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Leila Nasiry Khanlar

Bio: Leila Nasiry Khanlar is an academic researcher from Tokyo Medical and Dental University. The author has contributed to research in topics: Cubic zirconia & Bond strength. The author has an hindex of 1, co-authored 5 publications receiving 3 citations.

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Journal ArticleDOI
TL;DR: A comprehensive literature review was completed to summarize different additive manufacturing technologies that are available to fabricate zirconia and their clinical application is reported in this paper, which shows a promising outcome for utilizing AM of zirconsia in restorative, implant and regenerative dentistry.
Abstract: Additive manufacturing (AM) has many advantages and became a valid manufacturing technique for polymers and metals in dentistry. However, its application for dental ceramics is still in process. Among dental ceramics, zirconia is becoming popular and widely used in dentistry mainly due to its outstanding properties. Although subtractive technology or milling is the state of art for manufacturing zirconia restorations but still has shortcomings. Utilizing AM in fabricating ceramics restorations is a new topic for many researchers and companies across the globe and a good understanding of AM of zirconia is essential for dental professional. Therefore, the aim of this narrative review is to illustrate different AM technologies available for processing zirconia and discus their advantages and future potential. A comprehensive literature review was completed to summarize different AM technologies that are available to fabricate zirconia and their clinical application is reported. The results show a promising outcome for utilizing AM of zirconia in restorative, implant and regenerative dentistry. However further improvements and validation is necessary to approve its clinical application.

32 citations

Journal ArticleDOI
TL;DR: In this article, the effect of air-particle abrasion protocol and primer on surface topography and bond strength of resin cement to high-translucent zirconia ceramics was evaluated.
Abstract: Purpose To evaluate effect of air-particle abrasion protocol and primer on surface topography and bond strength of resin cement to high-translucent zirconia ceramics. Materials and methods Two hundred disk-shaped high-translucent zirconia specimens of 5Y-PSZ were prepared. The specimens were assigned to 5 groups in terms of particle type and air-particle abrasion pressure: (1) control (2) alumina with 0.2 MPa-air pressure [AB-0.2] (3) alumina with 0.4 MPa-air pressure [AB-0.4] (4) glass beads with 0.2 MPa-air pressure [GB-0.2] and (5) glass beads with 0.4 MPa-air pressure [GB-0.4]. Two different primers 1% MDP (Experimental) and MDP-silane primer (Clearfil Ceramic Primer Plus) was also tested. Stainless steel rods were bonded to the 5Y-PSZ specimens with PANAVIA V5. For each group, the tensile bond strength (TBS) was measured after 24h water storage (n = 10) and after 5,000 thermal-cycling (n = 10) at crosshead speed of 2 mm/min. The data were statistically analyzed using Weibull analysis. Surface roughness (Sa) was measured using a 3D-Laser Scanning Confocal Microscope (n = 5) and analyzed by t-test with Bonferroni correction. Surface topography using scanning electron microscopy (SEM) and surface elemental analysis using energy dispersion spectroscopy (EDX), and cross-section SEM at the interface with composite cement were also investigated. Results In MDP-silane groups, the highest TBS was observed in AB-0.4 after 24h and GB-0.4 after thermal-cycling (p 0.005). Conclusion Air-abrasion with different particle and blasting pressure can improve bonding to zirconia with proper primer selection. Particularly, glass beads abrasion followed by MDP-silane primer and alumina abrasion followed by MDP primer alone provided stable bond strength of resin cement to high-translucent zirconia after aging. High-translucent zirconia abraded with glass beads achieves a desirable bonding performance without creating surface microcracks which may hinder zirconia's mechanical properties. This article is protected by copyright. All rights reserved.

