/home/opencode/cpanel/stomaeduj_hacked/uploads/2018/02/Article_5_2_4.pdf ORTHODONTICS BONDING ORTHODONTIC RESIN CEMENT TO ZIRCONIUM OXIDE UNDER Original Article ORTHODONTICS LOAD AND THERMOCYCLING EFFECT Hind S. Hussein1a, Nader Abdulhameed1b, Chiayi Shen1c, Calogero Dolce2d, Jean-François Roulet1e* 1 Department of Restorative Dental Sciences, College of Dentistry, University of Florida 2 Department of Orthodontics, College of Dentistry, University of Florida a, BDS, Courtesy Clinical Assistant Professor b BDS, MS, PhD Student, Clinical Assistant Professor c PhD, Associate Professor d DDS, PhD, Professor e Dr med dent, Dr hc, Professor, Director of Center for Dental Biomaterials ABSTRACT DOI: 10.25241/stomaeduj.2018.5(2).art.4 Purpose: Evaluate the microshear bond strength (µSBS) of orthodontic resin cement to OPEN ACCESS This is an monolithic zirconium oxide ceramic (MZ) under orthodontic load (OL) and thermocycling Open Access article under the CC (TC) effect. BY-NC 4.0 license. Peer-Reviewed Article Materials and Methods: Glazed MZ blocks (Zenostar, Ivoclar Vivadent) were tested after air abrasion with 30-µm silica coated aluminum oxide (Al2O3) particles (CoJet, 3M ESPE). The Citation: Hussein HS, Abdulhameed N, Shen C, Dolce C, Roulet J-F. Bonding of specimens were randomly divided into 4 groups (n = 15): G1, OL with TC; G2, OL without orthodontic resin cement to zirconium TC; G3 no OL with TC; and G4, no OL, no TC (control). Orthodontic cement cylinders (Heliosit oxide under load and thermocycling. Stoma Edu J. 2018;5(2):102-108. Orthodontic, Ivoclar Vivadent) were bonded to the primed samples (Monobond Plus, Ivoclar Vivadent) using the Ultradent SBS system and light cured (SmartLite Max, Dentsply Academic Editor: Diana Dudea, DDS, PhD, Professor, “Iuliu Hațieganu” Sirona, 1400 mW/cm2, 40 s). G1 and G2 were subjected to 70 ± 15 N load perpendicular to University of Medicine and Pharmacy Cluj-Napoca, Cluj-Napoca, Romania the cylinder axis, G1 and G3 were thermo-cycled (5000 cycles 5-55°C, 90 s/cycle). G2 and G4 were stored in distilled water at 37 ± 1°C. The specimens were subjected to µSBS test Received: May 28, 2018 Revised: June 06, 2018 (crosshead speed 0.5 mm/min). Data were analyzed using two-way ANOVA, and one-way Acccepted: June 11, 2018 ANOVA and Tukey test (HSD). Published: June 12, 2018 Results: Two-way ANOVA for µSBS values (MPa) showed significant (p = 0.0004) load effects, *Corresponding author: Professor but not thermal effect (p = 0.2455) with significant load/thermocycling interactions (p < Jean-François Roulet, DMD, PhD, Dr hc Center for Dental Biomaterials, College 0.0001). The ranking of the single groups by Tukey test (α = 0.05) showed that G1 exhibited of Dentistry, University of Florida 1395 the highest µSBS (8.4 ± 2.8 MPa), G4 (6.3 ± 1.1 MPa) and G2 (5.8 ± 1.1 MPa) as a group was Center Drive, Room D9-26, Gainesville, FL 32608 Gainesville, FL 32608, USA Tel: second, and G2 and G3 (4.7 ± 1.1 MPa) as a group was the lowest. +1 352 273 5850; Fax: +1 352 846 1643, e-mail: jroulet@dental.ufl.edu Conclusion: G1, which is the closest to clinical reality, yielded the best results. Keywords: orthodontics, dental materials, orthodontic resin cement, monolithic zirconium oxide Copyright: © 2018 the Editorial Coun- cil for the Stomatology Edu Journal. ceramic, microshear bond strength test. 1. Introduction restorations [6]. Previous studies have reported that Due to the patients’ increased esthetic demands and the life expectancy of (3Y-TZP) zirconium oxide when the development of technology in dental materials, compared to PFM FDPs for posterior indication, is porcelain fused to metal (PFM) crowns and bridges are shorter because of the delamination and chipping being replaced by glass based ceramic materials and of veneering ceramic; to overcome this problem, the monolithic Zirconium oxide (MZ) [1]; they are more monolithic zirconium oxide (MZ) was introduced to the esthetic, biocompatible, resistant to wear, show low dental market [1,2,4,7]. thermal conductivity, and are color stable [2]. However, Full contour MZ FDPs are produced using CAD/CAM despite these advantages, the brittle nature of these technologies. The restorations are milled from blocks materials restricts their use [3]. which can be used either glazed or polished for better Therefore, there is a need for new materials which have esthetic results [8]. Although polishing may provide the same esthetic properties as glass based all ceramic sufficient esthetic appearance by decreasing the materials and a strong framework like PFM for fixed surface roughness, technicians like to glaze the ZrO2 dental prosthesis (FDPs). The introduction of zirconium surface to improve the esthetic properties. With this oxide fulfilled these requirements [4]. The advantages process, the glass will infiltrate the zirconium oxide [9]. of zirconium oxide include high fracture resistance and Since the number of adult patients who have been high flexural strength (> 1000 MPa), which allowed for seeking orthodontic treatment is increasing [9], it thinner restorations. Furthermore the material can be means that the orthodontist will sometimes apply stained which allows better esthetic results [5]. These orthodontic brackets on dental restorations rather than properties make it a very good candidate for aesthetic on enamel. In a clinical situation, the orthodontist may FDPs. The tetragonal zirconia polycrystals (TZP), not know the composition of all the ceramic crowns. especially 3 mol % Y2O3 stabilized zirconia (3Y-TZP) Since different ceramics require different bonding has been used as a material for dental and medical procedures and the lack of bonding protocols for 102 Stoma Edu J. 2018;5(2): 102-108 http://www.stomaeduj.com BONDING ORTHODONTIC RESIN CEMENT TO ZIRCONIUM OXIDE UNDER ORTHODONTICS LOAD AND THERMOCYCLING EFFECT these new materials, these situations may lead to early Original Article Table 1. Types, brands, manufacturers and chemical compositions of the debonding of orthodontic brackets [4]. Furthermore, in material used in this study. orthodontics the goal is not a maximum bond strength, but one that is adequate to withstand orthodontic Type and Manufacturer Chemical composition Brand forces. Finally, the bond should be reversible i.e. it should be easy to remove brackets without damaging Zirconium dioxide (ZrO2 + HfO2 the enamel or the restored teeth. + Y2O3) > 99.0%, yttrium oxide Zenostar Wieland, Ivoclar (Y2O3) 4.5 ≤ 6.0% Currently, there are several studies about the different Vivadent Hafnium oxide (HfO2) ≤ 5.0 %, surface conditioning protocols for orthodontic bonding aluminum oxide (Al2O3) + other to porcelain materials. They enhance the adhesion oxides ≤ 1.0 % either by mechanical conditioning such as “roughness by Glaze spray IPS e.max Isobutane 30-60%, propan-2-ol airborne particle abrasion” or by chemical conditioning Ceram 25-40% such as the use of hydrofluoric acid etch of glass-based Acratray Henry Schein; Poly Methyl methacrylate ceramics to increase the bond strength and/or silane Acrylic Powder Melville NY, (PMMA), calcium carbonate, titanium dioxide, benzoyl coupling agents or oxidic primers which change the (blue) USA Peroxide wettability of the surface, or by combination of both Acrylic Liquid Methyl methacrylate (MMA), mechanical and chemical surface treatments [10-12]. (Self cure) Henry Schein benzophenone, hydroquinone Although there is increased use for MZ crowns in dental 3M ESPE; St practice, there is not enough information available about CoJet Sand Paul, MN, USA 30-μm Al2O3 SiO2 how to bond orthodontic brackets on MZ [13]. The most Ivoclar Ethanol, 3-trimethoxysilylpropyl commonly method used to evaluate the performance Monobond Vivadent; methacrylate, methacrylate of orthodontic bonding systems and the bonding Plus Schaan, phosphoric acid ester, disulfide technique is by measuring shear bond strength [14]. Liechtenstein methacrylate Doing this, one should consider the effect of orthodontic Bis-GMA 50-100% Heliosit forces applied and the stress induced by water storage Orthodontic urethane dimethacrylate 10 Ivoclar Vivadent < 20% and thermocycling on the bond strength. This should Adhesive 1,10-decandiol dimethacrylate be simulated in vitro as an accelerated ageing process 10 < 20% [13]. In shear bond strength testing, the ideal direction Orthodontic ORTHO of pull is parallel to the loading interface. It has been wire TECHNOLOGY SS Straight Lengths 0.14. recognized that the direction of the debonding