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10 pages, 4932 KiB

Open AccessCommunication

Is a Zirconia Dental Implant Safe When It Is Available on the Market?

by Katarina Frigan, Jérôme Chevalier, Fei Zhang and Benedikt Christopher Spies

Ceramics 2019, 2(4), 568-577; https://doi.org/10.3390/ceramics2040044 - 12 Oct 2019

Cited by 8 | Viewed by 4381

Abstract

The market share of zirconia (ZrO₂) dental implants is steadily increasing. This material comprises a polymorphous character with three temperature-dependent crystalline structures, namely monoclinic (m), tetragonal (t) and cubic (c) phases. Special attention is given to the tetragonal phase when maintained [...] Read more.

The market share of zirconia (ZrO₂) dental implants is steadily increasing. This material comprises a polymorphous character with three temperature-dependent crystalline structures, namely monoclinic (m), tetragonal (t) and cubic (c) phases. Special attention is given to the tetragonal phase when maintained in a metastable state at room temperature. Metastable tetragonal grains allow for the beneficial phenomenon of Phase Transformation Toughening (PTT), resulting in a high fracture resistance, but may lead to an undesired surface transformation to the monoclinic phase in a humid environment (low-temperature degradation, LTD, often referred to as ‘ageing’). Today, the clinical safety of zirconia dental implants by means of long-term stability is being addressed by two international ISO standards. These standards impose different experimental setups concerning the dynamic fatigue resistance of the final product (ISO 14801) or the ageing behavior of a standardized sample (ISO 13356) separately. However, when evaluating zirconia dental implants pre-clinically, oral environmental conditions should be simulated to the extent possible by combining a hydrothermal treatment and dynamic fatigue. For failure analysis, phase transformation might be quantified by non-destructive techniques, such as X-Ray Diffraction (XRD) or Raman spectroscopy, whereas Scanning Electron Microscopy (SEM) of cross-sections or Focused Ion Beam (FIB) sections might be used for visualization of the monoclinic layer growth in depth. Finally, a minimum load should be defined for static loading to fracture. The purpose of this communication is to contribute to the current discussion on how to optimize the aforementioned standards in order to guarantee clinical safety for the patients. Full article

(This article belongs to the Special Issue Ceramics for Biomedical Applications)

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14 pages, 4184 KiB

Open AccessArticle

Osteogenic Enhancement of Zirconia-Toughened Alumina with Silicon Nitride and Bioglass^®

by Giuseppe Pezzotti, Elia Marin, Matteo Zanocco, Francesco Boschetto, Wenliang Zhu, Bryan J. McEntire, B. Sonny Bal, Tetsuya Adachi, Toshiro Yamamoto, Narisato Kanamura and Osam Mazda

Ceramics 2019, 2(4), 554-567; https://doi.org/10.3390/ceramics2040043 - 4 Oct 2019

Cited by 7 | Viewed by 3803

Abstract

Alumina (Al₂O₃) ceramic implants do not stimulate osteoblasts in vivo. Surface alterations targeted at changing the chemistry or topography have been proposed to enhance the bioactivity of alumina. This surface modification is intended to improve oxide bioceramic’s ability to [...] Read more.

Alumina (Al₂O₃) ceramic implants do not stimulate osteoblasts in vivo. Surface alterations targeted at changing the chemistry or topography have been proposed to enhance the bioactivity of alumina. This surface modification is intended to improve oxide bioceramic’s ability to integrate with the biological environment and, in particular, to rapidly osteointegrate. In this study, the surface of zirconia-toughened alumina (ZTA) was functionalized using two methods: (i) Surface laser-patterning and successive filling of patterned wells with powder mixtures of bioglass and Si₃N₄; and, (ii) Si₃N₄ coating by pulse-laser sintering. Functionalized ZTA surfaces were characterized with vibrational spectroscopy, biological testing, and laser microscopy. Both enhancements resulted in osteoblast activation, a property that is relevant to osteosynthesis. Full article

(This article belongs to the Special Issue Ceramics for Biomedical Applications)

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14 pages, 2734 KiB

Open AccessArticle

The Influence of Kinematic Conditions and Variations in Component Positioning on the Severity of Edge Loading and Wear of Ceramic-on-Ceramic Hip Bearings

by Murat Ali, Mazen Al-Hajjar, John Fisher and Louise M. Jennings

Ceramics 2019, 2(3), 488-501; https://doi.org/10.3390/ceramics2030037 - 1 Aug 2019

Cited by 3 | Viewed by 3516

Abstract

Dynamic separation and direct edge loading of hip replacement bearings can be caused by many factors, including implant positioning, implant design, changes in device over time, surgical variations and patient variations. Such dynamic separation and direct edge loading can lead to increased wear. [...] Read more.

