Characterisation of tribochemically assisted bonding of composite resin to porcelain and metal

Bonding Effectiveness of Veneering Ceramic to Zirconia after Different Grit-Blasting Treatments

Objective: To determine the effect of grit-blasting before and after sintering on the surface roughness of zirconia and the micro-tensile bond strength of a pressable veneering ceramic to zirconia. Methods: Pre-sintered zirconia blocks (IPS e.max ZirCAD, Ivoclar) were divided into four test groups of three specimens each and a control group ('CTR'; no surface treatment). Pre-S-30, Pre-S-50, and Pre-S-110 were grit-blasted with 30-µm SiO2-coated Al2O3, 50-µm Al2O3 and 110-µm Al2O3 particles, respectively, before sintering. Post-S-30 was grit-blasted with 30-µm SiO2-coated Al2O3 after sintering. For each treatment, the surface roughness was measured (Ra, Perthometer M4P, Mahr Perthen). After sintering the zirconia blocks, a liner was applied and a pressable ceramic (IPS e.max ZirPress, Ivoclar) was heat-pressed. Sixteen microbars were obtained from each block and submitted to micro-tensile bond-strength (µTBS) testing. Data were analyzed with one-way ANOVA. Any correlation between Ra and µTBS was evaluated (Sperman test). Results: Grit-blasting before sintering with 110-µm Al2O3 (RaPre-S-110 = 3.4 ± 0.4 µm), 50-µm Al2O3 (RaPre-S-50 = 2.3 ± 0.5 µm), and 30-µm SiO2-coated Al2O3 (RaPre-S-30 = 1.2 ± 0.2 µm) resulted in significantly higher roughness than grit-blasting after sintering with 30-µm SiO2-coated Al2O3 (RaPost-S-30 = 0.5 ± 0.1 µm). The highest µTBS was measured when the sintered zirconia was grit-blasted with 30-μm SiO2-coated Al2O3 (µTBSPost-S-30 = 28.5 ± 12.6 MPa), which was significantly different from that of specimens that were grit-blasted before sintering (µTBSPre-S-30 = 21.8 ± 10.4; µTBSPre-S-50 = 24.1 ± 12.6; µTBSPre-S-110 = 26.4 ± 14.1) or were not grit-blasted (µTBSCTR = 20.2 ± 11.2). Conclusions: Grit-blasting zirconia before sintering enhanced the surface roughness proportionally to the particle size of the sand used. Grit-blasting with 30-µm SiO2-coated Al2O3 after sintering improved bonding of the veneering ceramic to zirconia. Clinical Significance: As grit-blasting with 30-µm SiO2-coated Al2O3 after sintering improved bonding of the veneering ceramic to zirconia, it may reduce veneering ceramic fractures/chipping.

Influence of ceramic-coating techniques on composite-zirconia bonding: Strain energy release rate evaluation

OBJECTIVES

To compare ceramic-coating techniques versus conventional techniques on bonding between composite cements and zirconia by means of strain energy release rate (G_c, J/m²).

METHODS

Two sizes of zirconia bars (30 mm × 8 mm × 1.5 mm and 14.8 mm × 8 mm × 1.5 mm) were fabricated. Two smaller bars were treated and cemented to the surface of a large bar using one of the following methods: (i) AlN-nano-structured alumina coating with RelyX Unicem 2; (ii) HOT-DCM hotbond coating with G-Multi Primer and G-Cem Linkforce; (iii) LiDi-lithium disilicate glass-ceramic coating with Monobond N Primer and Multilink Speed; (iv) COJ-tribochemical silica treatment with RelyX Ceramic Primer and RelyX Unicem 2; (v) GCEM-alumina grit blasting with G-Multi Primer and G-Cem LinkForce; (vi) MUL-alumina grit blasting with Multilink Speed; and (vii) PAN-alumina grit blasting with Clearfil Ceramic Primer and Panavia F2.0. A total of 30 bilayered specimens in each group were stored in distilled water at 37 °C for 24 h and assigned to three subgroups (n = 10/test group): short-term test, thermocycling for 5000 cycles, and thermocycling for 10,000 cycles and tested in 4-point bending configuration. Results were analysed using two-way ANOVA, followed by one-way ANOVA and Games-Howell (α = 0.05). Failure mode and surfaces were analysed using optical microscopy and SEM.

RESULTS

The bonding (J/m²) of COJ and MUL groups was significantly higher than the other groups among all aging conditions. Thermocycling affected the bonding in COJ and GCEM groups.

SIGNIFICANCE

Surface pre-treatments and artificial aging affect the bonding between composite cements and zirconia.

Is the bond strength of zirconia-reinforced lithium silicate lower than that of lithium disilicate? A systematic review and metaanalysis

PURPOSE

This study systematically reviewed the literature to compare the bond strength of resin composites with that of zirconia-reinforced lithium silicate (ZLS) and lithium disilicate (LD).

STUDY SELECTION

This review was structured based on the Preferred Reporting Items for Systematic Reviews and MetaAnalyses (PRISMA 2020) statement. This study was registered at the International Prospective Register of Systematic Reviews (CRD42021256900). Studies were searched via PubMed, Web of Science, and Google Scholar databases without language or publication year limits. In vitro studies that evaluated the bond strength of the resin composites to ZLS and LD were included. The risk of bias in all the included articles was evaluated. Statistical analyses were performed using the Review Manager software (version 5.3, Cochrane Collaboration, Oxford, UK).

RESULTS

Of the 90 potentially related articles, the full texts of 16 articles were evaluated after screening. Finally, sevenstudies were included in the qualitative synthesis and meta-analysis. All the studies presented a medium risk of bias. The results showed no significant difference in bond strength between the ZLS and LD groups (P = 0.94, mean difference=0.08, and 95% confidence interval=-1.93 to 2.10). However, a significant difference was found in the subgroup analysis considering different types of aging treatments (P = 0.0008) and different types of bond strength tests (P < 0.00001).

CONCLUSION

The bond strength of resin composites was found to be similar to that of ZLS and LD, but different aging treatments and bond strength tests exhibited varying effects on the bond strength.

Effect of Immediate Dentin Sealing and Surface Conditioning on the Microtensile Bond Strength of Resin-based Composite to Dentin

This study evaluated the microtensile bond strength (μTBS) of resin-based composite (RBC) to dentin after different immediate dentin sealing (IDS) strategies and surface-conditioning (SC) methods and on two water storage times. Human molars (n=48) were randomly divided into eight experimental groups involving four different IDS strategies-IDS-1L with one layer of adhesive, IDS-2L with two layers of adhesive, IDS-F with one layer of adhesive and one layer of flowable RBC, and DDS (delayed dentin sealing) with no layer of adhesive (control)-and two different SC methods-SC-P with pumice rubbing and SC-PC with pumice rubbing followed by tribochemical silica coating. The μTBS test was performed after one week and after six months of water storage, being recorded as the "immediate" and "aged" μTBS, respectively. Composite-adhesive-dentin microspecimens (0.9×0.9×8-9 mm) were stressed in tension until failure to determine the μTBS. Failure mode and location of failure were categorized. Two-way analysis of variance was applied to analyze the data for statistically significant differences between the experimental groups (p<0.05). Two-way analysis of variance revealed no significant differences between the one-week μTBS specimens for IDS strategy (p=0.087) and SC methods (p=0.806). However, the interaction of IDS strategy and SC methods appeared statistically significant (p=0.016). The six-month specimen evaluation showed no significant difference in μTBS for SC (p=0.297) and SC/IDS interaction (p=0.055), but the μTBS of the IDS strategies differed significantly among them (p=0.003). For tribochemical silica-coated IDS, no significant effect of aging on μTBS was recorded (p=0.465), but there was a highly significant difference in μTBS depending on the IDS strategy (p<0.001). In addition, the interaction of IDS and aging was borderline statistically significant (p=0.045). The specimens failed mainly at the adhesive-dentin interface for all experimental groups. Dentin exposure during clinical procedures for indirect restorations benefits from the application of IDS, which was shown to result in higher bond strength. No significant differences were found between cleaning with solely pumice or pumice followed by tribochemical silica coating.

