The role of functional phosphoric acid ester monomers in the surface treatment of yttria-stabilized tetragonal zirconia polycrystals

Bonding affinity and durability of recycled zirconia

STATEMENT OF PROBLEM

While repurposing waste materials into zirconia blocks presents a promising avenue, uncertainty remains regarding whether the bonding properties of recycled zirconia align with those of commercially available zirconia.

PURPOSE

The purpose of this in vitro study was to evaluate the bonding affinity and durability of composite resin to recycled zirconia.

MATERIAL AND METHODS

A series of processing steps were performed with recycled zirconia residuals (Lava Plus; 3M Oral Care), including pulverization, sieving, heating, compaction, isostatic pressing, and presintering. The presintered blocks of recycled zirconia (Group R) and commercially available zirconia (Group C) were sectioned and sintered to create test specimens (10×10×1.5 mm). After polishing and airborne-particle abrasion, specimens within each group were bonded to composite resin cylinders using a resin cement (Multilink Speed; Ivoclar AG). The specimens were then divided into 3 subgroups for shear bond strength (SBS) testing: no further treatment, 10 000 thermocycles, and 30 000 thermocycles (n=10). X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), surface roughness, and contact angle were used to analyze the surface physicochemical differences between Groups C and R. Data were analyzed with 2-way ANOVA followed by the Tukey post hoc test for SBS values, Pearson chi-squared test for failure modes, and independent t test for grain size, surface roughness, and wettability (α=.05).

RESULTS

No significant difference was found in the SBS values between Group R and Group C (P=.403), while thermocycling significantly affected the SBS values (P<.05). Group R showed significantly greater Ra, Rz, and Rq values (P<.05) than did Group C. SEM analysis revealed that Group R exhibited more prominent grooves than Group C, while the XRD and EDS patterns exhibited similarities in both the crystalline phase and elemental composition. No significant difference was observed in the water contact angle between the 2 groups (P=.196).

CONCLUSIONS

The bonding protocol established for commercially available zirconia was comparable with that of recycled zirconia, but both decreased after thermocycling. The recycling process did not affect the crystalline phase or elemental composition of the zirconia, but it induced alterations in the surface roughness.

Influence of Battery Levels in Cordless LED Light-curing Units on Properties of Resin Cement and Glass Fiber Post Retention

PURPOSE

This study aimed to assess the impact of battery levels in single-peak and multi-peak light-curing units (LCUs) on irradiance, and their effects on glass fiber post push-out bond strength to root dentin and the degree of conversion of dual-cure universal resin cement.

METHODS AND MATERIALS

Sixty bovine roots underwent endodontic treatment and were randomly distributed into 6 groups (n=10), formed by combining two LCUs (single-peak and multipeak) and three battery levels (100%, 50%, and 10%). A spectrophotometer measured irradiance (mW/ cm2) and spectral irradiance (mW/cm2/nm). Push-out bond strength (PBS) tests occurred at three root regions (cervical, middle, and apical), with optical and scanning electron microscopy for failure mode analysis. Degree of conversion (DC) was evaluated across the root regions. Data were analyzed using two-way repeated measures ANOVA and the Tukey HSD test. The Fisher exact test verified failure modes (α=0.05).

RESULTS

As multipeak LCU battery levels decreased, emitted irradiance also diminished, with notable PBS reductions in the apical thirds. Failure modes were influenced by different conditions, primarily exhibiting mixed modes. Battery levels significantly impacted DC in the multipeak LCU, particularly in the cervical region, while the single-peak LCU exhibited DC reduction at the 10% battery level in the cervical region.

CONCLUSIONS

Emitted irradiance, resin cement DC, and glass fiber post bond strength to root dentin may be influenced by varying cordless LCUs and battery levels.

Dentin Bonding Durability of Four Different Recently Introduced Self-Etch Adhesives

