THE EFFECT of DIFFERENT SURFACE TREATMENTS on THE SHEAR BOND STRENGTH of LUTING CEMENTS TO TITANIUM

Statement of problem. Although titanium presents attractive physical and mechanical properties, there is a need for improving the bond at the titanium/luting cement interface for the longevity of metal ceramic restorations.Purpose. The purpose of this study was to evaluate the effect of surface treatments on the shear bond strength (SBS) of resin-modified glass ionomer and resin cements to commercially pure titanium (CP Ti).Material and methods. Two hundred and forty CP Ti cast disks (9.0 x 3.0 mm) were divided into 8 surface treatment groups (n=30): 1) 50 mu m Al2O3 particles; 2) 120 mu m Al2O3 particles; 3) 250 mu m Al2O3 particles; 4) 50 mu m Al2O3 particles + silane (RelyX Ceramic Primer); 5) 120 mu m Al2O3 particles + silane; 6) 250 mu m Al2O3 particles + silane; 7) 30 mu m silica-modified Al2O3 particles (Cojet Sand) + silane; and 8) 120 mu m Al2O3 particles, followed by 110 mu m silica-modified Al2O3 particles (Rocatec). The luting cements 1) RelyX Luting 2; 2) RelyX ARC; or 3) RelyX U100 were applied to the treated CP Ti surfaces (n=10). Shear bond strength (SBS) was tested after thermal cycling (5000 cycles, 5 degrees C to 55 degrees C). Data were analyzed by 2-way analysis of variance (ANOVA) and the Tukey HSD post hoc test (alpha=.05). Failure mode was determined with a stereomicroscope (x20).Results. The surface treatments, cements, and their interaction significantly affected the SBS (P<.001). RelyX Luting 2 and RelyX U100 exhibited similar behavior for all surface treatments. For both cements, only the group abraded with 50 mu m Al2O3 particles had lower SBS than the other groups (P<.05). For RelyX ARC, regardless of silane application, abrasion with 50 mu m Al2O3 particles resulted in significantly lower SBS than abrasion with 120 mu m and 250 mu m particles, which exhibited statistically similar SBS values to each other. Rocatec + silane promoted the highest SBS for RelyX ARC. RelyX U100 presented the highest SBS mean values (P<.001). All groups showed a predominance of adhesive failure mode.Conclusions. The adhesive capability of RelyX Luting 2 and RelyX U100 on the SBS was decisive, while for RelyX ARC, mechanical and chemical factors were more influential. (J Prosthet Dent 2012;108:370-376)

Effect of temporary cements on the shear bond strength of luting cements

Objective: The purpose of this study was to evaluate, by shear bond strength (SBS) testing, the influence of different types of temporary cements on the final cementation using conventional and self-etching resin-based luting cements. Material and Methods: Forty human teeth divided in two halves were assigned to 8 groups (n=10): I and V (no temporary cementation); II and VI: Ca(OH)(2)-based cement; III and VII: zinc oxide (ZO)based cement; IV and VIII: ZO-eugenol (ZOE)-based cement. Final cementation was done with RelyX ARC cement (groups I to IV) and RelyX Unicem cement (groups V to VIII). Data were analyzed statistically by ANOVA and Tukey's test at 5% significance level. Results: Means were (MPa): I - 3.80 (+/- 1.481); II - 5.24 (+/- 2.297); III - 6.98 (+/- 1.885); IV - 6.54 (+/- 1.459); V - 5.22 (+/- 2.465); VI - 4.48 (+/- 1.705); VII - 6.29 (+/- 2.280); VIII - 2.47 (+/- 2.076). Comparison of the groups that had the same temporary cementation (Groups II and VI; III and VII; IV and VIII) showed statistically significant difference (p<0.001) only between Groups IV and VIII, in which ZOE-based cements were used. The use of either Ca(OH) 2 based (Groups II and VI) or ZO-based (Groups III and VII) cements showed no statistically significant difference (p>0.05) for the different luting cements (RelyX (TM) ARC and RelyX (TM) Unicem). The groups that had no temporary cementation (Groups I and V) did not differ significantly from each other either (p>0.05). Conclusion: When temporary cementation was done with ZO- or ZOE-based cements and final cementation was done with RelyX ARC, there was an increase in the SBS compared to the control. In the groups cemented with RelyX Unicem, however, the use of a ZOE-based temporary cement affected negatively the SBS of the luting agent used for final cementation.