Comparison of Micro-Shear Bond Strength of Resin Cement to Zirconia With Different Surface Treatments Using Universal Adhesive and Zirconia Primer

Introduction: Increased demand for metal free fixed partial denture in recent years led to the developing of all ceramic material with excellent mechanical properties. One of the most popular all ceramic is zirconia which shows poor bonding properties. Recently, universal primer contains of silane and phosphate monomer for bond to zirconia have been introduced. The aim of this study is determination of the best method for bonding to zirconia based on the selection of the correct primer, suitable adhesive and best surface pretreatment. Methods: In this in vitro experimental study 16 sintered-zirconia blocks prepared in dimension of (18×6×2 mm) by CAD/CAM technology. Sample cleansed by ultrasonic device contain of 96% ethanol in 6 minutes, after air-drying, based on surface treatment randomly divided into 4 groups which each group divided into 2 sub-groups based on the use of a primer or universal bond: (1) no treatment: (a) cement + zirconia primer, (b) cement + universal bond. (2) Alumina pretreatment: (a) cement + zirconia primer, (b) cement + universal bond. (3) Cojet sand pretreatment: (a) cement + zirconia primer, (b) cement + universal bond. (4) laser pretreatment (a) cement + zirconia primer, (b) cement + universal bond. Composite disc prepared with condensation of composite resin in Tygon tube with integral diminution of 0.7 mm which cured for 40 sconds. Universal bond or zirconia primmer apply on the surface of the zirconia samples then cemented to composite disks by Panavia F2 according manufacture instructions. Microshear bond strength determined with universal testing machine. Failure mode assessed under stereomicroscope. Selected sample based on surface treatment evaluated under SEM. Data were analyzed using one-way analysis of variance (ANOVA). Results: Comparison of the 4 surface treatment groups revealed a significant difference and the highest bond belonged to Cojet and the lowest one to laser group. Conclusion: It seems that Universal Adhesive can to be considered as an alternative to bond to zirconia but the Cojet method is still required.

CO2 laser dentin surface treatment most effectively increased ceramic shear bond strength

BACKGROUND AND AIMS

The purpose of this study is to determine the effect of CO2 laser irradiation in comparison with sandblasting (Sb), hydrofluoric acid (Hf) and silane coupling agent (Si) on shear bond strength (SBS) of resin cement to CAD/CAM ceramics bonded to dentin.

MATERIAL AND METHODS

Forty-eight (CAD/CAM) ceramic discs were prepared and grouped by material, i.e. lithium disilicate (Emax CAD) and zirconia ceramic (Emax ZirCAD), distributed into four different groups: group A, lithium disilicate (Li) CO2/HF/Si; group B, Li: HF/Si; group C, zirconia (Zr) CO2/Sb/Si; group D, Zr: Sb/Si.

RESULTS

It was shown significant difference between irradiated and non-irradiated groups in terms of shear bond strength for zirconia ceramics (p value = 0.039).

CONCLUSION

CO2 laser irradiation increases shear bond strength for both CAD/CAM ceramics bonded to dentin.

An insight into current concepts and techniques in resin bonding to high strength ceramics

BACKGROUND

Reliable bonding between high strength ceramics and resin composite cement is difficult to achieve because of their chemical inertness and lack of silica content. The aim of this review was to assess the current literature describing methods for resin bonding to ceramics with high flexural strength such as glass-infiltrated alumina and zirconia, densely sintered alumina and yttria-partially stabilized tetragonal zirconia polycrystalline ceramic (Y-TZP) with respect to bond strength and bond durability.

METHODS

Suitable peer reviewed publications in the English language were identified through searches performed in PubMed, Google Search and handsearches. The keywords or phrases used were 'resin-ceramic bond', 'silane coupling agents', 'air particle abrasion', 'zirconia ceramic' and 'resin composite cements'. Studies from January 1989 to June 2015 were included.

RESULTS

The literature demonstrated that there are multiple techniques available for surface treatments but bond strength testing under different investigations have produced conflicting results.

CONCLUSIONS

Within the scope of this review, there is no evidence to support a universal technique of ceramic surface treatment for adhesive cementation. A combination of chemical and mechanical treatments might be the recommended solution. The hydrolytic stability of the resin ceramic bond should be enhanced.

Retentive Strength of Y-TZP Crowns: Comparison of Different Silica Coating Methods on the Intaglio Surfaces

Objective:

To evaluate the effect of different methods of silica deposition on the intaglio surface of yttrium oxide stabilized zirconia polycrystal (Y-TZP) crowns on the retentive strength of the crowns.

Methods:

One hundred simplified full-crown preparations produced from fiber-reinforced polymer material were scanned, and 100 Y-TZP crowns with occlusal retentions were milled. Crown/preparation assemblies were randomly allocated into five groups (n=20) according to the treatment of the intaglio surfaces: TBS = tribochemical silica coating via air-abrasion with 30-μm silica-coated alumina particles; GHF1 = application of thin glaze layer + hydrofluoric acid (HF) etching for 1 minute; GHF5 = glaze application + HF for 5 minutes; GHF15 = glaze application + HF for 15 minutes; NANO = silica nanofilm deposition (5 nm) via magnetron sputtering. All groups received a silane application. The surfaces of the preparations (polymer) were conditioned with 10% HF for 30 seconds and silanized. The crowns were cemented with resin cement, thermocycled (12,000 cycles; 5°C/55°C), stored for 60 days, and subjected to a retentive strength test (0.5 mm/min until failure). The retention data (MPa) were analyzed using one-way analysis of variance, Tukey tests, and Weibull analysis. Failures were classified as 50C (above 50% of cement in the crown) and 50S (above 50% of cement on the substrate).

Results:

The TBS (5.6±1.7 MPa) and NANO groups (5.5±1 MPa) had higher retentive strength than the other groups (p&lt;0.0001) and had the highest values of characteristic strength. There was no difference in Weibull modulus, except for the GHF1 group (lower values). The TBS and GHF15 groups, respectively, had 60% and 70% of their failures classified as 50C, while most of the other groups had 50S failures.

Conclusion:

Tribochemical silica coating and silica nanofilm deposition on the inner surface of zirconia crowns promoted a higher retentive strength.

Effect of MDP-Based Silane and Different Surface Conditioner Methods on Bonding of Resin Cements to Zirconium Framework

PURPOSE

To determine the shear bond strength (SBS) between zirconium framework and resin cements after different surface conditioner methods and after application of 10-methacryloyloxydecyl dihydrogen phosphate (MDP) based silane and a bonding agent mix.

MATERIALS AND METHODS

128 disc-shaped zirconium-oxide specimens were prepared. Specimens were placed in autopolymerizing acrylic resin. The bonding surface of specimens was smoothed consecutively with 600-, 800-, and 1200-grit silicon carbide papers under water cooling. Eight groups were prepared: CJ, Co-Jet; N, Nd-YAG laser; E, Er-YAG laser; NS, Nd-YAG laser + silane; ES, Er-YAG laser + silane; CJB, Co-Jet + bonding agent; NSB, Nd-YAG laser + silane + bonding agent; ESB, Er-YAG laser + silane + bonding agent. SEM analysis was performed under 2000× magnification. Dual- and self-cured resin cements were bonded to specimens, and shear force was applied. Data were analyzed with one-way ANOVA and Tukey's multiple comparison test (p < 0.05).

