Association of Different Primers and Resin Cements for Adhesive Bonding to Zirconia Ceramics Fernando Akio Maedaa / Marina Stella Bello-Silvab / Carlos de Paula Eduardoc / Walter Gomes Miranda Juniord / Paulo Francisco Cesare

Purpose: To evaluate the shear bond strength (SBS) to zirconia ceramics using different associations of primers and resin cements. Materials and Methods: Two blocks of LAVA zirconia (3Y-TZP) were randomly submitted to an application of three different commercially available primers: Alloy Primer (AP), Z-Prime Plus (ZP), and Signum Zirconia Bond (SZB). Nonprimed specimens were considered controls. After treatment, the 80 specimens (5 mm × 5 mm × 2 mm) were randomly cemented with one of the resin cements: Panavia F, Multilink, seT, and NX3. For cementation, cylinders of resin cement were built on the ceramic surfaces using the SDI SBS apparatus. The specimens were submitted to the SBS test. Fractured surfaces were observed under stereomicroscopy to determine the failure mode, and mean bond strength values were analyzed using the Kruskal-Wallis and Mann-Whitney tests (_ = 0.05). Results: Signum Zirconia Bond had the highest SBS compared to all other primers and the control group, regardless of the resin cement used. The highest values were obtained when associating Panavia F with Signum Zirconia Bond. Alloy Primer increased bonding values when associated with seT cement only. When no primer was used, no statistical difference was observed among resin cements. All specimens fractured due to adhesive failure. Conclusion: Signum Zirconia Bond is capable of increasing bonding values of resin cements to zirconia ceramics. Its association with Panavia F shows enhanced results when considering short-term adhesion to zirconia. Keywords: primers, resin cement, shear bond strength, zirconia. J Adhes Dent 2014; 16: 261–265. doi: 10.3290/j.jad.a31938


he use of dental ceramics for dental prosthetic rehabilitation has significantly increased in recent years due to several advantageous properties, such as excellent esthetics, high abrasion resistance, high


Postdoc, Department of Biomaterials and Oral Biology, School of Dentistry, University of São Paulo, São Paulo, Brazil. Study design, carried out the adhesion experiment as part of his PhD thesis.


Assistant Professor, Postgraduate Program in Biophotonics Applied to Health Sciences, Nove de Julho University, São Paulo, SP, Brazil; Special Laboratory of Lasers in Dentistry (LELO), Department of Restorative Dentistry, School of Dentistry, University of São Paulo, São Paulo, Brazil. Performed the adhesion experiment and fractography.


Full Professor, Special Laboratory of Lasers in Dentistry (LELO), Department of Restorative Dentistry, School of Dentistry, University of São Paulo, São Paulo, Brazil. Study design, statistical analysis, contributed significantly to the discussion of the results.


Assistant Professor, Department of Biomaterials and Oral Biology, School of Dentistry, University of São Paulo, São Paulo, Brazil. F. Maeda’s thesis advisor, responsible for original idea, study design, and discussion.


Associate Professor, Department of Biomaterials and Oral Biology, School of Dentistry, University of São Paulo, São Paulo, Brazil. Wrote manuscript, prepared table of results, conducted final literature review, coordinated discussion among all authors.

Correspondence: Dr. Paulo Francisco Cesar, Av. Prof. Lineu Prestes, 2227 São Paulo- SP Brazil 05619-000. Tel/Fax: +55-11-3091-7849. e-mail: [email protected]

Vol 16, No 3, 2014

Submitted for publication: 08.08.12; accepted for publication: 17.01.14

biocompatibility, low plaque accumulation, low thermal conductivity, and high color stability. 6,11 Among the dental ceramics available, those with high crystalline content are the best substitute for metallic infrastructures. Yttria-tetragonal zirconia polycrystal (3Y-TZP, or simply zirconia) is an example of a polycrystalline ceramic with high mechanical properties that can be used to produce prosthetic structures exposed to high forces in the posterior region of the oral cavity.19 In addition, the widespread use of CAD/CAM systems has helped increase the popularity of zirconia restorations in dental practice.9 Despite all the benefits of zirconia, the major drawback is its low potential for adhesion to resin cements. Unlike conventional porcelain, which can be etched by hydrofluoric acid to create mechanical retentions on the surface,10 zirconia is inert to acid etching due to its high crystalline content and the lack of a glassy phase.7 In an attempt to increase the bond strength between resin cements and zirconia, various treatments have been suggested in the literature. One of the most popular treatments is sandblasting with aluminum oxide (alumina), which is considered a straightforward technique.21 Another surface treatment proven to mediate good bond 261

