Effect of laboratory procedures and thermocycling on the shear bond strength of resin-metal bonding systems

An in vitro evaluation of bond strength and failure behavior between 3D-printed cobalt-chromium alloy and different types of denture base resins

OBJECTIVES

This study aimed to evaluate the shear bond strength and failure behavior between cobalt-chromium (Co-Cr) alloy and different types of denture base resins (DBRs) over time.

METHODS

Seventy-two disk-shaped specimens (8 mm in diameter and 2 mm in thickness) were manufactured using a selective laser melting technology-based metal 3D printer. Three types of DBRs were used: heat-cure (HEA group), cold-cure (COL group), and 3D-printable (TDP group) DBRs (n = 12 per group). Each DBR specimen was fabricated as a 5 mm × 5 mm × 5 mm cube model. The specimens of the TDP group were manufactured using a digital light processing technology-based 3D printer. Half of the DBRs were stored in distilled water at 37 °C for 24 h, whereas the remaining half underwent thermocycling for 10,000 cycles. Shear bond strength was measured using a universal testing machine; failure modes were observed, and metal surfaces were evaluated using energy dispersive spectrometry.

RESULTS

The shear bond strength did not differ between the DBR types within the non-thermocycled groups. Contrarily, the TDP group exhibited inferior strength compared to the HEA group (P = 0.008) after thermocycling. All three types of DBRs exhibited a significant decrease in the shear bond strength and an increased tendency toward adhesive failure after thermocycling.

CONCLUSIONS

The bond strength between 3D-printable DBRs and Co-Cr alloy was comparable to that of heat-and cold-cure DBRs before thermocycling. However, it exhibited a considerable weakening in comparison to heat-cure DBRs after simulated short-term use.

CLINICAL SIGNIFICANCE

The application of 3D-printable DBR in metal framework-incorporated removable partial dentures may be feasible during the early phase of the treatment. However, its application is currently limited because the bond strength between the 3D-printable DBR and metal may weaken after short-term use. Further studies on methods to increase the bond strength between these heterogeneous materials are required.

Bond strength of CAD/CAM denture teeth to a denture base resin in a milled monolithic unit

Purpose Herein, the bond strength (BS) of denture teeth to a denture base resin in a milled monolithic unit was investigated and compared with those of 3D printed teeth to a 3D printed denture base and prefabricated teeth to a heat-cured acrylic resin before and after thermocycling.Methods Sixty specimens of a denture tooth attached to a cylindrical denture base were fabricated following ISO Standard 19736. Three fabrication techniques-3D printing, conventional compression molding, and milling using monolithic technology-were employed to mill teeth and denture base parts as a single unit. The BS was investigated before and after thermocycling. Data were statistically analyzed using the Kruskal-Wallis test with Bonferroni correction (α = 0.05).Results Before thermocycling, the mean BS of the milled group was significantly higher than that of the conventional group (P = 0.002). The 3D printed group showed no statistically significant difference from the milled (P = 0.051) and conventional (P = 0.824) groups. After thermocycling, although the mean BS values of the milled (P = 0.00) and 3D printed 
(P = 0.01) groups were significantly higher than that of the conventional group, there was no significant difference between them (P = 0.226). Only the BS of the conventional group was significantly reduced by thermocycling (P = 0.00).Conclusions The milled monolithic fabrication technique, which eliminates the need for a bonding step, offered a promising combination of high-precision digital fabrication and a significantly high BS. The BS of the conventional group significantly decreased after thermocycling.

Effect of repair methods and materials on the flexural strength of 3D-printed denture base resin

PURPOSE

The aim of this study was to evaluate the flexural strength of a 3D-printed denture base resin (Cosmos Denture), after different immediate repair techniques with surface treatments and thermocycling.

MATERIALS AND METHODS

Rectangular 3D-printed denture base resin (Cosmos Denture) specimens (N = 130) were thermocycled (5,000 cycles, 5℃ and 55℃) before and after the different repair techniques (n = 10 per group) using an autopolymerized acrylic resin (Jet, J) or a hard relining resin (Soft Confort, SC), and different surface treatments: Jet resin monomer for 180 s (MMA), blasting with aluminum oxide (JAT) or erbium: yttrium-aluminum-garnet laser (L). The control group were intact specimens. A three-point flexural strength test was performed, and data (MPa) were analyzed by ANOVA and Games-Howell post hoc test (α = 0.05). Each failure was observed and classified through stereomicroscope images and the surface treatments were viewed by scanning electron microscope (SEM).

RESULTS

Control group showed the highest mean of flexural strength, statistically different from the other groups (P < .001), followed by MMA+J group. The groups with L treatment were statistically similar to the MMA groups (P > .05). The JAT+J group was better than the SC and JAT+SC groups (P < .05), but similar to the other groups (P > .05). Adhesive failures were most observed in JAT groups, especially when repaired with SC. The SEM images showed surface changes for all treatments, except JAT alone.