RESULTS

The SBS values differed from each other among the groups. While the CJB group showed the highest values, the N group showed the lowest. The treatment with MDP-based silane and bonding agent mix increased SBS values of each cement belonging to each group. SB values of dual-cure resin cement were higher than those of self-cure resin cements.

CONCLUSION

Different surface conditioner methods exhibit an important effect on the SBS of resin cements to zirconium. The application of MDP-based silane and bonding agent mix enhanced SB values.

Microtensile Bond Strength of a Resin Cement to Silica-Based and Y-TZP Ceramics Using Different Surface Treatments

PURPOSE

To evaluate the effects of different surface treatments on the microtensile bond strength (μTBS) of bonding between resin cement and lithia or zirconia-based ceramics using an in vitro study.

MATERIALS AND METHODS

Three zirconia ceramic blocks (IPS e.max ZirCAD) and three lithium disilicate ceramic blocks (IPS e.max CAD) were sintered and duplicated in resin composite. The zirconia specimens underwent various treatments (n = 1): (i) Sandblast + primer (ZiSa); (ii) sandblast + laser irradiation + primer (ZiSaLa); or (iii) laser irradiation + primer (ZiLa). The lithium disilicate specimens also underwent various treatments: (i) sandblast + HF + silane (LiSaE); (ii) sandblast + silane (LiSa); or (iii) sandblast + laser irradiation + silane (LiSaLa). The ceramic-composite blocks were cemented with resin cement and cut to produce bars with approx. 1 mm² bonding areas. The specimens were thermocycled, and bond strength tests were performed in a universal testing machine. The fracture type was determined by observing the fractured surface under a stereomicroscope. The mean bond strengths of the specimens were statistically analyzed using one-way ANOVA and Duncan's tests (α = 0.05).

RESULTS

Mean comparison of the μTBS showed no significant difference between LiSaE and LiSa (p > 0.05), but significant differences between LiSaE and other groups (p ≤ 0.01). No significant differences were found between the ZiSaLa and ZiSa groups (p > 0.05). The modes of failure in all groups were mostly adhesive (57% to 80%). The mean bond strengths in laser-irradiated ceramics were significantly lower than those from other surface treatments. All ZiLa specimens debonded before testing (pretest failure).

CONCLUSIONS

Lithium disilicate ceramic surface treated with a combination of sandblasting and silane application provided a bond strength comparable to that provided by sandblasting in combination with acid etching and applying silane. Groups treated with laser irradiation had significantly lower bond strengths than other groups.

Effect of thermocycling with or without 1 year of water storage on retentive strengths of luting cements for zirconia crowns

STATEMENT OF PROBLEM

Bond stability between zirconia crowns and luting cement and between cement and dentin is a main concern; however, only limited evidence is available as to its longevity.

PURPOSE

The purpose of this in vitro study was to measure the retentive strengths of 7 self-adhesive cements (RelyX Unicem Aplicap, RelyX Unicem Clicker, RelyX Unicem 2 Automix, iCEM, Maxcem Elite, Bifix SE, SpeedCem), 2 adhesive cements with self-etch primers (Panavia 21, SEcure), 1 glass ionomer cement (Ketac Cem), 1 resin-modified glass ionomer cement (Meron Plus), and 1 zinc phosphate cement for luting zirconia crowns (LAVA) to extracted teeth after thermocycling with or without 1 year of water storage.

MATERIAL AND METHODS

Two-hundred-forty extracted human molars (2 treatments; n=10 per cement) were prepared in a standardized manner. All cements were used according to the manufacturers' recommendations. The intaglios of the crowns were treated with airborne-particle abrasion. After thermocycling (×5000, 5°C/55°C) with or without 1 year of water storage, the cemented ceramic crowns were removed by using a Zwick universal testing device. Statistical analyses were done with the Wilcoxon rank sum and the 2-independent-samples Kolmogorov-Smirnov test.

RESULTS

Median retentive strengths [MPa] for specimens thermocycled only/thermocycled with 1 year of water storage were as follows: Panavia 21: 1.7/2.5, SEcure: 3.0/3.0, RelyX Unicem Aplicap: 3.1/3.4, RelyX Unicem Clicker: 4.1/4.2, RelyX Unicem 2 Automix: 3.8/3.1, iCEM: 2.3/2.7, Maxcem Elite: 3.0/3.2, Bifix SE: 1.7/1.7, SpeedCem: 1.3/1.6, Meron Plus: 3.1/2.7, Ketac Cem: 1.4/1.4, and zinc phosphate cement: 1.1/1.6. Statistically significant differences were found only among specimens thermocycled only or thermocycled with 1-year water storage (P<.001).

CONCLUSIONS

Significant differences in retentive strengths were observed among cements after thermocycling only or thermocycling with 1 year of water storage, but not for the effect of the additional 1 year of water storage.

The effect of thermal cycling on the shear bond strength of porcelain/Ti-6Al-4V interfaces

The aim of the study was to evaluate the effect of thermal cycling on the shear bond strength of the porcelain/Ti-6Al-4V interfaces prepared by two different processing routes and metallic surface conditions. Polished and SiO2 particle abraded Ti-6Al-4V alloy and Triceram bonder porcelain were used to produce the interfaces. Porcelain-to-metal specimens were processed by conventional furnace firing and hot pressing. Thermal cycling was performed in Fusayama's artificial saliva for 5000 cycles between 5 ± 1 and 60 ± 2°C. After thermal cycling, shear bond tests were carried out by using a custom-made stainless steel apparatus. The results were analyzed using t-Student test and non-parametric Kruskal-Wallis test (p<0.01). Most of the polished-fired specimens were fractured during thermal cycling; thus, it was not possible to obtain the shear bond strength results for this group. Sandblasted-fired, polished-hot pressed, and sandblasted-hot pressed specimens presented the shear bond strength values of 76.2 ± 15.9, 52.2 ± 23.6, and 59.9 ± 22.0 MPa, respectively. Statistical analysis indicated that thermal cycling affected the polished specimens processed by firing, whereas a significant difference was not observed on the other groups.

Novel zirconia surface treatments for enhanced osseointegration: laboratory characterization

Purpose. The aim of this study was to evaluate three novel surface treatments intended to improve osseointegration of zirconia implants: selective infiltration etching treatment (SIE), fusion sputtering (FS), and low pressure particle abrasion (LPPA). The effects of surface treatments on roughness, topography, hardness, and porosity of implants were also assessed. Materials and Methods. 45 zirconia discs (19 mm in diameter × 3 mm in thickness) received 3 different surface treatments: selective infiltration etching, low pressure particle abrasion with 30 µm alumina, and fusion sputtering while nontreated surface served as control. Surface roughness was evaluated quantitatively using profilometery, porosity was evaluated using mercury prosimetry, and Vickers microhardness was used to assess surface hardness. Surface topography was analyzed using scanning and atomic force microscopy (α = 0.05). Results. There were significant differences between all groups regarding surface roughness (F = 1678, P < 0.001), porosity (F = 3278, P < 0.001), and hardness (F = 1106.158, P < 0.001). Scanning and atomic force microscopy revealed a nanoporous surface characteristic of SIE, and FS resulted in the creation of surface microbeads, while LPPA resulted in limited abrasion of the surface. Conclusion. Within the limitations of the study, changes in surface characteristics and topography of zirconia implants have been observed after different surface treatment approaches. Thus possibilities for enhanced osseointegration could be additionally offered.