Cytotoxicity of resin-based luting cements to pulp cells

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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

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 (N=240) were airborne-particle abraded with the following particles (n=48): 50 μm Al2O3; 120 μm Al2O3; 30 μm silica-coated Al2O3 (Rocatec Soft); 120 μm Al2O3+110 μm silica-coated Al2O3 (Rocatec Plus); and Rocatec Plus. After silanization of the zirconia surface, composite resin disks were bonded with (n=12) 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 (P<.001). For RelyX ARC, Rocatec Soft and Rocatec Plus provided the highest SBS. In general, surface treatments did not influence the SBS of RelyX U100 and Panavia F. Regardless of the cement, no significant difference was found between 50 μm and 120 μm Al2O3 particles, between Rocatec Soft and Rocatec Plus, or between Rocatec Plus and 120 μm Al2O3 particles+Rocatec Plus. All groups showed adhesive failures. Different particle sizes provided differences in morphological patterns. The elemental composition comprised Al and Al/Si for alumina and silica-abraded zirconia. Conclusions Particle size did not influence the SBS of the groups abraded exclusively with alumina or silica-coated particles. RelyX ARC was more surface-treatment dependent than RelyX U100 or Panavia F.

Cytocompatibility of HEMA-free resin-based luting cements according to application protocols on dentine surfaces

To evaluate the transdentinal cytotoxicity of resin-based luting cements (RBLCs), with no HEMA in their composition, to odontoblast-like cells. Human dentine discs 0.3 mm thick were adapted to artificial pulp chambers (APCs) and placed in wells of 24-well plates containing 1 mL of culture medium (DMEM). Two categories of HEMA-free RBLCs were evaluated: group 1, self-adhesive Rely X Unicem (RU; 3M ESPE), applied directly to the dentine substrate; and group 2, Rely X ARC (RARC; 3M ESPE), applied to dentine previously acid-etched and treated with a bonding agent. In group 3 (control), considered as representing 100% cell metabolic activity, no treatment was performed on dentine. The APC/disc sets were incubated for 24 h or 7 days at 37 °C and 5% CO2 . Then, the extracts (DMEM + dental materials components that diffused through dentine) were applied to cultured odontoblast-like MDPC-23 cells for 24 h. After that, the cell viability (MTT assay), cell morphology (SEM), total protein production (TP) and alkaline phosphatase (ALP) activity were assessed. Data from MTT assay and TP production were analysed by Kruskal-Wallis and Mann-Whitney tests (α = 5%). Data from ALP activity were analysed by one-way anova and Tukey's test (α = 5%). In group 1, a slight reduction in cell viability (11.6% and 16.8% for 24-h and 7-day periods, respectively) and ALP activity (13.5% and 17.9% for 24-h and 7-day periods, respectively) was observed, with no significant difference from group 3 (control) (P > 0.05). In group 2, a significant reduction in cell viability, TP production and ALP activity compared with group 3 (control) occurred (P < 0.05), regardless of incubation time. Alteration in MDPC-23 cell morphology was observed only in group 2. HEMA-free Rely X ARC cement caused greater toxicity to odontoblast-like MDPC-23 cells than did Rely X Unicem cement when both resin-based luting materials were applied to dentine as recommended by the manufacturer.

Transdentinal cytotoxicity of resin-based luting cements to pulp cells

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Radiopacity evaluation of contemporary luting cements by digitization of images