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Table 1 Chemical compositions and manufacturers of investigated materials Material




ZrO2 (94%), Y2O3 (3%), HF (3%), zirconium dioxide partially stabilized yttrium in tetragonal phase (3 mol %)

3M-ESPE; St Paul, MN USA

Signum Zirconia Bond

Primer: acetone, MDP (10-methacryloyloxydecyl dihydrogen phosphate), acetic acid Bond: methyl methacrylate, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide

Heraeus Kulzer; Hanau, Germany

Alloy Primer

Acetone, MDP, VBATDT (6-[N- (4-vinylbenzyl) propylamino]-1,3,5-triazine 2,4-dithione)

Kuraray; Osaka, Japan

Z-Prime Plus

Organophosphate monomer, carboxylic acid monomer, biphenyl dimethacrylate, hydroxyethyl methacrylate (HEMA), ethanol

Bisco; Schaumburg, IL, USA


Bis-GMA (bisphenol A-glycidyl methacrylate), UDMA (urethane dimethacrylate), EBPADMA (ethoxylated bisphenol A-dimethacrylate), TEG-DMA (triethylene glycol dimethacrylate), mineral fillers

Kerr; Orange, CA, USA


Dimethacrylate, HEMA, barium glass filler, silicon dioxide filler, ytterbium trifluoride, catalysts, stabilizers, pigments

Ivoclar Vivadent; Schaan, Lichtenstein

seT PP

UDMA, camphorquinone, fluoroaluminosilicate glass, acidic monomer

SDI; Bayswater, Victoria, Australia

Panavia F

Paste A: MDP, hydrophobic and hydrophilic dimethacrylate, benzoyl peroxide, camphorquinone, colloidal silica Paste B: sodium fluoride, hydrophobic and hydrophilic dimethacrylate, diethanol-ptoluidine, T-isopropylic benzenic sodium sulfinate, barium glass, titanium dioxide, colloidal silica


Oxyguard II

Glycerol, polyethylene glycol, catalysts, accelerators, dyes


strength is tribochemical abrasion with silica-coated alumina particles (Rocatec, 3M-ESPE; St Paul, MN, USA). This surface treatment incorporates silica into the zirconia surface, favoring chemical interaction with the silane agent.4,20 Another approach to enhancing the bond strength of zirconia to resin cements is the use of primers containing phosphated molecules, which possess a chemical affinity for metallic oxides. MDP (10-methacryloyloxydecyl dihydrogen phosphate) is the molecule most frequently found in this type of primer,13,14,22 and it can also be found in resin cements and dental adhesives. Currently, different MDP-containing primers are available on the dental market with different compositions and application methods; however, there is no information available in the literature regarding their performance in association with different types of resin cements. A wide variety of resin cements are also available to clinicians, with different compositions, properties, activation modes, and modes of interaction with dentin. These resin cements can be chemically activated, photo-activated, dual curing, or self-adhesive, and may or may not contain MDP. There is no consensus in the literature regarding the best combination of primers and resin cements in terms of bonding to zirconia. The purpose of this study was thus to investigate the bond strength of zirconia to different resin cements associated with primers containing phosphate monomers. The tested hypothesis was that the different associations of primers and cements would lead to different bond strength values to zirconia. 262