Dynamic separation and direct edge loading of hip replacement bearings can be caused by many factors, including implant positioning, implant design, changes in device over time, surgical variations and patient variations. Such dynamic separation and direct edge loading can lead to increased wear. Different input kinematic conditions have been used for experimental hip simulator studies to produce clinically relevant elliptical contact wear paths between the bearings during gait. The aim of this study was to investigate the influence of input kinematics (two axes of rotation simulation conditions (without abduction/adduction) and three axes of rotation simulation conditions (with abduction/adduction and different loading profiles) and variations in component positioning (different levels of medial-lateral translational mismatch at standard and steep cup inclination angles) on the occurrence, severity of edge loading, dynamic separation and wear of size 36 mm ceramic-on-ceramic hip bearings on an electromechanical hip joint simulator. The results showed that, overall, either of the two axes or three axes input profiles were equally valid in providing a suitable preclinical testing method for assessing the occurrence and severity of edge loading and wear under edge loading conditions. In terms of component positioning, as cup inclination and medial-lateral translational mismatch increased, so did dynamic separation, axial load at the rim, severity of edge loading and wear. Full article

(This article belongs to the Special Issue Ceramics for Biomedical Applications)

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13 pages, 1902 KiB

Open AccessArticle

Functionalization of Hydroxyapatite Ceramics: Raman Mapping Investigation of Silanization

by David Siniscalco, Maggy Dutreilh-Colas, Zahi Hjezi, Julie Cornette, Nadia El Felss, Eric Champion and Chantal Damia

Ceramics 2019, 2(2), 372-384; https://doi.org/10.3390/ceramics2020029 - 22 May 2019

Cited by 25 | Viewed by 4866

Abstract

Surface modification of bioceramic materials by covalent immobilization of biomolecules is a promising way to improve their bioactivity. This approach implies the use of organic anchors to introduce functional groups on the inorganic surface on which the biomolecules will be immobilized. In this [...] Read more.

Surface modification of bioceramic materials by covalent immobilization of biomolecules is a promising way to improve their bioactivity. This approach implies the use of organic anchors to introduce functional groups on the inorganic surface on which the biomolecules will be immobilized. In this process, the density and surface distribution of biomolecules, and in turn the final biological properties, are strongly influenced by those of the anchors. We propose a new approach based on Raman 2D mapping to evidence the surface distribution of organosilanes, frequently used as anchors on biomaterial surfaces on hydroxyapatite and silicated hydroxyapatite ceramics. Unmodified and silanized ceramic surfaces were characterized by means of contact angle measurements, atomic force microscopy (AFM) and Raman mapping. Contact angle measurements and AFM topographies confirmed the surface modification. Raman mapping highlighted the influence of both the ceramic’s composition and silane functionality (i.e., the number of hydrolysable groups) on the silane surface distribution. The presence of hillocks was shown, evidencing a polymerization and/or an aggregation of the molecules whatever the silane and the substrates were. The substitution of phosphate groups by silicate groups affects the covering, and the spots are more intense on SiHA than on HA. Full article

(This article belongs to the Special Issue Ceramics for Biomedical Applications)

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15 pages, 5119 KiB

Open AccessArticle

Evidence of Phase Transitions and Their Role in the Transient Behavior of Mechanical Properties and Low Temperature Degradation of 3Y-TZP Made from Stabilizer-Coated Powder

by Frank Kern

Ceramics 2019, 2(2), 271-285; https://doi.org/10.3390/ceramics2020022 - 3 Apr 2019

Cited by 18 | Viewed by 4062

Abstract

The substance 3 mol% yttria stabilized zirconia (3Y-TZP) has become a commodity for the manufacture of components in biomedical and engineering applications. Materials made from stabilizer-coated rather than co-precipitated starting powders are known for their superior toughness and low temperature ageing resistance. The [...] Read more.

