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Zirconia Implants: Current Status and Future Prospects

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Biomaterials".

Deadline for manuscript submissions: closed (20 December 2022) | Viewed by 41012

Special Issue Editor

Prof. Dr. Dr. Jens Fischer

E-Mail Website
Guest Editor
Biomaterials and Technology, Department of Reconstructive Dentistry, University Center for Dental Medicine, University of Basel, 4058 Basel, Switzerland
Interests: material-tissue interaction; osseointegration; adhesive cementation; dental ceramics; composites; implant restorations

Special Issue Information

Dear Colleagues,

Implants are a valuable treatment option in dentistry to replace missing teeth. Zirconia implants seem to be a viable alternative to the titanium implants in use today. Early research has focused on the required strength and appropriate surface topography of such implants. The clinical success rates with the current zirconia implants are encouraging and prove that long-term stability and osseointegration can be achieved, which is a breakthrough in metal-free implantology. However, the ongoing research studies on zirconia implants demonstrate that some open questions remain to be answered.

This Special Issue of Materials aims to provide the most recent research results concerning dental zirconia implants. This Special Issue will cover technical aspects, such as implant material, design, and surface, biological aspects, such as cell attractiveness and bacterial adhesion, and clinical aspects, such as surgical techniques, prosthetic treatment, and clinical success. I kindly invite all those dedicating their work to zirconia implants to submit a manuscript in order to provide an altogether comprehensive overview of the state of the art. Papers on laboratory and clinical studies as well as reviews are equally welcome. I am looking forward to an outstanding Special Issue of Materials on this rapidly evolving and trend-setting area of dental therapy.

Prof. Dr. Dr. Jens Fischer
Guest Editor

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Keywords

  • dental implantology
  • zirconia implant
  • implant design
  • fracture load
  • surface topography
  • osseointegration
  • soft tissue attachment
  • bacterial adhesion
  • plaque formation
  • biocompatibility
  • implant-supported restoration
  • stress absorption

Published Papers (18 papers)