Effect of silica coating on bond strength between a gold alloy and metal bracket bonded with chemically cured resin

OBJECTIVE

The purpose of this study was to evaluate the effects of three different surface conditioning methods on the shear bond strength (SBS) of metal brackets bonded directly to gold alloy with chemically cured resin.

METHODS

Two hundred ten type III gold alloy specimens were randomly divided into six groups according to the combination of three different surface conditioning methods (aluminum oxide sandblasting only, application of a metal primer after aluminum oxide sandblasting, silica coating and silanation) and thermocycling (with thermocycling, without thermocycling). After performing surface conditioning of specimens in accordance with each experimental condition, metal brackets were bonded to all specimens using a chemically cured resin. The SBS was measured at the moment of bracket debonding, and the resin remnants on the specimen surface were evaluated using the adhesive remnant index.

RESULTS

Application of metal primer after aluminum oxide sandblasting yielded a higher bond strength than that with aluminum oxide sandblasting alone (p < 0.001), and silica coating and silanation yielded a higher bond strength than that with metal primer after aluminum oxide sandblasting (p < 0.001). There was no significant change in SBS after thermocycling in all groups.

CONCLUSIONS

With silica coating and silanation, clinically satisfactory bond strength can be attained when metal brackets are directly bonded to gold alloys using a chemically cured resin.

Intraoral treatment of veneering porcelain chipping of fixed dental restorations: a review and clinical application

BACKGROUND

Every dental ceramic system can experience failure of the veneering porcelain. However, the increasing popularity of all-ceramic crowns and fixed dental prostheses (FDPs) seems to have led to an increasing need to repair chipped veneering porcelain.

OBJECTIVES

The authors compared different methods to repair fractured ceramic restorations (porcelain-fused-to-metal and all-ceramic) and explain the basic principles of adhesion in these systems. They also evaluated the frequency and causes of failure in dental ceramic systems.

METHODS

This review is based on the results of PubMed and Google Scholar searches, as well as on a hand search of the scientific literature, resulting in 300 articles from 1977 to 2012. The authors used multiple key words (ceramic, repair, bonding, hydrofluoric acid, air abrasion, silane, phosphates, silicon dioxide) and different strategies (connecting different key words with OR, NOR and AND and truncation of the stem of words) to search the databases.

RESULTS

Because of differences in the material composition of ceramic systems (composed of metal, alumina or zirconia, glass-ceramics and feldspathic ceramics), different treatments are required for the exposed material surfaces after chipping. Use of hydrofluoric acid etching, air abrasion, tribochemical coating, silanization and metal primers or zirconia primers seem to be the most successful conditioning methods for durable bonding and repair.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Intraoral repair of a restoration offers a satisfying option for the patient when the restoration cannot be removed or replaced. Its success depends largely on the conditioning methods used for the fractured surfaces.

Effect of Artificial Aging and Surface Treatment on Bond Strengths to Dental Zirconia

The objective of this project was to study the influence of artificial aging and surface treatment on the microtensile bond strengths (μTBS) between zirconia and a phosphate monomer–based self-adhesive cement. Thirty zirconia disks (IPS e.max ZirCAD, Ivoclar Vivadent) were randomly assigned to two aging regimens: AR, used as received, which served as a control, and AG, artificial aging to simulate low-temperature degradation. Subsequently, the disks of each aging regimen were assigned to three surface treatments: NT, no surface treatment; CO, surface silicatization with CoJet sand (3M ESPE); and ZP, zirconia surface treated with Z-Prime Plus (Bisco Inc). Thirty discs were made of Filtek Z250 (3M ESPE) composite resin and luted to the zirconia discs using RelyX Unicem (3M ESPE). The specimens were sectioned with a diamond blade in X and Y directions to obtain bonded beams with a cross-section of 1.0 ± 0.2 mm. The beams were tested in tensile mode in a universal testing machine at a speed of 0.5 mm/min to measure μTBS. Selected beams were selected for fractographic analysis under the SEM. Statistical analysis was carried out with two-way analysis of variance and Dunnett T3 post hoc test at a significance level of 95%. The mean μTBS for the three AR subgroups (AR-NT, AR-CO, and AR-ZP) were significantly higher than those of the corresponding AG groups (p&lt;0.0001). Both AR-CO and AR-ZP resulted in statistically significant higher mean bond strengths than the group AR-NT (p&lt;0.006 and p&lt;0.0001, respectively). Both AG-CO and AG-ZP resulted in statistically significant higher mean bond strengths than the group AG-NT (both at p&lt;0.0001). Overall, AG decreased mean μTBS. Under the SEM, mixed failures showed residual cement attached to the zirconia side of the beams. CO resulted in a characteristic roughness of the zirconia surface. AR-ZP was the only group for which the amount of residual cement occupied at least 50% of the interface in mixed failures.

Characterizing ceramics and the interfacial adhesion to resin: II- the relationship of surface treatment, bond strength, interfacial toughness and fractography

The clinical success of resin bonding procedures for indirect ceramic restorations and ceramic repairs depends on the quality and durability of the bond between the ceramic and the resin. The quality of this bond will depend upon the bonding mechanisms that are controlled in part by the surface treatment that promote micromechanical and/or chemical bonding to the substrate. The objective of this review is to correlate interfacial toughness (K A) with fracture surface morphological parameters of the dental ceramic-resin systems as a function of ceramic surface treatment. This analysis is designed to identify mechanisms that promote adhesion of these ceramic-resin systems and an appropriate bond test method to yield relevant adhesion performance data.

Composite Resin to Yttria Stabilized Tetragonal Zirconia Polycrystal Bonding: Comparison of Repair Methods

Purpose

The purpose of the current study was to evaluate different approaches for bonding composite to the surface of yttria stabilized tetragonal zirconia polycrystal (Y-TZP) ceramics.

Methods

One hundred Y-TZP blocks were embedded in acrylic resin, had the free surface polished, and were randomly divided into 10 groups (n=10). The tested repair approaches included four surface treatments: tribochemical silica coating (TBS), methacryloxydecyldihidrogenphosphate (MDP)–containing primer/silane, sandblasting, and metal/zirconia primer. Alcohol cleaning was used as a “no treatment” control. Surface treatment was followed by the application (or lack thereof) of an MDP-containing resin cement liner. Subsequently, a composite resin was applied to the ceramic surface using a cylindrical mold (4-mm diameter). After aging for 60 days in water storage, including 6000 thermal cycles, the specimens were submitted to a shear test. Analysis of variance and the Tukey test were used for statistical analyses (α=0.05).

Results

Surface treatment was a statistically significant factor (F=85.42; p&lt;0.0001). The application of the MDP-containing liner had no effect on bond strength (p=0.1017). TBS was the only treatment that had a significantly positive effect on bond strength after aging.

Conclusion

Considering the evaluated approaches, TBS seems to be the best surface treatment for Y-TZP composite repairs. The use of an MDP-containing liner between the composite and Y-TZP surfaces is not effective.

Effects of silica coating and silane surface conditioning on the bond strength of rebonded metal and ceramic brackets

Objective

The aim of this study was to evaluate the effects of tribochemical silica coating and silane surface conditioning on the bond strength of rebonded metal and ceramic brackets.