The objectives of this study were to evaluate the bonding durability of four different self-etch adhesives to dentin after 24 h and thermal cycling (TC) and to measure the degree of polymerization conversion (DC) in situ. Two-step self-etch adhesives, Clearfil SE Bond 2 (SE2, Kuraray Noritake Dental) and G2-Bond Universal (G2B, GC), and one-step self-etch adhesives, Scotchbond™ Universal Plus Adhesive (SBU, 3M ESPE) and Clearfil Universal Bond Quick (UBQ, Kuraray Noritake Dental), were used. The labial surfaces of bovine teeth were ground to create flat dentin surfaces. The adhesives were applied according to the manufacturers' instructions. After resin composite buildup and 24 h water storage, the specimens were sectioned into beams and all groups were subjected to thermal stress for 0, 10,000 (10k), or 20,000 (20k) cycles followed by micro-tensile bond strength (µTBS) testing. In situ DC was investigated with a laser Raman microscope. The µTBS data were statistically analyzed and subjected to a Weibull analysis. The different groups were compared at the characteristic strength (63.2% probability of failure) (α = 0.05). Two-Way ANOVA was used to show the effect of different adhesives and thermal cycling on the mean DC% followed by Tukey's multiple comparison post hoc test. G2B/TC10k resulted in a significant increase in the µTBS compared to TC0. SBU/TC20k showed significantly higher µTBS compared to TC0. For comparison between different tested adhesives, SBU showed a significantly lower µTBS compared to G2B after TC10k. G2B and SBU showed a greater number of adhesive failures after TC. Mean DC% was different for each adhesive. The newly developed MDP- and HEMA-free 2-SEA showed similar bonding performance with the gold-standard 2-SEA. However, there is still room for further improvement in terms of SEAs.

MDP-salts as an adhesion promoter with MDP-primers and self-adhesive resin cement for zirconia cementation

PURPOSE

To evaluate the effect of zirconia priming with MDP-Salt before MDP containing primers and self-adhesive cement on the shear bond strength.

MATERIALS AND METHODS

Fully sintered high translucent zirconia specimens (n = 120) were assigned into 2 groups (n = 60 each): Control (No Pretreatment) and Methacryloyloxydecyl dihydrogen phosphate salt (MDP-Salt) pretreated. Each group was divided into 3 subgroups (n = 20) according to cementation protocol: 1) MDP + Silane primer and conventional resin cement, 2) MDP+ Bisphenyl dimethacrylate (BPDM) primer and conventional resin cement, and 3) MDP containing self-adhesive resin cement. Shear bond strength (SBS) was measured after 10,000 thermocycling. Contact angle was measured for tested groups. Surface topography was assessed using a 3D confocal laser scanning microscope (CLSM). Weibull analysis was performed for SBS and one-way ANOVA for contact angle and surface topography measurements (α = 0.05).

RESULTS

The use of MDP-Salt significantly improved the SBS (p < .05) for all tested subgroups. Self-adhesive cement showed an insignificant difference with MDP + Silane group for both groups (p > .05). MDP + BPDM showed a significantly lower characteristic strength compared to self-adhesive resin cement when both were pretreated with MDP-Salt. No difference between all tested groups in the surface topographic measurements while MDP-Salt showed the highest contact angle.

CONCLUSION

MDP-Salt pretreatment can improve bonding performance between zirconia and MDP containing products.

Interaction of different concentrations of 10-MDP and GPDM on the zirconia bonding

OBJECTIVES

To analyze the influence of different concentrations of 10-MDP and GPDM used, combined or not, on the bonding to zirconia.

METHODS

Specimens of zirconia and a resin-composite (7 mm length, 1 mm width, and 1 mm thick) were obtained. The experimental groups were obtained according to the functional monomer (10-MDP and GPDM) and the concentrations (3 %, 5 %, and 8 %). For the groups with combined 10-MDP and GPDM, the agents were used with a proportion of 50 %/50 % wt until reaching the 3 %, 5 % and 8 % concentrations. All monomers were diluted in ethanol to obtain the primers. Two control groups were established: ethanol (negative control) and a commercial reference Monobond N (positive control). The zirconia surface treatment was performed with the primer application followed by the bonding to a resin-composite sample with a light-curing resin cement. Twenty-four hours after the adhesive procedure, a microtensile test was performed and the failure pattern of each sample was analysed with a stereoscopic magnifying glass. Data were analysed by a two-way ANOVA and Dunnet test.

RESULTS

All experimental primers presented a higher bond strength than the negative control (ethanol). Excepting the 8 % GPDM primer, all groups presented statistically similar bond strength compared to the positive control, with a predominance of adhesive failure.

SIGNIFICANCE

10-MDP, GPDM, and the combination of both for the concentrations tested promote an effective chemical bonding to zirconia. However, using 10-MDP and GPDM in the same primer has no synergistic effect.