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15 pages, 4049 KiB  
Article
In Vitro Investigation of Material Combinations for Meso- and Suprastructures in a Biomimetic Approach to Restore One-Piece Zirconia Implants
by Reto Nueesch, Sabrina Karlin, Jens Fischer and Nadja Rohr
Materials 2023, 16(4), 1355; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16041355 - 05 Feb 2023
Viewed by 1094
Abstract
The aim of this study was to find a suitable material combination to avoid cement excess in the marginal region of one-piece zirconia implant-supported restorations by means of a hybrid crown consisting of a meso- and a suprastructure. One-piece zirconia implants (n [...] Read more.
The aim of this study was to find a suitable material combination to avoid cement excess in the marginal region of one-piece zirconia implant-supported restorations by means of a hybrid crown consisting of a meso- and a suprastructure. One-piece zirconia implants (n = 120) were embedded in epoxy resin. Microfilled resin composite mesostructures (n = 60), designed as caps, were bonded on the implant abutment with a primer only. A molar crown was constructed and cemented with a resin cement on top of the mesostructure as a suprastructure out of feldspar ceramic (n = 12), lithium-disilicate (n = 24), or zirconia (n = 24). Fracture load (n = 6) and retention force (n = 6) were measured immediately after storage in distilled water at 37 °C for 24 h, as well as after an additional exposure to artificial aging in a chewing simulator and simultaneous thermal cycling. For the measurement of the fracture load, monolithic crowns made of the employed restorative materials and identical in shape to the hybrid crowns served as controls (n = 6 each). Fracture load values for feldspar ceramic and lithium-disilicate hybrid crowns were slightly higher than those for the respective monolithic crowns at baseline and after aging, which was statistically significant only for feldspar crowns after aging. In contrast, fracture load values for zirconia monolithic crowns were higher than those for zirconia hybrid crowns, which was only statistically significant after aging. Artificial aging reduced the fracture load of feldspar and lithium-disilicate crowns both for hybrid and monolithic crowns. The effect was only statistically significant for lithium disilicate hybrid crowns. The fracture load for hybrid and monolithic zirconia crowns was increased by artificial aging without reaching statistical significance. The retention force of lithium-disilicate and zirconia hybrid crowns was not affected by artificial aging. Taking into account retention force and fracture load, lithium-disilicate hybrid crowns showed promising results. Full article
(This article belongs to the Special Issue Zirconia Implants: Current Status and Future Prospects)
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17 pages, 5261 KiB  
Article
Effect of Hydrogen Peroxide on the Surface and Attractiveness of Various Zirconia Implant Materials on Human Osteoblasts: An In Vitro Study
by Taskin Tuna, Martin Wein, Brigitte Altmann, Thorsten Steinberg, Jens Fischer and Wael Att
Materials 2023, 16(3), 961; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16030961 - 20 Jan 2023
Cited by 1 | Viewed by 1793
Abstract
The aim of this in vitro study was to investigate the effect of hydrogen peroxide (H2O2) on the surface properties of various zirconia-based dental implant materials and the response of human alveolar bone osteoblasts. For this purpose, discs of [...] Read more.
The aim of this in vitro study was to investigate the effect of hydrogen peroxide (H2O2) on the surface properties of various zirconia-based dental implant materials and the response of human alveolar bone osteoblasts. For this purpose, discs of two zirconia-based materials with smooth and roughened surfaces were immersed in 20% H2O2 for two hours. Scanning electron and atomic force microscopy showed no topographic changes after H2O2-treatment. Contact angle measurements (1), X-ray photoelectron spectroscopy (2) and X-ray diffraction (3) indicated that H2O2-treated surfaces (1) increased in hydrophilicity (p < 0.05) and (2) on three surfaces the carbon content decreased (33–60%), while (3) the monoclinic phase increased on all surfaces. Immunofluorescence analysis of the cell area and DNA-quantification and alkaline phosphatase activity revealed no effect of H2O2-treatment on cell behavior. Proliferation activity was significantly higher on three of the four untreated surfaces, especially on the smooth surfaces (p < 0.05). Within the limitations of this study, it can be concluded that exposure of zirconia surfaces to 20% H2O2 for 2 h increases the wettability of the surfaces, but also seems to increase the monoclinic phase, especially on roughened surfaces, which can be considered detrimental to material stability. Moreover, the H2O2-treatment has no influence on osteoblast behavior. Full article
(This article belongs to the Special Issue Zirconia Implants: Current Status and Future Prospects)
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11 pages, 1554 KiB  
Article
Influence of Surface Treatment and Accelerated Ageing on Biaxial Flexural Strength and Hardness of Zirconia
by Nadja Rohr, Angela Jacqueline Schönenberger and Jens Fischer
Materials 2023, 16(3), 910; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16030910 - 18 Jan 2023
Viewed by 1194
Abstract
The aim was to investigate how the surface treatment and the process of accelerated ageing of zirconia for dental implants affect the biaxial flexural strength and hardness. Zirconia discs with a diameter of 12.6 mm were subjected to either one of the following [...] Read more.
