J Clin Exp Dent. 2018;10(12):e1167-76.Shear bond strength of ceramic bracket bonded to different surface-treated ceramicJournal section: Prosthetic DentistryPublication Types: .4317/jced.55330Shear bond strength of ceramic bracket bondedto different surface-treated ceramic materialsNiwut Juntavee 1, Apa Juntavee 2, Krittaphat Wongnara 3, Pimkhwan Klomklorm 3, Ronnaphum Khechonnan 3Department of Prosthodontics, Faculty of Dentistry, Khon Kaen University, Khon Kaen, ThailandDepartment of Pediatric Dentistry, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand3Division of Biomaterials and Prosthodontics Research, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand12Correspondence:Department of ProsthodonticsFaculty of DentistryKhon Kaen UniversityKhon Kaen, [email protected]: 29/09/2018Accepted: 25/10/2018Juntavee N, Juntavee A, Wongnara K, Klomklorm P, Khechonnan R. Shearbond strength of ceramic bracket bonded to different surface-treated ceramicmaterials. J Clin Exp Dent. do/volumenes/v10i12/jcedv10i12p1167.pdfArticle Number: 55330 Medicina Oral S. L. C.I.F. B 96689336 - eISSN: 1989-5488eMail: [email protected] in:PubmedPubmed Central (PMC)ScopusDOI SystemAbstractBackground: This study evaluated the effect of ceramic surface treatments on bond strength of ceramic brackets tomachine-able ceramics and ceramic veneering metal.Material and Methods: Machined ceramic specimens (10x10x1.5 mm) were prepared from Empress CAD (EP),and e.max CAD (EM). Ceramic veneering metal specimens (PF) were fabricated from sintered d.Sign porcelain(1.27 mm thickness) over d.Sign 10 metal (0.23 mm thickness). Each ceramic was divided into 3-groups andtreated surface by Er-YAG laser (LE) or etching with 9.6% HF acid for 5 seconds (A5) or 15 seconds (A15). Resinadhesive (Transbond -XT) was used for attaching ceramic brackets for each group (n 15) and cured with LED(Bluephase ) for 50 seconds. Specimens were immersed in distilled water for 24 hours before testing for shearbond at crosshead speed of 1.0 mm/min. The data were analyzed for the differences in bond strength with ANOVAand Tukey’s multiple comparisons (α 0.05). De-bond surfaces were microscopically examined.Results: Bond strength (MPa) were 12.65 1.14 for EMA5, 14.50 2.21 for EMA15, 13.97 1.17 for EMLE, 12.40 1.95for PFA5, 15.85 3.13 for PFA15, 14.06 2.17 for PFLE, 12.12 1.54 for EPA5, 15.65 1.57 for EPA15, 12.89 1.17 forEPLE. Significant differences in bond strength among groups were found related to surface treatment (p 0.05),but not significant difference upon type of ceramics (p 0.05). A15 provided higher bond strength than LE and A5(P 0.05). No damage of ceramic surface upon de-bonding was indicated except for A15 tends to exhibit ditching.LE showed more uniform treated surface for bonding and no surface destruction upon de-bond compared to others.Conclusions: Bond strength was affected by surface treatment. Both LE and A15 treated surface provided higher bondstrength than A5. Considering possibly inducing defect on ceramic surface, LE seems to provide better favorablesurface preparation than others. Treated ceramic surface with Er-YAG prior to bracket bonding is recommended.Key words: Ceramic, ceramic bracket, Er-YAG, laser, shear bond strength, surface treatment.e1167

J Clin Exp Dent. 2018;10(12):e1167-76.Shear bond strength of ceramic bracket bonded to different surface-treated ceramicIntroductionorthodontic treatment. This appears to be a problem as itis virtually impossible for clinicians to differentiate between various types of ceramic on existing restorationsin clinical situations. Therefore, the procedure of bonding brackets to existing ceramic restorations requiresconsideration of an appropriate technique that ensuresa durable bonding bracket and that the ceramic surfaceremains damage free after de-bonding (12). Since theinert property of ceramic surfaces does not facilitateadhesion through adhesive materials, several