Surface modifications of zirconia with plasma pretreatment and polydopamine coating to enhance the bond strength and durability between zirconia and titanium

The aim of this study was to assess the shear bond strength and durability between plasma-pretreated and polydopamine (PDA)-coated zirconia and titanium. Four groups were prepared according to the different surface treatments (untreated ZrO₂, plasma-pretreated ZrO₂, PDA-coated ZrO₂, and plasma-pretreated and PDA-coated ZrO₂ (PP+PDA-ZrO₂). The surface topography and roughness, contact angle, and elemental analysis of the coatings of the four groups were investigated, and the bond strength and durability of the specimens were evaluated based on shear bond strength and thermocycle tests. Physical and chemical characterization results confirmed that PDA coatings can be successfully formed on zirconia substrates. The roughness and hydrophilicity were significantly higher in the PP+PDA-ZrO₂ group_, which demonstrated better shear bond strength and durability between zirconia and titanium. The plasma pretreatment of zirconia substrates can enhance the stability of the PDA coating layer, and hybrid surface modifications can provide several bonding advantages for clinical use.

MDP Salts: A New Bonding Strategy for Zirconia

Durable resin-ceramic adhesion may influence the clinical success of ceramic restorations, which has been one of the challenging issues in dentistry. The present study assessed the bond strength and chemical interaction of 10-methacryloxydecyl dihydrogen phosphate (MDP), MDP+silane, and MDP-salt primers to alumina-blasted zirconia ceramic by tensile bond strength test, surface elemental composition with x-ray photoelectron spectroscopy analysis, contact angle measurement, surface morphology with scanning electron microscopy, and surface topography with 3-dimensional confocal laser scanning microscope analyses. MDP-salt showed the highest tensile bond strength before and after thermocycling when compared with MDP and MDP+silane (P < 0.05). The measured contact angle values differed significantly (P < 0.001) in the order of MDP-salt > control (no chemical pretreatment) > MDP+silane > MDP. There was no difference in surface roughness (P = 0.317) and surface topography among all tested groups. Zirconia treated with MDP-salt showed phosphorus peaks in addition to zirconia and alumina peaks. MDP-salt has zirconia priming properties, which improves bonding performance to resin cement.

Influence of 10-methacryloyloxydecyl dihydrogen phosphate (MDP) incorporated experimental cleaners on the bonding performance of saliva-contaminated zirconia ceramic

OBJECTIVES

To assess the efficacy of experimental cleaners containing 10-methacryloyloxydecyl dihydrogen phosphate (MDP) on the saliva decontamination of ceramic and their influence in restoring zirconia's adherence to resin cement.

MATERIALS AND METHODS

Four hundred sixty alumina-blasted zirconia specimens were categorized into saliva-contaminated and uncontaminated groups which were treated with ceramic primer (P), experimental cleaner 1 (C1), C1 followed by P (C1P), experimental cleaner 2 (C2), and C2 followed by P (C2P). Stainless-steel rods were then attached to the specimens using PanaviaV5 cement (Kuraray Noritake Dental; Tokyo, Japan). Tensile bond strength (TBS) test was performed after 24 h and 5000 thermocycling processes. X-ray photoelectron spectroscopy (XPS) analysis and contact angle measurement of the specimen were performed. The TBS data were analyzed by Weibull analysis and three-way ANOVA. Contact angle data were analyzed by two-way ANOVA (α = 0.05).

RESULTS

C2P groups showed the highest TBS in all conditions among tested groups. Saliva contamination led to a significant reduction of TBS in primer- and cleaner-treated groups, with no significant impact on C2P. Adhesive failure was predominant in contaminated groups except with the C1P and C2P groups. XPS revealed that a nitrogen peak was observed on contaminated groups but not in primed groups. The contact angle was significantly affected by saliva contamination, the cleaners, and/or ceramic primer usage (p < 0.001).

CONCLUSIONS

The MDP cleaner followed by the MDP primer protocol may overcome the effect of saliva contamination and improve the resin-ceramic bond strength.

CLINICAL RELEVANCE

It is recommended to use a combination of MDP-containing cleaner 2 and ceramic primer as a chair-side chemical pretreatment for zirconia substrate with or without saliva contamination.

