Effect of surface treatments on the shear bond strength of luting cements to Y-TZP ceramic Plínio Sciasci, DDS, MSC,a Filipe Oliveira Abi-Rached, DDS, MSc, PhD,b Gelson Luis Adabo, DDS, MSc, PhD,c Paolo Baldissara, DDS, MSc, PhD,d and Renata Garcia Fonseca, DDS, MSc, PhDe Araraquara Dental School, São Paulo State University (UNESP), Araraquara, São Paulo, Brazil; School of Dentistry, Alma Mater Studiorum, University of Bologna, Bologna, Italy Statement of problem. Because zirconia is a glass-free material, alternative surface treatments such as airborne-particle abrasion or silica coating should be used for long-term bonding. However, these surface treatments in combination with different bonding agents and luting cements have not yet been studied. Purpose. The purpose of the study was to evaluate the effect of surface treatments on the shear bond strength (SBS) of luting cements to Y-TZP ceramic. Material and methods. Zirconia disks (N¼240) were airborne-particle abraded with the following particles (n¼48): 50 mm Al2O3; 120 mm Al2O3; 30 mm silica-coated Al2O3 (Rocatec Soft); 120 mm Al2O3þ110 mm silica-coated Al2O3 (Rocatec Plus); and Rocatec Plus. After silanization of the zirconia surface, composite resin disks were bonded with (n¼12) RelyX Luting 2; RelyX ARC; RelyX U100; and Panavia F. The bonded specimens were thermocycled (10 000 cycles) and tested for SBS. Failure mode was determined with a stereomicroscope (20). The morphology and elemental composition of airborne-particle abraded surfaces were evaluated with scanning electron microscopy (500) and energy-dispersive x-ray spectroscopy (50). Results. Surface treatments, cements, and their interaction were significant (P99%

Bio-Art Dental Equipment Ltd

120 mm Al2O3 particles


Bio-Art Dental Equipment Ltd

Rocatec Soft

30 mm silica-coated Al2O3 particles


Rocatec Plus

110 mm silica-coated Al2O3 particles


MPS, ethanol, water


MDP, HEMA, hydrophilic aliphatic dimethacrylate, dl-camphorquinone, water

Kuraray Medical Inc

MPS, hydrophobic aromatic dimethacrylate

Kuraray Medical Inc

Methacrylated polycarboxylic acid, Bis-GMA, HEMA, silanated zirconia/silica filler, fluoroaluminosilicate (FAS) glass, water


Bis-GMA, TEGDMA, silanated zirconia/silica filler


RelyX U100 (self-etching resin cement)

Glass powder, methacrylated phosphoric acid esters, TEGDMA, silanated silica filler


Panavia F 2.0 (adhesive resin cement)

Paste A: MDP, DMA, silanated silica filler, dl-camphorquinone Paste B: DMA, silanated barium glass filler, sodium fluoride

Kuraray Medical Inc

Filtek Z350XT

Bis-GMA, UDMA, TEGDMA, Bis-EMA(6), zirconia/silica filler


RelyX Ceramic Primer Clearfil SE Bond Primer Clearfil Porcelain Bond Activator RelyX Luting 2 (resin-modified glass ionomer cement) RelyX ARC (resin cement)

MPS, 3-methacryloyloxypropyl trimethoxysilane; MDP, 10-methacryloyloxydecyl dihydrogen phosphate; Bis-GMA, bisphenol A diglycidyl ether dimethacrylate; HEMA, 2-hydroxyethyl methacrylate; TEGDMA, triethylene glycol dimethacrylate; DMA, dimethacrylates; UDMA, uretane dimethacrylate; BisEMA(6), bisphenol A polyethylene glycol diether dimethacrylate.

custom-made metal split matrix (5 mm internal diameter and 2 mm thick). The top surface and 2 diametrically opposed sides of the disks were each light polymerized (Radii-Cal lightpolymerizing unit; SDI Ltd) for 40 seconds for a total of 120 seconds14 at a constant intensity of 800 mW/cm2. The silane coupling agents were applied for 20 seconds to the airborne-particleabraded zirconia surface and left to dry for 60 seconds at room temperature. The zirconia disk was positioned in an alignment apparatus with the treated surface facing up. All luting cements were proportioned by weight, mixed according to their manufacturing instructions, placed onto the bottom surface of the resin disks, and positioned over the zirconia specimen. Next, a weight of 1000 g was applied on top of the resin disk for 10 minutes14 with a custom-made device. Except for the RelyX Luting 2, after excess removal, the cements were light polymerized in 2 different positions (equidistant sides) of the cementation line for a total of 80 seconds under the conditions described

Sciasci et al

previously. All specimens were thermocycled in distilled water between 5 C and 55 C for 10 000 cycles, with a dwell time of 30 seconds in each bath. The bonded disks were attached to a custom-made special holder and tested for SBS in a mechanical testing machine (EMIC DL2000; EMIC Equipment and Systems Testing Ltd) with a 1 kN load cell (Fig. 1). According to the method of Fawzy and El-Askary,40 a uniaxial tensile force was applied to the adhesive interface at a constant crosshead speed of 0.5 mm per minute until failure. SBS values were recorded (MPa). The data were analyzed statistically by SPSS software (IBM). The assumptions of the analysis were satisfied (Shapiro-Wilk, .07P.97; Levene, P¼.30), and the data were analyzed by 2-way ANOVA to test the effect of surface treatment, luting cement type (except for RelyX Luting 2, which failed spontaneously), and their interaction on the SBS. The Tukey honestly significant difference post hoc test (a¼.05) was applied to determine the differences among means.

Debonded specimens were examined under a stereomicroscope (M80; Leica Microsystems Ltd) at 20 magnification by a single trained observer, and failure mode was classified as: adhesive, cohesive within the cement layer or within the composite resin, or as a combination of both (mixed), according to the predominant mode of failure in each quadrant of the zirconia surface.48 Although RelyX Luting 2 debonded spontaneously, its groups were also analyzed concerning failure mode. To analyze the zirconia surface morphology, 2 additional specimens from each airborne-particle abrasion condition were mounted on metallic stubs and analyzed under a field emission scanning electron microscope (JSM7500F; JEOL Ltd) at 500 magnification with an accelerating voltage of 2.0 kV. To determine the elemental composition, these same specimens were mounted on metallic stubs and examined qualitatively under 50 magnification and 7.0 kV accelerating voltage by a field emission scanning electron microscope (JSM-






1 SBS test apparatus.

Table II.

Two-way ANOVA

Source of Variation






Surface treatment





Effect of surface treatments on the shear bond strength of luting cements to Y-TZP ceramic.

Because zirconia is a glass-free material, alternative surface treatments such as airborne-particle abrasion or silica coating should be used for long...
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