Review
Materials Science, Multidisciplinary
M. K. G. Abbas, S. Ramesh, S. F. H. Tasfy, K. Y. Sara Lee
Summary: This review provides a comprehensive overview of alumina-zirconia composites (ATZs), including the properties of zirconia and alumina ceramics, methods for combining them, and the effects of sintering conditions on their performance. Previous studies have reached a consensus on the influence of sintering temperature, sintering time, and alumina content, and microwave sintering has demonstrated superiority. By understanding the factors influencing ATZ, tailored composites with desired properties can be produced for specific applications.
MATERIALS TODAY COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Jose D. Avila, Amit Bandyopadhyay
Summary: The use of Ti64 alloy reinforced with ZTA can effectively address the galvanic-induced corrosion failure issue when coupling CoCr alloy femoral heads with titanium hip stems. After parameter optimization, the Ti64 + 5wt.%ZTA (5ZTA) composition showed a more reliable interface, reduced porosity, and increased hardness.
Article
Nanoscience & Nanotechnology
Jianqi Chen, Weili Wang, Xiaoning Sun, Guoxun Sun, Yanjie Liang
Summary: Nacre-like alumina ceramics with zirconia particles uniformly distributed between the layers are successfully fabricated using freeze casting and hot pressing. The addition of zirconia greatly improves the flexural strength and fracture toughness of the material. Microstructure observation and fracture behavior analysis reveal that the enhanced mechanical properties are attributed to the bioinspired nacre-like structure and stress-induced transformation toughening.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Ceramics
Maoyin Li, Bart Van Meerbeek, Bensu Tunca, Stevan Cokic, Jef Vleugels, Fei Zhang
Summary: Three different alumina sources were used to prepare 12Ce-TZP-based alumina-toughened-zirconia (ATZ) composites, showing significant differences in microstructure and properties. Boehmite-based composites exhibited higher indentation fracture resistance, strength, and reliability compared to aluminium nitrate and alumina-particle based equivalents.
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
(2021)
Article
Chemistry, Physical
Hiroto Nakai, Masanao Inokoshi, Kosuke Nozaki, Kumiko Yoshihara, Akihiro Matsukawa, Noriyuki Nagaoka, Watcharapong Tonprasong, Shunsuke Minakuchi
Summary: In this study, the surface morphology, surface texture, and osteoblast response of additively manufactured zirconia and alumina-toughened zirconia (ATZ) were evaluated in comparison with titanium. The results showed that the additively manufactured zirconia had comparable or better cell response compared to titanium, indicating its potential as a promising dental implant material.
Article
Chemistry, Physical
Alex Tchinda, Laetitia Chezeau, Gael Pierson, Richard Kouitat-Njiwa, B. H. Rihn, Pierre Bravetti
Summary: The biocompatibility of rough and smooth surfaces of Y-TZP and ZrO2 discs was evaluated in this study. The results showed similar cell proliferation rates and coverage between Y-TZP and ZrO2 discs and control cells, regardless of the surface topography. Transcriptomic analysis indicated the excellent biocompatibility of Y-TZP, with differentially expressed transcripts mainly involved in mineral uptake and immune response pathways.
Article
Materials Science, Ceramics
Mushtaq Alam, Ezhilan Manivannan, Mohamed Rizwan, Gopika Gopan, Maheswaran Mani, Sanjeevi Kannan
Summary: Fused deposition modeling (FDM) has been used to design 3D printed PLA/ZTA composites, and the optimum combination ratio has been determined through experiments. Finite element analysis (FEA) simulation studies showed consistent results with the experimental findings.
INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY
(2023)
Article
Materials Science, Ceramics
Y. H. Su, P. P. Jing, Y. X. Li, D. L. Ma, F. Y. Yue, Y. X. Leng
Summary: Cu doping is used to improve the lubrication and fracture toughness of zirconia-toughened alumina (ZTA) in total hip arthroplasty. The study investigates the effect of Cu doping on the biocompatibility of ZTA ceramics. Cu doping reduces the stability of tetragonal zirconia, resulting in a phase transition and pore formation on the ZTA surface. Cu doping enhances the adhesion and viability of osteoblasts, but influences the morphology and pro-inflammatory response of macrophages.