Effect of Air-Abraded Versus Laser-Fused Fluorapatite Glass-Ceramics on Shear Bond Strength of Repair Materials to Zirconia

Zirconia repair could be a feasible alternative option to total replacement in fractured zirconia-based restorations. Maximising the bond strength by enriching zirconia with fluorapatite glass-ceramics (FGC) powder has been addressed and compared to other surface treatments. Besides resin composite, other repair materials have been proposed and compared. Zirconia blocks received different surface treatments (A-sandblasting with tribochemical silica-coated alumina (CoJet). B-sandblasting with FGC powder (FGC), C-fluorapatite glass-ceramic coat+ neodymium-doped yttrium aluminum garnet laser irradiation (FGC + Nd: YAG), and D-no surface treatment). The surface roughness, topography, and crystallinity were investigated by a profilometer, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses, respectively. For each surface treatment, three repair materials (feldspathic porcelain, lithium disilicate, and resin composite) were bonded to zirconia with 10, Methacryloyloxydecyl dihydrogen phosphate (MDP)-Monobond Plus/ Multilink Automix. Bonded specimens were thermocycled for 10,000 cycles and tested for shear bond strength (SBS) at a speed of 1 mm/min, followed by the analysis of the mode of failure. FGC + Nd: YAG laser group reported the highest surface roughness and monoclinic content compared to CoJet, FGC, and control groups. The highest mean SBS was found in FGC-blasted zirconia, followed by FGC + Nd: YAG laser and CoJet treated groups. However, the lowest SBS was found in control groups regardless of the repair material. Sandblasting zirconia with FGC powder increased SBS of resin to zirconia with lower monoclinic phase transformation compared to FGC + Nd: YAG or CoJet groups.

Influence of Hydrofluoric and Nitric Acid Pre-Treatment and Type of Adhesive Cement on Retention of Zirconia Crowns

Background: The aim of this study was to test the impact of hot acids etching and two types of adhesive cement on the retention of zirconia crowns. Methods: Forty maxillary premolars were prepared, and zirconia crowns were designed and fabricated with proximal extensions, then divided into 4 groups (n = 10). Group AP; the crowns were air-abraded and cemented using Panavia SA Cement. Group AL; the crowns were air- abraded and cemented using GC LinkForce. Group AHP; the crowns were air-abraded, etched with the hot acids (48% hydrofluoric acid and 69% nitric acid), and cemented using Panavia SA Cement. Group AHL; the crowns were air-abraded, etched with the hot acids, and cemented using GC LinkForce. Each zirconia crown was pre-treated and bonded to its corresponding tooth. After thermocycling (5–55 °C/10,000), the retention test was performed and the load required to dislodge the crown was reported in Newton (N), and mode of failure was recorded. The retention strength (MPa) was calculated for each tested variable and statistically analyzed. Results: Group AHP showed the highest mean value of the retention strength, followed by group AP then group AHL. Group AL showed the lowest value. A statistically significant effect (p = 0.001) of the hot acids etching on the retention of zirconia crown was found. Also, there was a significant effect (p = 0.000) of the cement type. The interaction between surface treatment and the cement type has no significant impact (p = 0.882). The main mode of failure for Panavia SA Cement is mixed mode of failure, while for G-CEM LinkForce is adhesive failure. Conclusions: Hot acid etching pre-treatment improved the retention of zirconia crown. Usage of Panavia SA Cement with hot acids etching is effective can be used for adhesive cementation of zirconia crown.

Effect of zirconia decontamination protocols on bond strength and surface wettability

OBJECTIVE

To evaluate the effects of human saliva decontamination protocols on bond strength of resin cement to zirconia (Y-PSZ), wettability, and microbial decontamination.

MATERIALS AND METHODS

Zirconia plates were sandblasted and divided into (a) not contaminated, (b) contaminated with human saliva and: (c) not cleaned, (d) cleaned with air-water spray, (e) cleaned with 70% ethanol, (f) cleaned with Ivoclean, or (g) cleaned with nonthermal atmospheric plasma (NTAP). The wettability and microbial decontamination of the surfaces were determined after saliva contamination or cleaning. Monobond Plus (Ivoclar Vivadent) was applied after cleaning, followed by Variolink LC (Ivoclar Vivadent). The samples were stored 1 week before shear bond strength (SBS) testing, and data (SBS and wettability) were analyzed by one-way analysis of variance and Tukey test (α = .05).

RESULTS

Saliva contamination reduced SBS to zirconia compared to not contaminated. Both Ivoclean and NTAP produced higher SBS compared to not cleaned and were not significantly different from the not contaminated. Ivoclean produced the highest contact angle, and NTAP the lowest. With the exception of using just water-spray, all cleaning protocols decontaminated the specimens.