CONCLUSION

Denture bases fabricated with 3D-printed resin should be preferably repaired with MMA+J. SC and JAT+SC showed the worst results. Blasting impaired the adhesion of the SC resin.

Effect of nano-zinc oxide and nano-chitosan particles on the shear bond strength of dental composites used as orthodontic adhesive

BACKGROUND

This study aimed to evaluate the effect of the combination of zinc oxide nanoparticles (NPs) and chitosan NPs on the shear bond strength (SBS) of composites used for orthodontic bonding.

METHODS

Four groups of composites (n = 10), containing 0%, 1%, 5%, and 10% w/w NP fillers, respectively, were used to bond brackets to the surfaces of 40 intact bovine incisors. After 1000 rounds of thermal cycling at 5°C-55°C, all specimens were mounted in acrylic blocks. The SBS was tested using a universal testing machine, and the adhesive remnant index scores were registered using a stereomicroscope. Data were statistically analyzed using a 1-way ANOVA and the Kruskal-Wallis test.

RESULTS

The highest value of mean SBS was found in the control group, and the lowest value was found in the group with composite containing 10% NPs. The adhesive remnant index did not differ significantly among the groups (P = 0.823).

CONCLUSIONS

Incorporation of 1% and 5% zinc oxide and chitosan NPs had no effect on the SBS of composite, and the obtained SBS values were similar to that of the control group.

Colour stability of sectional laminate veneers: A laboratory study

BACKGROUND

This study aimed to evaluate the colour stability of sectional laminate veneers (SLVs) fabricated with four and cemented with two different materials.

METHODS

Eighty SLVs were prepared with a thickness of 0.2-0.4 mm from IPS e.max CAD, Lava Ultimate, CEREC Blocs and IPS InLine and were cemented with Variolink Veneer and Variolink N to form eight groups (n:10). After cementation, specimens underwent 5000 thermocyles prior to immersion in a coffee solution.

RESULTS

Colour change before and after thermal cycling did not reveal significant differences (P > 0.05). After coffee immersion, significant colour change was observed in all groups (P > 0.05). Only IPS InLine cemented with Variolink Veneer was considered clinically acceptable (∆E < 3.3). According to observer scorings, marginal discolouration was higher in Lava Ultimate, while no discolouration was observed in IPS InLine. Dual or light-curing resin cements showed insignificant differences.

CONCLUSIONS

SLVs fabricated with different aesthetic materials underwent perceptible (∆E > 3.3) discolouration except for the IPS InLine cemented with light-curing resin cement. Cementation with either dual-curing or light-curing resin cements does not by itself affect colour stability. The highest marginal discolouration was in the Lava Ultimate group while no discolouration was detected in the IPS InLine group.

Effect of metal primers on the bond strength of resin cement to Co-Cr alloy

BACKGROUND

To evaluate the effects of adhesive systems and primer systems on microshear bond strength of chemically activated resin cemented to Co-Cr cast dental alloy.

METHODS

Seventy-two rectangular blocks of Co-Cr metal alloy were manufactured and air-abraded with 50-μm Al2O3 particles. Metal primers (alloy primer [AP] or Clearfil ceramic primer [CP]) and adhesives (Adper Scotchbond Multi-Purpose Adhesive activated by Adper Scotchbond Multi-Purpose Adhesive Catalyst [SASC], or Primer & Bond 2.1 activated by Self Cure Activator [PBCA]) were applied and subsequently divided into six groups (SASC; AP+SASC; CP+SASC; PBCA; AP+PBCA; CP+PBCA; N.=12). Then, resin cement (Enforce) was applied. Data about microshear bond strength values were statistically evaluated by analysis of variance and Tukey's test.

RESULTS

The bond strength was lower (P<0.001) in groups with adhesive system alone (SASC and PBCA) compared with groups with addition of primers alloy primer (AP+SASC and AP+PBCA) and ceramic primer (CP+SASC and CP+PBCA).

CONCLUSIONS

The application of primers improves the bond strength of the cement resin to the Co-Cr metal alloy.

Comparison of the effectiveness of Tokuyama and GC II metal primer on the bond strength of acrylic resins to Ti-6Al-7Nb

Statement of Problem:

Because of the toxicity of vanadium in Ti-6Al-4V alloy, next generation of titanium alloys is proposed to focus on niobium-containing alloy, but for clinical applications, it is crucial for this alloy to bond with acrylic resins with or without the use of primers. However, literature was lacking about the effect of primers on bonding of autopolymerizing resins to Ti-6Al-7Nb.

Objectives:

To evaluate the effect of different metal primers on the shear bond strength of acrylic resin to Ti-6Al-7Nb.