force Dentsply GAC will affect the results [15]. In clinical orthodontic practice, Orthodontic international, brackets Stainless Steel. bonding the brackets and placement of arch wire might INC Bohemia, be done in the same visit. Hence, force could be applied NY, USA to the bracket within the first hour after bonding and then sintered in a furnace at 1530°C (Sintramat S1 High regardless of the relatively low magnitude of the force, Temperature Furnace, Ivoclar Vivadent) with a heating it could have an adverse effect on the bond strength. rate of 8°C/min and a holding time of two hours. It was reported that the polymerization of adhesives All the specimens were glazed with (IPS e.max should quickly reach a minimum value to enable the Ceram glaze spray, Ivoclar Vivadent) according to the adhesive to resist bonding failure when tying in initial manufacturer’s directions (770°C). The glazing material arch wires [16]. was applied in an even layer on the specimen in the The objective of this study was to evaluate the thermo usual manner and then all the specimens were fired cycling effect accompanied by orthodontic force on according to the manufacturer’s direction in a furnace the micro shear bonding strength of orthodontic resin (Programat EP 5000, Ivoclar Vivadent). After completion cement on glazed monolithic zirconium oxide surface of the firing process the samples were removed from conditioned by air abrasion with silica coated alumina the furnace and allowed to cool to room temperature particles. in a place protected from draft. The following null hypotheses were tested: 1) The All specimens were then embedded in autopolymer- thermo cycling (TC) does not influence the shear bond izing acrylic resin (powder and liquid, Acratray Blue, strength, 2) The orthodontic load does not influence Henry Schein, Melville, NY, USA). First, the specimens the shear bond strength, and 3) The orthodontic load were held in place on a smooth surface with a piece of with TC does not influence the shear bond strength. two-sided adhesive tape. Then, powder and liquid of acrylic resin was mixed (1:3) and poured into the molds to produce cylinders measuring 2.5 cm in diameter and 2. Material and methods 2.3 cm in length (Ultradent Products, South Jordan, UT, The types, brands, manufacturers and chemical USA). After autopolymerization started, the mold was composition of the material used in this study are listed placed in a container with cold water to decrease the in Table 1. polymerization temperature. After polymerization, the cylinders were removed from 2.1. Specimen Preparation the mold and the two-sided adhesive tape was removed. One monolithic zirconium oxide (MZ) material was The specimen surfaces were then cleaned with ethanol tested in this study (Zenostar, Ivoclar Vivadent, (Table 1). The cylinders were ground with 120-grit silicon Schaan, Liechtenstein). The specimens were received carbide abrasive paper under running water for about 1 in nonsintered blocks. They were cut into squares min to ensure a parallel surface to the bottom surface of approximately (9 mm × 9 mm × 4 mm). They were the clamp into which the cylinders were placed during Stomatology Edu Journal 103 BONDING ORTHODONTIC RESIN CEMENT TO ZIRCONIUM OXIDE UNDER ORTHODONTICS LOAD AND THERMOCYCLING EFFECT bonding. Original Article The specimens (N = 60), were randomly divided in two subgroups. Half of the specimens with orthodontic load (n = 30) and the other half without orthodontic load (n = 30). The orthodontic load and the non-orthodontic load specimens were further randomly divided into two subgroups: thermo cycling (TC) group and non-thermo cycling (non-TC) group (n = 15 per group) (Fig. 1). 2.2. Surface Conditioning Methods All the specimen’s surfaces were conditioned using air abrasion with an intraoral air-abrasion device (Microetcher, Danville Engineering, San Ramon, CA, USA) with 30 μm silica-coated Al2O3 (CoJet Sand, 3M ESPE, St Paul, MN, USA), perpendicular to the surface from approximately 10 mm for 20 s in circling motions at 2.8 bar. After air abrasion, the specimen surfaces were air blown to remove the remnants of the powder. 