Material and Methods

Twenty debonded metal and 20 debonded ceramic brackets were randomly assigned to receive one of the following surface treatments (n=10 for each group): (1) sandblasting (control); (2) tribochemical silica coating combined with silane. Brackets were rebonded to the enamel surface on the labial and lingual sides of premolars with a light-polymerized resin composite. All specimens were stored in distilled water for 1 week and then thermocycled (5,000 cycles) between 5-55°C. Shear bond strength values were measured using a universal testing machine. Student's t-test was used to compare the data (α=0.05). Failure mode was assessed using a stereomicroscope, and the treated and non-treated bracket surfaces were observed by scanning electron microscopy.

Results

Rebonded ceramic brackets treated with silica coating followed by silanization had significantly greater bond strength values (17.7±4.4 MPa) than the sandblasting group (2.4±0.8 MPa, P<0.001). No significant difference was observed between the rebonded metal brackets treated with silica coating with silanization (15±3.9 MPa) and the sandblasted brackets (13.6±3.9 MPa). Treated rebonded ceramic specimens primarily exhibited cohesive failure in resin and adhesive failure at the enamel-adhesive interface.

Conclusions

In comparison to sandblasting, silica coating with aluminum trioxide particles followed by silanization resulted in higher bond strengths of rebonded ceramic brackets.

Effect of silica coating combined to a MDP-based primer on the resin bond to Y-TZP ceramic

The aim of this study was to evaluate the influence of silica coating and 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-based primer applications upon the bonding durability of a MDP-based resin cement to a yttrium stabilized tetragonal zirconia (Y-TZP) ceramic. Ninety-six Y-TZP tabs were embedded in an acrylic resin (free surface for adhesion: 5 × 5 mm(2)), ground finished and randomly divided into four groups (N = 24) according to the ceramic surface conditioning: (1) cleaning with isopropanol (ALC); (2) ALC + phosphoric acid etching + MDP-based primer application (MDP-primer); (3) silica coating + 3-methacryloyloxypropyl trimethoxysilane (MPS)-based coupling agent application (SiO2 + MPS-Sil); and (4) SiO2 + MDP-primer. The MDP-based resin cement was applied on the treated surface using a cylindrical mold (diameter= 3 mm). Half of the specimens from each surface conditioning were stored in distilled water (37 °C, 24 h) before testing. Another half of the specimens were stored (90 days) and thermo-cycled (12,000 x) during this period (90 d/TC) before testing. A shear bond strength (SBS) test was performed at a crosshead speed of 0.5 mm/min. Two factors composed the experimental design: ceramic conditioning strategy (in four levels) and storage condition (in two levels), totaling eight groups. After 90 d/TC (Tukey; p < 0.05), SiO2 + MDP-primer (24.40 MPa) promoted the highest SBS. The ALC and MDP-primer groups debonded spontaneously during 90 d/TC. Bonding values were higher and more stable in the SiO2 groups. The use of MDP-primer after silica coating increased the bond strength.

Adhesion/cementation to zirconia and other non-silicate ceramics: where are we now?

Non-silicate ceramics, especially zirconia, have become a topic of great interest in the field of prosthetic and implant dentistry. A clinical problem with use of zirconia-based components is the difficulty in achieving suitable adhesion with intended synthetic substrates or natural tissues. Traditional adhesive techniques used with silica-based ceramics do not work effectively with zirconia. Currently, several technologies are being utilized clinically to address this problem, and other approaches are under investigation. Most focus on surface modification of the inert surfaces of high strength ceramics. The ability to chemically functionalize the surface of zirconia appears to be critical in achieving adhesive bonding. This review will focus on currently available approaches as well as new advanced technologies to address this problem.

Adhesive Quality of Self-adhesive and Conventional Adhesive Resin Cement to Y-TZP Ceramic Before and After Aging Conditions

Chairside tribochemical silica coating and silanization on the YTZP surface appears to be essential to adhere this substrate to resin cements. Cleaning with isopropanol promotes weak and unstable resin adhesion.

Bond strength of resin cement to yttrium-stabilized tetragonal zirconia ceramic treated with air abrasion, silica coating, and laser irradiation

OBJECTIVE

The purpose of this study was to evaluate the shear bond strength of a resin cement to yttrium-stabilized tetragonal zirconia (Y-TZP) surfaces treated with air abrasion, silica coating, or CO(2), Er:YAG, or Nd:YAG laser irradiation, or irradiated by each laser after air abrasion.

BACKGROUND DATA

Optimized methods are needed to improve the adhesive bonding between resin cement and Y-TZP ceramic.

METHODS

Twelve specimens were irradiated with each laser at different parameters and examined by scanning electron microscopy to determine which parameters to use in this study. One hundred forty-one Y-TZP discs were assigned to nine groups: C, no treatment; AA, air abrasion; CJ, silica coating; ER, Er:YAG laser; ND, Nd:YAG laser; CO, CO(2) laser; AA+ER, air abrasion + Er:YAG laser; AA+ND, air abrasion + Nd:YAG laser; AA+CO, air abrasion + CO(2) laser. The composite cylinders were fabricated. After the surface treatments, the specimens were silanized and composite cylinders were cemented with the resin cement. The shear bond strength test was performed after specimens were stored in water for 24 h and after thermocycling for 500 cycles.

RESULTS

The highest bond strength was obtained in the AA group and was similar to that of the CJ group. In C, ER, CO, ND, AA+ND, and AA+CO groups, the shear bond strengths were similar to each other according to the Duncan test results. The lowest bond value was obtained in the AA+ER group.

CONCLUSION

Although air abrasion and silica coating were the most effective surface treatment methods, CO(2) and Er:YAG laser irradiation alone or Nd:YAG laser irradiation after air abrasion may be used as an alternative treatment method to increase the bond strength between resin cement and Y-TZP material.

Direct comparison of the bond strength results of the different test methods: a critical literature review

OBJECTIVE

The goal of this paper is to undertake a literature search collecting all dentin bond strength data obtained for six adhesives with four tests (shear, microshear, tensile and microtensile) and to critically analyze the results with respect to average bond strength, coefficient of variation, mode of failure and product ranking.

METHOD

A PubMed search was carried out for the years between 1998 and 2009 identifying publications on bond strength measurements of resin composite to dentin using four tests: shear, tensile, microshear and microtensile. The six adhesive resins were selected covering three step systems (OptiBond FL, Scotch Bond Multi-Purpose Plus), two-step (Prime & Bond NT, Single Bond, Clearfil SE Bond) and one step (Adper Prompt L Pop).

RESULTS

Pooling results from 147 references showed an ongoing high scatter in the bond strength data regardless which adhesive and which bond test was used. Coefficients of variation remained high (20-50%) even with the microbond test. The reported modes of failure for all tests still included high number of cohesive failures. The ranking seemed to be dependant on the test used.

SIGNIFICANCE

The scatter in dentin bond strength data remains regardless which test is used confirming Finite Element Analysis predicting non-uniform stress distributions due to a number of geometrical, loading, material properties and specimens preparation variables. This reopens the question whether, an interfacial fracture mechanics approach to analyze the dentin-adhesive bond is not more appropriate for obtaining better agreement among dentin bond related papers.