Materials and Methods:

A total of 30 dis-shaped wax patterns (10 mm in diameter and 2 mm thickness) were prepared and casted using Ti-6Al-7Nb. After casting, the disk surfaces were finished with abrasive paper under water. Specimens were equally divided into three groups on the basis of the use of primer: metal primer (GC II metal primer) (Group 1), Universal Tokuyama primer (Group 2), no primer (Group 3). Tape of 50 μm thickness was applied on each of the specimens. Then, self-cure acrylic resin was mixed and applied on the center part of the tape, on which Bernouilles tube was placed. The tensile bond strength was measured with a universal testing machine. The data were obtained for all the specimens and analyzed using Statistical Package for Social Sciences version 17.0 at a statistically significance level of <0.05.

Results:

Mean tensile force was maximum for Group 2 (28.58 ± 39.40 N) and minimum for control Group 3 (6.24 ± 10.97 N), thereby showing a significant inter-group difference (P < 0.001). On applying post hoc test (Tukey HSD), both the Group 1 and Group 2 showed a statistically significant difference as compared to control Group 3; however, the difference between two experimental groups was not statistically significant (P > 0.05).

Conclusions:

Tokuyama primer and GC II metal primer had a significant effect on improving the bond strength between autopolymerizing denture base resin and Ti-6Al-7Nb.

The Effect of Artificial Aging on The Bond Strength of Heat-activated Acrylic Resin to Surface-treated Nickel-chromium-beryllium Alloy

PURPOSE

The debonding load of heat-activated polymethylmethacrylate (PMMA) denture base resin material to a nickel-chromium-beryllium (Ni-Cr-Be) alloy conditioned by three different surface treatments and utilizing two different commercial bonding systems was investigated.

MATERIALS AND METHODS

Denture resin (Lucitone-199) was bonded to Ni-Cr-Be alloy specimens treated with Metal Primer II, the Rocatec system with opaquer and the Rocatec system without opaquer. Denture base resin specimens bonded to non-treated sandblasted Ni-Cr-Be alloy were used as controls. Twenty samples for each treatment condition (80 specimens) were tested. The 80 specimens were divided into two categories, thermocycled and non-thermocycled, containing four groups of ten specimens each. The non-thermocycled specimens were tested after 48 hours' storage in room temperature water. The thermocycled specimens were tested after 2,000 cycles in 4°C and 55°C water baths. The debonding load was calculated in Newtons (N), and collected data were subjected by non parametric test Kruskal-Wallis One Way Analysis of Variance on Ranks and Dunn's post hoc test at the α = 0.05.

RESULTS

The Metal Primer II and Rocatec system without opaquer groups produced significantly higher bond strengths (119.9 and 67.6 N), respectively, than did the sandblasted and Rocatec system with opaquer groups, where the bond strengths were 2.6 N and 0 N, respectively. The Metal Primer II was significantly different from all other groups (P<0.05). The bond strengths of all groups were significantly decreased (P<0.05) after thermocycling.

CONCLUSIONS

Although thermocycling had a detrimental effect on the debonding load of all surface treatments tested, the Metal Primer II system provided higher values among all bonding systems tested, before and after thermocycling.

Retention strength between veneering resin composites and laser-sintered cobalt-chromium alloy

The purpose of the present study was to evaluate the retention strength between a resin composite veneering material and three types of cobalt-chromium (Co-Cr) alloy substrates. Co-Cr alloy specimens with 81 retention devices (LSR), with 144 retention devices (LDR), and without retention device (LN) were fabricated using a laser-sintering system. The specimens were air-abraded with alumina, conditioned with a primer [Alloy primer (AP) or M.L. primer (ML)], and veneered with a light-polymerized resin composite (Gradia). Three control groups (LSR-N, LDR-N, and LN-N) without primer were also prepared. After 20,000 thermocycles in 4 and 60 °C water, tensile retention strengths were determined using a universal testing machine. Data were analyzed by analysis of variance and a post hoc Tukey-Kramer HSD test (α = 0.05, n = 8). The highest retention strengths were obtained in LSR-AP (28.3 MPa), LSR-ML (23.3 MPa), LDR-AP (26.9 MPa), and LDR-ML (27.8 MPa), and these values were not significantly different. In the absence of a retention device, the retention strengths were significantly different in the following order: LN-N (0.1 MPa) < LN-ML (12.4 MPa) < LN-AP (20.2 MPa). The specimens without primer were significantly different in the following order: LN-N (0.1 MPa) < LSR-N (15.4 MPa), LDR-N (17.1 MPa). No significant difference was found between the numbers of retention devices, which were 81 and 144. In conclusion, the combined use of the primers and the retention devices is recommended when the laser-sintered Co-Cr alloy is veneered with the resin composite materials to maximize the retention strength.

Effect of metal primers and tarnish treatment on bonding between dental alloys and veneer resin

PURPOSE

The aim of this study was to evaluate the effect of metal primers on the bonding of dental alloys and veneer resin. Polyvinylpyrrolidone solution's tarnish effect on bonding strength was also investigated.