The aim was to investigate how the surface treatment and the process of accelerated ageing of zirconia for dental implants affect the biaxial flexural strength and hardness. Zirconia discs with a diameter of 12.6 mm were subjected to either one of the following treatments: polishing (Zp); polishing and heat treatment at 1250 °C for 1 h (Zpt); machining (Zm); machining and heat treatment (Zmt); or sandblasting, acid-etching, and heat treatment (Z14) (n = 45 per group). Biaxial flexural strength and Martens hardness (HM) were measured without further treatment and after accelerated ageing for 5 h or 5 × 5 h according to ISO 13356 (n = 15 per group). Two-way ANOVA was applied to test the effect of surface treatment and ageing (α = 0.05). The reliability of the specimens was described with Weibull two-parameter distribution of biaxial flexural strength data. Overall, the surface treatment (p < 0.001) and ageing (p = 0.012) revealed a significant effect on biaxial flexural strength values, while HM was only affected by the surface treatment (p < 0.001) but not ageing (p = 0.160). Surface treatment significantly affected HM (p < 0.001) but not ageing (p = 0.160). The applied surface treatments affected the biaxial flexural strength and HM of zirconia. For accelerated ageing, a duration of both 5 h and 5 × 5 h is recommended to evaluate the effect of surface treatments. Zm was the most reliable surface as it was least affected by ageing and provided low standard deviations of biaxial flexural strength values. Full article
(This article belongs to the Special Issue Zirconia Implants: Current Status and Future Prospects)
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20 pages, 13814 KiB  
Article
Digital Light Processing of Zirconia Suspensions Containing Photocurable Monomer/Camphor Vehicle for Dental Applications
by Seo-Young Yang, Young-Hag Koh and Hyoun-Ee Kim
Materials 2023, 16(1), 402; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16010402 - 01 Jan 2023
Cited by 2 | Viewed by 1532
Abstract
This study reports the utility of solid camphor as a novel diluent in photocurable hexanediol diacrylate (HDDA) monomer to manufacture 4 mol% yttria partially stabilized zirconia (4Y-PSZ) components for dental applications by digital light processing (DLP). The use of a 65 wt% HDDA–35 [...] Read more.
This study reports the utility of solid camphor as a novel diluent in photocurable hexanediol diacrylate (HDDA) monomer to manufacture 4 mol% yttria partially stabilized zirconia (4Y-PSZ) components for dental applications by digital light processing (DLP). The use of a 65 wt% HDDA–35 wt% camphor solution allowed 4Y-PSZ suspensions to have reasonably low viscosities (1399 ± 55.8 mPa·s at a shear rate of 75 s−1), measured by a cone/plate viscometer, at a high solid loading of 48 vol%, where 4Y-PSZ particles prepared by calcination of as-received 4Y-PSZ granules, followed by a ball-milling process, were used with assistance of a dispersant. These 4Y-PSZ suspensions could be successfully applied to our custom-made DLP machine for manufacturing 4Y-PSZ components. To this end, several processing parameters, including layer thickness of 4Y-PSZ suspension, UV illumination time for layer-by-layer photocuring process, and initial dimensions of 4Y-PSZ objects, were tightly controlled. As sintering temperature increased from 1300 °C to 1500 °C, relative density and grain size of 4Y-PSZ objects increased, and cubic phase content also increased. Thus, after sintering at the highest temperature of 1500 °C for 3 h, high mechanical properties (biaxial flexural strength = 911 ± 40.7 MPa, hardness = 1371 ± 14.4 Hv) and reasonably high optical transmittance (translucency parameter = 7.77 ± 0.32, contrast ratio = 0.809 ± 0.007), evaluated by a spectrophotometer, were obtained due to a high relative density (97.2 ± 1.38%), which would be useful for dental applications. Full article
(This article belongs to the Special Issue Zirconia Implants: Current Status and Future Prospects)
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11 pages, 2798 KiB  
Article
Effects of Excimer Laser Treatment of Zirconia Disks on the Adhesion of L929 Fibroblasts
by Yoshihiko Akashi, Yoshiaki Shimoo, Hayato Hashiguchi, Kei Nakajima, Katsutoshi Kokubun and Kenichi Matsuzaka
Materials 2023, 16(1), 115; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16010115 - 22 Dec 2022
Cited by 1 | Viewed by 1457
Abstract
The adhesion of zirconia and soft tissue is very important for the success of zirconia implants. The aim of this study was to characterize the effects of excimer laser treatment of zirconia on the adhesion of L929 fibroblasts. In this study, polished zirconia [...] Read more.
The adhesion of zirconia and soft tissue is very important for the success of zirconia implants. The aim of this study was to characterize the effects of excimer laser treatment of zirconia on the adhesion of L929 fibroblasts. In this study, polished zirconia disks treated with an excimer laser were the experimental group and untreated zirconia disks were the control group. Surface roughness and contact angles of zirconia disks were measured. mRNA expression levels of integrin β1 and collagen type I α1 in L929 fibroblasts cultured on zirconia disks were measured using qRT-PCR. Cell morphology was evaluated using 3D laser microscopy and the expression of vinculin was characterized using confocal microscopy. There was no significant difference in the surface roughness of zirconia disks, but contact angles were significantly lower. mRNA expression of integrin β1 was significantly higher at 3, 6 and 24 h and of collagen type I α1 was significantly higher at 6 and 24 h. L929 fibroblasts tended to form elongated microspikes and vinculin colocalization in those microspikes. Furthermore, vinculin was strongly expressed in filopodia of L929 fibroblasts at 24 h. These results suggest that excimer laser treatment improves adhesion between zirconia disks and L929 fibroblasts. Full article
(This article belongs to the Special Issue Zirconia Implants: Current Status and Future Prospects)
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13 pages, 2564 KiB  
Article
Cytokines Activate JAK–STAT Signaling Pathway in MG-63 Cells on Titanium and Zirconia
by Khaled Mukaddam, Sabrina Ruggiero, Steffen M. Berger, Dietmar Cholewa, Sebastian Kühl, Daniel Vegh, Michael Payer, Michael M. Bornstein, Farah Alhawasli and Elizaveta Fasler-Kan
Materials 2022, 15(16), 5621; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15165621 - 16 Aug 2022
Cited by 2 | Viewed by 1447
Abstract
