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The European Journal of Prosthodontics... May 2018Zirconia is suggested in many clinical situations due to acceptable biocompatibility, lower price compared with gold restorations, and better appearance than traditional... (Review)
Review
INTRODUCTION
Zirconia is suggested in many clinical situations due to acceptable biocompatibility, lower price compared with gold restorations, and better appearance than traditional metal ceramic restorations. New translucent monolithic zirconia has been developed to merge strength with improved tooth-colour matching. This work aims to review relevant articles on new translucent zirconia restorative materials.
METHODS
The published articles on translucent zirconia were searched through PubMed, Medline, Google scholar, and indexed journals using the following keywords: translucent zirconia, transparent zirconia, and tooth colored zirconia. The most relevant articles were selected and reviewed.
RESULT
Introduction of translucent zirconia, has brought the advantages such as less tooth preparation, biological compatibility, high strength, good mechanical properties, and less antagonist wear. However, the effects of altering material constituents to increase translucency on properties such as phase transformation and low temperature degradation may warrant further investigations.
CONCLUSION
Translucent zirconia can be prescribed in many clinical situations and may provide less complicated procedures compared with the production of multilayer restorations of opaque zirconia cores and translucent feldspathic veneers. This may otherwise decrease fabrication time and defects, improve biological properties, reduce abutment tooth reduction, and result in less antagonist tooth attrition.
Topics: Dental Materials; Dental Prosthesis Design; Dental Restoration, Permanent; Humans; Materials Testing; Surface Properties; Zirconium
PubMed: 29797847
DOI: 10.1922/EJPRD_01759Ghodsi13 -
Dental Materials : Official Publication... Apr 2022To evaluate the effect of the ceramic processing and aging method on the microstructure, optical, and mechanical properties of a third generation ultra-translucent... (Review)
Review
OBJECTIVES
To evaluate the effect of the ceramic processing and aging method on the microstructure, optical, and mechanical properties of a third generation ultra-translucent zirconia, yttria partially stabilized zirconia (5Y-PSZ).
METHODS
In-house discs were obtained through uniaxial and isostatic pressing an ultra-translucent Y-PSZ powder and sintering at 1450 °C for 2 h. As control, a commercial disc was milled from pre-sintered blocks fabricated with the same 5Y-PSZ powder through isostatic pressing and sintered under the same protocol. Discs were allocated into three groups according to aging condition as immediate (non-aged) and aged using autoclave or hydrothermal reactor at 134ºC for 20 h at 2.2 bar. Crystalline content and microstructure were evaluated using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Optical properties were determined using reflectance data to calculate the contrast ratio (CR) and translucency parameter (TP). Mechanical properties were assessed by Vickers hardness, fracture toughness and biaxial flexural strength tests.
RESULTS
XRD spectra revealed a prevalence of cubic (70%) and tetragonal (30%) phases, and the SEM images showed a dense fully crystalline ceramic matrix for both materials. Crystalline content and microstructure of the in-house and commercial 5Y-PSZs were not affected by aging. As-sintered 5Y-PSZs demonstrated similar CR (~0.6) and TP (~18) values, as well as Vickers hardness (~14 GPa) and fracture toughness (~3.8 Mpa.m), with no significant alteration after both aging methods. In-house and commercial Y-PSZs Weibull moduli ranged from 3.0 to 5.3. 5Y-PSZ processing methods resulted in similar characteristic strength after sintering (592-618 Mpa). While commercial 5Y-PSZ showed no significant influence of aging on strength, hydrothermal reactor aging significantly decreased the in-house Y-PSZ characteristic strength (474 Mpa). Both 5Y-PSZs demonstrated high reliability up to 300-Mpa strength missions, with no detrimental effect of aging (88-100%).
SIGNIFICANCE
Irrespective of the processing method, ultra-translucent 5Y-PSZ showed high aging resistance and translucency stability, as well as strength corresponding to the indication up to short-span anterior prostheses.