MATERIALS AND METHODS

Disk-shape metal specimens (diameter 8 mm, thickness 1.5 mm) were made from 3 kinds of alloy (Co-Cr, Ti and Au-Ag-Pd alloy) and divided into 4 groups per each alloy. Half specimens (n=12 per group) in tarnished group were immersed into polyvinylpyrrolidone solution for 24 hours. In Co-Cr and Ti-alloy, Alloy Primer (MDP + VBATDT) and MAC-Bond II (MAC-10) were applied, while Alloy Primer and V-Primer (VBATDT) were applied to Au-Ag-Pd alloys. After surface treatment, veneering composite resin were applied and shear bond strength test were conducted.

RESULTS

Alloy Primer showed higher shear bond strength than MAC-Bond II in Co-Cr alloys and Au-Ag-Pd alloy (P<.05). However, in Ti alloy, there was no significant difference between Alloy Primer and MAC-Bond II. Tarnished Co-Cr and Au-Ag-Pd alloy surfaces presented significantly decreased shear bond strength.

CONCLUSION

Combined use of MDP and VBATDT were effective in bonding of the resin to Co-Cr and Au-Ag-Pd alloy. Tarnish using polyvinylpyrrolidone solution negatively affected on the bonding of veneer resin to Co-Cr and Au-Ag-Pd alloys.

Comparative study between laser sintering and casting for retention of resin composite veneers to cobalt-chromium alloy

The purpose of this study was to evaluate and compare the bond strengths between resin composite veneer and laser-sintered cobalt-chromium (Co-Cr) alloy with and without retention devices (Laser-R and Laser-N respectively). Cast Co-Cr alloy with and without retention devices (Cast-R and Cast-N respectively) were also prepared for fabrication technique comparison. Disk-shaped Co-Cr alloy specimens were air-abraded with alumina and veneered with a veneering system, Estenia C&B (ES) or Ceramage (CE). After 20,000 thermocycles, tensile testing was performed. Data were analyzed by ANOVA and multiple comparison test. When no retention devices were present, no significant differences were observed between Laser-N/ES and Cast-N/ES, or between Laser- N/CE and Cast-N/CE, but ES exhibited significantly higher bond strength than CE. With retention devices, Laser-R/ES, Cast- R/ES and Laser-R/CE showed no significant differences, and their retention strengths were significantly higher than that of Cast- R/CE. Compared to cast Co-Cr alloy, laser-sintered Co-Cr alloy with retention devices provided better retention durability for resin composite-veneered prostheses.

Comparative study of the shear bond strength of various veneering materials on grade II commercially pure titanium

PURPOSE

To compare the shear bond strength of various veneering materials to grade II commercially pure titanium (CP-Ti).

MATERIALS AND METHODS

Thirty specimens of CP-Ti disc with 9 mm diameter and 10 mm height were divided into three experimental groups. Each group was bonded to heat-polymerized acrylic resin (Lucitone 199), porcelain (Triceram), and indirect composite (Sinfony) with 7 mm diameter and 2 mm height. For the control group (n=10), Lucitone 199 were applied on type IV gold alloy castings. All samples were thermocycled for 5000 cycles in 5-55℃ water. The maximum shear bond strength (MPa) was measured with a Universal Testing Machine. After the shear bond strength test, the failure mode was assessed with an optic microscope and a scanning electron microscope. Statistical analysis was carried out with a Kruskal-Wallis Test and Mann-Whitney Test.

RESULTS

The mean shear bond strength and standard deviations for experimental groups were as follows: Ti-Lucitone 199 (12.11 ± 4.44 MPa); Ti-Triceram (11.09 ± 1.66 MPa); Ti-Sinfony (4.32 ± 0.64 MPa). All of these experimental groups showed lower shear bond strength than the control group (16.14 ± 1.89 MPa). However, there was no statistically significant difference between the Ti-Lucitone 199 group and the control group, and the Ti-Lucitone 199 group and the Ti-Triceram group. Most of the failure patterns in all experimental groups were adhesive failures.

CONCLUSION

The shear bond strength of veneering materials such as heat-polymerized acrylic resin, porcelain, and indirect composite to CP-Ti was compatible to that of heatpolymerized acrylic resin to cast gold alloy.

Evaluation of shear bond strength of repair acrylic resin to Co-Cr alloy

PURPOSE

The purpose of this study was to investigate the impact of different surface treatment methods and thermal ageing on the bond strength of autopolymerizing acrylic resin to Co-Cr.

