Zirconia Surface Research Articles

Using Genipin to Immobilize Bone Morphogenetic Protein-2 on Zirconia Surface for Enhancing Cell Adhesion and Mineralization in Dental Implant Applications.

Our objective in this study was to promote cell responses through the immobilization of bone morphogenetic protein-2 (BMP-2) on roughened zirconia (ZrO2) through using the natural cross-linker genipin in dental implant applications. Field emission scanning electron microscope, X-ray photoelectron spectroscopy, and attenuated total reflection-Fourier transform infrared spectroscopy were used to analyze the surface characterizations, including the topography, chemistry, and functional groups, respectively, of the test specimens. Human bone marrow mesenchymal stem cells (hMSCs) were used to detect cell responses (adhesion, proliferation, and mineralization). The surface characterizations analysis results revealed that genipin was effective in immobilizing BMP-2 on roughened zirconia surfaces. BMP-2 proved effective in promoting the adhesion and mineralization of hMSCs on roughened zirconia. The surface modification proposed has potential in zirconia dental implant applications.

Effect of laser irradiation on the adhesion of resin-based materials to zirconia: a systematic review and meta-analysis

This systematic review and meta-analysis were made to evaluate the bond strength behavior and failure mode of zirconia surfaces treated by laser irradiation and to highlight the main characteristics and parameters of each laser system. The PubMed, the Scopus, and the Web of Science databases were searched for articles without limit on year of publication, in accordance with the PRISMA guidelines. Forty-three in vitro studies were included and meta-analyses were performed to compare the bond strength values found after the use of lasers, and to quantify the percentage of failures. When compared to untreated groups, the bond strength values found for the lasers ranged from 1.4 to 30.16 MPa for CO2; 1.18 to 40.33 MPa for Nd:YAG; 0 to 22.72 MPa for Er:YAG; and 0.5 to 34.92 MPa for Er,Cr:YSGG. Statistical analysis indicated high heterogeneity in-between the comparisons of different lasers (p ˂ 0.05). When compared to other treatments, the results of the meta-analysis were favorable for tribochemical silica coating (TSC) and airborne-particle abrasion (APA) (p ˂ 0.05), except for the CO2 laser. Adhesive failures were predominant (68.28% for CO2; 65.23% for Nd:YAG; 76% for Er:YAG and 71.91% for Er,Cr:YSGG laser), followed by mixed and cohesive failures. Based on the results of this study, the conditioning of zirconia surfaces through laser irradiation increases the bond strength values when compared to untreated surfaces, regardless of the type of laser used. However, except for CO2 laser, TSC and APA still show superior bond strength results.

Acid etching and silica coating effects on Y-TZP topography and ceramic/resin cement bond strength

Zirconia-based (Y-TZP) dental prostheses' retention loss remains one of the most frequently reported difficulties in dental practice. Selective Infiltration Etching (SIE) treatment has been proposed to alter the final Y-TZP topography improving its bond strength to resin cement. SIE consists of glass film deposition on the Y-TZP surface before glass removal with 10% hydrofluoric acid etching. This study's objective was to investigate the effects of SIE protocol steps on Y-TZP topography and its consequence on its bond strength to resin cement. The SIE protocol was divided into two main steps: silica coating (first step) and glass dissolution by hydrofluoric acid (second step), and the null hypothesis was that the SIE treatment has the same bond quality independently of the HF exposition time. Atomic Force Microscopy (AFM), Scanning Electron and Transmission Electron microscopy were used to characterize the zirconia surfaces. The bond strength was evaluated by the interfacial fracture toughness test, and data were analyzed by ANOVA and Tukey's Test (5%). As the main result, it was shown that, when exposed during sufficient time, the 10% HF can etch zirconia at room temperature, which is responsible for topographic changes, significantly improving the bond quality. Additionally, no glass components or dihedral angles modifications were observed at Y-TZP grain boundaries after silica coating. With the study limitations, it was possible to infer that the surface-modifying agent in SIE protocol is the HF etching, and the null hypothesis was rejected.