attemptswere made to revolutionize the ceramic surface to promote adhesion through mechanical, chemical, or othercombinations (13,14). The mechanical approach caninvolve roughening the ceramic surface by grinding itwith diamond bur, sandpaper disc, or blasting with Al2O3abrasives (15). However, these procedures produced apermanently destructive effect on the ceramic surface.The chemical approaches entail acid etching to providebonding affinity to adhesive materials to adhere to ceramic restoration (16). Furthermore, the application of9.5%–10% hydrofluoric acid (HF) was reported to becapable of creating irregularities on the ceramic surface,enabling micromechanical interlocking for resin adhesive (2,4,17,18). Extremely strong HF acid etching wasrequired to produce a clinically acceptable bond strength; however, this method increased the risk of cohesivefailure of ceramic during the de-bonding process anddamaged the ceramic glazed surface.Several lasers, such as neodymium-doped yttrium aluminum garnet (Nd-YAG), carbon dioxide (CO2), anderbium-doped yttrium aluminum garnet (Er-YAG), arebeing increasingly employed in dental practice for softand hard tissue removal, cavity preparations, conditioning, and decontamination (19). Among them, Er-YAGis classified as a solid type laser that is appropriatelyutilized with hard dental tissue structure (20,21). TheEr-YAG laser can produce an infrared range of 2,940nm that can be absorbed by water and the OH-group ofhydroxyapatite (22). Er-YAG has been used for the modification of enamel surface for bracket bonding (23). Itappears to be suitable for ceramic surface modificationfor retaining adhesive resin because its energy emissionis almost completely absorbed by the ceramic material(24,25). A few studies have investigated its capabilityin ceramic surface modification (26-28). However, noconsensus has been reached in the literature with regardto Er-YAG treated ceramic’s ability to allow suitablebracket bonding (29).Due to the advancement in the development of machinable ceramic material, the search for appropriate selectionand manipulation for ceramic materials that can achievesufficient bond strength between the ceramic bracketwith different ceramic materials was conceptualized forthis study. The aim was to compare the effects of differentceramic surface treatments on machinable ceramic res-Ceramics have been widely utilized as restorative materials to repair damaged teeth in the form of veneers,crowns, and bridges due to their aesthetic property, highfracture resistance, and biocompatibility (1). Conventional silica-based ceramics consisting of feldspar andquartz are generally used in veneering metal for metalceramic restoration. The increasing demand for aesthetic and precise restoration has led to the developmentof advanced ceramics materials for the fabrication ofceramic restorations based on digital technology. Ceramic restorations are nowadays more commonly foundin adult orthodontic patients seeking treatment. There isan increasing likelihood that orthodontic brackets andattachments require to be placed on existing ceramicrestorations. Ceramic material does not facilitate thebonding of bracket since the glazed surface of ceramicmaterials are inert for bonding with adhesive resin (2).Maintaining brackets on ceramic restorations can beproblematic. Bonding failure rates have been reportedto be 9.8% in 2 years (3). This is a considerably highfailure rate compared to other adhesive procedures usedin restorative dentistry. The retentive strength betweenresin adhesive and ceramic restoration was reported tobe insufficient (4). Although conventional orthodonticbanding can be employed instead of bonding, its resultsare unattractive, especially for anterior teeth, and it isnot possible to place orthodontic bands on the bridge’sabutment. The bond strength of bracket to ceramic restoration must be adequate to withstand orthodontic forcethroughout the