2.3. Bonding Procedures Specimen surfaces were coated with a thin layer of Universal Primer (Monobond Plus, Ivoclar Vivadent) that Figure 1. Experimental sequence, MZ= Monolithic Zirconium oxide ce- was left for 60 seconds to allow it to react, and then the ramic, TC= Thermocycling effect. remaining excess was removed with a strong stream of air. Each specimen was fixed to a bonding clamp with a special mold (Ultradent Shear Bond Test, Ultradent Products, Inc., South Jordan, UT, USA) to assure flat substrate surfaces and to standardize the diameter (2.3 mm) of the resin composite. Orthodontic resin (Heliosit Orthodontic, Ivoclar Vivadent) was applied to the surface using the bonding mold. Composite was applied in the mold and light cured (SmartLite Max, Dentsply Sirona, York, PA, USA, 1400 mW/cm2, 40 s) (Fig. 2). All specimens were stored in distilled water at 37 ± 1°C. As next step, orthodontic brackets were bonded to the acrylic next to the embedded specimens of the load groups. The position was selected to apply a force of approximately 70 ± 15 g (0.69 ± 0.14 N) with Figure 2. The Pencil line is tangent to the composite cylinder and it is 0.5 mm higher than the position of the bracket on the both side of MZ, in order an orthodontic wire (SS 0.14) (Fig. 3) to the bonded to provide 70 ± 15 g (0.69 ± 0.14 N) load force by the orthodontic wire. composite cylinders. The force was measured by using a Dontrix gauge (TP Orthodontics, Inc., La Porte, IN, USA). The orthodontic load group and the non-orthodontic load group were further randomly divided into two subgroups (n = 15): the thermo cycling (TC) group and the non-TC group (Fig. 1). Before testing the microshear bond strength all the specimens of the TC group were thermocycled in a Chewing Simulator device (CS-4SD Mechatronic GmbH, Feldkirchen, Westerham, Germany) for 5000 cycles between 5°C and 55°C with a dwell time of 30 seconds with the mechanical load component of the machine turned off. At the same time, all the specimens of the non-TC group were stored in distilled water at 37 ± 1°C. The position of the brackets to be bonded to the resin block is marked on both sides of the composite/MZ Figure 3. Top view showing the final design after adding orthodontic sample. The specimens were subjected to µSBS test using wire to composite cylinder. an universal machine (Instron 1125, Norwood, MA, USA, 0.05) for shear used to determine significant differences Fig. 4) (crosshead speed 0.5 mm/min). between the group dependent on the variable with and without application of load and/or TC. 2.4. Statistical Analysis Means and standard deviations of the shear bond strength were calculated for all groups [9]. Microshear 3. Results bond strength data (MPa) were submitted to a two- Two-way ANOVA for µSBS values (MPa) showed highly way ANOVA (SAS 9.4). Multiple comparisons were made significant (p = 0.0004) effects, however highly signifi- using the Tukey´s Studentized Range (HSD) Test (α = cant load/thermocycling interactions were found (Tab. 104 Stoma Edu J. 2018;5(2): 102-108 http://www.stomaeduj.com BONDING ORTHODONTIC RESIN CEMENT TO ZIRCONIUM OXIDE UNDER ORTHODONTICS LOAD AND THERMOCYCLING EFFECT 2). Therefore, no main effects could be shown. The sub- Original Article sequent one-way ANOVA and the Tukey test (α = 0.05) showed that thermal cycling with load (G1) had the great- est shear bond strength (8.4 ± 2.8 MPa) while the thermal cycling alone (G3) had the least shear bond strength (4.7 ± 1.1 MPa) among the groups. Comparing the results of µSBS values for the adhesive system with and without the application of TC eliminates the effect of the load (G3, G4) and showed that there was significant difference be- tween them and there was a significant difference with load (G1, G2). The result shows a nonsignificant reduction in µSBS values between the load without TC effect (G2) and TC without load (G3) (Fig. 5). Figure 4. Sample loaded in universal Instron machine. 