Time-dependent reactive oxygen species inhibit Streptococcus mutans growth on zirconia after a helium cold atmospheric plasma treatment

As an efficient strategy for the modification of material surfaces, cold atmospheric plasma (CAP) has been used in dentistry to improve hard and soft tissue integration of dental implant materials. We previously found the Streptococcus mutans growth was inhibited on the surface of zirconia implant abutment after a 60-second helium cold atmospheric plasma treatment. However, the mechanism of bacterial growth inhibition on CAP-treated zirconia has not been fully understood. The duration of bacterial inhibition effectiveness on CAP-treated zirconia has also been insufficiently examined. In this work, we assume that reactive oxygen species (ROS) are the primary cause of bacterial inhibition on CAP-treated zirconia. The ROS staining and an ROS scavenger were utilized to evaluate the bacterial intracellular ROS level, and to determine the role of ROS in bacterial growth inhibition when seeded on CAP-treated zirconia. The time-dependent effectiveness of CAP treatment was determined by changes in surface characteristics and antibacterial efficacy of zirconia with different storage times after CAP treatment. This study confirmed that the presence of reactive oxygen species on the zirconia surface after CAP treatment inhibits the growth of Streptococcus mutans on the material surface. Although the antibacterial efficacy of the 60-second CAP-treated zirconia decreased over time, there were fewer bacteria on the treated surface than those on the untreated surface after 14 days.

Femtosecond Ti: Sa ultra short-pulse laser irradiation effects on the properties and morphology of the zirconia surface after ageing

Femtosecond pulses from a Ti:Sapphire laser were used to irradiate specimens of yttria-stabilised (35% mol) tetragonal zirconia (Y-TZP) with the purpose of studying the effects of the irradiations on their surface properties and morphology after ageing. Zirconia disks were divided into eight groups (n = 32) according to their surface treatment and subsequent ageing: Control: no treatment; sandblasting: Al2O3 sandblasting 50 μm; and ultrashort laser pulses irradiation with 25 μJ pulses, considering two different scanning steps based on the width between two grooves. These groups were duplicated and submitted to ageing. The surfaces were analysed using scanning electron microscopy (SEM), and X-ray diffraction. A finite element analysis, a biaxial flexure test, as well as fractographic and Weibull analyses, were performed. The strengths of the disks were statistically different for the treatment factor, and the principal stresses seemed to be concentrated at the centre of the specimens, as predicted by the computer simulations. Ageing decreased the strengths for all groups and increased the Weibull modulus for the laser group with the 40 μm-width between two grooves. The sandblasting group presented the highest monoclinic phase peak. Although the most significant strength was found within the sandblasting group, the phase transformation was favourable to the laser groups. The Weibull modulus was higher for the laser group with the 60 μm-width between two grooves, confirming the highest homogeneity of its failure distribution. Regardless of the surface treatment, strength was decreased with ageing in all groups. The femtosecond Ti:Sa ultra-short pulse laser irradiation can be suggested as an alternative to the gold standard sandblasting in long-term Y-TZP zirconia rehabilitations, such as crowns and veneers.

Influence of zirconia surface treatments of a bilayer restorative assembly on the fatigue performance.