treatment period (5). It is crucial to applyan appropriate adhesive procedure that encourages sufficient bond strength during the course of orthodontictreatment and minimizes damage to ceramic restoration(6). It is also equally important that the restoration befree of damage and remain in the mouth after the de-bonding of the bracket at the end of the treatment (7). Thus,the adherence force should be sufficient to withstandbracket dislodgment throughout the treatment as well asoffer feasibility in bracket removal without generatingexcessive force that can possibly create defect on the ceramic restorations (8).Adherence force between orthodontic brackets and ceramics depends on many variables including the kindof bracket, ceramics, adhesive material, and methodof ceramic surface treatment (9). Previous studies reported that the bond strength of either enamel or ceramic material to ceramic bracket is higher as comparedto that of enamel or ceramic to metal bracket (10,11).Thus, it often exhibits ceramic surface damage uponceramic bracket’s de-bonding. The different composition and crystalline structure of ceramic materials mayrequire a different bonding technique to ensure sufficient adhesion of bracket to ceramic that is capable ofwithstanding orthodontic and masticatory forces duringe1168

J Clin Exp Dent. 2018;10(12):e1167-76.Shear bond strength of ceramic bracket bonded to different surface-treated ceramictorative materials and conventional ceramic veneer metal on the shear bond strength of ceramic brackets. Twotypes of machinable ceramics, including IPS Empress CAD (EP; Ivoclar Vivadent, Schaan, Liechtenstein) andIPS e.max CAD (EM, Ivoclar Vivadent, Schaan, Liechtenstein) and one type of conventional metal ceramics(PF), using IPS d.SIGN porcelain (Ivoclar Vivadent,Schaan, Liechtenstein) veneering to cast metal substructure (IPS d.sign 10, Ivoclar Vivadent, Schaan, Liechtenstein) that were surface treated with three differentmethods, including Er-YAG lased (LE), HF etched for 5seconds (A5), and HF etched for 15 seconds (A15), bonded to ceramic bracket (Inspire ICE , Ormco, Orange,CA, USA) with adhesive resin (Transbond XT, 3MUnitek, St. Paul, MN, USA) were evaluated for shearbond strength (Table 1). The null hypothesis was that ErYAG lased surface of machinable ceramics and conventional ceramic veneer metal would result in comparablebond strength for ceramic bracket in relation to the HFetched surface for 5 and 15 seconds.Table 1: Materials, company and their compositions used in this study.MaterialsIPS d.Sign -10 Non-noble metal ceramicalloyCompanyCompositionIvoclar-VivadentNi 58.7 %, Cr 25.0 %, Mo 12. %, Si 1.7 %, Fe 1.9 %, Ce 1.0%, Co Inc., Amherst, NY,1.0 %.USAIPS d.Sign porcelainIvoclar-VivadentSiO2 50-65 %, AL2O3 8-20 %, K 2O 7-13 %, Na2O 4-12 %, CaO 0.1-6.0Fluoroapatite leuciteInc., Amherst, NY,%, F 0.1-3.0 %. Additional oxides (SrO. B2O3. Li2O, CeO2, BaO, ZnO,USATiO2, ZrO2) and pigment 0.0-3.0 %Ivoclar-VivadentSiO2 60-65 %, AL2O3 16-20 %, K 2O 10-14 %, Na2O 3.5-6.5 %, otherInc., Amherst, NY,oxides 0.5-7.0 % and pigment 0.2-1.0 %porcelainIPS Empress CAD Leucite reinforced glassceramicIPS e.Max CADLithium disilicate glassceramicInspire ICEUSAIvoclar-VivadentSiO2 57-80 %, Li2O 11-19 %, K 2O 0-13 %, P2O5 0-11 %, ZrO2 0-8 %,Inc., Amherst, NY,ZnO 0-8 %, other and coloring agent 0-12 %USAOrmco, Orange,Clear polycrystalline sapphire bracketCA, USAEr YAG Laser-AT Fideliswith R02-non contactFotona, Ljubljana,Erbium-doped yttrium aluminum garnet, wavelength of 2,940 nm,Sloveniapower of 200 mJ, 10 W, MSP mode (100-ụs pulse length), and 20 HzUltradent product9.6 % Hydrofluoric acidhand pieceUltradent EtchInc., South Jordan,UT, USATransbond XT3M Unitek, St.Conventional hybrid resin cementPaul, MN, USABis-GMA, Bis-EMA, TEGDMA, and fillers (73–77% silanated quartzand silica)Porcelain PrimerBluephase G1600Ormco, Glendora,Etanol 60-100 %,CA, USA3-trimethoxysilylpropyl methacrylate 10-30 %Ivoclar-Vivadent,Light-emitting diode curing machineAmherst, NY,Spectrum 430-480 nm, intensity 1600 mW/cm 2, Optical fiber diameterUSA8 mm.e1169