MATERIALS AND METHODS

Co-Cr alloy specimens were divided into five groups according to the surface conditioning methods. C: No treatment; SP: flamed with the Silano-Pen device; K: airborne particle abrasion with Al2O3; Co: airborne particle abrasion with silica-coated Al2O3; KSP: flamed with the Silano-Pen device after the group K experimental protocol. Then, autopolymerized acrylic resin was applied to the treated specimen surfaces. All the groups were divided into two subgroups with the thermal cycle and water storage to determine the durability of the bond. The bond strength test was applied in an universal test machine and treated Co-Cr alloys were analyzed by scanning electron microscope (SEM). Two-way analysis of variance (ANOVA) was used to determine the significant differences among surface treatments and thermocycling. Their interactons were followed by a multiple comparison' test performed uing a post hoc Tukey HSD test (α=.05).

RESULTS

Surface treatments significantly increased repair strengths of repair resin to Co-Cr alloy. The repair strengths of Group K, and Co significantly decreased after 6,000 cycles (P<.001).

CONCLUSION

Thermocycling lead to a significant decrease in shear bond strength for air abrasion with silica-coated aluminum oxide particles. On the contrary, flaming with Silano-Pen did not cause a significant reduction in adhesion after thermocycling.

Investigation into the effect of use of metal primer on adhesion of heat cure acrylic resin to cast titanium: an in vitro study

The availability of adhesive primers capable of bonding chemically to base metal alloys without well defined passive oxide surface film has been improved significantly over the last decade. Therefore, the purpose of the study was to compare and evaluate the effect of metal primer on adhesion of heat cure acrylic resin to cast titanium. Shear bond strength test was conducted on 80 commercially pure titanium cast metal heat-cure acrylic resin discs treated with different surface treatments. The first group received no surface treatment (group I); the second group was subjected to sandblasting (group II); the third group was treated with bonding agent (alloy primer) (group III) and the fourth was treated with sandblasting and alloy primer (group IV). After the samples were surface treated, acrylic resin was mixed, packed and processed over the test area of cast titanium. Ten specimens of each group were immersed in distilled water for 24 h followed by thermocycling for 20,000 cycles. Shear bond-strength between the heat cure acrylic resin and titanium was evaluated using Instron universal testing machine. Debonded specimens of all the groups were subjected to SEM analysis. The bond failure (MPa) was analyzed by ANOVA and Duncan's multiple comparison tests. Surface treatment with sandblasting, followed by the application of alloy primer showed maximum shear bond strength before and after thermocycling (24.50 ± 0.59 and 17.39 ± 1.56 MPa respectively).The bond strength values are found to be in decreasing magnitudes as group IV > group III > group II > group I. The following pretreatment to improve the shear bond strength of heat cure acrylic resin to titanium is recommended in order to attain the maximum bond strength in cast titanium frameworks for various prostheses: sandblasting, cleaning in an ultrasonic bath for 10 min and air drying followed by application of a bonding agent uniformly on the sandblasted cast titanium surface before packing with heat cure acrylic resin.

The influence of steam cleaning procedures on the surface roughness of commonly used type III dental stone for the fabrication of removable dentures

OBJECTIVE

This study investigated the possible detrimental effects of steam treatment on the surface of type III dental stone, which is a common laboratory material used for the construction of removable dentures.

MATERIAL AND METHODS

Forty dental stone specimens were prepared and divided into four groups (A, B, C and D), and group A was used as the control group. The other groups were treated with steam from a standard distance for varying durations (30, 60 and 120 s).

RESULTS

The duration of steam cleaning significantly increased Ra values (F = 63.150, p = 0.000). Similarly, the duration of steam application was directly correlated with the weight changes (F = 17.721, p = 0.000). A significant amount of dental stone can be removed from the surface while treating with steam.

CONCLUSION

These studies demonstrated that expanded periods of steam cleaning cause weight loss and abrade the surface of type III dental stones; therefore, these devices should be used with caution during denture fabrication procedures.

Shear bond strength between Ni-Cr alloy bonded to a ceramic substrate

INTRODUCTION

The aim of this study was to evaluate the shear bond strength between a Ni-Cr alloy and a ceramic system submitted or not to thermocycling.

MATERIALS AND METHODS

Forty-eight cylinder blocks of Ni-Cr with 3.0 mm diameter by 4.0 mm hight and 48 disc-shaped specimens (7.0 mm in diameter by 2.0 mm thick) composed of ceramic were prepared. The Ni-Cr cylinder blocks were randomised in two groups of 24 specimens each. One group was submitted to air-particle abrasion (sandblasting) with 50 μm Al(2)O(3) (0.4-0.7 MPa) during 20 s, and the other group was submitted to mechanical retentions with carbide burrs. Each group was subdivided into other two groups (n = 12), submitted or not to thermocycling (500 cycles, 5-55°C). The cylinder blocks were bonded to the disc-shaped ceramic specimens under 10 N of load. The shear bond strengths (MPa) were measured using a universal testing machine at a cross head speed of 0.5 mm/min and 200 kgf of load. The data were submitted to statistical analysis (anova and Tukey's test).