Although titanium has been traditionally used as the gold standard for dental implants, recent years have seen the widespread application of zirconia implants given their superiority with regards to reduced bacterial adhesion, inflammation and cellular-interaction in terms of bio-compatibility. The JAK–STAT signaling pathway [...] Read more.
Although titanium has been traditionally used as the gold standard for dental implants, recent years have seen the widespread application of zirconia implants given their superiority with regards to reduced bacterial adhesion, inflammation and cellular-interaction in terms of bio-compatibility. The JAK–STAT signaling pathway plays an important role in bone remodeling and formation. The aim of the study was to investigate the activation of the JAK–STAT pathway through different cytokines in osteoblast-like cells (MG-63) on zirconia in comparison to titanium discs. IFN-γ induced the very strong activation of STAT1 protein, IFN-α activated both STAT1 and STAT3 molecules, IL-6 activated STAT3 and IL-4 induced the activation of STAT6 on both surfaces. The activation of STAT proteins was confirmed by western blot, immunofluorescence and flow cytometry using phospho-specific anti-STAT antibodies, which recognize only phosphorylated STAT proteins. The incubation of MG-63 cells with IFN-γ caused the upregulation of MHC class I and class II proteins when MG-63 cells were grown on zirconia and titanium discs. In sum, the present study shows that the JAK–STAT pathway is activated in MG-63 cells when they are incubated on titanium or zirconia surfaces. Full article
(This article belongs to the Special Issue Zirconia Implants: Current Status and Future Prospects)
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11 pages, 1855 KiB  
Article
Results at the 1-Year Follow-Up of a Prospective Cohort Study with Short, Zirconia Implants
by Marc Balmer, Carolin Fischer, Miha Pirc, Christoph H. F. Hämmerle and Ronald E. Jung
Materials 2022, 15(16), 5584; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15165584 - 15 Aug 2022
Cited by 2 | Viewed by 1257
Abstract
The objective of this study was to clinically and radiologically evaluate the performance of a short (8 mm), 1-piece, zirconia implant after an observation period of 1 year in function. A total of 47 patients with 1 missing tooth in the position of [...] Read more.
The objective of this study was to clinically and radiologically evaluate the performance of a short (8 mm), 1-piece, zirconia implant after an observation period of 1 year in function. A total of 47 patients with 1 missing tooth in the position of a premolar or molar were recruited. Short (8 mm), 1-piece, zirconia implants were placed and loaded after a healing period of 2 to 4 months with monolithic crowns made of 3 different materials. Implants were followed up for one year and clinically and radiologically assessed. A total of 46 implants were placed. One was excluded since no primary stability was achieved at implant placement. At the 1-year follow-up, mean marginal bone loss 1 year after loading was 0.05 ± 0.47 mm. None of the implants showed marginal bone loss greater than 1 mm or clinical signs of peri-implantitis. A total of 2 implants were lost during the healing phase and another after loading, resulting in a survival rate of 93% after 1 year. All lost implants showed a sudden increased mobility with no previous signs of marginal bone loss or peri-implant infection. The short, 8 mm, zirconia implants showed stable marginal bone levels over the short observation period of 1 year. Although they revealed slightly lower survival rates, they can be suggested for the use in sites with reduced vertical bone. Scientific data are very limited, and long-term data are not yet available, and therefore, they are needed. Full article
(This article belongs to the Special Issue Zirconia Implants: Current Status and Future Prospects)
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16 pages, 5950 KiB  
Article
Zirconia versus Titanium Implants: 8-Year Follow-Up in a Patient Cohort Contrasted with Histological Evidence from a Preclinical Animal Model
by Warwick J. Duncan, Sunyoung Ma, Allauddin Siddiqi and Reham B. Osman
Materials 2022, 15(15), 5322; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15155322 - 02 Aug 2022
Cited by 2 | Viewed by 2204
Abstract
Zirconia ceramic (ZC) implants are becoming more common, but comparisons between preclinical histology and long-term clinical trials are rare. This investigation comprised (1) 8-year clinical follow-up of one-piece ZC or titanium (Ti) implants supporting full overdentures and (2) histomorphometric analysis of the same [...] Read more.
Zirconia ceramic (ZC) implants are becoming more common, but comparisons between preclinical histology and long-term clinical trials are rare. This investigation comprised (1) 8-year clinical follow-up of one-piece ZC or titanium (Ti) implants supporting full overdentures and (2) histomorphometric analysis of the same implants in an animal model, comparing implants with various surface treatments. Methods: (1) Clinical trial: 24 completely edentulous participants (2 groups of N = 12) received 7 implants (one-piece ball-abutment ZC or Ti; maxilla N = 4, mandible N = 3) restored with implant overdentures. Outcomes after 8-years included survival, peri-implant bone levels, soft-tissue responses, and prosthodontic issues. (2) Preclinical trial: 10 New Zealand sheep received 4 implants bilaterally in the femoral condyle: Southern Implants ZC or Ti one-piece implants, identical to the clinical trial, and controls: Southern ITC® two-piece implants with the same surface or Nobel (NBC) anodised (TiUnite™) surface. %Bone-implant contact (%BIC) was measured after 12 weeks of unloaded healing. Results: 8 of 24 participants (33%) of an average age of 75 ± 8 years were recalled; 21% of original participants had died, and 46% could not be contacted. 80.4% of implants survived; excluding palatal sites, 87.5% of Ti and 79% of ZC implants survived. All failed implants were in the maxilla. Three ZC implants had fractured. Bone loss was similar for Ti vs. ZC; pocket depths (p = 0.04) and attachment levels (p = 0.02) were greater for Ti than ZC implants. (1.7 ± 1.6 mm vs. 1.6 ± 1.3 mm). All implants in sheep femurs survived. %BIC was not statistically different for one-piece blasted surface Ti (80 ± 19%) versus ZC (76 ± 20%) or ITC® (75 ± 16 mm); NBC had significantly higher %BIC than ITC (84 ± 17%, p = 0.4). Conclusion: Short-term preclinical results for ZC and Ti one-piece implants showed excellent bone-implant contact in unloaded femoral sites. This differed from the long-term clinical results in older-aged, edentulous participants. While ZC and Ti implants showed equivalent performance, the risks of peri-implantitis and implant loss in older, completely edentulous patients remain a significant factor. Full article