4. Discussion The first and third null hypotheses had been rejected, the second one had been accepted. The conditioning technique used in this study (17), gritblasting with CoJet (Al2O3 silica coated sand) was selected for the following reasons: glass based ceramics can be etched with Hydrofluoric acid (HF) to achieve an excellent micromechanical surface topography for bonding. On the other hand, ZrO cannot be etched with HF at room temperature at all. Sandblasting with CoJet works well on glass-based ceramics as well. Since the orthodontists do not know which ceramic has Figure 5. Means and standard deviations of μSBS values between the TC been used, with the method used they are on the safe and non-TC group with or without the orthodontic load. Bars connected with a line are in the same statistical group (Tukey test, α=0.05). side. It would be the protocol of choice in the clinical routine [17]. Due to increased esthetics most MZ FDPs are glazed or stained, according to the study of Canigur et al. [4] “the CoJet yields higher bond strength values. The CoJet cre- ates micro retentive sites by increasing surface area and roughness” [18-20] “silica coated particles not only rough- Figure 6. The principle of CoJet treatment: the silica coated alumina par- ticles create micro roughness of the surface due to the kinetic energy and en the surface, they also have a chemical effect: because of leave silica embedded inside the surface, so it can react chemically with a blasting pressure, the embedded silica and alumina par- primer (Silane) [21]. ticles can then chemically react with the silane coupling agent“ (Fig. 6) [21]. “The improved chemical bonding with Table 2. Two-way ANOVA for µSBS values (MPa). Note that the 2-way silane coupling agents in this approach is advocated to be ANOVA showed highly significant differences (Model p<0.0001). However the key factor for a higher resin bond strength.” there were higly significant interactions (Load x Thermal). Since the orthodontist does not know the details of Mean F the fabrication process of the crown where a bracket Source DF Anova SS Pr > F Square Value should be bonded to, it is better to consider the ZrO Model 3 110.1178850 36.7059617 13.25 <.0001 surfaces were all glazed. With the gritblasting the glaze Error 56 155.1204133 2.7700074 may be partially or totally removed but using CoJet. A Corrected silica layer is deposited regardless of the composition 59 265.2382983 Total of the underlying surface, thus allowing the use of Load 1 38.86540167 38.86540167 14.03 0.0004 Silane as a primer. Thermal 1 3.81528167 3.81528167 1.38 0.2455 Spontaneous debonding of brackets is one of the most common clinical problems in fixed orthodontic therapy. Load +Thermal 1 67.43720167 67.43720167 24.35 <.0001 There are two major interfaces that can be subjected to deboning: the enamel or restorative material/adhesive Table 3. Means and Standard deviations of the 4 tested groups. Same interface and the adhesive/bracket interface [22] . In this letters in the Tukey Grouping column mean no statistically significant dif- study, we tested the restorative material (ZrO)/adhesive ference. interface and it was decided not to use brackets for the following reasons: The shear bond strength between TRET N Mean STD Tukey Grouping orthodontic cement and the ceramic surface was the TC _Load (G1) 15 8.4320 2.76480 A only topic of interest. If we had used brackets we would have had to deal with the bracket-cement interface as Control (G4) 15 6.3180 1.09754 B well, which was investigated in the past abundantly Load (G2) 15 5.8073 1.06452 B C [23-25]. Furthermore, it was necessary to eliminate TC (G3) 15 4.7020 1.04792 C possible confounding factors such as geometry, mesh design of the bracket base, or bracket material, all of Stomatology Edu Journal 105 BONDING ORTHODONTIC RESIN CEMENT TO ZIRCONIUM OXIDE UNDER ORTHODONTICS LOAD AND THERMOCYCLING EFFECT which may influence the test results [23-25]. Therefore, bond strength of bis-GMA resin composites, regardless Original Article we opted for a shear bond test which is the closest to of air abrasion or silica coating and silanization. Hence, the clinical reality. We assume that the main reason for because no long-term aging was performed in this bracket failure is shear. The shear bond strength test study, the results should be carefully and critically was performed with an orthodontic resin composite evaluated, considering that bonding in orthodontics cylinder in order to eliminate tilting moments as much is semi-permanent. However, at least 24-month water as possible. However, we understand elastic and plastic storage should be preferred