7 citations

Journal ArticleDOI
Abstract: Statement of problem Additive manufacturing (AM) is a technology that has been recently introduced into dentistry for fabricating dental devices, including interim restorations. Printing orientation is one of the important and influential factors in AM that affects the accuracy, surface roughness, and mechanical characteristics of printed objects. However, the optimal print orientation for best bond strength to 3D-printed interim restorations remains unclear. Purpose The purpose of this in vitro study was to evaluate the effect of printing orientation on the surface roughness, topography, and shear bond strength of AM interim restorations to composite resin. Material and methods Disk-shaped specimens (O20×10 mm) were designed by a computer-aided design software program (Geomagic freeform), and a standard tessellation language (STL) file was obtained. The STL file was used for the AM of 60 disks in 3 different printing orientations (0, 45, and 90 degrees) by using E-Dent 400 C&B material. An autopolymerizing interim material (Protemp 4) was used as a control group (CNT), and specimens were fabricated by using the injecting mold technique (n=20). Surface roughness (Sa, Sz parameters) was measured by using a 3D-laser scanning confocal microscope (CLSM) at ×20 magnification. For shear bond testing, the specimens were embedded in polymethylmethacrylate autopolymerized resin (n=20). A flowable composite resin was bonded by using an adhesive system. The specimens were stored in distilled water at 37 °C for 1 day and thermocycled 5000 times. The shear bond strength (SBS) was measured at a crosshead speed of 1 mm/min. The data were analyzed by 1-way ANOVA, followed by the Tukey HSD test (α=.05). Results The 45-degree angulation printing group reported the highest Sa, followed by the CNT and the 90-degree and 0-degree angulations with significant difference between them (P Conclusions Printing orientation significantly impacted the surface roughness of 3D-printed resin for interim restorations. However, printing orientation did not significantly affect the bond strength with composite resin.

7 citations

Journal ArticleDOI
TL;DR: Milled zirconia had a higher surface roughness and bond strength to composite resin cement than AM zirConia, and porosities in AM zIRconia decreased the bond strength with significant pretest failures.
Abstract: PURPOSE To investigate the bond strength of resin cement to additively manufactured (AM) zirconia with different porosities when compared to milled zirconia. MATERIALS AND METHODS A 12 × 5 mm disk virtual design file was used to fabricate a total of 48 disks divided into 4 groups: 3 groups were AM with different porosities including 0%-porosity (AMZ0 group), 20%-porosity (AMZ20 group), and 40%-porosity (AMZ40 group), and 1 milled zirconia (control or CNCZ group). The dimensions of all specimens were measured using a digital caliper. A 3D- confocal laser scanner was used to analyze surface morphology and measure the surface roughness (Sa), followed by SEM analysis. Tensile bond strength of composite resin cement to specimens was measured before and after aging procedures using a universal testing machine (n = 10). Failure modes were evaluated under a light microscope. Volumetric change data was analyzed using one-way ANOVA, and two-way ANOVA was used to compare bond strength values (α = 0.05). RESULTS There was a significant difference in volumetric changes among the groups. The CNCZ group showed the least changes in diameter 0.027 ± 0.029 mm and thickness 0.030 ± 0.012 mm and AM zirconia with 40% porosity showed the most volumetric changes in diameter 5.237 ± 0.023 mm. ANOVA test indicated an overall significant difference in surface roughness across all groups (F = 242.6, p < 0.001). The CNCZ group showed the highest mean Sa of 1.649 ± 0.240 µm, followed by AMZ40 group with Sa of 0.830 ± 0.063 µm, AMZ20 group with Sa of 0.780 ± 0.070 µm, and the AMZ0 group with Sa of 0.612 ± 0.063 µm. Two-way ANOVA showed significant difference in bond strength between the CNCZ group 12.109 ± 3.223 MPa and the AMZ0 group 8.629 ± 0.914 MPa, with significant pretest failures in specimens with porosities. Thermal cycling methods reduced the bond strength non-significantly in CNCZ group with no effect in the AMZ0 group. CONCLUSION Milled zirconia had a higher surface roughness and bond strength to composite resin cement than AM zirconia, and porosities in AM zirconia decreased the bond strength with significant pretest failures.