(This article belongs to the Special Issue Zirconia Implants: Current Status and Future Prospects)
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12 pages, 3922 KiB  
Article
Stability of Cantilever Fixed Dental Prostheses on Zirconia Implants
by Nadja Rohr, Reto Nüesch, Rebecca Greune, Gino Mainetti, Sabrina Karlin, Lucia K. Zaugg and Nicola U. Zitzmann
Materials 2022, 15(10), 3633; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15103633 - 19 May 2022
Cited by 3 | Viewed by 1800
Abstract
Background: The objective was to determine the optimal connector size and position within zirconia disks for implant-supported cantilever fixed dental prostheses (ICFDP). Methods: Two-unit ICFDPs (n = 60) were designed for the premolar region with connector sizes of either 9 or 12 [...] Read more.
Background: The objective was to determine the optimal connector size and position within zirconia disks for implant-supported cantilever fixed dental prostheses (ICFDP). Methods: Two-unit ICFDPs (n = 60) were designed for the premolar region with connector sizes of either 9 or 12 mm2 and positioned in the enamel or dentin layer of two different types of zirconia disks. The restorations were milled and cemented onto zirconia implants. After simulated chewing for 1.2 Mio cycles, the fracture load was measured and fractures were analyzed. Results: No fractures of ICFDPs or along the implants were detected after simulated aging. The mean fracture load values were significantly higher for a connector size of 9 mm2 (951 N) compared with 12 mm2 (638 N). For the zirconia material with a higher biaxial flexural strength, the fracture load values were increased from 751 to 838 N, but more implant fractures occurred. The position within the zirconia disk did not influence the fracture load. Conclusions: A connector size of 9 mm2 and a zirconia material with a lower strength should be considered when designing ICFDPS on zirconia implants to reduce the risk of fractures along the intraosseous implant portion. Full article
(This article belongs to the Special Issue Zirconia Implants: Current Status and Future Prospects)
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16 pages, 5006 KiB  
Article
Laser Structured Dental Zirconium for Soft Tissue Cell Occupation—Importance of Wettability Modulation
by Susanne Staehlke, Philip Oster, Susanne Seemann, Fabian Kruse, Jakob Brief and Barbara Nebe
Materials 2022, 15(3), 732; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15030732 - 19 Jan 2022
Cited by 6 | Viewed by 1715
Abstract
Various approaches are being pursued to physico-chemically modify the zirconia neck region of dental implants to improve the integration into the surrounding soft tissue. In this study, polished zirconia discs were laser microstructured with periodic cavities and convex waves. These zirconia samples were [...] Read more.
Various approaches are being pursued to physico-chemically modify the zirconia neck region of dental implants to improve the integration into the surrounding soft tissue. In this study, polished zirconia discs were laser microstructured with periodic cavities and convex waves. These zirconia samples were additionally activated by argon plasma using the kINPen®09. The surface topography was characterized by scanning electron microscopy and the surface wettability by water contact angle. The in vitro study with human gingival fibroblasts (HGF-1) was focused on cell spreading, morphology, and actin cytoskeleton organization within the first 24 h. The laser-induced microstructures were originally hydrophobic (e.g., 60 µm cavities 138.4°), but after argon plasma activation, the surfaces switched to the hydrophilic state (60 µm cavities 13.7°). HGF-1 cells adhered flatly on the polished zirconia. Spreading is hampered on cavity structures, and cells avoid the holes. However, cells on laser-induced waves spread well. Interestingly, argon plasma activation for only 1 min promoted adhesion and spreading of HGF-1 cells even after 2 h cultivation. The cells crawl and grow into the depth of the cavities. Thus, a combination of both laser microstructuring and argon plasma activation of zirconia seems to be optimal for a strong gingival cell attachment. Full article
(This article belongs to the Special Issue Zirconia Implants: Current Status and Future Prospects)
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12 pages, 1401 KiB  
Article
Immediate Restoration of Single-Piece Zirconia Implants: A Prospective Case Series—Long-Term Results after 11 Years of Clinical Function
by Elisabeth Steyer, Valentin Herber, Martin Koller, Dániel Végh, Khaled Mukaddam, Norbert Jakse and Michael Payer
Materials 2021, 14(22), 6738; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14226738 - 09 Nov 2021
Cited by 9 | Viewed by 2138
Abstract
Objectives: The aim of this prospective case series was to evaluate single-piece zirconia implants restored with lithium disilicate CAD/CAM crowns through a long-term follow-up. Methods: In this trial, 20 one-piece zirconia implants were placed in 20 patients. Implants were restored (i) immediately with [...] Read more.