Topics: Ceramics; Dental Materials; Materials Testing; Powders; Reproducibility of Results; Surface Properties; Yttrium; Zirconium
PubMed: 35272865
DOI: 10.1016/j.dental.2022.02.016 -
The Journal of Prosthetic Dentistry May 2022More translucent dental zirconias have been developed by incorporating the cubic phase and reducing the tetragonal phase content that undergoes transformation...
STATEMENT OF PROBLEM
More translucent dental zirconias have been developed by incorporating the cubic phase and reducing the tetragonal phase content that undergoes transformation toughening, leading to reduced mechanical properties. Whether the clinically relevant mechanical property of the edge chipping toughness of the material is also reduced is unclear.
PURPOSE
The purpose of this in vitro study was to evaluate the edge chipping toughness and translucency of translucent zirconia, 3mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP), and lithium disilicate.
MATERIAL AND METHODS
Two translucent zirconia products, Katana and Lava Esthetic; one 3Y-TZP, Lava Plus; and one lithium disilicate, IPS e.max Press were prepared and tested for phase composition via X-ray diffraction (XRD) (n=3), translucency via a spectrophotometer (n=20), and edge chipping via a universal testing machine with a custom-machined specimen holder and diamond indenter (n=20). The 3Y-TZP and lithium disilicate served as the optimal control materials for edge chipping and translucency, respectively. Translucency was compared with 1-way ANOVA and edge toughness with ANCOVA (α=.05).
RESULTS
The XRD showed the 3Y-TZP to be almost completely tetragonal phase compared with the 2 translucent zirconia products that were predominantly cubic. Katana UTML and IPS e.max Press had a statistically similar (P>.05) translucency that was significantly (P<.05) greater than that of Lava Esthetic and Lava Plus. The edge toughness of Katana UTML was 304 N/mm, IPS e.max Press was 354 N/mm, Lava Esthetic was 394 N/mm, and Lava Plus was 717 N/mm, with significance rankings of Katana UTM
CONCLUSIONS
Some translucent zirconias had translucency similar to that of lithium disilicate; however, as translucency increased with increased cubic content, edge toughness decreased.
Topics: Ceramics; Dental Materials; Esthetics, Dental; Materials Testing; Surface Properties; Zirconium
PubMed: 33581865
DOI: 10.1016/j.prosdent.2020.12.009 -
Dental Materials Journal Jan 2023This review describes the development of ultra-high translucent zirconia (referred to as UHTZ) using new manufacturing technology and its characterization results. The... (Review)
Review
This review describes the development of ultra-high translucent zirconia (referred to as UHTZ) using new manufacturing technology and its characterization results. The development of UHTZ was primarily due to the adoption of two basic manufacturing technologies, "Cyclic CIP" and "Plus Y Technology". This manufacturing technology could provide stable processing characteristics, which improves chipping resistance during milling. Furthermore, the enlargement factor (processing coefficient) for UHTZ is smaller than those for conventional products. In general, the higher the light transmittance, the lower the flexural strength. Despite its extremely high translucency, the most significant feature of UTHZ is that its flexural strength is comparable to that of 5Y. Furthermore, UHTZ has higher chemical durability and uniform microstructure, which results in less wear on the opposing teeth and superior discoloration resistance. Therefore, UHTZ is a new option for inlay, onlay, and laminate veneer applications, where lithium disilicate glass ceramics has been widely used.
Topics: Materials Testing; Dental Porcelain; Ceramics; Zirconium; Flexural Strength; Surface Properties
PubMed: 36631076
DOI: 10.4012/dmj.2022-243 -
Dental Materials : Official Publication... Sep 2023The aim of this study was to evaluate the influence of the sandblasting treatment on the microstructure, optical and mechanical properties of multi-layered translucent...
OBJECTIVE
The aim of this study was to evaluate the influence of the sandblasting treatment on the microstructure, optical and mechanical properties of multi-layered translucent zirconia.
