength varies in each study. This study aims to optimize the air-particle abrasion protocol.

Material and methods

820 cylindrical nickel-chrome specimens divided equally into 82 groups (n:10). The specimens' s surfaces were air-particle abraded with 50, 110, 250 μm Al₂O₃ at 25, 50,75 psi for 10, 20, 30 s at a distance of 10, 20, 30 mm. To determine the surface roughness, profilometer and atomic force microscope were used. Veneering ceramic was fired onto the specimens and shear bond tests were performed with a universal testing machine. Statistical analyzed were performed using analysis of variance (Kolmogorov–Smirnov).

Results

The difference of surface roughness between all groups were statistically significant (P < .05). The highest surface roughness value was measured in 110 μm, 75 psi, 20 mm and 30 s. The higher bond strength values were obtained in 110 μm, 75 psi groups and no statistically significant difference was observed within each group.

Conclusion

While all the air-particle abrasion parameters were effective on surface roughness, only the pressure and grain size make statistically significant difference on shear bond strength.

Retention of zirconia copings over smooth and airborne-particle-abraded titanium bases with different resin cements

STATEMENT OF PROBLEM

How cement type and the surface treatment of a titanium base affect the retention of zirconia copings on titanium bases is unclear.

PURPOSE

The purpose of this in vitro study was to evaluate the dislodging forces of zirconium oxide copings cemented on implant-supported titanium bases with different luting agents and to examine the influence of airborne-particle abrasion on titanium surfaces.

MATERIAL AND METHODS

Thirty implant laboratory analogs (BioHorizons) were fixed in metal blocks, and 30 prosthetic titanium bases (BioHorizons) were tightened with 35 Ncm of torque. Zirconium oxide copings with a luting-gap size of 30 μm were produced by using the Lava (3M ESPE) technology. The specimens were bonded to the titanium bases with 3 different resin cements (G-CEM LinkAce, RelyX U200, and Ceka Site). The specimens were kept in artificial saliva at 37°C for 24 hours and then subjected to a dynamic loading of 5000 cycles with a mastication simulator (SD Mechatronic) with thermocycling between 5°C and 55°C. The tensile force was measured by using a universal testing machine (Zwick/Roell) at a crosshead speed of 5 mm/min. After the measurement, the cement was cleaned from the titanium bases and zirconia copings. The titanium bases were airborne-particle abraded with 50-μm aluminum oxide (Al₂O₃) particles, and the bonding process was repeated. The statistical analysis included descriptive analysis, 2-way ANOVA, the Tukey post hoc, and simple main effect tests (α=.05).

RESULTS

Bond strengths were significantly different according to the cement type used and before and after airborne-particle abrasion (P<.05). The cement retentiveness before airborne-particle abrasion was as follows: G-CEM LinkAce (1338 ±69 N)>RelyX U200 (665 ±36 N)>Ceka Site (469 ±22 N). The differences among all the cement types before airborne-particle abrasion were statistically significant (P<.05). After airborne-particle abrasion, retention decreased in all the groups, and the ranking of the cements' retentiveness remained the same: G-CEM LinkAce (662 ±65 N)>RelyX U200 (352 ±21 N)>Ceka Site (122 ±17 N). After airborne-particle abrasion, the differences among all the cements remained statistically significant (P<.05). The comparison within the groups before and after airborne-particle abrasion revealed that abrading the titanium bases with 50-μm Al₂O₃ decreased the bond strength for all the tested cements.

CONCLUSIONS

The cement type had a significant influence on the retention of the zirconia copings, and abrading the titanium bases with 50-μm Al₂O₃ significantly decreased the dislodging force of the coping from the titanium base.

Effect of different surface treatments and retainer designs on the retention of posterior Pd-Ag porcelain-fused-to-metal resin-bonded fixed partial dentures