CERAMICS INTERNATIONAL
(2023)
Article
Materials Science, Ceramics
M. K. G. Abbas, S. Ramesh, K. Y. Sara Lee, Y. H. Wong, C. Y. Tan, U. Johnson Alengaram, P. Ganesan, Farayi Musharavati, Erfan Zalnezhad
Summary: The effect of copper oxide doping on the densification, microstructure evolution, and mechanical characteristics of alumina toughened zirconia ceramic composites was investigated. The addition of 0.2 wt% copper oxide improved densification and mechanical properties without affecting the phase stability, while higher dopant levels were detrimental to the material.
CERAMICS INTERNATIONAL
(2022)
Article
Materials Science, Ceramics
Nouhaila Khalile, Clemence Petit, Christophe Meunier, Francois Valdivieso
Summary: This study investigates the influence of zirconia on the microwave sintering of zirconia-toughened alumina. Through sintering experiments using different types of zirconia powders, it was found that 8 mol% yttria-stabilized zirconia exhibited better densification when sintered without susceptor. The behavior of the samples during the intermediate stage of sintering also showed variations, with the samples containing 3 and 8 mol% yttria-stabilized zirconia being easier to densify compared to the samples with unstabilized and 10 mol% ceria-stabilized zirconia. These differences can be attributed to the chemical composition of zirconia.
CERAMICS INTERNATIONAL
(2023)
Article
Biochemistry & Molecular Biology
Alessandro Alan Porporati, Yvonne Modinger, Sarah Fischer, Sara Polajzer, Melanie Mettang, Ulrike Deisinger, Matejka Podlogar, Rihard Trebse, Nika Lovsin
Summary: Ten percent of patients undergoing total hip arthroplasty (THA) require revision surgery. The study compared the toxicity and immunogenicity of nanoparticles from Al2O3, zirconia-toughened alumina (ZTA), and cobalt chrome (CoCr) in THP-1 macrophage cell line and human primary macrophages. Results showed that ZTA is a non-toxic implant material with no immunogenic effects in vitro.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2023)
Article
Chemistry, Multidisciplinary
Chae-Young Lee, Sujin Lee, Jang-Hoon Ha, Jongman Lee, In-Hyuck Song, Kyoung-Seok Moon
Summary: Porous ceramics with high chemical and thermal stability, especially reticulated porous ceramics, exhibit high porosity and good permeability. By adjusting processing conditions, the compressive strength of reticulated porous ZTA can be improved.
APPLIED SCIENCES-BASEL
(2021)
Article
Materials Science, Ceramics
Seema Patil, Deepak Rajaram Patil, In Chul Jung, Jungho Ryu
Summary: This study systematically investigated the effect of cooling rates on the microstructural evolution and residual stress of ATZ composites after sintering. The results showed that the ATZ composite with a cooling rate of -1 degrees C/min exhibited the highest fracture toughness and the lowest tensile residual stress.
CERAMICS INTERNATIONAL
(2022)
Article
Chemistry, Physical
Jide Han, Berfu Goksel, Shiva Mohajernia, Manuela Sonja Killian, Jozef Vleugels, Annabel Braem, Sylvie Castagne
Summary: Zirconia toughened alumina (ZTA) is commonly used in hip joint implants and cutting tools due to its unique properties. The difference in material properties between zirconia and alumina phases leads to the selectivity of phase melting and the disintegration of alumina grains during laser processing. This selective phase melting phenomenon makes the material removal mechanism of the nanocomposite significantly different from that of single-phase materials.
APPLIED SURFACE SCIENCE
(2023)
Article
Materials Science, Ceramics
Y. Wade-Zhu, J. Wade-Zhu, H. Wu, J. Binner, B. Vaidhyanathan
Summary: The ballistic impact performance of nanocrystalline zirconia-toughened alumina (nZTA) ceramics was compared to monolithic alumina, showing no significant advantage in penetration resistance. Deformation analysis of fragments indicated that both nZTA and alumina experienced similar levels of plastic deformation, with finer fragments exhibiting more plastic deformation. These results were further confirmed through fracture surface observations and subsurface dislocation analysis using SEM and TEM.
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
(2021)
Article
Dentistry, Oral Surgery & Medicine
Matthias Kern, Christoph Behrendt, Elfriede Fritzer, Ralf J. Kohal, Ralph G. Luthardt, Nadine Frfr von Maltzahn, Michael Radel, Daniel R. Reissmann, Franz Sebastian Schwindling, Stefan Wolfart, Nicole Passia
Summary: The study aimed to investigate the impact of loading protocols on single dental implants in edentulous mandibles. Results showed that immediate loading led to lower survival rates compared to delayed loading, suggesting that immediate loading should be considered only in exceptional cases.