METHODS
Samples of yttria-stabilized zirconia were prepared by stratifying four layers (L1, L2, L3 and L4) of ML-type KATANA multi-layered monolithic discs, whose surfaces were then sandblasted with alumina particles (110 µm and 0.2 MPa) in order to evaluate its effect on the presence of different crystalline phases as well as on the optical and mechanical properties of each of the four layers. The optical characterization was carried out by measuring the reflectance spectrum and colorimetric parameters by UV-Vis spectrophotometric analysis and the transmittance curves were indirectly obtained using the Kubelka-Munk model (KM). Microstructural, structural, mechanical and roughness characterizations were also performed using SEM, XRD, biaxial flexural strength B3B, and light interferometry, respectively RESULTS: According to the KM model there are different degrees of translucency between the upper and lower layers of the monolithic discs, but there was no influence of the AlO-sandblasting treatment on this optical property. The disk pigmentation causes greater absorption of light below 600 nm, decreasing the transmittance rate to values below 25% in this region of the spectrum. The yellowing index presented higher values for inner disk layers L3 and L4, in agreement with the highest values of the light absorption coefficient K observed for these layers. The roughness of the samples did not change significantly with the surface treatment performed and the sandblasting did not result in new crystalline phases. SEM analysis showed the presence of different grain sizes in all layers analyzed, being related to the co-occurring presence of cubic (c-ZrO) and tetragonal (t-ZrO) phases in similar contents (∼ 50 wt%). The Weibull statistical analysis, in turn, showed an increase in the Weibull characteristic stress value (σ) for most layers subjected to sandblasting, except for the second layer (central region of the disk). It was also verified an increase in the value of the structural reliability of the material (m), referring to the samples of the central region of the disc (L2 and L3 layers) after sandblasting.
SIGNIFICANCE
The pigmentation in the disk causes a decrease of the transmittance rate to values well below 25% in the region of the spectrum 400-600 nm and the inner layers (L3 and L4) have even lower transmittance than the outer layers in this spectrum range. Although the CR index indicates variation related to the AlO-sandblasting treatment, the transmittance spectra of KM model show that the sandblasting did not cause a significant change in the transmittance rate of the four analyzed layers. Also, there is no significant difference in the light scattering of the different layers of the disc, either before or after AlO-sandblasting treatment.
Topics: Dental Materials; Materials Testing; Reproducibility of Results; Surface Properties; Zirconium; Yttrium; Ceramics
PubMed: 37474437
DOI: 10.1016/j.dental.2023.07.005 -
Journal of International Oral Health :... Apr 2013Sclerosis of dentinal tubules may be a response to pathological or physiological insult in the crown & root. The mechanism by which apical translucency is produced is... (Review)
Review
BACKGROUND
Sclerosis of dentinal tubules may be a response to pathological or physiological insult in the crown & root. The mechanism by which apical translucency is produced is still uncertain. The increase in size of the apical zone of sclerotic dentin in human teeth has been used often in forensic science as a method of age estimation. However, only few studies have been done to compare percentage of translucency between vital and non-vital teeth. Conflicting concepts exist regarding the amount of translucent dentin in the vital & non vital teeth and correlation of this variation with age of the subject.
AIMS
To investigate the amount and distribution of apical translucent dentin in group-matched vital and non-vital teeth.
MATERIALS AND METHODS
Study was conducted on 70 extracted teeth, which were subjected for vitality test before extraction, and divided into two groups (vital & non-vital teeth) with a minimum of 35 teeth in each group. Ground sections of 150µ thickness were observed under Stereomicroscope and photographed. The distribution of area and length was measured on the images captured, using PROPLUS IMAGE ANALYSIS SOFTWARE version 4.1.0.0 software.