The aim of this study was to investigate the adhesive property of palladium-silver alloy (Pd-Ag) and the simulated clinical performance of Pd-Ag porcelain-fused-to-metal (PFM), resin-bonded, fixed partial dentures (RBFPDs). A total of 40 Pd-Ag discs (diameter=5 mm) were prepared and divided into the following four groups (n=10): a) No sandblasting, used as a control; and b, 50 µm; c, 110 µm; and d, 250 µm aluminum oxide (Al₂O₃) particles, respectively. Another 50 discs were pre-sandblasted and divided into five groups (n=10) subjected to different treatments: e) Sandblasting, used as a control; f) silane; g) alloy primer; h) silica coating + silane and i) silica coating + alloy primer. All 90 discs were bonded to enamel with Panavia F 2.0 and then subjected to shear bond strength (SBS) testing. The fracture surfaces were examined by scanning electron microscopy. Next, 40 missing maxillary second premolar models were restored with one of the four following RBFPD designs (n=10): I) A premolar occlusal bar combined with molar double rests (MDR); II) both occlusal bars with a wing (OBB); III) a premolar occlusal bar combined with a molar dental band (MDB); and IV) two single rests adjacent to the edentulous space with a wing (SRB) used as a control. All specimens were aged with thermal cycling and mechanical loading. Subsequently, they were loaded until broken. The data were analyzed by one-way analysis of variance. Al₂O₃ (250 µm) abrasion provided the highest SBS (P<0.05). The alloy primer and silica + silane exhibited increased SBS. Furthermore, fracture analysis revealed that the failure mode varied among the different treatments. Whereas MDB exhibited the highest retention (P<0.05), that of OBB was greater than that of MDR (P<0.05), and the control exhibited the lowest retention. Abrasion with Al₂O₃ (250 µm) effectively increased the adhesive property of Pd-Ag. Additionally, treatment with the alloy primer and silica coating + silane was able to increase the adhesive property of abraded Pd-Ag. Under the present conditions, all three modified retainer types provided improved outcomes for Pd-Ag PFM RBFPDs compared with the control.

Comparison of the effect of different surface treatments on the bond strength of different cements with nickel chromium metal alloy: An in vitro study

Background

For success of any indirect metal restoration, a strong bond between cement and the intaglio surface of metal is imperative. The aim of this study is to evaluate and compare the effect of different surface treatment on the tensile and shear bond strength of different cements with nickel–chromium alloy.

Material and Methods

120 premolars were sectioned horizontally parallel to the occlusal surface to expose the dentin. Wax patterns were fabricated for individual tooth followed by casting them in nickel chromium alloy. 60 samples were tested for tensile bond strength, and the remaining 60 for shear bond strength. The samples were divided into three groups (of 20 samples each) as per the following surface treatment: oxidation only, oxidation and sandblasting, or oxidation, sandblasting followed by application of alloy primer. Each group was subdivided into 2 subgroups of 10 samples each, according to the bonding cement i.e RM-GIC and resin cement. Samples were subjected to thermocycling procedure followed by evaluation of bond strength.

Results

Two-way analyses of variance (ANOVA) was performed to compare the means of tensile and shear bond strength across type of surface treatment and cement, followed by post hoc parametric analysis. For all tests ‘p’ value of less than 0.05 was considered statistically significant.

Conclusions

The surface treatment of oxidation and sandblasting followed by application of alloy primer offered the maximum tensile and shear bond strength for both RM GIC and resin cement. Resin cement exhibited greater tensile and shear bond strength than RM-GIC for all the three surface treatment methods.

Key words:Resin cement, resin modified glass ionomer cement, oxidation, sandblasting, alloy primer, tensile bond strength, shear bond strength, universal testing machine.

The effect of ultrafast fiber laser application on the bond strength of resin cement to titanium

The purpose of this study was to investigate the effect of ultrafast fiber laser treatment on the bond strength between titanium and resin cement. A total of 60 pure titanium discs (15 mm × 2 mm) were divided into six test groups (n = 10) according to the surface treatment used: group (1) control, machining; group (2) grinding with a diamond bur; group (3) ultrafast fiber laser application; group (4) resorbable blast media (RBM) application; group (5) electro-erosion with copper; and group (6) sandblasting. After surface treatments, resin cements were applied to the treated titanium surfaces. Shear bond strength testing of the samples was performed with a universal testing machine after storing in distilled water at 37 °C for 24 h. One-way ANOVA and Tukey's HSD post hoc test were used to analyse the data (P < 0.05). The highest bond strength values were observed in the laser application group, while the lowest values were observed in the grinding group. Sandblasting and laser application resulted in significantly higher bond strengths than control treatment (P < 0.05). Ultrafast fiber laser treatment and sandblasting may improve the bond strength between resin cement and titanium.

Tensile Strength of Resin Cements Used with Base Metals in a Simulating Passive Cementation Technique for Implant-Supported Prostheses

Abstract The aim of this study was to analyze the tensile strength of two different resin cements used in passive cementation technique for implant-supported prosthesis. Ninety-six plastic cylinders were waxed in standardized forms, cast in commercially pure titanium, nickel-chromium and nickel-chromium-titanium alloys. Specimens were cemented on titanium cylinders using self-adhesive resin cement or conventional dual-cured resin cement. Specimens were divided in 12 groups (n=8) in accordance to metal, cement and ageing process. Specimens were immersed in distilled water at 37 °C for 24 h and half of them was thermocycled for 5,000 cycles. Specimens were submitted to bond strength test in a universal test machine EMIC-DL2000 at 5 mm/min speed. Statistical analysis evidenced higher tensile strength for self-adhesive resin cement than conventional dual-cured resin cement, whatever the used metal. Self-adhesive resin cement presented higher tensile strength compared to conventional dual-cured resin cement. In conclusion, metal type and ageing process did not influence the tensile strength results.