Influence of simplified silica coating method on the bonding strength of resin cement to dental alloy

This study evaluated the effectiveness of a simplified silica coating method (CoJet System) on the bonding strength of resin cements to dental alloy. Bonding strength of the specimens treated with metal primer after alumina sandblasting was compared with those treated with silica coating and silane coupling agent after alumina sandblasting. Furthermore, the influence of silane coupling agent on bonding strength was compared between one-liquid and two-liquid silane coupling agents. Measurement of shear bond strength before and after thermal cycling revealed that the group treated with silica coating in one step without alumina sandblasting yielded high bonding strength. As for the influence of silane coupling agent, treatment with two-liquid silane coupling agent achieved higher mean shear bond strength than with one-liquid silane coupling agent. Findings in this study indicated that silicatization by means of this simplified silica coating method was effective in improving the bonding strength to dental alloy.

Effect of conditioning methods on the microtensile bond strength of phosphate monomer-based cement on zirconia ceramic in dry and aged conditions

The objective of this study was to evaluate the durability of bond strength between a resin cement and aluminous ceramic submitted to various surface conditioning methods. Twenty-four blocks (5 x 5 x 4 mm(3)) of a glass-infiltrated zirconia-alumina ceramic (In-Ceram Zirconia Classic) were randomly divided into three surface treatment groups: ST1-Air-abrasion with 110-mum Al2O3 particles + silanization; ST2-Laboratory tribochemical silica coating method (110-microm Al2O3, 110-microm silica) (Rocatec) + silanization; ST3-Chairside tribochemical silica coating method (30-microm SiO(x)) (CoJet) + silanization. Each treated ceramic block was placed in its silicone mold with the treated surface exposed. The resin cement (Panavia F) was prepared and injected into the mold over the treated surface. Specimens were sectioned to achieve nontrimmed bar specimens (14 sp/block) that were randomly divided into two conditions: (a) Dry-microtensile test after sectioning; (b) Thermocycling (TC)-(6,000x, 5-55 degrees C) and water storage (150 days). Thus, six experimental groups were obtained (n = 50): Gr1-ST1 + dry; Gr2-ST1 + TC(;) Gr3-ST2 + dry; Gr4-ST2 + TC; Gr5-ST3 + dry; Gr6-ST3 + TC. After microtensile testing, the failure types were noted. ST2 (25.1 +/- 11) and ST3 (24.1 +/- 7.4) presented statistically higher bond strength (MPa) than that of ST1 (17.5 +/- 8) regardless of aging conditions (p < 0.0001). While Gr2 revealed the lowest results (13.3 +/- 6.4), the other groups (21.7 +/- 7.4-25. 9 +/- 9.1) showed statistically no significant differences (two-way ANOVA and Tukey's test, alpha = 0.05). The majority of the failures were mixed (82%) followed by adhesive failures (18%). Gr2 presented significantly higher incidence of ADHESIVE failures (54%) than those of other groups (p = 0.0001). Both laboratory and chairside silica coating plus silanization showed durable bond strength. After aging, air-abrasion with 110-microm Al(2)O(3) + silanization showed the largest decrease indicating that aging is fundamental for bond strength testing for acid-resistant zirconia ceramics in order to estimate their long-term performance in the mouth.

Effect of operating air pressure on tribochemical silica-coating

OBJECTIVE

Alumina and zirconia are inert to conventional etching and need to be initially conditioned with, for example, silicatization. The aim of the present study was to evaluate the effect of operating air pressure of tribochemical silica-coating method on the shear bond strength of composite resin to ceramic substrates.

MATERIAL AND METHODS

Alumina (Procera Alumina, Nobel Biocare) and zirconia (LAVA; 3M ESPE and Procera Zirconia; Nobel Biocare) were airborne particle silica-coated (CoJet; 3M ESPE) using selected, clinically available air pressures of 150, 220, 300, and 450 kPa. The surfaces were silanized with silane coupling agent (ESPE Sil; 3M ESPE) and coated with adhesive resin (3M Multipurpose resin; 3M ESPE). Particulate filler resin composite (Z250; 3M ESPE) stubs (diameter 3.6 mm, height 4.0 mm) were added onto ceramics and light-cured for 40 s. The test specimens (n=18/group) were thermocycled (6000 x 5-55 degrees C) and shear bond strengths were measured with a cross-head speed of 1.0 mm/min. Fracture surfaces were examined with SEM, and an elemental analysis (EDS) was carried out to determine silica content on the substrate surface.

RESULTS

The highest bond strengths were obtained with the highest pressures. ANOVA showed significant differences in bond strength between the ceramics (p<0.05) and between the specimens treated at various air pressures (p<0.05).

CONCLUSIONS

Clinically, the operating air pressure of silicatization may have a significant effect on bond strength to non-etchable ceramics.

Adhesives with different pHs: effect on the MTBS of chemically activated and light-activated composites to human dentin

PURPOSE

To evaluate the bond strength between human dentin and composites, using two light-activated single-bottle total-etch adhesive systems with different pHs combined with chemically activated and light-activated-composites. The tested hypothesis was that the dentin bond strength is not influenced by an adhesive system of low pH, combined with chemically activated or light-activated composites.

MATERIAL AND METHOD

Flat dentin surfaces of twenty-eight human third molars were allocated in 4 groups (n=7), depending on the adhesive system: (One Step Plus-OS and Prime & Bond NT-PB) and composite (light-activated Filtek Z-100 [Z100] and chemically activated Bisfil 2B [B2B]). Each adhesive system was applied on acid-etched dentin and then one of the composites was added to form a 5 mm-high resin block. The specimens were stored in tap water (37 degrees C/24 h) and sectioned into two axes, x and y. This was done with a diamond disk under coolant irrigation to obtain beams with a cross-section area of approximately 0.8 mm(2). Each specimen was then attached to a custom-made device and submitted to the microtensile test (1 mm*min-1). Data were analyzed using two-way ANOVA and Tukey's tests (p<0.05).

RESULTS

The anticipated hypothesis was not confirmed (p<0.0001). The bond strengths (MPa) were not statistically different between the two adhesive systems when light-activated composite was used (OS+Z100 = 24.7+/-7.1 feminine; PB+Z100 = 23.8+/-5.7 feminine). However, with use of the chemically activated composite (B2B), PB (7.8+/-3.6b MPa) showed significantly lower dentin bond strengths than OS (32.2+/-7.6 feminine).

CONCLUSION

The low pH of the adhesive system can affect the bond of chemically activated composite to dentin. On the other hand, under the present conditions, the low pH did not seem to affect the bond of light-activated composites to dentin significantly.

Characterization and surface treatment effects on topography of a glass-infiltrated alumina/zirconia-reinforced ceramic

OBJECTIVE

Characterize the microstructure, composition and some physical properties of a glass-infiltrated alumina/zirconia-reinforced ceramic (IZ) and the effect of surface treatment on topography.

METHODS

IZ ceramic specimens were fabricated according to ISO6872 instructions and polished through 1 microm alumina abrasive. Quantitative and qualitative analyses were performed using scanning electron microscopy (SEM), backscattered imaging (BSI), electron dispersive spectroscopy (EDS) and stereology. The elastic modulus (E) and Poisson's ratio (nu) were determined using ultrasonic waves, and the density (rho) using a helium pycnometer. The following ceramic surface treatments were used: AP-as-polished; HF-etching with 9.5% hydrofluoric acid for 90 s; SB-sandblasting with 25 microm aluminum oxide particles for 15s and SC-blasting with 30 microm aluminum oxide particles modified by silica (silica coating) for 15s. An optical profilometer was used to examine the surface roughness (Ra) and SEM-EDS were used to measure the amount of silica after all treatments.

RESULTS

The IZ mean property values were as follows: rho=4.45+/-0.01 g/cm(3); nu=0.26 and E=245 GPa. Mean Ra values were similar for AP- and HF-treated IZ but significantly increased after either SC or SB treatment (p<or=0.05). The surface concentration of Si(K) increased 76% after SC treatment.