This study evaluated the influence of different surface treatments of zirconia used to enhance bonding with veneering porcelain, and thermocycling on the resistance to porcelain cracking and delamination during fatigue test. Bilayer ceramic discs were made from zirconia blocks (IPS e.max Zircad MO, Ivoclar Vivadent - 0.7 mm thickness) and randomized into 8 groups (n= 15) according to two factors: 'zirconia surface treatment' (Control; Grinding - diamond bur; Air-abrasion - aluminum oxide particles; and Liner - application of a ceramic liner [IPS e.max Zirliner, Ivoclar Vivadent]); and 'thermocycling' (presence - 12,000 thermal cycles; 5-55ºC; or absence). The discs were veneered with porcelain (IPS e.max Ceram, Ivoclar Vivadent - 0.7 mm; totaling 1.4 mm thickness) according to ISO 6872:2015 for biaxial flexure strength testing. Fatigue tests (step-stress approach; 20 to 100 MPa; step of 10 MPa; 10,000 cycles per step; 10 Hz frequency) were run, followed by the data analysis (Kaplan-Meier and Mantel-Cox post-hoc tests). Analysis of roughness, topography, crystallographic phase arranges and fractography were also executed. The surface treatment and thermocycling did not influence the porcelain crack nor delamination resistance. When only comparing the surface treatments for crack resistance outcome, the liner application depicted the worst fatigue performance in comparison to grinding and air-abrasion, while all groups were similar for delamination. Neither the surface treatment of the zirconia nor the thermocycling influences the porcelain crack resistance or the resistance to delamination of the bilayer porcelain-veneered zirconia specimens.

Sb-doped zirconium dioxide submicron fibers for separation of pertechnetate (TcO4 –) from aqueous solutions

ABSTRACT Submicron ZrO2 fibers with three different Sb-doping levels (5, 10 and 15 cation%) were produced with an electroblowing synthesis for removal of 99TcO4 –. The Sb-doped ZrO2 fibers showed high selectivity toward 99TcO4 –, which was not interfered by ClO4 –, NO3 – or Cl– ions and showed no selectivity toward ReO4 –. The optimal pH range for the 99Tc separation was 2–6 but the Sb-doped fibers maintained very high uptake level throughout the studied pH range of 1–10. According to the uptake experiments, Sb(III) is assumed to reduce Tc(VII) to Tc(IV) that is then adsorbed by the zirconia surface.

Shear Bond Strength of the Metal Bracket to Zirconium Ceramic Restoration Treated by the Nd: YAG Laser and Other Methods: An In Vitro Microscopic Study.

Introduction: Providing reliable bonding of the bracket base and the zirconia surface is required to apply orthodontic force. The purpose of this scientific experiment was to evaluate the efficacy of three different methods of surface preparation for Zirconia, including surface roughening, sandblasting and the Nd: YAG laser, in the shear bond strength (SBS) of the orthodontic brackets. Methods: Fifty-four discs of zirconia were divided into three groups of 18: A) Hydrofluoric acid etching, B) sandblasting, and C) Nd: irradiation using the power of 1.5 W for 10 seconds. After bonding the brackets, the samples were slowly thermo-cycled (1000 times) for 24 hours. The SBS test was performed by a universal testing machine at a head speed of 0.5 mm/min. The adhesive remnant index (ARI) was scored at a magnification of 10 in the stereo microscope. All data were collected and analyzed using the variance, Kruskal-Wallis, Tukey, Don, and Weibull tests (α = 0.05). Results: The HF acid etching group (6.11± 0.94 MPa) had the highest SBS, which was followed by the laser group (6 ± 0.61 MPa) and the sandblast group (3.1080 ± 0.82 MPa). There was a significant statistical difference between the laser and HF groups and the sandblast group (P < 0.05) and no significant difference between the HF group and the laser group (P = 0.03). Conclusion: Based on the obtained bond strength, the Nd: YAG laser with a power of 1.5 W could be a substitute treatment method for the HF acid-etching.