5 citations

Journal ArticleDOI
TL;DR: In this paper, the fracture resistance of additively manufactured monolithic zirconia and bi-layered alumina toughened ZIRconia crowns on implants was compared using a universal testing machine at a crosshead speed of 2 mm/min.
Abstract: (1) Background: This study compared the fracture resistance of additively manufactured monolithic zirconia and bi-layered alumina toughened zirconia crowns on implants. (2) Methods: Maxillary model with a dental implant replacing right second bicuspid was obtained. Custom abutments and full-contour crowns for additively manufactured monolithic zirconia and bi-layered alumina reinforced zirconia crowns (n = 10) were fabricated. The crowns were cemented to implant-supported zirconia abutments and the assembly fixed onto resin blocks. Fracture resistance was measured using a universal testing machine at a crosshead speed of 2 mm/min. A Kruskal-Wallis test was used to analyze the data. (3) Results: Although additively manufactured monolithic zirconia crowns demonstrated a higher mean fracture resistance than bi-layered alumina toughened zirconia crowns, statistical analysis revealed no significant difference in fracture resistance between the two groups. All specimens fractured at the implant-abutment interface. (4) Conclusions: Additively manufactured bi-layered alumina toughened zirconia crowns demonstrated similar fracture resistance to additively manufactured monolithic zirconia crowns when cemented to implant-supported zirconia abutments.

5 citations


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Journal ArticleDOI
TL;DR: The bond strength of lithium-disilicate ceramics was improved with 5% γ-MPTS in MDP primer, and MDP primers alone are best suited for efficient bonding of resin cement with zirconia ceramic.
Abstract: Objectives The purpose of the study was to evaluate the effects of the ratio of different concentrations of silane to 1 wt% 10-methacryloyloxydecyl dihydrogenphosphate (MDP) in primer on the performance and durability of bonding to silica-based and zirconia ceramics. Methods Phosphoric acid–treated lithium–disilicate (LD) and alumina-blasted zirconia specimens were assigned to five groups according to surface chemical treatment with different concentrations of γ-methacryloxypropyltrimethoxysilane (γ-MPTS) to 1 wt% MDP containing primer as follows: S0) without γ-MPTS; S1) 1 wt% γ-MPTS; S2) 2 wt% γ-MPTS; S5) 5 wt% γ-MPTS and S10) 10 wt% γ-MPTS. After priming, stainless-steel rods were bonded to the specimens with PanaviaV5 cement. Tensile bond strength (TBS) test was evaluated after 24-h (TC0) or 5000 thermocycling (TC5K). The wettability of primer-treated surfaces was measured using contact angle measurements. Surface elemental composition of zirconia was determined with X-ray photoelectron spectroscopy (XPS). The TBS data were analyzed using Weibull analysis. Contact angle data were analyzed by three-way analysis of variance (α = 0.05). Results Before thermocycling, S5 (34.3 ± 4.5 MPa) showed the highest TBS compared to S1 (27.8 ± 5.2 MPa) and S2 (29.7 ± 4.8 MPa), and insignificant difference with S10 (30.6 ± 6.2 MPa) in LD. For zirconia there was no significant difference in all silane containing primers with S0 (p > 0.05). Thermocycling decreased TBS for all experimental groups among both ceramics (p Significance The bond strength of lithium-disilicate ceramics was improved with 5% γ-MPTS in MDP primer. Moreover, increasing percentage of γ-MPTS by more than 5% has not improved the bond strength, conversely, it can alter the long-term durability of the bonded ceramic. MDP primers alone are best suited for efficient bonding of resin cement with zirconia ceramic.