J Clin Exp Dent. 2018;10(12):e1167-76.Shear bond strength of ceramic bracket bonded to different surface-treated ceramicMaterial and Methodspulse length). A laser was lased perpendicular to the ceramic surface at the distance of 7 mm from the ceramicsurface and in the central area of 4 x 4 mm with a watercoolant for 20 seconds.-Bonding bracket to ceramic treated surfaceEach ceramic specimen was bonded with ceramic bracket (Inspire ICE) with adhesive resin (Transbond XT).The porcelain primer (Ormco, Glendora, CA, USA) wasapplied to the ceramic surface with a microbrush for 5seconds and blown gently. The resin adhesive was introduced to the bracket’s base and firmly placed on theceramic specimen with gentle force for approximately5 N for 5 seconds to control the 25 micrometer of cement film thickness using a veneer caliper (Mitutoyo,Neuss, Germany). The excess cement was removed andthen polymerized with a light-curing unit (Bluephase G-1600, Ivoclar Vivadent, Schaan, Liechtenstein) for 50seconds (10 seconds on each side and 10 seconds abovethe bracket). All samples were reserved in distilled waterat 37 C for 24 hours before testing.-Evaluation of shear bond strengthThe specimen was mounted in a custom made jig for testing in a universal testing machine (Lloyd InstrumentsLtd., West Sussex, United Kingdom) as depicted in Figure 1(A). The load was vertically applied through thestraight knife-edged chisel at the bracket-ceramic interface at a constant crosshead speed of 1.0 mm/min until bond failure happened. The loads at failure (P) wererecorded and calculated for shear bond strength (σ) bydividing the failure load with the bracket base area (A),as illustrated in equation 1.σ P/A.Equation 1-Microscopic evaluationThe de-bonded bracket base and ceramic surface wereexamined visually under an optical stereomicroscope(Nikon, Melville, NY, USA) at 10 x magnification to ascertain the mode of failure (FM), ceramic surface damage index (CDI), and adhesive resin remnant index (ARI)(2,8,9). The FM was determined as follows:Type I: Interfacial failure between bracket and adhesiveresin (90% or more of bracket base was exposed and10% or less of ceramic was free of adhesive).Type II: Interfacial failure between adhesive resin andceramic (10% or less of bracket base was exposed and90% or more of ceramic was free of adhesive).Type III: Failure of bracket (Fracture of bracket duringremoval, left part of bracket bonded on ceramic).Type IV: Failure of ceramic (A portion of the ceramicwas removed with the bracket base without loss of morethan 10% of the adhesive from the bracket base).Type V: Combination failure (Less than 90% but morethan 10% of the bracket base was exposed or more than10% but less than 90% of ceramic was free of adhesive).The CDI was classified as follows:0: No detectable ceramic surface damage. The surface-Machinable ceramic specimen preparationThe IPS Empress CAD (EP) and IPS e.max CAD(EM) ceramic specimens (n 50/each) were cut fromthe machinable ceramic blocks into square shape discswith the dimensions 10 10 1.7 mm (length x width x thickness) using a sectioning machine (MecatomeT180, Presi, Eybens, France). The ceramic specimenswere polished to a series of 800, 1200, 2000, and 4000abrasiveness of silicon carbide disc in the polishing machine (ECOMET 3, Buhler, Lake Bluff, IL, USA). Thediamond suspension (Metadi , LakeBluff, IL, USA) wasused to polish to obtain a smooth surface with the finaldimensions of 10 10 1.5 mm (length x width x thickness). The EP specimens were then glazed, while theEM specimens were crystalized and glazed in the porcelain furnace (Programat CS, Ivoclar-Vivadent, Schaan,Liechtenstein) following the manufacturer’s firing schedule at 850 C for 1 minute.