for orthodontic bond deformation of the cylinder may have some negative strength testing [32], since it is usually the average effects on the shear bond strength measured. We are period for complete orthodontic treatment with fixed well aware that in orthodontic treatment brackets appliances, and significant decreases may be expected transmit forces to the teeth in all directions, however under such prolonged aging conditions compared to unexpected debondings usually occur under shear. The shorter durations of only a few days to several months brackets used in this study were used to apply shear [30,33]. The bond strength is affected by aging only forces to the bonded cylinders and were attached to when a mechanical pre-treatment is not applied prior the resin-embedding material (Fig. 3). to an MDP-containing primer [34]. Wegner and Kern Thermocycling is a standard procedure for accelerated [25] also showed that the bond strength of an MDP- ageing in bond strength tests in vitro. In this study, all containing resin composite did not change significantly the specimens of the TC group were thermocycled in after aging [25]. For this reason, the use of universal a chewing simulator device for 5000 cycles between primers containing methacrylate phosphoric acids and 5°C and 55°C with a dwell time of 30 seconds with the silane should be preferred after air-abrasion protocols. mechanical load component of the machine turned The results (Fig. 5) were not as anticipated. All samples off. At the same time, all the specimens of the non- of the present study were stored in water for the same TC group were stored in distilled water at 37 ± 1°C. time (2 weeks); the only difference is that some groups Extensive water storage and thermal cycling seem to be were subjected to additional stress (Load or TC) of the important parameters to simulate intraoral conditions interface before being subjected to shear stress to and to stress bonding interfaces. Literature data show failure. One could assume that additional stress would that thermocycling had a much higher impact on the weaken the interface. This only happened for TC, which durability of the resin bond strength to zirconia than confirms the trend in other studies. However direct did water storage at a constant temperature alone [26]. comparisons are difficult or problematic, because of Loading the samples represented the clinical reality. the different methods used in different studies. The Kiel In clinical orthodontic practice, bonding of brackets group has extensively looked into the bond strength and placement of the arch wires can be done in the of composites to ceramics, especially zirconium oxide same visit, particularly after rebonding of debonded ceramic. However they use tensile strength as a testing brackets. Hence, force could be applied to the bracket method and very long water storage (up to 2 years) within the first hour after bonding. This force could and high numbers of TC (37,500) [35-38]. As a general affect polymerization of the orthodontic adhesive and trend they found for most adhesive techniques that subsequently its bond strength. water storage with or without TC has a negative effect The force magnitude used for orthodontic tooth on bonded interfaces. movements varies depending on the type of movement There are a few studies that use shear or microshear [16]. In this study, 70 ± 15 g (0.69 ± 0.14 N) was applied. bond strength. When looking at the bond strength This force is considered the optimal orthodontic force. of surfaces that have been silicatized (Rocatec, CoJet In the clinical situation the average force transmitted to or similar procedures) water storage and TC also a bracket during mastication was reported to be 40 to decreased the shear bond strength [20,39]. On the 120 N, the surface area of the bracket is approximately other hand, Lüthy et al. [40] found for some bonding 11.9 mm2 and therefore it should be able to resist procedures no significant differences between TC and stress values between 6 and 8 MPa [16], during fixed water storage and water storage alone). orthodontic treatment for clinical success [27]. The Since the load applied corresponded to the load that mean bond strength values of brackets bonded is usually