The aim of this study was to evaluate the radiopacity of two conventional cements (Zinc Cement and Ketac Cem Easymix), one resin-modified glass ionomer cement (RelyX Luting 2) and six resin cements (Multilink, Bistite II DC, RelyX ARC, Fill Magic Dual Cement, Enforce and Panavia F) by digitization of images. Methods. Five disc-shaped specimens (10×1.0 mm) were made for each material, according to ISO 4049. After setting of the cements, radiographs were made using occlusal films and a graduated aluminum stepwedge varying from 1.0 to 16 mm in thickness. The radiographs were digitized, and the radiopacity of the cements was compared with the aluminum stepwedge using the software VIXWIN-2000. Data (mmAl) were submitted to one-way ANOVA and Tukey's test (=0.05). Results. The Zinc Cement was the most radiopaque material tested (<0.05). The resin cements presented higher radiopacity (<0.05) than the conventional (Ketac Cem Easymix) or resin-modified glass ionomer (RelyX Luting 2) cements, except for the Fill Magic Dual Cement and Enforce. The Multilink presented the highest radiopacity (<0.05) among the resin cements. Conclusion. The glass ionomer-based cements (Ketac Cem Easymix and RelyX Luting 2) and the resin cements (Fill Magic Dual Cement and Enforce) showed lower radiopacity values than the minimum recommended by the ISO standard.

Human pulp response to resin cements used to bond inlay restorations

Objective. The aim of this study was to evaluate the pulp response following cementation of inlays using two different resin cements.Methods. Deep Class V cavities were prepared on the buccal surface of 34 sound human premolars. impressions were taken and inlays were prepared which were cemented with the following luting materials-Group 1: Rely X(TM) Unicem. (3M ESPE); Group 2: Variolink(R) II (Ivoclar Vivadent). in Group 3 (control), after lining the cavity floor with Dycal(R) (Dentsply Caulk) the inlays were cemented with Rely X(TM) Unicem. Four additional teeth were used as an intact control group. For Variolink(R) II, the adhesive system Excite was used as part of the cementation procedure. After 7 or 60 days, the teeth were extracted and processed for histological assessment.Results. At 7 days, Rely X(TM) Unicern and Variolink(R) II system triggered in two samples a mild and moderate inflammatory response, respectively. At 60 days, the pulpal response decreased for both groups. A discrete persistent inflammatory response occurred in Group 2 in which displacement of resin components across the dentin tubules was observed. In the control group, normal histological characteristics were observed. The inflammatory response and tissue disorganization were related to the remaining dentin thickness between the cavity floor and the pulp tissue.Significance. Techniques for inlay cementation using distinct luting cements may cause specific pulpal damage. Variolink(R) II associated with the adhesive system Excite cause more aggressive effects to the pulp-dentin complex than Rely X(TM) Unicern cement when both are used to cement inlay restorations. (C) 2005 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Evaluation of glass ionomer cements properties obtained from niobium silicate glasses prepared by chemical process

Glass ionomer cements (GICs) are glass and polymer composite materials. These materials currently find use in the dental field. The purpose of this work is to obtain systems based on composition 4.5SiO(2)-3Al(2)O(3)-XNb2O5-2CaO to be used in Dentistry. The systems were prepared by chemical route at 700 degrees C. The results obtained by XRD and DTA showed that all systems prepared are glasses. The structures of the obtained glasses were compared to commercial material using Al-27 and Si-29 MAS NMR. The analysis of MAS NMR spectra indicated that the systems developed and commercial material are formed by SiO4 and AlO4 linked tetrahedra. The properties of glass ionomer cements based on the glasses prepared with several niobium contents were studied. Setting and working times of the cement pastes, microhardness and diametral tensile strength were evaluated for the experimental GICs and commercial luting cements. It was concluded that setting time of the cement pastes increased with increasing niobium content of the glasses (X). The properties to the GICs such as setting time and microhardness were influenced by niobium content. (c) 2005 Elsevier B.V. All rights reserved.