The substance 3 mol% yttria stabilized zirconia (3Y-TZP) has become a commodity for the manufacture of components in biomedical and engineering applications. Materials made from stabilizer-coated rather than co-precipitated starting powders are known for their superior toughness and low temperature ageing resistance. The reason for this phenomenon is however still not fully understood. In this study, 3Y-TZP materials hot pressed at 1300–1450 °C for 1 h were characterized. It was found that at a sintering temperature of 1375 °C, a transition from fine grain to coarse grain microstructure associated with a shift from tough and ageing resistant to brittle and prone to ageing was observed. The detailed analysis of the phase composition by X-ray diffraction revealed that TZPs consists of up to five crystallographically different phases of zirconia simultaneously whose contents dynamically change with sintering temperature. At low sintering temperature, the predominant phases are a tetragonal phase with low yttria content and large domain size and high tetragonality together with a cubic phase of high yttria content. At high temperature, a tetragonal phase of higher yttria content and lower tetragonality is formed together with a cubic phase of lower yttria content. Full article

(This article belongs to the Special Issue Ceramics for Biomedical Applications)

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11 pages, 11630 KiB

Open AccessArticle

Coatings Based on Organic/Non-Organic Composites on Bioinert Ceramics by Using Biomimetic Co-Precipitation

by Tomasz Engelmann, Gaëlle Desante, Norina Labude, Stephan Rütten, Rainer Telle, Sabine Neuss and Karolina Schickle

Ceramics 2019, 2(2), 260-270; https://doi.org/10.3390/ceramics2020021 - 3 Apr 2019

Cited by 5 | Viewed by 3381

Abstract

Bioinert ceramics have been commonly used in the field of orthopedic and dentistry due to their excellent mechanical properties, esthetic look, good biocompatibility and chemical inertness. However, an activation of its bioinert surface could bring additional advantages for better implant-integration in vivo. Therefore, [...] Read more.

Bioinert ceramics have been commonly used in the field of orthopedic and dentistry due to their excellent mechanical properties, esthetic look, good biocompatibility and chemical inertness. However, an activation of its bioinert surface could bring additional advantages for better implant-integration in vivo. Therefore, we introduce an innovative biomimetic co-precipitation technique by using modified simulated body fluid (SBF) to obtain a composite coating made of organic/non-organic components. The zirconia samples were soaked in SBF containing different concentrations of protein (0.01, 0.1, 1, 10 and 100 g/l). Bovine serum albumin (BSA) was applied as a standard protein. During the soaking time, a precipitation of calcium phosphate took place on the substrate surfaces. The proteins were incorporated into the coating during precipitation. Morphology changes of precipitated hydroxyapatite (HAp) due to the presence of proteins were observed on SEM-images. The presence of proteins within the coating was proven by using SEM/energy dispersive X-ray spectroscopy (EDX) and immunohistochemical analysis. We conclude that it is possible to co-precipitate the organic/non-organic composite on inert ceramic by using the wet-chemistry method. In future studies, BSA could be replaced by targeted proteins appropriate to the application area. This method could create new biomaterials, the surfaces of which could be tailored according to the desires and requirements of their use. Full article

(This article belongs to the Special Issue Ceramics for Biomedical Applications)

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10 pages, 1545 KiB

Open AccessArticle

Ammonium Hydroxide Mediated Hydrothermal Crystallization of Hydroxyapatite Coatings on Titanium Substrate

by Katarzyna Suchanek, Marcin Perzanowski, Janusz Lekki, Martyna Strąg and Marta Marszałek

Ceramics 2019, 2(1), 180-189; https://doi.org/10.3390/ceramics2010016 - 19 Mar 2019

Cited by 10 | Viewed by 4391

Abstract

Controlled growth of hydroxyapatite (HAp) coatings on titanium substrate plays an important role in the fabrication of the composites for bone tissue engineering. We describe the synthesis of the crystalline hydroxyapatite coatings on the Ti/TiO₂ substrate through a hydrothermal method by using [...] Read more.