CLINICAL ORAL IMPLANTS RESEARCH
(2021)
Article
Dentistry, Oral Surgery & Medicine
Christian Wesemann, Benedikt Christopher Spies, Guido Sterzenbach, Florian Beuer, Ralf Kohal, Gregor Wemken, Marei Kruegel, Stefano Pieralli
Summary: This study aimed to compare the wear resistance of polymers in injection molding, subtractive, and additive manufacturing, and analyze their relationship with enamel antagonist wear and material properties. The results showed that occlusal devices manufactured using different methods did not differ significantly in wear resistance and antagonist wear, but exhibited some variations in material properties.
Article
Dentistry, Oral Surgery & Medicine
Florian Kernen, Stefan Schlager, Veronica Seidel Alvarez, Juergen Mehrhof, Kirstin Vach, Ralf Kohal, Katja Nelson, Tabea Fluegge
Summary: The accuracy of intraoral scanners is crucial for computer-aided design and computer-aided manufacturing (CAD-CAM) dentistry. This clinical study compared the accuracy of intraoral scanning with different devices to extraoral scanning. The results showed that extraoral scans had higher precision and trueness compared to intraoral scans, except for complete-arch scans with one specific intraoral scanner. Short-span scans had higher precision and trueness compared to complete-arch scans.
JOURNAL OF PROSTHETIC DENTISTRY
(2022)
Article
Chemistry, Physical
Sebastian Berthold Maximilian Patzelt, Marei Kruegel, Christian Wesemann, Stefano Pieralli, Julian Nold, Benedikt Christopher Spies, Kirstin Vach, Ralf-Joachim Kohal
Summary: The study compared conventional to digital workflows in occlusal splint production and found that the digital workflow was more time efficient and led to better fit than the conventional workflow.
Article
Chemistry, Physical
Aimen Bagegni, Vincent Weihrauch, Kirstin Vach, Ralf Kohal
Summary: The use of screwless Morse taper IAC can eliminate mechanical complications and provide stable implant-abutment connections. Screw-retained hexagonal IAC showed the highest retention stability, while screwless Morse taper IACs remained stable for extended periods of time, making them a valid treatment option for single-tooth replacement.
Article
Engineering, Biomedical
Kerstin Rabel, Julian Nold, Daniela Pehlke, James Shen, Anze Abram, Andraz Kocjan, Siegbert Witkowski, Ralf -Joachim Kohal
Summary: This study compared self-glazed zirconia restorations with conventionally CAD/CAM milled and glazed controls and found that self-glazed zirconia restorations have higher surface microstructural homogeneity and fracture strength. The fracture strength of self-glazed zirconia restorations decreased after dynamic loading but remained significantly higher than the conventionally glazed controls. Therefore, this study suggests that self-glazed zirconia restorations are stable for clinical application and further research is needed to prove their clinical applicability.
JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS
(2022)
Article
Chemistry, Physical
Babak Saravi, Anselm Flohr, Sebastian B. Patzelt, Benedikt C. Spies, Derek Hazard, Ralf J. Kohal
Summary: This study evaluated the physico-mechanical properties of PEEK abutments as implant dentistry materials using a chewing simulator model. By comparing surface roughness, microgaps, and fracture loads between PEEK abutments and zirconia abutments, it was found that PEEK abutments performed better in load-bearing properties and could be a feasible alternative to zirconia abutments.
Article
Chemistry, Physical
Malin Strasding, Samir Abou-Ayash, Thomas Laziok, Sam Doerken, Ralf-Joachim Kohal, Sebastian Berthold Maximilian Patzelt
Summary: The purpose of this study was to analyze the clinical and patient-reported outcomes of patients restored with non-precious metal alloy double crown-retained removable partial dentures (NP-D-RPDs). The results showed that non-precious metal alloy partially veneered NP-D-RPDs are an efficient alternative to precious metal alloy RPDs with excellent patient-reported outcomes.