Tensile strength of Ni-Cr copings subjected to inner surface sandblasting using different cementing agents: An in vitro study

OBJECTIVES

To evaluate the effect of thermal cycling and inner surface treatment with aluminum oxide at different granulations on the tensile strength of Ni-Cr copings cemented with different cementing agents.

MATERIALS AND METHODS

Ninety-six metal copings were manufactured and divided into two groups: before and after thermal cycling (n = 48). The copings of both groups were internally treated by sandblasting with aluminum oxide particles of 100 (n = 24) and 320 (n = 24) mesh. The copings were cemented on previously manufactured metal cores using zinc phosphate (n = 8), conventional glass ionomer (CGIC) (n = 8) and resin-modified glass ionomer (RMGIC) (n = 8) cements. The tensile strength before and after thermal cycling was then determined (Newtons).

RESULTS

The tensile strength before and after thermal cycling was significantly higher in copings cemented with RMGIC compared to CGIC (p < 0.05) and was similar to that for zinc phosphate (p > 0.05). Thermal cycling and sandblasting of the inner surface of the metal copings with different granulations did not influence retention (p > 0.05).

CONCLUSIONS

Zinc phosphate cements and RMGIC showed similar retention. Additionally, the retention of the cements was not influenced by either thermal cycling or the particle size of the aluminum oxide.

In vitro tensile strength of luting cements on metallic substrate

The aim of this study was to determine the tensile strength of crowns cemented on metallic substrate with four different types of luting agents. Twenty human maxillary molars with similar diameters were selected and prepared to receive metallic core castings (Cu-Al). After cementation and preparation the cores were measured and the area of crown's portion was calculated. The teeth were divided into four groups based on the luting agent used to cement the crowns: zinc phosphate cement; glass ionomer cement; resin cement Rely X; and resin cement Panavia F. The teeth with the crowns cemented were subjected to thermocycling and later to the tensile strength test using universal testing machine with a load cell of 200 kgf and a crosshead speed of 0.5 mm/min. The load required to dislodge the crowns was recorded and converted to MPa/mm(2). Data were subjected to Kruskal-Wallis analysis with a significance level of 1%. Panavia F showed significantly higher retention in core casts (3.067 MPa/mm(2)), when compared with the other cements. Rely X showed a mean retention value of 1.877 MPa/mm(2) and the zinc phosphate cement with 1.155 MPa/mm(2). Glass ionomer cement (0.884 MPa/mm(2)) exhibited the lowest tensile strength value. Crowns cemented with Panavia F on cast metallic posts and cores presented higher tensile strength. The glass ionomer cement showed the lowest tensile strength among all the cements studied.

Shear bond strength of self-adhesive resin cements to base metal alloy

STATEMENT OF PROBLEM

Many self-adhesive cements have been introduced in the past few years, with little or no data regarding their clinical performance. This study investigated the shear bond strength of some recently introduced self-adhesive resin cements.

PURPOSE

The purpose of this study was to evaluate the shear bond strength of self-adhesive and conventional resin-based cements to a base metal alloy.

MATERIAL AND METHODS

Four groups (10-12 each) that comprised 3 self-adhesive cements (SmartCem2; RelyX Unicem; seT SDI) and a conventional resin-based cement (RelyX ARC) were tested. Cylindrical cement specimens (diameter, 3 mm; height, 3 mm) were applied to nickel-free base metal alloy (Sheradent) disks with a diameter of 12 mm, and the surface was treated with airborne-particle abrasion of 50 μm aluminum oxide. The metal disks were fixed in brass molds specifically designed for the shear bond test device. Test specimens were incubated at 37°C for 24 hours and then the shear bond was tested with a Zwick Roll testing machine at a 0.8 mm/min cross-head speed. In addition, bond failures were investigated and categorized as adhesive, cohesive, or mixed. Shear bond strengths were calculated by dividing the maximum debonding force over the cross-sectional area of each specimen. One-way ANOVA and the Tukey (honestly significant difference) post hoc test were used to test statistical significant differences among the groups (α=.05).

RESULTS

Statistical analysis showed significant differences among different resin cements (F=14.34, P<.001). The highest mean shear bond strength was observed for SmartCem2 (14.18 MPa), and the lowest was reported for seT (3.52 MPa). The observed failure mode in all the materials was adhesive in nature, which occurred at the resin-metal interface.

CONCLUSIONS

The early bond strength of self-adhesive resin cements varied significantly among the tested materials. SmartCem2 showed the highest bond strength, which was 4 times the strength observed for seT SDI.