used in the clinic, one can expect that it has to natural teeth are significantly lower than those little effect on the bond strength, which confirms the obtained for surfaces other than enamel, especially clinical observations (few debondings of brackets). when a chemical promoter such as silane is used during This explains that the control and load group showed bonding [28]. These results may imply that universal the same shear bond strength. Since there are no primer application alone, prior to bonding, would other publications that have subjected samples to already enhance the bond strength of the orthodontic orthodontic load, it is not possible to compare the resin composite tested. However, it is known that in vitro results of the present study with others. bond strength values are often higher than in clinical It was surprising to see that the group with orthodontic situations, and biodegradation of resin composites in load in combination with TC showed the best results, the oral environment over time may even decrease which is difficult to explain. It seems that there is a these values [29,32]. In addition, aging procedures synergetic effect of load and TC. It is known that, due have a detrimental effect on the bond strength values to polymerization shrinkage, stress will be build up of resin composites when compared to non-aging test at the interface. This stress can be slightly increased conditions. [22,30,31]. in one direction by the orthodontic load. 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Dent J Orthod Dentofacial Orthop. 2010;137(5):615-622.e3. doi: Mater. 2006;22(2):195-200. doi: 10.1016/j.dental.2005.04.016. 10.1016/j.ajodo.2009.12.021. [Full text links] [PubMed] Google Scholar(336) Scopus(179) [Full text links] [PubMed] Google Scholar(69) Scopus(29) 34. 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(1):28-33. doi: 10.1002/jbm.b.30424. [Full text links] [PubMed] Google Scholar(235) Scopus(134) Hind S. HUSSEIN BDS, Courtesy Clinical Assistant Professor Department of Restorative Dental Sciences College of Dentistry, University of Florida FL 32608 Gainesville, USA CV Dr. Hind S Hussein graduated in 2011 (BDS) from the Almustansiryah University, Baghdad, Iraq. Between 2012 and 2014 she worked in a public hospital and a private clinic in Baghdad. In 2013 she was certified in Orthodontics. In 2014 she completed her Advanced Post Graduate Multispecialty Residency qualifying as a General Dentist. In 2014, Dr. Hussein joined the University of Florida (UF) as Visiting scientist (Restorative Dental Science and Orthodontics). In 2017 she was certified as UF Graduate Assistant Teacher with a technology program. Since 2017 up to the present, she has been an UF, a Courtesy Clinical Assistant Professor, with the Operative Dentistry and Prosthodontics, of the Department of Restorative Dental Sciences. Since 2014 she has been successfully involved in many research projects in dental materials. In 2017, Dr. Hussein submitted two US patents. Dr. Hussein is a member of several professional organizations including the Iraqi Dental Association, AADR and IADR. Questions 1. Hydrofluoric acid is used to increase the surface roughnes for bonding for the following ceramics? qa. Zirconium Oxide; qb. Lithium disilicate ceramic only; qc. All glass based ceramics; qd. Leucite reinforced ceramic only. 2. The treatment with Co-jet sand provides the following? qa. Roughens the surface; qb. Roughens the surface and deposits a layer of silica; qc. Cleans the surface; qd. Polishes the surface. 3. Which surfaces can be primed with silane? qa. Base metals; qb. Gold alloys; qc. Oxide ceramics e.g. Zirconium oxide; qd. Surfaces containing silica, e.g. glass based ceramics. 4. Which is the ideal clinical protocol to bond to an all ceramic crown made out of an unknown ceramic? qa. Roughen surface with Co-jet, prime with Silane and use resin based orthodontic cement; qb. Etch with hydrofluoric acid, prime with silane and use resin based orthodontic cement; qc. Etch with phosphoric acid, use universal primer and use resin based orthodontic cement; qd. Roughen surface with Aluminumoxide sand, use silane and cement bracket with glass ionomer cement. 108 Stoma Edu J. 2018;5(2): 102-108 http://www.stomaeduj.com