CONCLUSIONS

Both Ivoclean and NTAP overcame the effects of saliva contamination, producing an SBS to zirconia comparable to the positive control.

CLINICAL SIGNIFICANCE

Dental ceramics should be cleaned prior to resin cementation to eliminate the effects of human saliva contamination, and Ivoclean and NTAP are considered suitable materials for this purpose.

Effects of alumina-blasting pressure on the bonding to super/ultra-translucent zirconia

OBJECTIVES

Translucent zirconia has brought the advantages such as less tooth preparation, biological compatibility, high strength, good mechanical properties, and less antagonist wear. This study's aim was to elucidate how clinically relevant surface treatments; alumina-abrasion and priming effect on bond strength of Y-PSZ in three different translucency grades after long-term water storage.

MATERIALS AND METHODS

Three highly translucent Y-PSZ grades were ground flat with #600-grit SiC paper. Four different surface treatments (untreated, alumina blasting at 0.1 MPa or 0.2 MPa or 0.4 MPa) and two resin cements (PANAVIA V5 and PANAVIA SA CEMENT PLUS AUTOMIX) were tested. The bonded specimens were stored in water for 1 day, 30 days and 150 days and tensile bond strength (TBS) were measured with universal testing machine at a crosshead speed of 2 mm/min (n=10). The surface roughness (Sa) measurement and surface morphology analysis without alumina-blasting pressure (untreated) and with alumina-blasting pressures (0.1 MPa, 0.2 MPa and 0.4 MPa) for three different zirconia grades were evaluated with 3D-Laser Scanning Confocal Microscope.

RESULTS

Different alumina-blasting pressures and different storage periods affected the bonding of resin cement to translucent zirconia. The Weibull moduli increased in some groups after 150 days storage. After 1 day and 30 days storage, 0.4 MPa alumina-blasting pressure provided superior bond strength, however, after 150 days, 0.2 MPa gave reliable and stable bond strength.

SIGNIFICANCE

Alumina-blasting pressure of 0.2 MPa was the most effective for reliable and durable bonding performance to translucent zirconia after long-term water storage.

Bonding of different self-adhesive resins to high-strength composite resin block treated with surface conditioning

PURPOSE

This study aimed to evaluate the effects of chemical conditioning and self-adhesive resins (SARs) on the bonding of mechanically conditioned high-strength composite resin block (HSCRB).

METHODS

Eighteen sections of HSCRB (KZR-CAD HR 3 Gammatheta, Yamakin) were treated with alumina air abrasion and randomly divided into 3 groups according to the SARs for bonding: RelyX Unicem 2 (RXU), SA Luting Plus (SAL), and G-Cem ONE (GCO). The sections were further divided into 3 subgroups according to the chemical conditioning of the adherend surfaces: no conditioning (C), universal adhesive (UA), and a mixture of γ-MPTS and 10-MDP (MM). After the surface conditioning, the sections were cemented with the SARs. Each cemented section was cut into 40 beams. Half of the beams were thermocycled (4°C/60°C, 10,000 cycles). The micro-tensile bond strength (μTBS) values were measured using a universal testing machine. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), contact angles, and surface roughness measurements were performed on the adherend surfaces of each subgroup.

RESULTS

RXU showed the highest μTBS values among the 3 SARs tested, while MM application exhibited the highest μTBS values among the 3 chemical conditioning methods tested. After thermocycling, the samples in the RXU/MM, RXU/UA, and GCO/MM groups showed no significant changes in the μTBS values, whereas the others showed a significant reduction.

CONCLUSIONS

The bond strength of HSCRB was influenced by the chemical conditioning, SARs, and aging. γ-MPTS and 10-MDP application yielded higher μTBS values of mechanically treated HSCRB than the UA.