MATERIALS AND METHODS Descriptions of the materials used in this study, including composition and manufacturers, are listed in Table 1. The following factors were evaluated: 1) primer, four levels: no treatment (control), Alloy Primer, Z-Prime Plus, and Signum Zirconia Bond; 2) resin cement, four levels: seT, NX3, Multilink, and Panavia F. Eighty blocks of zirconia for CAD/CAM (LAVA, 3M-ESPE; St Paul, MN, USA) measuring 5 mm × 5 mm × 2 mm were sintered in a furnace (Zyrcomat, Vita Zahnfabrik; Bad Säckingen, Germany) at 1530°C for 2 h (25°C/min) and were cooled for 7.5 h.2 The blocks were embedded in acrylic resin, leaving ceramic surfaces exposed. The 80 specimens were randomly divided into 4 groups (n = 20), three of which received an application of one of the three primers. Primers were applied to the ceramic surface with a microbrush, according to the guidelines shown in Table 2. No primer was applied to specimens of the control group. After this, the 20 specimens of each group were mounted in a shear bond strength (SBS) testing device using one of the four resin cements (seT, NX3, Multilink, and Panavia F) (n = 5), as described below. The SDI (Southern Dental Industries; Bayswater, Victoria, Australia) device for standardization of the SBS test was used (Fig 1). The ceramic specimens were mounted in the testing device, and the metallic cylinder was firmly fixed onto their upper surface. Resin cements were handled according to guidelines shown in Table 2 and injected into the metallic cylinder. A small portion of the resin cement was applied to one extremity of the acrylic pin, which The Journal of Adhesive Dentistry

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Table 2 Materials and procedures Material


Alloy Primer

Apply a uniform layer by microbrush; allow to dry for 40 s.

Signum Zirconia Bond

Apply a uniform layer of Signum Zirconia Bond I by microbrush; apply a thin uniform layer of Signum Zirconia Bond II by microbrush; photo-activate for 40 s.

Z-Prime Plus

Apply a uniform layer of primer by microbrush; apply a gentle air stream for 5 s with a triple syringe.

Panavia F

Mix the two pastes in a ratio of 1:1 for 20 s; insert the cement into a metallic cylinder of the SDI device; place the acrylic tube in the cylinder and then remove the excess cement; photo-activate for 20 s; then apply a layer of Oxyguard II for 90 s; finally, remove Oxyguard II with a triple syringe.

seT PP

Manipulate the dual-syringe dual-curing cement by the self-mixing tip; insert the cement into the metallic cylinder of the SDI device; place the acrylic tube in the cylinder and then remove the excess cement; wait 30 s; photo-activate for 20 s.


Manipulate by the self-mixing tip; insert the cement into the metallic cylinder of the SDI device; place the acrylic tube in the cylinder and then remove the excess cement; photo-activate for 20 s.


Dispense pastes from the Multilink syringe at a 1:1 ratio; mix for 20 s; insert the cement into the metallic cylinder of the SDI device; place the acrylic tube in the cylinder and then remove the excess cement.





Fig 1 a. Zirconia Y-TZP blocks were embedded in acrylic resin with the upper surface exposed. b. The specimens were fixed in the device for standardization of the shear bond strength test (SDI). c. The metallic cylinder was positioned on the specimen surface and filled with resin cement. The acrylic pin was positioned inside the metallic cylinder. d. After photo-activation of resin cement, the specimen-cylinder sets were stored in distilled water and then submitted to SBS testing.

was positioned inside the metallic cylinder. After removing any excess, the resin cement was photo-activated if necessary. The sets of specimen/cylinders were stored in 37ºC distilled water for 24 hbefore being adapted to a metallic matrix and coupled to the universal testing machine (Kratos IKCL3 USB, Kratos Dinamometros; São Paulo, Brazil). All specimens were loaded to failure at a crosshead speed of 0.5 mm/min using a knife-edge blade placed parallel to and in contact with the bonded surface. SBS was obtained and the values (MPa) were statistically analyzed using Minitab 16 software (MINITAB; State College, PA, USA). The Kruskal-Wallis test was followed by the Mann-Whitney test, with a global significance level of 5%. Power analysis was conducted using PASS 12 software (NCSS; Kaysville, UT, USA). Fracture surfaces were observed using stereomicroscopy (20X, Model SZ61, Olympus; Tokyo, Japan), and the failure modes were determined as 1) adhesive failure at the resin/zirconia interface, 2) cohesive failure inside the resin material, or 3) a combination of adhesive and cohesive failures inside the resin material.13 Vol 16, No 3, 2014