RESULTS

The air-particle abrasion group exhibited significantly higher shear bond strength when compared to drilled group (p < 0.05).

CONCLUSIONS

Thermocycling decreased significantly the bond strengths for all groups tested.

The effect of surface treatment on bond strength of layering porcelain and hybrid composite bonded to zirconium dioxide ceramics

PURPOSE

The purpose of this study was to investigate the differences between Rocatec (as surface treatment) and #600 polishing (as control) on shear bond strength of layering porcelain and hybrid composite to zirconium dioxide ceramics.

METHODS

Manufactured zirconia blocks used in this study were yttrium partially stabilized zirconia (YTZ(®)), and veneering materials were NobelRondo Zirconia Dentin A2 High Value (NZR) and Estenia C&B (ES). Total 48 zirconia blocks were fabricated (10 mm × 10 mm × 20 mm). The blocks of 24 each were treated by Rocatec and #600 paper, respectively. Surface treated zirconia blocks were divided into two groups, according to veneering materials of NZR and ES. NZR was fired and ES was polymerized to zirconia. The fabricated specimen was fixed to mounting jig and applied shear force using the universal testing machine at a crosshead speed of 0.5 mm/min. All results were statistically analyzed by two-way ANOVA and Tukey's test. EPMA analysis and SPM analysis of specimen interface were carried out.

RESULTS

Mean shear bond strength of each condition was: NZR/#600; 23.3 (S.D. ±7.0) MPa, NZR/Rocatec; 26.9 (S.D. ±7.0) MPa, ES/#600; 10.7 (S.D.±2.4) MPa, ES/Rocatec; 12.5 (S.D.±0.8) MPa.

CONCLUSIONS

From the results of this study, shear bond strength of layering porcelain to zirconia was higher than that of restorative hybrid resin. However the more study will be needed, the appropriate choice of materials became the gides to the expansion of the applied cases of metal-free prothesis.

Adhesion properties in systems of laminated pigmented polymers, carbon-graphite fiber composite framework and titanium surfaces in implant suprastructures

OBJECTIVE

For long-term stability the adhering interfaces of an implant-retained supraconstruction of titanium/carbon-graphite fiber-reinforced (CGFR) polymer/opaquer layer/denture base polymer/denture teeth must function as a unity. The aim was to evaluate adhesion of CGFR polymer to a titanium surface or CGFR polymer to two different opaquer layers/with two denture base polymers.

MATERIALS AND METHODS

Titanium plates were surface-treated and silanized and combined with a bolt of CGFR polymer or denture base polymer (Probase Hot). Heat-polymerized plates of CGFR polymer (47 wt% fiber) based on poly(methyl methacrylate) and a copolymer matrix were treated with an opaquer (Sinfony or Ropak) before a denture base polymer bolt was attached (Probase Hot or Lucitone 199). All specimens were heat-polymerized, water saturated (200 days) and thermally cycled (5000 cycles, 5/55 degrees C) before shear bond testing.

RESULTS

Silicatized titanium surfaces gave higher bond strength to CGFR polymer (16.2+/-2.34 and 18.6+/-1.32) MPa and cohesive fracture than a sandblasted surface (5.9+/-2.11) MPa where the fracture was adhesive. The opaquer Sinfony gave higher adhesion values and mainly cohesive fractures than the opaquer Ropak. Different surface treatments (roughened or polished) of the CGFR polymer had no effect on bond strength.

SIGNIFICANCE

The fracture surfaces of silicatized titanium/CGFR polymer/opaquer layer (Sinfony)/denture base polymers were mainly cohesive. A combination of these materials in an implant-retained supraconstruction is promising for in vivo evaluation.

Adhesive bonding of resin composite to various Ni-Cr alloy surfaces using different metal conditioners and a surface modification system

PURPOSE

This study evaluated the effect of three metal conditioners [Metal Photo Primer (MPP), Cesead II Opaque Primer (OP), Targis Link (TL)], and one surface modification system [Siloc (S)] on the shear bond strength (SBS) of a prosthetic composite material to Ni-Cr alloy.

MATERIALS AND METHODS

Rivet-shaped specimens were cast, and three surface treatments were evaluated: Polishing (P); sandblasting with either 50 microm (50SB) or 250 microm (250SB) Al(2)O(3). All products were applied to half of the specimens, while the other half remained without the materials. Veneering resin composite (8-mm diameter, 2-mm thick) was applied and light-exposed for 90 seconds in a laboratory light-curing unit. The specimens were stored in water at 37 degrees C for 24 hours, and half were subjected to 500 thermal cycles consisting of water baths at 4 degrees C and 60 degrees C. All specimens were submitted to SBS test (0.5 mm/min) until failure. Failure patterns were determined using optical and scanning electron microscope (SEM) analysis. Data were analyzed by ANOVA and post hoc Tukey's test (preset alpha of 5%).