Efficacy of Different Surface Treatments on the Bond Strength of Resin cement to Zirconia Ceramic

Purpose: The plan for this study was to anatomise the effect of alternative surface treatments to enhance bonding to zirconia. Materials and Methods: forty discs of zirconia (Prettau,zircon zhan, Italy) were prepared using Isomet 4000 precision Saw then discs were divided into 5 groups. Group 1, control; Group2, zirconia discs were treated with50-mm Al2O3 particles; Group 3, zirconia discs were received hand grinding; Group 4, zirconia discs were treated by a CO2 laser and Group 5, zirconia discs were treated using ERYAG laser. Composite resin discs were constructed and cemented to zirconia samples with panavia cement. For the bond strength test, a universal testing machine was used. Results: the highest shear bond strength was recorded for (Hand grinding) group (2) while the lowest mean value was recorded for control group (1). Conclusions: Treatment of Zirconia Surfaces with hand grinding or sandblasting increased shear bond strength. Treatment of Zirconia with CO2 and ERYAG lasers increased shear bond strength of zirconia, with the CO2 laser being higher than ERYAG laser.

Microstructure and mechanical properties of fully sintered zirconia glazed with an experimental glass

The need for improved mechanical properties in regions of higher masticatory loads led to the introduction of zirconia in dentistry. However, zirconia needs a characterization and glaze to have a more natural, tooth-like appearance. An experimental glass was produced based on the sol-gel method to exhibit a thermal expansion coefficient similar to that presented by zirconia. The experimental glass was used as glazing material on the previously sintered zirconia (vita YZ) surface. There was a significant reduction in the roughness and hardness of the material, caused by the formation of smooth, void-free and highly uniform glass coating. The glass infiltrated among superficial zirconia grains and caused the formation of monoclinic zirconia at the zirconia/glass interface. A consequent decrease in surface roughness and an increase in flexural strength and reliability was then observed in the experimental glass group. On the other hand, a significant decrease in the reliability of conventionally glazed group was observed. Therefore, the use of experimental glass instead of conventional glaze can improve the mechanical properties, smoothness, and mechanical reliability of fully sintered zirconia.

Primer-Treated Ceramic Bracket Increases Shear Bond Strength on Dental Zirconia Surface.

The purpose of this study is to evaluate the shear bond strength (SBS) of a primer-treated ceramic bracket on dental zirconia and to compare it with conventional ceramic bracket bonding on surface-treated zirconia. Sintered and finished dental zirconia was sandblasted. Samples were divided according to the treated surfaces: no treatment (X), ceramic primer on zirconia (Z), ceramic primer on bracket base (B), and ceramic primer on both zirconia and bracket base (ZB). The ceramic bracket was bonded on zirconia and SBS was measured before (T0) and after 10,000 cycles of thermocycling (Tf). The failed surfaces were examined under field emission scanning electron microscope (FE-SEM), and adhesive remnant index (ARI) was evaluated. SBS was significantly higher in ZB and significantly lower in X in both T0 and Tf. There was no significant difference between Z and B. In X and B, adhesive failure occurred while ZB showed mixed failures. There was no apparent change in the zirconia surface except for the existence of some adhesive and resin remnants. The application of ceramic primer on the bracket base increased the bonding strength to the level of conventional bonding with fewer adhesive remnants. The highest bonding strength was obtained when the primer-treated bracket was bonded on the primer-treated zirconia.

Evaluation of Different Zirconia Surface Treatments on their Microhardness

Evaluation of Different Zirconia Surface Treatments on their Microhardness

Research progress on surface treatment technology of zirconia implant

Zirconia material has a color closer to human natural teeth, and has excellent mechanical properties and good biocompatibility, therefore it is expected to become an ideal material for dental implants. In order to improve the osteogenic properties of zirconia implants, a variety of surface treatment techniques emerge in two categories: non-coating method and coating method. Different surface treatment technologies have their advantages and disadvantages. In this paper, the recent progress of zirconia surface treatment technology is reviewed.

Effect of Methacryloyloxydecyl Dihydrogen Phosphate-Containing Silane and Adhesive Used Alone or in Combination on the Bond Strength and Chemical Interaction With Zirconia Ceramics Under Thermal Aging.