RESULTS Descriptive statistics (means and standard deviations) of the bond strength data and results of the Mann-Whitney test (p < 0.05) are shown in Table 3. The KruskalWallis yielded a p-value of 0.0001. The power analysis indicated that the statistical power for the different experimental groups was at least 90%. Table 3 shows that the use of the primer Signum Zirconia Bond resulted in significantly higher SBS in comparison to all other groups regardless of the resin cement used. Further, the SBS values obtained for Z-prime and Alloy Primer were statistically similar regardless of the resin cement; however, these primers only mediated SBS values higher than the control in association with some of the cements. For Z-Prime, only the association with Panavia and NX3 resulted in significantly higher SBS values than the control. For Alloy Primer, only the association with Multilink resulted in similar bond strength in relation to the control. The resin cements were ranked differently in terms of SBS depending on the primer used. For the control group, 263

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Table 3 Mean values and standard deviations of SBS data and Mann-Whitney test (p < 0.05)  




Alloy Primer

Panavia F 4.7 (0.65)Ac 20.8 (1.38)Aa 8.7 (1.47)Ab

6.9 (0.76)Ab


3.9 (1.36)Ac 15.8 (2.73)Ba 6.0 (0.22)Ab

7.7 (0.53)Ab

NX 3

3.8 (1.03)Ac 12.7 (2.61)Ba 9.2 (1.14)Ab

6.9 (1.54)Ab


4.1 (0.55)Ab 9.0 (1.91)Ca 5.2 (0.80)Bb 3.7 (0.40)Bb

* Significant differences are shown within columns using superscript capital letters and within rows using superscript lower-case letters.

no statistical differences were observed among the resin cements. When SZB was used, Panavia resulted in a significantly higher mean SBS value than all other cements. seT and NX3 resulted in similar SBS values, which were significantly higher than those obtained for Multilink. For Z-Prime and Alloy Primer, the resin cements were ranked similarly in terms of SBS: Panavia, seT, and NX3 obtained similar SBS values, and Multilink resulted in the lowest SBS values. When considering the association of each primer with the resin cement, it is important to note that the combination of Panavia F and Signum Zirconia Bond resulted in a mean SBS value statistically higher than that of all other associations. Neither the control nor the experimental groups showed spontaneous debonding of the cylinders before the mechanical test. All fractures occurred exclusively due to adhesive failure (100%).

DISCUSSION This study evaluated the adhesion of zirconia to different cements in combination with various metal primers. The results indicated that the resin cement, the type of primer, and the interaction between them significantly affect the final bond strength of the specimen, confirming the study’s hypothesis. The SBS test was carried out using a device specifically developed for this purpose. This type of test is often criticized for presenting a non-homogeneous stress distribution along the adhesive interface, which may lead to over- or underestimation of the results, because most of the failures initiate in the substrate and not in the adhesive interface.5,23,24 However, the device used resulted in good standardization of the bond strength method, because it contains a rigid metal ring that is fixed around the adhesive area and remains attached to the specimen during the test. This probably led to a more homogeneous stress distribution at the interface, as suggested by fractographic results showing 100% adhesive failure. The primers used in this study were directly applied to the as-sintered zirconia specimens, without any polishing or additional mechanical treatment of the bonding sur264