Bond and topography evaluation of a Y-TZP ceramic with a superficial low-fusing porcelain glass layer after different hydrofluoric acid etching protocols

Abstract Introduction Despite being one of the most studied ceramics today, zirconia still does not have a well-defined adhesion protocol. Objective Evaluate the influence of different etching times and hydrofluoric acid (HF) concentrations on the zirconia surface and bond strength between a vitrified Y-TZP ceramic and a resin cement. Materials and method The zirconia surface treatments were: sandblasting with silica-coated alumina (Co); glaze application + 5% HF etching for 5s (G5-5s), 10s (G5-10s) or 20s (G5-20s); glaze application + 10% HF etching for 5s (G10-5s), 10 (G10-10s) or 20s (G10-20s) . Then, cement cylinders (3.3 × 3.3 mm) were built up for shear bond test on all specimens. The specimens were subjected to 6000 thermal cycling before the test. Fractures were analyzed by stereomicroscope. Data were statistically analyzed by Kruskal-Wallis and Dunn statistical tests (5%). Extra samples of each group were made to obtain profilometry and scanning electron microscopy (SEM). Result Zirconia-cement bond strength was affected by the ceramic surface treatments (p = 0.001). G10-5s (2.71 MPa) recorded the highest bond strength values, followed by the Co (2.05 MPa) while G5 groups had the lowest bond value. Adhesive failure of the samples predominated. The image analysis revealed G5 groups seem to have a lower roughness when compared to groups treated by 10% HF. The creation of pores in the low-fusing porcelain glass layer surface occurred only when 10% HF was used. Conclusion The low-fusing porcelain glass layer application was able to overcome the sandblasting and obtain a greater adhesive bond to the resinous cement, however, only when 10% HF was used for an interval of 5 seconds.

Effect of different times of nonthermal argon plasma treatment on the microtensile bond strength of self-adhesive resin cement to yttria-stabilized tetragonal zirconia polycrystal ceramic

STATEMENT OF PROBLEM

Nonthermal argon plasma may increase the surface energy of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) dental ceramics. However, studies that evaluated the effect of increased plasma treatment times on the bond strength of resin cements to Y-TZP ceramics are lacking.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of different nonthermal argon plasma (NTAP) treatment times on the surface energy and bond strength of a self-adhesive resin cement to Y-TZP ceramic.

MATERIAL AND METHODS

Forty-eighty Y-TZP plates were divided into 2 groups (n=24): as-sintered (AS) and airborne-particle abrasion (APA) with 50-μm Al₂O₃, which were subdivided into 4 groups (n=6) according to the time of NTAP treatment: 0, 20, 60, and 120 seconds. The surface energy was evaluated with a goniometer. Forty Y-TZP blocks submitted to the same surface treatments (8 groups; n=5) were cemented to composite resin blocks, using a self-adhesive resin cement. After storage in distilled water at 37°C for 24 hours, the Y-TZP-composite resin blocks were cut into beams and submitted to a microtensile bond strength (μTBS) test. Data were analyzed using 2-way ANOVA and the Tukey honestly significant differences test (α=.05).

RESULTS

Treatment with NTAP increased the surface energy for AS and APA groups (P<.05). For both groups, the μTBS was as follows: 0 seconds < 20 seconds < 60 seconds = 120 seconds (P<.05). Only after 120 seconds of NTAP treatment was the μTBS of APA higher than that of AS (P<.05).

CONCLUSIONS

Treatment with NTAP improved the surface energy and increased the μTBS of self-adhesive resin cement to Y-TZP ceramic, with higher times of plasma treatment resulting in higher bond strength.

In vitro shear bond strength between fluorinated zirconia ceramic and resin cements

PURPOSE

The purpose of this study was to evaluate the efficiency of a gas-phase fluorination method under different fluorination periods through using two resin cements.

MATERIALS AND METHODS

84 zirconia specimens in dimensions of 5 mm × 5 mm × 2 mm were prepared and surface treated with 50 µm aluminum oxide particles or gas phase fluorination for 2 min, 5 min, or 10 min. One specimen in each group was surface analyzed under scanning electron microscope. The remaining specimens were bonded to composite cylinders in dimensions of 2 mm diameter and 3 mm high with Panavia SA Plus or Variolink N. Then, the specimens were stored in 37℃ distilled water for 24 hours and shear bond strength test was applied at a speed of 1 mm/min.

RESULTS

The highest shear bond strength values were observed in the samples fluorinated for 5 minutes and cemented with Panavia SA Plus. Variolink N did not elicit any statistical differences between surface treatments. Panavia SA Plus resin cement and Variolink N resin cements featured statistically significant difference in shear bond strength values only in the case of 5 minutes of fluorination treatment.

CONCLUSION

According to the results of this study, application of 5 minutes of fluorination with 10-methacryloyloxydecyl dihydrogen phosphate monomer (MDP) containing Panavia SA Plus resin cement increased the resin bond strength of zirconia. Fluorination of the zirconia surface using conventional resin cement, Variolink N, did not lead to an increase in bond strength.