RESULTS

The SBS values of OP and TL groups were higher than those of MPP and S within the 50SB treatment (p < 0.05). No significant difference in SBS was noted between OP and TL as well as between MPP and S. On the other hand, no significant differences were found among conditioners within the 250SB group (p > 0.05). The SBS values of MPP, OP, and S from the 250SB group were higher than those from 50SB (p < 0.05). No significant difference in SBS was noted among most groups with conditioners after thermocycling. The only exception was observed for MPP, which showed an increase in SBS after thermocycling (p < 0.05). Differences in SBS were noted among the groups with conditioners (p < 0.05), and no significant difference in SBS was noted between TL and OP groups, which showed the highest values among all within the P group. No significant difference was noted between MPP and S. Debonded surfaces showed adhesive failures predominantly located between metal surface and opaque resin.

CONCLUSIONS

The OP and TL conditioners and surface sandblasting with 250 microm Al(2)O(3) promoted the highest SBS between resin and the Ni-Cr metal surface.

Effect of bracket base conditioning

INTRODUCTION

The aim of this study was to compare the effect of a silicoating system, the influence of sandblasting, and the effect of a silane-coupling agent after sandblasting on the shear bond strength of stainless steel foil-mesh brackets. To simulate the oral environment, all specimens were thermocycled (6000 times at 5 degrees C and 55 degrees C) in a mastication device before testing.

METHODS

Four bracket groups were tested: group 1 consisted of 20 metal brackets that were sandblasted on the base; group 2 contained 20 brackets that were sandblasted, and a silane-coupling agent was applied; in group 3, the surface of the base of 20 metal brackets was treated by using a tribochemical system; and group 4 was the control group. The brackets were bonded with a light-curing adhesive to extracted third molars, and the shear bond strength and the adhesive remnant index score were determined. The brackets of group 1 were reconditioned after debonding with sandblasting and tested again (group 5).

RESULTS

Sandblasting and tribochemical treatment of brackets improved the shear bond strength of stainless steel brackets. Combined sandblasting and silane-coupling treatment offers no benefit of increased in-vitro strength.

CONCLUSIONS

The bond of resins to tribochemically silicoated stainless steel brackets seems to be sufficient to strengthen the bond between the adhesive and the metal bracket. This treatment is mainly indicated for low-compliance patients or teeth that are difficult to bond.

Spark erosion as a metal–resin bonding system

PURPOSE

Resin to metal bond strength of two commercial and one experimental metal-resin bonding system for crown and bridge veneer composites was evaluated.

MATERIALS AND METHODS

All specimens were prepared and tested according to ISO 10477 Amendment 1. A high precious alloy (HPA), a Co/Cr-alloy (Co/Cr) and pure titanium (Ti) were wet-ground to a final surface finish of 800 grit and air-dried. Twenty specimens of each metal were treated with Rocatec (RO), 20 with a Silano-Pen (SP), and 20 with the experimental spark-erosion (SE) bonding system. A light-curing opaque and a crown and bridge veneer composite were applied to each metal specimen. Ten specimens of each metal and bonding system were stored in water for 24h at 37 degrees C, 10 were thermocycled (TC) 5000 times in a water-bath between +5 and +55 degrees C prior to measuring shear bond strength (SBS). Scanning electron microscopy (SEM) was used to examine the treated metal surfaces.

RESULTS

After 24h SE generated significantly higher SBS values on Ti than RO (p<0.05). SP revealed the highest SBS for Co/Cr. After TC significant decreases occurred for RO on HPA, for SP on Co/Cr and Ti, and for SP on Ti. SE revealed the highest mean bond values for all metals. These results and SEM proved that no sandblasting is required for SE to obtain good bond strength.

SIGNIFICANCE

The experimental spark-erosion bonding system is an easy and very effective method for surface-treating alloys to obtain high SBS values for crown and bridge veneer composites.

Shear Bond Strength Evaluation of Different Veneering Systems on Ni-Cr Alloys

PURPOSE

The aim of this study was to evaluate the shear bond strength of four esthetic veneering materials on nickel-chromium (Ni-Cr) alloy.

MATERIALS AND METHODS

Forty square patterns (10 x 10 x 1.5 mm) were cast with Ni-Cr, divided equally into four groups, and received four treatments for veneering: conventional porcelain-fused-to-metal (PFM), Artglass, Targis/Vectris, and Biodent light-cured prosthodontic composite resins. After sandblasting of the cast metal surfaces with 50 micro m alumina, the composites were applied to the surfaces according to manufacturers' recommendations. Shear bond strength was determined at a crosshead speed of 0.5 mm/min. Results were analyzed statistically with Kruskal-Wallis analysis of variance and multiple comparison tests.