face. This experimental design aimed to simulate what is usually observed clinically for zirconia dental prostheses, because many clinicians prefer to leave the inner surface of these structures untouched after sintering in order to avoid undesirable phase transformations. The primers selected for the study reflect a wide range of compositions/applications in order to verify whether these differences influence the final bond strength by means of interaction with the different resin cements. For instance, Alloy Primer contains MDP and 6-(N-(4-vinylbenzyl)propylamino)-1,3,5-triazine-2,4-dithione (VBATDT), and its application requires only a uniform layer of the product with a brush, whereas Z-Prime Plus consists of a mixture of organophosphate monomers, carboxylic acid, and HEMA, and its application also requires only a uniform layer of the product with a brush. Signum Zirconia Bond includes MDP, acetic acid, acetone, and methyl methacrylate (MMA); first, a mixture of acetic acid, acetone, and MDP is applied, and only after that is a layer of MMA applied and photo-activated. The Signum Zirconia Bond primer was the only one that obtained better SBS than the control for all resin cements tested. Unlike the other primers, which come in a single bottle, this one has two distinct bottles. The first bottle contains the primer itself, with MDP, acetic acid, and acetone. Acetone is included in this primer’s composition to increase the surface wettability of zirconia.22 The second bottle contains MMA and diphenyl phosphinoxide and should be photo-activated right after application. In this way, after use of the primer, the surface of the zirconia becomes similar to dentinal surfaces after the application of a conventional three-step adhesive system. The results obtained in this study corroborate those reported by other authors,22 which showed higher SBS values when Signum Zirconia Bond was used. According to those authors, in addition to the well-known effect of MDP, the MMA found in this product establishes primary bonds with the methacrylate present in the resin cement, resulting in increased bond strength. The Z-Prime Plus showed better SBS results in comparison to the control only for Panavia F and NX3. This primer is presented as one bottle containing a mixture of carboxylic acid monomer and organophosphate. Similar to silane molecules, the organophosphate monomers have an organofunctional portion, usually a methacrylate group, which can be copolymerized with the monomers of the resin cement. These phosphate monomers also have phosphoric acid groups that bind to zirconia.15 The positive results found for Z-Prime Plus associated with Panavia F and NX3 are consistent with other studies in the literature and suggest that this increase in bond strength is most likely related to the presence of organophosphate monomers.3,14 However, it has been demonstrated that the presence of carboxylic acid monomers in Z-Prime Plus can weaken the connection between this primer and methacrylate groups found in self-adhesive resin cements,14 which could explain the low SBS values obtained for the association of Z-Prime Plus and seT. Alloy Primer is composed of MDP and VBATDT monomers. In this study, this primer was able to increase the The Journal of Adhesive Dentistry

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SBS values in comparison to the control when associated with Panavia F, seT and NX3 cements. Similar results were observed by Lorenzoni et al14 and Souza et al.8 Although the three primers tested in this study contain phosphate monomers, the differences observed among SBS values suggest that the additional monomers found in their composition can affect bond strength. Furthermore, variations in chemical composition, wettability, viscosity, and mechanical properties of each resin cement may also be responsible for changes in the adhesion to zirconia.7,16,22 The resin cements of the present study were selected in order to provide a wide range of compositions and properties that may influence the bond strength results. This variation is extremely relevant from a clinical standpoint, because clinicians need to choose among the various types of resin cements available. Thus, Multilink was chosen because it is a chemically activated cement, seT represents self-adhesive cements, NX3 represents dualcuring cements without phosphate monomers, and Panavia F represents dual-curing cements that contain MDP. Some authors attribute the high bond strength between zirconia and Panavia F to the fact that this cement contains MDP.12,16,18,25 This monomer is also found in all three metal primers used in this study. The MDP monomer has been proven effective in creating a strong bond between the resin cement and zirconia, as well as other alloys and pure metals.1 This bonding occurs due to direct binding of the ester monomer to the metal oxides, such as zirconia. In other words, the connection takes place through a reaction between the hydroxyl groups of the MDP monomer and the hydroxyl groups of the zirconia surface.1,17,25




The simplicity of the application procedure of metal primers17 and the positive results obtained in this study for some associations of primers and cements indicate that such primers can significantly improve the adhesion of some resin cements to zirconia. It is expected that this method does not induce phase transformation of zirconia from tetragonal to monoclinic, as observed in mechanical surface treatments. Clinicians should be aware of the composition of both the primer and the resin cement chosen in order to take advantage of the main features of each material.


5. 6. 7. 8.

9. 10. 11. 12. 13.


15. 16.






23. 24. 25.