SIGNIFICANCE

HF is an inadequate surface treatment for bonding resins to IZ ceramic. Treating IZ with either SB or SC produced greater Ra values and the SC showed a significant increase in the surface concentration of silica, which may enhance bonding to resin via silane coupling.

Effect of zirconium-oxide ceramic surface treatments on the bond strength to adhesive resin

STATEMENT OF PROBLEM

Surface treatment methods used for resin bonding to conventional silica-based dental ceramics are not reliable for zirconium-oxide ceramics.

PURPOSE

The aim of this study was to compare the effects of airborne-particle abrasion, silanization, tribochemical silica coating, and a combination of bonding/silane coupling agent surface treatment methods on the bond strength of zirconium-oxide ceramic to a resin luting agent.

MATERIAL AND METHODS

Sixty square-shaped (5 x 5 x 1.5 mm) zirconium-oxide ceramic (Cercon) specimens and composite resin (Z-250) cylinders (3 x 3 mm) were prepared. The ceramic surfaces were airborne-particle abraded with 125-microm aluminum-oxide (Al(2)O(3)) particles and then divided into 6 groups (n = 10) that were subsequently treated as follows: Group C, no treatment (control); Group SIL, silanized with a silane coupling agent (Clearfil Porcelain Bond Activator); Group BSIL, application of the adhesive 10-methacryloyloxydecyl dihydrogen phosphate monomer (MDP)-containing bonding/silane coupling agent mixture (Clearfil Liner Bond 2V/ Porcelain Bond Activator); Group SC, silica coating using 30-microm Al(2)O(3) particles modified by silica (CoJet System); Group SCSIL, silica coating and silanization (CoJet System); and Group SCBSIL, silica coating and application of an MDP-containing bonding/silane coupling agent mixture (Clearfil Liner Bond 2V/Porcelain Bond Activator). The composite resin cylinders were bonded to the treated ceramic surfaces using an adhesive phosphate monomer-containing resin luting agent (Panavia F). After the specimens were stored in distilled water at 37 degrees C for 24 hours, their shear bonding strength was tested using a universal testing machine at a crosshead speed of 0.5 mm/min. Debonded specimen surfaces were examined with a stereomicroscope to assess the mode of failure, and the treated surfaces were observed by scanning electron microscopy. Bond strength data were analyzed using 1-way analysis of variance and the Duncan test (alpha = .05).

RESULTS

The bond strengths (mean +/- SD; MPa) in the groups were as follows: Group C, 15.7 +/- 2.9; Group SIL, 16.5 +/- 3.4; Group BSIL, 18.8 +/- 2.8; Group SC, 21.6 +/- 3.6; Group SCSIL, 21.9 +/- 3.9; and Group SCBSIL, 22.9 +/- 3.1. The bond strength was significantly higher in Group SCBSIL than in Groups C, SIL, and BSIL (P<.001), but did not differ significantly from those in Groups SC and SCSIL. Failure modes were primarily adhesive at the interface between zirconium and the resin luting agent in Groups C and SIL, and primarily mixed and cohesive in Groups SC, SCSIL, and SCBSIL.

CONCLUSION

Tribochemical silica coating (CoJet System) and the application of an MDP-containing bonding/silane coupling agent mixture increased the shear bond strength between zirconium-oxide ceramic and resin luting agent (Panavia F).

Shear bond strength of metal-ceramic repair systems

STATEMENT OF PROBLEM

When clinical fractures of the ceramic veneer on metal-ceramic prostheses can be repaired, the need for remake may be eliminated or postponed. Many different ceramic repair materials are available, and bond strength data are necessary for predicting the success of a given repair system.

PURPOSE

This study evaluated the shear bond strength of different repair systems for metal-ceramic restorations applied on metal and porcelain.

MATERIAL AND METHODS

Fifty cylindrical specimens (9 x 3 mm) were fabricated in a nickel-chromium alloy (Vera Bond II) and 50 in feldspathic porcelain (Noritake). Metal (M) and porcelain (P) specimens were embedded in a polyvinyl chloride (PVC) ring and received 1 of the following bonding and resin composite repair systems (n=10): Clearfil SE Bond/Clearfil AP-X (CL), Bistite II DC/Palfique (BT), CoJet Sand/Z100 (CJ), Scotchbond Multipurpose Plus/Z100 (SB) (control group), or CoJet Sand plus Scotchbond Multipurpose Plus/Z100 (CJSB). The specimens were stored in distilled water for 24 hours at 37 degrees C, thermal cycled (1000 cycles at 5 degrees C to 55 degrees C), and stored at 37 degrees C for 8 days. Shear bond tests between the metal or ceramic specimens and repair systems were performed in a mechanical testing machine with a crosshead speed of 0.5 mm/min. Mean shear bond strength values (MPa) were submitted to 1-way ANOVA and Tukey honestly significant difference tests (alpha=.05). Each specimen was examined under a stereoscopic lens with x30 magnification, and mode of failure was classified as adhesive, cohesive, or a combination.

RESULTS

On metal, the mean shear bond strength values for the groups were as follows: MCL, 18.40 +/- 2.88(b); MBT, 8.57 +/- 1.00(d); MCJ, 25.24 +/- 3.46(a); MSB, 16.26 +/- 3.09(bc); and MCJSB, 13.11 +/- 1.24(c). On porcelain, the mean shear bond strength values of each group were as follows: PCL, 16.91 +/- 2.22(b); PBT, 18.04 +/- 3.23(ab); PCJ, 19.54 +/- 3.77(ab); PSB, 21.05 +/- 3.22(a); and PCJSB, 16.18 +/- 1.71(b). Within each substrate, identical superscript letters denote no significant differences among groups.

CONCLUSIONS

The bond strength for the metal substrate was significantly higher using the CJ system. For porcelain, SB, CJ, and BT systems showed the highest shear bond strength values, and only SB was significantly different compared to CL and CJSB (P<.05).

CLINICAL IMPLICATIONS

This study suggests that when fracture involves only feldspathic porcelain, any of the evaluated systems may be used, since the fracture occurred on the porcelain substrate and not on the bond interface of porcelain-restorative material. However, for the nickel-chromium alloy tested, the CoJet Sand system showed the best results for repair.

In vitro retentive strength of zirconium oxide ceramic crowns using different luting agents

STATEMENT OF PROBLEM

In contrast to gold crowns, in vitro determination of the retentive strength of all-ceramic crowns is more difficult because components allowing connection to testing apparatus are not as easily integrated into the all-ceramic material. Nevertheless, retentive strength data are crucial for obtaining information about the potential clinical performance of luting cements for all-ceramic restorations. Therefore, a new in vitro model was necessary to evaluate the retentive strength of all-ceramic crowns.

PURPOSE

The purpose of this in vitro study was to determine the retentive strength of 4 resin-cement systems, a compomer, a glass-ionomer cement, a resin-modified glass-ionomer cement, and a self-adhesive resin for luting zirconium oxide ceramic crowns.