Achieving durable bonding to zirconia is fundamental for the application of a methacryloyloxydecyl dihydrogen phosphate (MDP)-containing silane solution or an MDP-containing silane solution associated with an MDP-containing universal adhesive. Objectives: To evaluate the effect of a methacryloyloxydecyl dihydrogen phosphate (MDP)-containing silane coupling agent and universal adhesive, used alone or in combination, on the microshear bond strength (μSBS) to zirconia after 24 hours of water storage (24h) and after 10,000 thermocycles (TC), complemented with chemical analysis of the surface to establish the presence of MDP on the surface of the zirconia after bonding procedures.Methods and Materials: Thirty computer-aided design/computed-aided manufacturing blocks of zirconia were cut into four sections (6×6×6 mm) and sintered. Zirconia sections (n=96) were assigned to 24 groups according to three factors: 1) silane (no silane, Monobond S [MBS], Monobond P [MB+]), 2) adhesive + resin cement (no adhesive + Enforce [ENF], no adhesive + RelyX Ultimate [REX], Prime&Bond Elect + Enforce [PBE/ENF], Scotchbond Universal + RelyX Ultimate [SBU/REX]), and 3) thermocycling (no thermocycling [24h], 10,000 thermocycles [TC]). Upon silane/adhesive application, cylinder-shaped matrices were filled with resin cement and light cured. Specimens were tested in μSBS (1.0 mm/min) after 24h or TC. The μSBS data were analyzed using twoway ANOVA and Tukey's post hoc test (α=0.05). In addition, micro-Raman spectroscopy was used to analyze the zirconia surface for immediate chemical interaction analysis (n=24).Results: For the 24h condition, PBE/ENF resulted in lower mean μSBS than both groups with silane without PBE (MBS and MB+ groups; p<0.001). SBU alone or MB+ alone and MB+ associated with SBU showed the highest mean μSBS (p<0.001). For the TC condition, all groups showed a significant decrease in mean μSBS compared with those of 24h (p<0.001), with the exception of MB+ associated to SBU (p>0.05). However, the application of MB+ alone or MB+ associated to SBU resulted in higher mean μSBS (p<0.001) after TC than the remaining TC groups. In terms of chemical interaction, only the SBU groups, alone or combined with both of the silane agents, were associated with the methacrylate groups after rinsing.Conclusions: The results of the current study support the use of an MDP-containing silane solution or an MDP-containing silane solution associated with an MDP-containing universal adhesive for bonding to air-abraded zirconia, as a more stable bonding after thermocycling.

Tribological Behaviour of Ti or Ti Alloy vs. Zirconia in Presence of Artificial Saliva

Abutment is the transmucosal component in a dental implant system and its eventual appearance has a major impact on aesthetics: use of zirconia abutments can be greatly advantageous in avoiding this problem. Both in the case of one and two-piece zirconia abutments, a critical issue is severe wear between the zirconia and titanium components. High friction at this interface can induce loosening of the abutment connection, production of titanium wear debris, and finally, peri-implant gingivitis, gingival discoloration, or marginal bone adsorption can occur. As in vivo wear measurements are highly complex and time-consuming, wear analysis is usually performed in simulators in the presence of artificial saliva. Different commercial products and recipes for artificial saliva are available and the effects of the different mixtures on the tribological behaviour is not widely explored. The specific purpose of this research was to compare two types of artificial saliva as a lubricant in titanium–zirconia contact by using the ball on disc test as a standard tribological test for materials characterisation. Moreover, a new methodology is suggested by using electrokinetic zeta potential titration and contact angle measurements to investigate the chemical stability at the titanium–lubricant interface. This investigation is of relevance both in the case of using zirconia abutments and artificial saliva against chronic dry mouth. Results suggest that an artificial saliva containing organic corrosion inhibitors is able to be firmly mechanically and chemically adsorb on the surface of the Ti c.p. or Ti6Al4V alloy and form a protective film with high wettability. This type of artificial saliva can significantly reduce the friction coefficient and wear of both the titanium and zirconia surfaces. The use of this type of artificial saliva in standard wear tests has to be carefully considered because the wear resistance of the materials can be overestimated while it can be useful in some specific clinical applications. When saliva is free from organic corrosion inhibitors, wear occurs with a galling mechanism. The occurrence of a super-hydrophilic saliva film that is not firmly adsorbed on the surface is not efficient in order to reduce wear. The results give both suggestions about the experimental conditions for lab testing and in vivo performance of components of dental implants when artificial saliva is used.