Chen L, Suh BI, Kim J, Tay FR. Evaluation of silica-coating techniques for zirconia bonding. Am J Dent 2011;24:79-84. Cristoforides P, Amaral R, May LG, Bottino MA, Valandro LF. Composite resin to yttria stabilized tetragonal zirconia polycrystal bonding: comparison of repair methods. Oper Dent 2012;37:263-271. DeHoff PH, Anusavice KJ, Wang Z. Three-dimensional finite element analysis of the shear bond test. Dent Mater 1995;11:126-131. Denry I, Kelly JR. State of the art of zirconia for dental applications. Dent Mater 2008;24:299-307. Derand T, Molin M, Kvam K. Bond strength of composite luting cement to zirconia ceramic surfaces. Dent Mater 2005;21:1158-1162. Dias de Souza GM, Thompson VP, Braga RR. Effect of metal primers on microtensile bond strength between zirconia and resin cements. J Prosthet Dent 2011;105:296-303. Filser F, Kocher P, Gauckler LJ. Net-shaping of ceramic components by direct ceramic machining. Assembly Automation 2003;23:382-390. Jardel V, Degrange M, Picard B, Derrien G. Correlation of topography to bond strength of etched ceramic. Int J Prosthodont 1999;12:59-64. Kelly JR, Denry I. Stabilized zirconia as a structural ceramic: an overview. Dent Mater 2008;24:289-298. Kern M, Barloi A, Yang B. Surface conditioning influences zirconia ceramic bonding. J Dent Res 2009;88:817-822. Koizumi H, Nakayama D, Komine F, Blatz MB, Matsumura H. Bonding of resin-based luting cements to zirconia with and without the use of ceramic priming agents. J Adhes Dent 2012;14:385-392. Lorenzoni F, Leme V, Santos L, de Oliveira P, Martins L, Bonfante G. Evaluation of chemical treatment on zirconia surface with two primer agents and an alkaline solution on bond strength. Oper Dent 2012;37:625-633. Magne P, Paranhos MP, Burnett LH, Jr. New zirconia primer improves bond strength of resin-based cements. Dent Mater 2010;26:345-352. Nothdurft FP, Motter PJ, Pospiech PR. Effect of surface treatment on the initial bond strength of different luting cements to zirconium oxide ceramic. Clin Oral Investig 2009;13:229-235. Özcan M, Nijhuis H, Valandro LF. Effect of various surface conditioning methods on the adhesion of dual-cure resin cement with MDP functional monomer to zirconia after thermal aging. Dent Mater J 2008;27: 99-104. Silva L, Costa A, Queiroz J, Bottino M, Valandro L. Ceramic primer heat-treatment effect on resin cement/Y-TZP bond strength. Oper Dent 2012;37:634-640. Silva NRFA, Sailer I, Zhang Y, Coelho PG, Guess PC, Zembic A, Kohal RJ. Performance of zirconia for dental healthcare. Materials 2010;3:863-896. Smith RL, Villanueva C, Rothrock JK, Garcia-Godoy CE, Stoner BR, Piascik JR, Thompson JY. Long-term microtensile bond strength of surface modified zirconia. Dent Mater 2011;27:779-785. Thompson JY, Stoner BR, Piascik JR, Smith R. Adhesion/cementation to zirconia and other non-silicate ceramics: where are we now? Dent Mater 2011;27:71-82. Ural C, Kulunk T, Kulunk S, Kurt M, Baba S. Determination of resin bond strength to zirconia ceramic surface using different primers. Acta Odontol Scand 2011;69:48-53. Van Noort R, Noroozi S, Howard IC, Cardew G. A critique of bond strength measurements. J Dent 1989;17:61-67. Versluis A, Tantbirojn D, Douglas WH. Why do shear bond tests pull out dentin? J Dent Res 1997;76:1298-1307. Yoshida K, Tsuo Y, Atsuta M. Bonding of dual-cured resin cement to zirconia ceramic using phosphate acid ester monomer and zirconate coupler. J Biomed Mater Res B Appl Biomater 2006;77:28-33.



Blatz MB, Sadan A, Martin J, Lang B. In vitro evaluation of shear bond strengths of resin to densely-sintered high-purity zirconium-oxide ceramic after long-term storage and thermal cycling. J Prosthet Dent 2004;91:356-362. Borba M, de Araujo MD, Fukushima KA, Yoshimura HN, Cesar PF, Griggs JA, Della Bona A. Effect of the microstructure on the lifetime of dental ceramics. Dent Mater 2011;27:710-721.

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Clinical relevance: The combination of one resinbased cement containing MDP and a primer composed of MMA and MDP improved the bond strength to zirconia-based restorations, compared to other combinations of cements and primers.


Association of different primers and resin cements for adhesive bonding to zirconia ceramics.

To evaluate the shear bond strength (SBS) to zirconia ceramics using different associations of primers and resin cements...
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