Objectives: The aim of this prospective case series was to evaluate single-piece zirconia implants restored with lithium disilicate CAD/CAM crowns through a long-term follow-up. Methods: In this trial, 20 one-piece zirconia implants were placed in 20 patients. Implants were restored (i) immediately with lithium disilicate CAD/CAM provisionals, and (ii) permanently four months after surgery. Patients were followed for 11 years. Clinical parameters and radiological measurements of the zirconia implants were assessed. For the statistical analysis, paired t-test was applied. Results: Four implants were counted as implant failure due to the loss of implant stability, resulting in a Kaplan–Meier survival rate of 80% up to 11 years. The mean bleeding on probing values were 19.1% (SD ± 13.1) and 18.2% (SD ± 17.6) 96 and 11 years after implant placement, respectively. The plaque index revealed a significant decrease over time (p < 0.001) with a value between 25.9% (SD ± 5.7) and 12.6% (SD ± 10.0) at baseline and 11-years follow-up respectively. The marginal bone level revealed a significant decrease 4, 8, and 11 years after implant insertion (p = 0.001, p = 0.019, and p = 0.027, respectively). Conclusions: Immediately loaded zirconia single-piece implants showed a suitable success rate in clinical and radiographic outcomes. Full article
(This article belongs to the Special Issue Zirconia Implants: Current Status and Future Prospects)
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12 pages, 2210 KiB  
Article
In Vitro Investigations in a Biomimetic Approach to Restore One-Piece Zirconia Implants
by Reto Nueesch, Sabrina Märtin, Nadja Rohr and Jens Fischer
Materials 2021, 14(16), 4361; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14164361 - 04 Aug 2021
Cited by 4 | Viewed by 1776
Abstract
The objective of this study was to evaluate the fracture load and retention force of different bonding systems while restoring one-piece zirconia implants with a novel cementation approach using a mesostructure. Polymer-infiltrated ceramic mesostructures (n = 112) were therefore designed as caps [...] Read more.
The objective of this study was to evaluate the fracture load and retention force of different bonding systems while restoring one-piece zirconia implants with a novel cementation approach using a mesostructure. Polymer-infiltrated ceramic mesostructures (n = 112) were therefore designed as caps on the implant abutment, and a molar feldspathic ceramic crown was constructed on top of it as a suprastructure. For cementation, different bonding systems were used. Fracture load and retention force were measured immediately after storage in water at 37 °C for 24 h (n = 8) as well as after artificial aging in a chewing simulator and subsequent thermal cycling (n = 8). Combined restorations showed higher fracture load compared to monolithic restorations of polymer-infiltrated ceramic (n = 8) or feldspathic ceramic (n = 8) identical in shape. However, the fracture load of the combined restorations was significantly affected by aging, independent of the primers and cements used. Restorations cemented with primers containing methyl methacrylate and 10-methacryloyloxydecyl dihydrogen phosphate exhibited the highest retention force values. Aging did not affect the retention force significantly. Similar fracture load values can be expected from combination restorations when compared with monolithic crowns. Full article
(This article belongs to the Special Issue Zirconia Implants: Current Status and Future Prospects)
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9 pages, 6337 KiB  
Article
Additively Manufactured Zirconia for Dental Applications
by Hiroto Nakai, Masanao Inokoshi, Kosuke Nozaki, Keiji Komatsu, Shingo Kamijo, Hengyi Liu, Makoto Shimizubata, Shunsuke Minakuchi, Bart Van Meerbeek, Jef Vleugels and Fei Zhang
Materials 2021, 14(13), 3694; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14133694 - 01 Jul 2021
Cited by 45 | Viewed by 4097
Abstract
We aimed to assess the crystallography, microstructure and flexural strength of zirconia-based ceramics made by stereolithography (SLA). Two additively manufactured 3 mol% yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP: LithaCon 3Y 230, Lithoz; 3D Mix zirconia, 3DCeram Sinto) and one alumina-toughened zirconia (ATZ: 3D Mix [...] Read more.
We aimed to assess the crystallography, microstructure and flexural strength of zirconia-based ceramics made by stereolithography (SLA). Two additively manufactured 3 mol% yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP: LithaCon 3Y 230, Lithoz; 3D Mix zirconia, 3DCeram Sinto) and one alumina-toughened zirconia (ATZ: 3D Mix ATZ, 3DCeram Sinto) were compared to subtractively manufactured 3Y-TZP (control: LAVA Plus, 3M Oral Care). Crystallographic analysis was conducted by X-ray diffraction. Top surfaces and cross-sections of the subsurface microstructure were characterized using scanning electron microscopy (SEM). Biaxial flexural strength was statistically compared using Weibull analysis. The additively and subtractively manufactured zirconia grades revealed a similar phase composition. The residual porosity of the SLA 3Y-TZPs and ATZ was comparable to that of subtractively manufactured 3Y-TZP. Weibull analysis revealed that the additively manufactured LithaCon 3Y 230 (Lithoz) had a significantly lower biaxial flexural strength than 3D Mix ATZ (3D Ceram Sinto). The biaxial flexural strength of the subtractively manufactured LAVA Plus (3M Oral Care) was in between those of the additively manufactured 3Y-TZPs, with the additively manufactured ATZ significantly outperforming the subtractively manufactured 3Y-TZP. Additively manufactured 3Y-TZP showed comparable crystallography, microstructure and flexural strength as the subtractively manufactured zirconia, thus potentially being a good option for dental implants. Full article
(This article belongs to the Special Issue Zirconia Implants: Current Status and Future Prospects)
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11 pages, 4143 KiB  
Article
Hydrothermal Ageing and Its Effect on Fracture Load of Zirconia Dental Implants
by Laurent Gremillard, Agnès Mattlet, Alexandre Mathevon, Damien Fabrègue, Bruno Zberg and Marc Stephan
Materials 2021, 14(11), 3103; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14113103 - 05 Jun 2021
Cited by 5 | Viewed by 2014
Abstract