18 citations

Journal ArticleDOI
TL;DR: In this paper , powder injection molding (PIM) binder compositions for the material extrusion (MEX) additive manufacturing of zirconia parts were evaluated in a ring-on-ring setup.
Abstract: The aim of this study is the evaluation of powder injection molding (PIM) binder compositions for the material extrusion (MEX) additive manufacturing of zirconia parts. Four commercial PIM binder compositions were selected and mixed with 45 vol% of yttria-stabilized zirconia powder. Due to the brittle characteristic of the obtained ceramic feedstocks, a screw based pellet printing head was used for printing dense zirconia structures. To compare 3D printing performance, additionally a commercially available zirconia filament was used in this study. Application of PIM binder compositions was limited either due to phase separation during processing, poor printing performance or delamination during solvent debinding. Only one of the PIM based feedstock compositions could be successfully printed, debound and sintered. A ring-on-ring setup was used to investigate the equibiaxial flexural strength after sintering for both pellet and filament printed disks. For benchmarking, cold isostatic pressed (CIP) ceramic discs were fabricated by commercial, ready-to-press, zirconia powder. The ring-on-ring results showed a low Weibull modulus (3

17 citations

Journal ArticleDOI
TL;DR: In vitro studies on the success and durability of bonding protocols to high-translucent zirconia are reviewed, suggesting that resin bonding protocols successfully applied to conventional zirConia are also the most successful for high- translucent zIRconia.
Abstract: OBJECTIVES Several systematic literature reviews have assessed the scientific evidence on resin bonding protocols to conventional 3 mol% ytrria-stabilized zirconia (3Y-TZP) ceramics. It has been widely discussed, however, that the differing composition and physical properties of new high-translucent zirconia generations (4Y-TZP and 5Y-TZP) may require alternative bonding materials and procedures. This paper reviewed in vitro studies on the success and durability of bonding protocols to high-translucent zirconia. MATERIAL AND METHODS A systematic search of PubMed and Cochrane Library for in vitro studies on bonding to new zirconia generations published until November 2020 was conducted and complemented by a manual search. Studies selected for review fulfilled the applied inclusion and exclusion criteria. The quality of the included studies was assessed with the Cochrane risk-of-bias tool for randomized trials. RESULTS Of 629 screened articles, 18 were included in this review. They investigated different surface pretreatment methods, primers, resin cements, aging procedures, and bond strength test protocols. The limited number of the identified studies and the heterogeneity of the extracted data did not allow to conduct a meta-analysis. CONCLUSIONS The available evidence suggests that resin bonding protocols successfully applied to conventional zirconia are also the most successful for high-translucent zirconia. Airborne particle abrasion and special phosphate monomer-containing primers or composite resin cements provide long-term durable resin bonds. CLINICAL SIGNIFICANCE Durable bonds can be established between high-translucent zirconia and resin cements. The bonding materials and procedures applied do not compromise their physical properties.

14 citations

Journal ArticleDOI
TL;DR: A review and discussion of current resin-bonding protocols to most commonly used dental ceramics can be found in this paper , where the type and composition of the specific ceramic determines the selection of the most effective bonding protocol.

6 citations

Journal ArticleDOI
TL;DR: In this article , a review of 3D printing of bioinert ceramics is presented, focusing on the different medical applications that can be achieved by 3D-printing of bio-inert materials.
Abstract: Three-dimensionally printed metals and polymers have been widely used and studied in medical applications, yet ceramics also require attention. Ceramics are versatile materials thanks to their excellent properties including high mechanical properties and hardness, good thermal and chemical behavior, and appropriate, electrical, and magnetic properties, as well as good biocompatibility. Manufacturing complex ceramic structures employing conventional methods, such as ceramic injection molding, die pressing or machining is extremely challenging. Thus, 3D printing breaks in as an appropriate solution for complex shapes. Amongst the different ceramics, bioinert ceramics appear to be promising because of their physical properties, which, for example, are similar to those of a replaced tissue, with minimal toxic response. In this way, this review focuses on the different medical applications that can be achieved by 3D printing of bioinert ceramics, as well as on the latest advances in the 3D printing of bioinert ceramics. Moreover, an in-depth comparison of the different AM technologies used in ceramics is presented to help choose the appropriate methods depending on the part geometry.

6 citations