RESULTS

Mean shear bond strength values were 34.96 MPa for PFM, 14.17 MPa for Targis/Vectris, 13.64 MPa for Artglass, and 10.56 MPa for Biodent. The PFM group exhibited significantly higher bond strength values compared with the other three groups (p < 0.001).

CONCLUSION

PFM showed considerably higher shear bond strength values than the three metal-resin bonding techniques.

Shear bond strength of three veneering resins to a Ni-Cr alloy using two bonding procedures

Composite veneering materials are used as alternatives to porcelain in fixed prosthodontics. Mechanical retention of the resin on the metal framework has been associated with the formation of gaps at the resin/alloy interface, and failure of the restoration. Several chemical bonding systems have been introduced to promote resin adhesion. The purpose of the present study was to evaluate the shear bond strength of three photocured composites (Artglass, Solidex & Signum+) to a Ni-Cr alloy.72 wax disks covered with 150-mum diameter beads were cast and divided in two equal groups. In the first group, Metal Photo Primer was applied on the casting surface, while the Siloc system was used in the second. Each group was divided in three subgroups of 12 samples, in which the three composites were photocured. Half of the specimens of each subgroup were subjected to 1000 and 5000 thermal cycles (5 and 55 degrees C) respectively. All specimens were tested in shear in a universal testing machine. The Siloc-Solidex group showed the highest bond strength (17.3 +/- 3.7 MPa). No statistically significant difference was found between specimens treated with Metal Photo Primer or Siloc. Thermocycling did not significantly affect the bond strength values. Solidex showed an adhesive failure mode for both alloy surface treatments, while Artglass and Signum+ exhibited combination failures. Conclusively, the appropriate alloy surface treatment - resin combination can significantly improve the resin-alloy shear bond strength. Specifically, Solidex resin exhibited significantly higher bond values compared with Artglass and Signum+, for both surface treatments and thermocycling procedures.

Influence of electron beam irradiation on the alloy-to-resin bond strength

The aim of this study was to investigate whether postcuring using electron beam irradiation had an effect on the bond strength of resin-to-base-metal after priming their surfaces using silicoating methods or functional monomers. Composite cylinders were bonded on a restricted area of 5 mm2 to flat rectangular titanium and cobalt-chromium specimens. Under investigation were the silicoating system Rocatec, the thiol-phosphate system Metal Primer II and the phosphate ester SR Link. Tensile strength and shear bond strength were determined for the three test groups in each case: (i) after 24 h, (ii) after electron beam irradiation (100 kGy), and (iii) after irradiation (100 kGy) + 12,000 cycles of thermal cycling (5 degrees /55 degrees C). The bond strength was highly affected by irradiation and the metal priming method used. However, the tribochemical silicoating method and phosphate-ester group showed no significant statistical change in bond strength. Only the thiol-phosphate system showed considerably higher tensile and shear bond strengths after irradiation. Thermal cycling did not deteriorate this bond and there was a tendency for higher bond strength on titanium. As a result it was determined that thiol-phosphate primers in combination with postcuring using electron beam irradiation can considerably improve the bond strength between resins and titanium or cobalt-chromium alloys.

Vergleichende Untersuchungen zur Eignung eines neuen Oberflächenkonditionierungsverfahrens (Airsonic Mini Sandblaster®) in der Klebebrückentechnik / Comparative Studies on the Applicability of a New Surface Conditioning System (Airsonic Mini Sandblaster®) in Adhesive Bridging Technic

The object of this work was to investigate a new surface conditioning system for hydrolysis-stable metal-polymer bonds in dental prosthetics. The application of the adhesive SiO2-interface layer was achieved tribochemically by the use of a miniaturised sand blasting instrument (Airsonic Mini Sandblaster, Co. Hager and Werken, Duisburg, Germany) using the SiO2 coated Rocatec blasting medium. An advantage of this instrument is the possibility of decreasing costs for dentist and patient and also the time of treatment by connecting the device to the dental chair. Evaluation of applicability was based on the composition and morphology of the coatings applied to different dental alloys (titanium, NiCr, CoCr). In addition, the strength of metal-polymer bonds prior to and after physiological ageing was determined by tensile shear testing. In all cases the Airsonic Mini Sandblaster coatings proved to be equivalent to the original Rocatec system in terms of the parameters tested, such as structure and composition of the coating, and adhesivity. Irrespective of the adhesive alloy-dependent adhesive strengths in the region of 24-30 MPa were achieved; no significant decrease in strength caused by degrading of the bonds occurred. Bonding strengths are within the range reported in the literature for the Rocatec system, and are appreciably above clinically required minimum strength of 10 MPa as enamel strength. The results demonstrate the applicability of the Airsonic Mini Sandblaster in practice. By employing the procedure at the dental chair the process of silicating and subsequent silanising can be transferred from the dental laboratory to the dentist's practice. In this way, a reduction in treatment time and costs is achieved, and the reliable handling of the coating system is also improved.