-Metal ceramic specimen preparationThe conventional metal ceramic specimens (PF) (n 50)were fabricated in a square-shaped disc. The metal discsof size 10 10 0.23 mm were casted, sandblasted with50 microns aluminous oxide, and cleaned with distilledwater in the ultrasonic machine. The opaque porcelainwas applied to the metal surface, subsequently fired ina porcelain furnace according to the firing temperaturerecommended by the manufacturer. The opaque porcelain thickness of 0.27 mm needed to be achieved afterfiring for no more than two times. The dentine porcelainwas condensed onto the fired opaque porcelain using aporcelain condenser (Shofu Co., Shiba, Japan) and firedin the porcelain furnace according to the manufacturerrecommended firing schedule. The dentin porcelain thickness of 1.5 mm was produced upon firing for not morethan twice. The body porcelain was polished and glazedaccording to the manufacturer’s recommendation at 850 C for 1 minute to derive the final metal-ceramic discdimension of 10 10 1.5 mm.-Ceramic surface treatmentThe specimens in each group were cleaned in the ultrasonic cleaner (3M Unitek, St.Paul, USA) for 15 minutesto remove any surface residues and were then dividedinto three groups (15 samples each) for surface treatment with 3 different techniques, including HF etchedfor 5 seconds (A5), HF etched for 15 seconds (A15), andEr-YAG lased surface (L). The 9.5 % HF gel (Ultradent Etch, Ultradent product Inc., South Jordan, UT, USA)was painted with a microbrush in the central area sized 4x 4 mm of the ceramic for either 5 or 15 seconds, cleansed with spray water, and dried with an air-blower. Thelaser-treated groups (LE) were irradiated with Er-YAGlaser (AT Fidelis, Fotona, Ljubljana, Slovenia) througha non-contact hand-piece (R02; 1.3 mm in diameter), atthe power of 200 mJ, 10 W, 20 Hz, in MSP mode (100-ụse1170

J Clin Exp Dent. 2018;10(12):e1167-76.Shear bond strength of ceramic bracket bonded to different surface-treated ceramicFig. 1: (A) Specimen was mounted in a testing jig and compressively load at the bracket-ceramic interface to determine for(B) shear bond strength of ceramic bracket to different ceramic materials upon different surface techniques, (C) significantdifferences in shear bond strength upon different surface treatment techniques were indicated, and (D) revealed Weibullsurvival probability of shear bond for each group.remained intact, retaining the same condition as previous;1: Localized detectable ceramic surface alteration limited to superficial surface observed under microscope;2: Generalized detectable ceramic surface alteration limited to superficial surface observed under microscope;3: Localized visually detectable ceramic surface damage, significantly repair required with composite resin;4: Generalized visually detectable ceramic surface damage, significantly repair required with composite resin;5: Localized ceramic surface damage or fracture;6: Generalized ceramic surface damage of fracture.The ARI were scored as follows:0: no adhesive resin remained on ceramic;1: 50% of adhesive resin remained on ceramic;2: 50 % of adhesive resin remained on ceramic;3: adhesive resin mostly remained on ceramic, showingan imprint of the bracket base.The treated ceramic surface for each group was microscopically evaluated for different patterns of surface treatments. The samples were sputter coated withgold-palladium in a coating machine (K 500X, Emitech,Asford, UK) and examined with a scanning electron microscope (SEM, S-3000N, Hitachi, Tokyo, Japan) at x5000 magnification.-Statistical analysisThe data was statistically analyzed using SPSS/PC Ver-sion 20 software (IBM, Armonk, NY, USA). An analysis of variance (ANOVA) was employed to determinethe significant effect of shear bond strength on differentceramics as well as ceramic surface treatment methodsand their interactions. Post-hoc Tukey’s multiple comparison was determined for significant difference between each factor at 95% level of confidence. Wei