MATERIAL AND METHODS

One-hundred-twenty extracted human teeth were randomly divided into 12 groups (n = 10) and prepared in a standardized manner (5-degree taper, 3-mm occlusogingival height). All-ceramic crowns (Lava) were fabricated in a standardized manner for each tooth. The following cements and corresponding bonding regimens were used to lute the crowns to the teeth according to manufacturers' recommendations: CO, Compolute/EBS Multi; CO/RT, Compolute/EBS Multi/Rocatec; CB, Superbond C and B; CB/RT, Superbond C and B/Rocatec; CB/PL, Superbond C&B/Porcelain Liner M; PA, Panavia F; DC, Dyract Cem Plus/Xeno III; CH/PL, Chemiace II/Porcelain Liner M; RL, RelyX Luting, K/C, Ketac Cem/Ketac Conditioner; K, Ketac Cem; and RU, RelyX Unicem. After thermal cycling (5000 cycles, 5 degrees C-55 degrees C), the outer surfaces of the cemented zirconium oxide ceramic crowns were treated (Rocatec) to improve bonding and then placed into a low-shrinkage epoxy resin block (Paladur). The block/crown and tooth components for each specimen were connected to opposing ends of a universal testing machine so that crown retention could be measured. Crowns were removed from teeth along their path of insertion. The retentive surface area (mm 2 ) was determined individually for each tooth. Statistical analyses were performed using the Wilcoxon exact test, (alpha =.05) and a Bonferroni correction (alpha =.001).

RESULTS

The median (minimum/maximum) retentive strength values (MPa) were as follows: CO, 1.7 (0.6/4.3); CO/RT, 3.0 (1.3/5.4); CB, 4.8 (3.7/7.9); CB/RT, 8.1 (4.2/12.7); CB/PL, 5.3 (3.7/10.2); PA, 4.0 (3.3/5.1); DC, 3.3 (2.1/5.6); CH/PL, 4.0 (1.3/6.3); RL, 4.7 (2.8/6.6); K/C, 1.8 (0.6/2.3); K, 1.9 (0.2/4.5); and RU, 4.8 (2.5/6.7). Superbond C&B (+ Rocatec) specimens showed the highest median retentive strength, but were not significantly different from Superbond C&B without Rocatec pretreatment of the all-ceramic crown's inner surface. Compolute specimens also did not benefit significantly from the Rocatec pretreatment. Within the materials used without pretreatment of the ceramic, Superbond C&B, Panavia, Dyract Cem Plus, RelyX Luting, and RelyX Unicem showed the highest median retentive strength values and were not significantly different.

CONCLUSION

Within the conditions of this study, the compomer-cement, the resin-modified glass-ionomer cement, and the self-adhesive resin luting agent had the same level of retentive quality as the resin luting agents, Superbond C&B, and Panavia. Rocatec pretreatment of the ceramic surface did not improve the retentive strengths of Compolute and Superbond C&B.

The effect of ceramic surface treatment on bonding to densely sintered alumina ceramic

STATEMENT OF PROBLEM

Ceramic surface treatment is crucial for bonding to resin. High crystalline ceramics are poorly conditioned using traditional procedures.

PURPOSE

The purpose of this study was to evaluate the effect of silica coating on a densely sintered alumina ceramic relative to its bond strength to composite, using a resin luting agent. Material and methods Blocks (6 x 6 x 5 mm) of ceramic and composite were made. The ceramic (Procera AllCeram) surfaces were polished, and the blocks were divided into 3 groups (n = 5): SB, airborne-particle abrasion with 110-microm Al 2 O 3 ; RS, silica coating using Rocatec System; and CS, silica coating using CoJet System. The treated ceramic blocks were luted to the composite (W3D Master) blocks using a resin luting agent (Panavia F). Specimens were stored in distilled water at 37 degrees C for 7 days and then cut in 2 axes, x and y, to obtain specimens with a bonding area of approximately 0.6 mm 2 (n = 30). The specimens were loaded to failure in tension in a universal testing machine, and data were statistically analyzed using a randomized complete block design analysis of variance and Tukey's test (alpha=.05). Fractured surfaces were examined using light microscopy and scanning electron microscopy to determine the type of failure. Energy-dispersive spectroscopy was used for surface compositional analysis.

RESULTS

Mean bond strength values (MPa) of Groups RS (17.1 +/- 3.9) ( P =.00015) and CS (18.5 +/- 4.7) ( P =.00012) were significantly higher than the values of Group SB (12.7 +/- 2.6). There was no statistical difference between Groups RS and CS. All failures occurred at the adhesive zone.

CONCLUSION

Tribochemical silica coating systems increased the tensile bond strength values between Panavia F and Procera AllCeram ceramic.

Shear bond strength of aesthetic materials bonded to Ni-Cr alloy

OBJECTIVES

This study was undertaken to evaluate the shear bond strength of four materials used as aesthetic material bonded to Ni-Cr alloy.

METHODS

Sixty-eight alloy discs were prepared and divided equally into four groups, and received four treatments for veneering: conventional feldspathic porcelain (Noritake EX-3) and three light-cured prosthodontic composite resins (Artglass, Solidex and Targis). The aesthetic materials were applied after metal structure conditioning in accordance with the manufacturers' recommendations. The specimens were stored in distilled water at 37 degrees C for 7 days. A universal testing machine was used to measure the shear bond strength of the specimens at a cross head speed of 0.5 mm/min. Fractured specimens were examined by using both optical and scanning electron microscope.

RESULTS

The analysis of variance and Tukey's test showed that the strongest mean shear bond was obtained with Noritake EX-3 (mean shear bond strength 42.90+/-7.82 MPa). For composites, the highest mean shear bond strength was observed for Targis (12.30+/-1.57 MPa); followed by Solidex (11.94+/-1.04 MPa) and Artglass (10.04+/-0.75 MPa). Optical analysis of the fractured surfaces indicated that for Targis and Noritake EX-3 all failures were a mixture of both cohesive and adhesive patterns. As for Artglass and Solidex, the fractures were mainly adhesive in nature.

CONCLUSIONS

The Solidex system was equivalent to the Targis system in bond strength and exhibited greater strength than the Artglass system. The porcelain fused-to-metal showed considerably higher shear bond strength than the three metal-resin bonding techniques.

Resin-ceramic bonding: a review of the literature

Current ceramic materials offer preferred optical properties for highly esthetic restorations. The inherent brittleness of some ceramic materials, specific treatment modalities, and certain clinical situations require resin bonding of the completed ceramic restoration to the supporting tooth structures for long-term clinical success. This article presents a literature review on the resin bond to dental ceramics. A PubMed database search was conducted for in vitro studies pertaining to the resin bond to ceramic materials. The search was limited to peer-reviewed articles published in English between 1966 and 2001. Although the resin bond to silica-based ceramics is well researched and documented, few in vitro studies on the resin bond to high-strength ceramic materials were identified. Available data suggest that resin bonding to these materials is less predictable and requires substantially different bonding methods than to silica-based ceramics. Further in vitro studies, as well as controlled clinical trials, are needed.

Conference report. Direct adhesive materials: current perceptions and evidence--future solutions

This paper reports the proceedings, including the consensus views of an Australasian expert group convened to consider current perceptions, evidence and future solutions in the field of direct adhesive materials. This group, in anticipating a trend to preservative dentistry, formed the view that caries risk assessment should increasingly influence the selection of restorative materials. In low caries risk patients, aesthetic demands typically favour the use of resin-based composites. Interactive (biomimetic) materials based on glass-ionomer chemistry have particular application in high caries risk patients. Teaching in dental schools, continuing education programmes and research, both in the laboratory and in the clinical environment should be more attuned to the ever-increasing use of tooth-coloured restorative materials in everyday clinical practice. Linked to this trend are changes in patient--dentist relationships, whereby patients should be encouraged to become more involved in treatment decision-making. Expert group meetings are suggested to be of value in addressing some of the shortfall between the need for good evidence and the relentless challenge of the introduction of new products and concepts in the field of direct adhesive materials.