Controlled growth of hydroxyapatite (HAp) coatings on titanium substrate plays an important role in the fabrication of the composites for bone tissue engineering. We describe the synthesis of the crystalline hydroxyapatite coatings on the Ti/TiO₂ substrate through a hydrothermal method by using ethylenediamine tetraacetic acid disodium salt (Na₂EDTA) and varying concentrations of ammonium hydroxide (NH₄OH) in calcium-phosphate precursor solution. Na₂EDTA serves as a chelating agent, while NH₄OH is used as an alkaline source and crystal growth modifier. We characterized the HAp coatings using x-ray diffraction, scanning electron microscopy, and Raman spectroscopy. We also performed the elemental chemical analysis by means of a particle induced x–ray emission method. Our results show that there is a pH limit for which the hydrothermal deposition of HAp on titanium occurs. Moreover, we observed that NH₄OH had a measurable influence on the coating thickness as well as on the size and shape of the HAp crystals. We found that with the increase of NH₄OH concentration, the thickness of the Hap layer increases and its morphology changes from irregular flakes to well-defined hexagonal rods. Full article

(This article belongs to the Special Issue Ceramics for Biomedical Applications)

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18 pages, 6864 KiB

Open AccessArticle

Calcium Phosphate Powder Synthesized from Calcium Acetate and Ammonium Hydrophosphate for Bioceramics Application

by Tatiana Safronova, Valery Putlayev, Yaroslav Filippov, Tatiana Shatalova, Evgeny Karpushkin, Dmitrii Larionov, Gilyana Kazakova and Yury Shakhtarin

Ceramics 2018, 1(2), 375-392; https://doi.org/10.3390/ceramics1020030 - 15 Dec 2018

Cited by 8 | Viewed by 5356

Abstract

Calcium phosphate powder was synthesized at room temperature from aqueous solutions of ammonium hydrophosphate and calcium acetate without pH adjusting at constant Ca/P molar ratio 1.5. Phase composition of the as-synthesized powder depended on the precursors concentration: At 2.0 M of calcium acetate [...] Read more.

Calcium phosphate powder was synthesized at room temperature from aqueous solutions of ammonium hydrophosphate and calcium acetate without pH adjusting at constant Ca/P molar ratio 1.5. Phase composition of the as-synthesized powder depended on the precursors concentration: At 2.0 M of calcium acetate in the starting solution, poorly crystallized hydroxyapatite was formed, 0.125 M solution of calcium acetate afforded brushite, and the powders synthesized from 0.25–1.0 M calcium acetate solutions were mixtures of the mentioned phases. Firing at 1100 °C led to complete elimination of the reaction by-products, yet the phase composition of the annealed compacted samples was the following: When 2.0 M solution of calcium acetate was used, the obtained ceramics consisted of β-Ca₃(PO₄)₂, whereas at 0.125 to 1.0 M of calcium acetate, the ceramics was a mixture of β-Ca₃(PO₄)₂ and β-Ca₂P₂O₇. Synthesized calcium phosphate powders can be used as the powdered precursors for biocompatible bioresorbable composite ceramics production. Full article

(This article belongs to the Special Issue Ceramics for Biomedical Applications)

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Review

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9 pages, 1114 KiB

Open AccessReview

Direct Laser Interference Patterning of Bioceramics: A Short Review

by Douglas Fabris, Andrés Fabián Lasagni, Márcio C. Fredel and Bruno Henriques

Ceramics 2019, 2(4), 578-586; https://doi.org/10.3390/ceramics2040045 - 28 Oct 2019

Cited by 28 | Viewed by 4690

Abstract

Bioceramics are a great alternative to use in implants due to their excellent biocompatibility and good mechanical properties. Depending on their composition, bioceramics can be classified into bioinert and bioactive, which relate to their interaction with the surrounding living tissue. Surface morphology also [...] Read more.

Bioceramics are a great alternative to use in implants due to their excellent biocompatibility and good mechanical properties. Depending on their composition, bioceramics can be classified into bioinert and bioactive, which relate to their interaction with the surrounding living tissue. Surface morphology also has great influence on the implant biological behavior. Controlled texturing can improve osseointegration and reduce biofilm formation. Among the techniques to produce nano- and micropatterns, laser texturing has shown promising results due to its excellent accuracy and reproducibility. In this work, the use of laser techniques to improve surface morphology of biomaterials is reviewed, focusing on the application of direct laser interference patterning (DLIP) technique in bioceramics. Full article

(This article belongs to the Special Issue Ceramics for Biomedical Applications)

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