Article
Dentistry, Oral Surgery & Medicine
Ralf-Joachim Kohal, Christopher von Schierholz, Julian Nold, Benedikt C. C. Spies, Erik Adolfsson, Kirstin Vach, Felix Burkhardt
Summary: The objective of this study was to investigate the fracture strength and potential phase transformation of an injection-molded two-piece zirconia implant restored with a zirconia abutment after loading and/or aging. The results showed that dynamic loading and the combination of loading and aging reduced the fracture strength of the implant abutment combination. Hydrothermal treatment caused a shallow transformation zone which had no influence on the fracture strength.
CLINICAL ORAL IMPLANTS RESEARCH
(2023)
Article
Chemistry, Multidisciplinary
Alexander Welle, Kerstin Rabel, Matthias Schwotzer, Ralf Joachim Kohal, Thorsten Steinberg, Brigitte Altmann
Summary: With the increasing use of zirconia-based nano-ceramics in dentistry, it is important to examine the potential biological effects of released nanoparticles on oral tissues like bone. This study used ToF-SIMS to investigate the internalization of differently sized zirconia nanoparticles (ZrNP) into human osteoblasts and found that ZrNP were internalized by the cells in a size-dependent manner. The study also showed that exposure to ZrNP had a negative effect on the metabolic activity of the cells, with the smallest ZrNP having the most pronounced effect.
Article
Engineering, Biomedical
Ralf-Joachim Kohal, Kirstin Vach, Frank Butz, Benedikt Christopher Spies, Sebastian Berthold Maximilian Patzelt, Felix Burkhardt
Summary: The study investigated the clinical and radiological outcome of one-piece zirconia oral implants supporting three-unit fixed dental prostheses after three years. 54 implants were placed in 27 patients through a one-stage surgery and immediate provisionalization. Standardized radiographs were taken at different time points to evaluate bone loss and soft-tissue parameters. The zirconia implants exhibited a cumulative survival rate of 98.1% after three years, with a mean marginal bone loss of 2.16 mm. However, high peri-implantitis incidence and low implant success rate were observed, indicating a possible concern for long-term stability.
JOURNAL OF FUNCTIONAL BIOMATERIALS
(2023)
Article
Engineering, Biomedical
Ralf-Joachim Kohal, Felix Burkhardt, Jerome Chevalier, Sebastian Berthold Maximilian Patzelt, Frank Butz
Summary: This 5-year prospective cohort investigation evaluated the outcomes of a one-piece zirconia implant system for single tooth replacement. Follow-ups showed a cumulative implant survival rate of 78.2% after 5 years. Patient satisfaction was higher compared to pre-treatment measurements.
JOURNAL OF FUNCTIONAL BIOMATERIALS
(2023)
Article
Engineering, Biomedical
Ralf-Joachim Kohal, Anja Trinkner, Felix Burkhardt, Sebastian Berthold Maximilian Patzelt, Kirstin Vach, Monika Kuster, Anze Abram, Andraz Kocjan, Julian Nold
Summary: The aim of this study was to evaluate the long-term stability of one-piece diameter reduced zirconia oral implants under loading and artificial aging. The results showed that dynamic loading, hydrothermal aging, and the combination of loading and aging did not significantly affect the stability of the implants. The implant system was able to resist physiological chewing forces and maintain stability over a long service period.
JOURNAL OF FUNCTIONAL BIOMATERIALS
(2023)
Article
Engineering, Biomedical
Babak Saravi, Julia Ilbertz, Kirstin Vach, Ralf J. Kohal, Sebastian B. M. Patzelt
Summary: Computerized optical impression making (COIM) is a rising trend in dental prosthetics for removable dentures, but its accuracy compared with traditional impression-making techniques remains uncertain. A study evaluating the accuracy of COIM in partially edentulous jaws found that it captured dental hard tissue more accurately than mucosal areas, likely due to software algorithms filtering out mobile tissues. Clinically, caution is needed when using COIM for prosthetics involving mucosal tissues as deviations could compromise the fit and longevity.
JOURNAL OF FUNCTIONAL BIOMATERIALS
(2023)
Article
Chemistry, Physical
Aimen Bagegni, Justus Borchers, Samuel Beisel, Sebastian B. M. Patzelt, Kirstin Vach, Ralf Kohal
Summary: This study evaluated the effects of different luting agents on the bonding between zirconium dioxide crowns and titanium bonding bases. The results showed that most luting agents were suitable for cementation of zirconium dioxide crowns, meeting the recommended debonding force value.