Due to growing demand for metal-free dental restorations, dental ceramics, especially dental zirconia, represent an increasing share of the dental implants market. They may offer mechanical performances of the same range as titanium ones. However, their use is still restricted by a lack [...] Read more.
Due to growing demand for metal-free dental restorations, dental ceramics, especially dental zirconia, represent an increasing share of the dental implants market. They may offer mechanical performances of the same range as titanium ones. However, their use is still restricted by a lack of confidence in their durability and, in particular, in their ability to resist hydrothermal ageing. In the present study, the ageing kinetics of commercial zirconia dental implants are characterized by X-ray diffraction after accelerated ageing in an autoclave at different temperatures, enabling their extrapolation to body temperature. Measurements of the fracture loads show no effect of hydrothermal ageing even after ageing treatments simulated a 90-year implantation. Full article
(This article belongs to the Special Issue Zirconia Implants: Current Status and Future Prospects)
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12 pages, 3519 KiB  
Article
A Novel Zirconia-Based Composite Presents an Aging Resistant Material for Narrow-Diameter Ceramic Implants
by Felix Burkhardt, Markus Harlass, Erik Adolfsson, Kirstin Vach, Benedikt Christopher Spies and Ralf-Joachim Kohal
Materials 2021, 14(9), 2151; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14092151 - 23 Apr 2021
Cited by 7 | Viewed by 1702
Abstract
A novel ceria-stabilized zirconia-alumina-aluminate composite (Ce-TZP-comp) that is not prone to aging presents a potential alternative to yttrium-stabilized zirconia for ceramic oral implants. The objective of this study was to evaluate the long-term stability of a one-piece narrow-diameter implant made of Ce-TZP-comp. Implant [...] Read more.
A novel ceria-stabilized zirconia-alumina-aluminate composite (Ce-TZP-comp) that is not prone to aging presents a potential alternative to yttrium-stabilized zirconia for ceramic oral implants. The objective of this study was to evaluate the long-term stability of a one-piece narrow-diameter implant made of Ce-TZP-comp. Implant prototypes with a narrow (3.4 mm) and regular (4.0 mm) diameter were embedded according to ISO 14801, and subgroups (n = 8) were subsequently exposed to dynamic loading (107 cycles, 98N) and/or hydrothermal treatment (aging, 85 °C). Loading/aging was only applied as a combined protocol for the 4.0 mm diameter implants. One subgroup of each diameter remained untreated. One sample was cross-sectioned from each subgroup and evaluated with a scanning electron microscope for phase-transformation of the lattice. Finally, the remaining samples were loaded to fracture. A multivariate linear regression model was applied for statistical analyses (significance at p < 0.05). All samples withstood the different loading/aging protocols and no transformation propagation was observed. The narrow diameter implants showed the lowest fracture load after combined loading/aging (628 ± 56 N; p < 0.01), whereas all other subgroups exhibited no significantly reduced fracture resistance (between 762 ± 62 and 806 ± 73 N; p > 0.05). Therefore, fracture load values of Ce-TZP-comp implants suggest a reliable intraoral clinical application in the anterior jaw regions. Full article
(This article belongs to the Special Issue Zirconia Implants: Current Status and Future Prospects)
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15 pages, 4856 KiB  
Article
Failure Load and Fatigue Behavior of Monolithic Translucent Zirconia, PICN and Rapid-Layer Posterior Single Crowns on Zirconia Implants
by Frank A. Spitznagel, Sara Röhrig, Robert Langner and Petra C. Gierthmuehlen
Materials 2021, 14(8), 1990; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14081990 - 15 Apr 2021
Cited by 5 | Viewed by 2040
Abstract
This laboratory study aimed to evaluate the thermo-mechanical fatigue behavior and failure modes of monolithic and rapid-layer posterior single-crowns (SCs) supported by zirconia implants. Methods: 120 all-ceramic crowns supported by one-piece zirconia implants (ceramic.implant; vitaclinical) were divided into five groups (n = [...] Read more.
This laboratory study aimed to evaluate the thermo-mechanical fatigue behavior and failure modes of monolithic and rapid-layer posterior single-crowns (SCs) supported by zirconia implants. Methods: 120 all-ceramic crowns supported by one-piece zirconia implants (ceramic.implant; vitaclinical) were divided into five groups (n = 24 each): Group Z-HT: 3Y-TZP monolithic-zirconia (Vita-YZ-HT); Group Z-ST: 4Y-TZP monolithic-zirconia (Vita-YZ-ST); Z-XT: 5Y-TZP monolithic-zirconia (Vita-YZ-XT); Group E: monolithic-polymer-infiltrated ceramic network (PICN,Vita-Enamic); Group RL (rapid layer): PICN-“table-top” (Vita-Enamic), 3Y-TZP-framework (Vita-YZ-HT). Half of the specimens of each group (n = 12) were exposed to fatigue with cyclic mechanical loading (F = 198N, 1.2-million cycles) and simultaneous thermocycling (5–55 °C). Single-load-to-failure testing (Z010, Zwick) was performed for all specimens without/with fatigue application. Data analysis was performed using ANOVA, Tukey’s post-hoc test, two-sample t-test and Bonferroni correction (p < 0.05). Results: All specimens survived fatigue exposure. Significant differences in failure loads were detected among groups (p ≤ 0.004). Materials Z-HT and Z-ST showed the highest failure loads followed by Z-XT, RL and E. The influence of fatigue was only significant for material RL. Conclusions: All types of tested materials exceeded clinically acceptable failure load values higher than 900N and can be recommended for clinical use. Z-HT and Z-ST appear to be highly reliable towards fatigue. Rapid-layer design of PICN and YZ-HT might be an interesting treatment concept for posterior implant SCs. Full article
(This article belongs to the Special Issue Zirconia Implants: Current Status and Future Prospects)
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Review