Changes on degree of conversion of dual-cure luting light-cured with blue LED

The indirect adhesive procedures constitute recently a substantial portion of contemporary esthetic restorative treatments. The resin cements have been used to bond tooth substrate and restorative materials. Due to recently introduction of the self-bonding resin luting cement based on a new monomer, filler and initiation technology has become important to study the degree of conversion of these new materials. In the present work the polymerization reaction and the filler content of dual-cured dental resin cements were studied by means of infra-red spectroscopy (FT-IR) and thermogravimetry (TG). Twenty specimens were made in a metallic mold (8 mm diameter × 1 mm thick) from each of 2 cements, Panavia® F2.0 (Kuraray) and RelyX™ Unicem Applicap (3M/ESPE). Each specimen was cured with blue LED with power density of 500 mW/cm 2 for 30 s. Immediately after curing, 24 and 48 h, and 7 days DC was determined. For each time interval 5 specimens were pulverized, pressed with KBr and analyzed with FT-IR. The TG measurements were performed in Netzsch TG 209 under oxygen atmosphere and heating rate of 10°C/min from 25 to 700°C. A two-way ANOVA showed DC (%) mean values statistically significance differences between two cements (p < 0.05). The Tukey's test showed no significant difference only for the 24 and 48 h after light irradiation for both resin cements (p > 0.05). The Relx-Y™ Unicem mean values were significantly higher than Panavia® F 2.0. The degree of conversion means values increasing with the storage time and the filler content showed similar for both resin cements. © 2009 Pleiades Publishing, Ltd.

Efficacy of Surface Treatments on the Bond Strength of Resin Cements to Two Brands of Zirconia Ceramic

Purpose: To compare the shear bond strength (SBS) of two cements to two Y-TZP ceramics subjected to different surface treatments.Materials and Methods: Zirconia specimens were made from Lava (n = 36) and IPS e.max ZirCAD (n = 36), and their surfaces were treated as follows: no treatment (control), silica coating with 30-mu m silica-modified alumina (Al2O3) particles (CoJet Sand), or coating with liners Lava Ceram for Lava and Intensive ZirLiner for IPS e.max ZirCAD. Composite resin cylinders were bonded to zirconia with Panavia F or RelyX Unicem resin cements. All specimens were thermocycled (6000 cycles at 5 degrees C/55 degrees C) and subjected to SBS testing. Data were analyzed by post-hoc test Tamhane T2 and Scheffe tests (alpha = 0.05). Failure mode was analyzed by stereomicroscope and SEM.Results: With both zirconia brands, CoJet Sand showed significantly higher SBS values than control groups only when used with RelyX Unicem (p = 0.0001). Surface treatment with liners gave higher SBS than control groups with both ceramic brands and cements (p < 0.001). With both zirconia brands, the highest SBS values were obtained with the CoJet and RelyX Unicem combination (> 13.47 MPa). Panavia F cement showed significantly better results when coupled with liner surface treatment rather than with CoJet (p = 0.0001, SBS > 12.23 MPa). In untreated controls, Panavia F showed higher bond strength than RelyX Unicem; the difference was significant (p = 0.016) in IPS e.max ZirCAD. The nontreated specimens and those treated with CoJet Sand exhibited a high percentage of adhesive and mixed A (primarily adhesive) failures, while the specimens treated with liners presented an increase in mixed A and mixed C (primarily cohesive) failures as well as some cohesive failure in the bulk of Lava Ceram for both cements.Conclusion: CoJet Sand and liner application effectively improved the SBS between zirconia and luting cements. This study suggests that different interactions between surface treatments and luting cements yield different SBS: in clinical practice, these interactions should be considered when combining luting cements with surface treatments in order to obtain the maximum bond strength to zirconia restorations.

Development of an experimental glass ionomer cement containing niobium and fluoride

Glass ionomer cements (GICs) are currently used for various dental applications such as luting cements or as restorative materials. The calcium fluoro-alumino-silicate system is the basis for degradable glasses used to obtain the GICs. The purpose of the present paper is to add niobium to conventional glass system because according to previous papers niobium addition improves the chemical resistance and the mechanical properties of glasses. Therefore, the GICs prepared from these glasses would result in cements with higher chemical and mechanical resistance. The niobium fluoride powders were prepared using the sol-gel process and were characterized by X-ray diffraction, differential thermal analysis (DTA) and Al-27 and Si-29 MAS NMR. The results obtained by XRD showed that the powders prepared by this method are glass-ceramic. In the DTA curve was detected the presence of T-g and T-c temperatures. The analysis of MAS NMR spectra indicated that the framework of the powders is formed by SiO4 and AlO4 linked tetrahedra which are essential structures to yield the cements. Thus, we concluded that niobium fluoride silicate powders can be used in the preparation of GICs. (c) 2005 Elsevier B.V. All rights reserved.