Laser-assisted production of HAp-coated zirconia structured surfaces for biomedical applications

ObjectivesThe aim of this study was to develop a novel design for implants surface functionalization through the production of HAp-coated zirconia structured surfaces by means of hybrid laser technique. The HAp-rich structured surfaces were designed to avoid hydroxyapatite (HAp) coating detachment from the zirconia surface during implant insertion, thus guaranteeing an effective osseointegration. Materials and methodsThe functionalization process of zirconia surface started by creating micro-textures using a Nd:YAG laser and subsequent deposition of a HAp coating on the designated locations by dip-coating process. Afterwards, a CO2 laser was used to sinter the HAp coating. The potential of the HAp-coated zirconia structured surfaces was inspected concerning HAp bioactivity preservation, surface wettability, HAp coating adhesion to the textured surfaces and mechanical resistance of zirconia, as assessed by different approaches. ResultsThe functionalized surfaces exhibited a superhydrophilic behavior (2.30 ± 0.81°) and the remaining results showed that through the hybrid strategy, it is possible to maintain the HAp bioactivity as well as promote a strong adhesion of HAp coating to the textured surfaces even after high energy ultrasonic cavitation tests and friction tests against bovine bone. It was also verified that the flexural strength of zirconia (503 ± 24 MPa) fulfills the strict requirements of the ISO 13356:2008 standard and as such is expectable to be enough for biomedical applications. SignificanceThe promising results of this study indicate that the proposed surface design can open the window for manufacturing zirconia-based implants with improved bioactivity required for an effective osseointegration as it avoids the coating detachment problem during the implant insertion.

The impact of surface alteration on epithelial tissue attachment after the mechanical cleaning of titanium or zirconia surface.

Mechanical plaque removal may alter the surface morphology of the gingival penetration part of the implant. We applied an air-powered abrasive system (AP), titanium curette (TC), stainless curette (SC), ultrasound scaler (US), and titanium brush (TB) which are commonly used to remove plaque, to titanium or zirconia and the changes in surface morphology and the epithelial attach against substrata. (a) The morphological changes of titanium and zirconia after mechanical cleaning were assessed by scanning electron microscopy and a roughness analyser. (b) Oral epithelial cells of rats were inoculated on the surface of the materials after mechanical cleaning, and the adherence of epithelial cells was observed. (c) The maxillary first molars were extracted from the rats and replaced by experimental titanium or zirconia implants. The length of the immunoreactive laminin-332 band was observed at the implant-peri-implant epithelium interface. (a) The surface roughness increased in experimental groups except the AP group. (b) Among the experimental groups, the AP group showed the highest number of attached cells. (c) The length of the immunoreactive laminin-332 band was longer in the control group than those in all five experimental groups. Among the experimental groups, the AP group showed the longest band. All mechanical cleaning methods increased the surface roughness of the materials except AP. AP did not cause distinct implant surface alterations. Surface alteration caused by mechanical cleaning may evoke inferior for epithelial attachment and reduce resistance against foreign infiltration.