Jump to: Research

18 pages, 2391 KiB  
Review
Surface Structure of Zirconia Implants: An Integrative Review Comparing Clinical Results with Preclinical and In Vitro Data
by Nadja Rohr, Blerta Hoda and Jens Fischer
Materials 2022, 15(10), 3664; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15103664 - 20 May 2022
Cited by 13 | Viewed by 1682
Abstract
Background: The purpose of this review was to analyze and correlate the findings for zirconia implants in clinical, preclinical and in vitro cell studies in relation to surface structure. Methods: Electronic searches were conducted to identify clinical, preclinical and in vitro cell studies [...] Read more.
Background: The purpose of this review was to analyze and correlate the findings for zirconia implants in clinical, preclinical and in vitro cell studies in relation to surface structure. Methods: Electronic searches were conducted to identify clinical, preclinical and in vitro cell studies on zirconia implant surfaces. The primary outcomes were mean bone loss (MBL) for clinical studies, bone-to-implant contact (BIC) and removal torque (RT) for preclinical studies and cell spreading, cell proliferation and gene expression for cell studies. The secondary outcomes included comparisons of data found for those surfaces that were investigated in all three study types. Results: From 986 screened titles, 40 studies were included for data extraction. In clinical studies, only micro-structured surfaces were investigated. The lowest MBL was reported for sandblasted and subsequently etched surfaces, followed by a sinter and slurry treatment and sandblasted surfaces. For BIC, no clear preference of one surface structure was observable, while RT was slightly higher for micro-structured than smooth surfaces. All cell studies showed that cell spreading and cytoskeletal formation were enhanced on smooth compared with micro-structured surfaces. Conclusions: No correlation was observed for the effect of surface structure of zirconia implants within the results of clinical, preclinical and in vitro cell studies, underlining the need for standardized procedures for human, animal and in vitro studies. Full article
(This article belongs to the Special Issue Zirconia Implants: Current Status and Future Prospects)
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26 pages, 10065 KiB  
Review
Classification and Properties of Dental Zirconia as Implant Fixtures and Superstructures
by Seiji Ban
Materials 2021, 14(17), 4879; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14174879 - 27 Aug 2021
Cited by 31 | Viewed by 8317
Abstract
Various types of zirconia are widely used for the fabrication of dental implant superstructures and fixtures. Zirconia–alumina composites, such as ATZ and NanoZR, are adequate for implant fixtures because they have excellent mechanical strength in spite of insufficient esthetic properties. On the other [...] Read more.
Various types of zirconia are widely used for the fabrication of dental implant superstructures and fixtures. Zirconia–alumina composites, such as ATZ and NanoZR, are adequate for implant fixtures because they have excellent mechanical strength in spite of insufficient esthetic properties. On the other hand, yttria-stabilized zirconia has been used for implant superstructures because of sufficient esthetic properties. They are classified to 12 types with yttria content, monochromatic/polychromatic, uniform/hybrid composition, and monolayer/multilayer. Zirconia with a higher yttria content has higher translucency and lower mechanical strength. Fracture strength of superstructures strongly depends on the strength on the occlusal contact region. It suggests that adequate zirconia should be selected as the superstructure crown, depending on whether strength or esthetics is prioritized. Low temperature degradation of zirconia decreases with yttria content, but even 3Y zirconia has a sufficient durability in oral condition. Although zirconia is the hardest dental materials, zirconia restorative rarely subjects the antagonist teeth to occlusal wear when it is mirror polished. Furthermore, zirconia has less bacterial adhesion and better soft tissue adhesion when it is mirror polished. This indicates that zirconia has advantageous for implant superstructures. As implant fixtures, zirconia is required for surface modification to obtain osseointegration to bone. Various surface treatments, such as roughening, surface activation, and coating, has been developed and improved. It is concluded that an adequately selected zirconia is a suitable material as implant superstructures and fixtures because of mechanically, esthetically, and biologically excellent properties. Full article
(This article belongs to the Special Issue Zirconia Implants: Current Status and Future Prospects)
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