Bioactivation of zirconia surface with laminin protein coating via plasma etching and chemical modification

Surface modification offers a promising alternative to provide bioactivity to implanted inert biomaterials, improving their integration and performance with living tissues. In this contribution, zirconia has been used as a substrate to investigate the biofunctionalization process, designed to add surface bioactivity to a bioinert biomaterial. We intended to attach laminin-5, known for its ability to bind epithelial cells in soft tissue, to the surface of the extracellular matrix protein. First, the zirconia surface was etched and activated with argon plasma and subsequently it was chemically functionalized with calcium and phosphate ions. Zirconia surface activation was monitored by means of a wettability test, whereas functionalization with calcium and phosphate ions was evaluated by confocal Raman microscopy, Z-potential and X-ray Photoelectron Spectroscopy (XPS). The binding of laminin-5 protein to the zirconia surface was carried out by means of adsorption and confirmed by XPS. Then, we used SEM and AFM to observe a homogeneous covering of globular protein over the zirconia surface. Furthermore, epithelial cell response over zirconia surfaces was assayed to show that biofunctionalized surfaces enhance cell adhesion to a greater extent than substrates without protein coating. Our results indicate how the zirconia surface can be modified using argon plasma, in order to enable its bioactivation with the laminin-5 protein.

Effects of air-abrasion pressure on mechanical and bonding properties of translucent zirconia.

The purpose of this in vitro study was to investigate the effects of different air-abrasion pressures on flexural strength and shear bond strength of a translucent zirconia. The translucent zirconia surface was treated with 50 μm abrasive alumina particles at different pressure: 0.1 MPa; 0.2 MPa; 0.3 MPa; 0.4 MPa; 0.5 MPa; untreated specimens were used as control group (n = 33). For each group, three-point bending test was used to evaluate the flexural strength, and surface characterizations were analyzed. Following adhesive bonding and water storage for 24 h, specimens were subdivided into groups baseline and aged (5000 thermocycles). Then, shear bond strength was measured and failure mode was recorded. Statistical analysis was performed with one-way ANOVA and Tukey test (α = 0.05). Increasing air-abrasion pressure (0.3 MPa, 0.4 MPa, and 0.5 MPa) decreased the flexural strength. Higher air-abrasion pressure resulted in rougher zirconia surfaces and caused more microcracks. The highest shear bond strength was obtained for zirconia surfaces abraded at 0.2 MPa (15.88 ± 2.70 MPa) and 0.3 MPa (14.32 ± 1.12 MPa). Aging did not decrease the strength for all groups except control group (p < 0.001). Air-abrasion with 50 μm abrasive alumina particles at 0.2 MPa could achieve good strength for translucent zirconia ceramics while maintaining adequate and durable bonding with resin cement. A total of 0.2 MPa is recommended for air-abrasion procedure applied before a dental restoration fabricated with translucent zirconia is bonded to resin cement.

Influence of ns-Nd:YAG laser surface treatment on the tensile bond strength of zirconia to resin-matrix cements

The main aim of this study was to assess the effect of ns-Nd:YAG laser structuring over zirconia green compacts on the adhesion of sintered zirconia to resin-matrix cements. Zirconia (3Y-TZP) compacts were divided according to the type of surface modification: GB – alumina grit-blasted sintered specimens; G8L – laser structured zirconia green compacts (square pattern 8 lines); G16L - laser structured zirconia green compacts (square pattern 16 lines); G8L/GB – alumina grit-blasted G8L specimens after sintering. Specimens of same group were cleaned, cemented using a dual cure resin-matrix cement and aged in distilled water for 24 h (37 °C). Afterwards, the tensile bond strength was measured using a universal test machine. Specimens were analyzed by field emission guns scanning electron microscopy (FEGSEM) and white light interferometry (WLI). Laser-structured surfaces showed higher roughness values and improved morphological aspects for adhesion to resin-matrix cements. Higher tensile bond strength mean values of zirconia to resin-matrix cements were recorded for G8L (16.7 ± 3.8 MPa) and G16L (13.6 ± 3.0 MPa) groups when compared to those recorded for ordinary grit-blasted zirconia surfaces to resin-matrix cements (10 ± 3.1 MPa). The highest tensile bond strength results were recorded for the G8L/GB group (24.2 ± 7.6 MPa). The laser texturing of green zirconia surfaces promoted an increase in roughness and changes in morphological aspects of sintered zirconia for improved adhesion to resin-matrix cements.