RESULTS AND CONCLUSIONS
The present study revealed significant differences (p < 0.05) in apical translucency of dentin, when both vital and non-vital teeth types were compared. There was more apical translucency present in non-vital when compared with vital teeth at any given age. Key words: Apical translucency; vital teeth; non-vital teeth. How to cite this article: Selvamani M, Madhushankari G S, Basandi P S, Donoghue M, Nayak V, Diwakar G. Effect of Vitality on Translucent Dentine - A Study. J Int Oral Health 2013; 5(2):1-7.
PubMed: 24155584
DOI: No ID Found -
The Journal of Prosthetic Dentistry Apr 2023Translucent zirconias have been developed with better esthetics than high-strength zirconias by reducing opacity. However, studies on their translucency and strength are...
STATEMENT OF PROBLEM
Translucent zirconias have been developed with better esthetics than high-strength zirconias by reducing opacity. However, studies on their translucency and strength are sparse.
PURPOSE
The purpose of this in vitro study was to compare the relationship between translucency and biaxial flexural strength of recently developed high-translucency zirconia, high-strength zirconia, and lithium disilicate ceramics.
MATERIAL AND METHODS
Disks (n=12) were fabricated for 5 ceramic materials: high-strength zirconia (BruxZir 16 shaded), translucent zirconia (BruxZir Anterior shaded, Katana UTML, Katana STML), and lithium disilicate (IPS e.max, Press HT, and LT). A standard tessellation language (STL) file was designed, and the specimen milled, finished, and glazed according to manufacturer's instructions for each material. The translucency parameter was calculated against black and white backgrounds and white and stump shade with ND4 background by using a spectrophotometer. Biaxial flexural strength was calculated by using the 3-ball test. The load was applied at a crosshead speed of 0.5 mm/min with a 49-N load cell until failure occurred. Translucency parameter and biaxial flexural strength data were analyzed with 1-way analysis of variance (ANOVA). A Tukey honest significant difference multiple comparison test was used to determine significant differences (α=.05).
RESULTS
The IPS e.max HT was more translucent against both backgrounds (32.85 for black/white and 15.34 for white/stump), while BruxZir 16 was the least translucent (19.78 for B/W and 8.83 for W/S). All groups tested differed in translucency (P<.001) except for BruxZir Anterior and Katana STML, which were not significantly different (P=.052). For biaxial flexural strength, BruxZir 16 had the highest strength (995.44 MPa) and e.max HT, the lowest (186.75 MPa). No significant differences were found between BruxZir anterior and Katana STML, Katana UTML and IPS e.max LT, or IPS e.max LT and IPS e.max HT (P>.05). Translucency parameter values using both backgrounds were strongly correlated (r=0.99). However, biaxial flexural strength values were inversely related to translucency parameter values when using black/white and white/stump shade but with high correlation (r=-0.777 and -0.756 respectively).
CONCLUSIONS
Lithium disilicate was the most translucent and yet the weakest material, whereas high-strength zirconia was the most opaque ceramic and the strongest. Katana UTML had the highest translucency but was weakest among translucent and high-strength zirconia materials. Overall, translucency was negatively correlated with biaxial flexural strength.
Topics: Flexural Strength; Esthetics, Dental; Ceramics; Analysis of Variance
PubMed: 34303523
DOI: 10.1016/j.prosdent.2021.06.019 -
Folia Medica Apr 2022A young female patient with chronic left side chest pain warranted a work-up. Chest X-ray suggested left hyper-translucency. High resolution computed tomography scan...
A young female patient with chronic left side chest pain warranted a work-up. Chest X-ray suggested left hyper-translucency. High resolution computed tomography scan revealed left atretic apicoposterior segmental bronchus with an area of hyper-translucency suggestive of bronchial atresia. Fiberoptic bronchoscopy findings were normal. Spirometry showed moderate restriction with mild obstruction. It is a rare developmental anomaly characterised by interruption of normal bronchial continuity. Most commonly, it involves the apicoposterior segmental bronchus of left upper lobe as seen in our case. Since it is a benign condition, surgical treatment or any aggressive method of treatment is not required. However, intervention may be required in case of life threatening complications.
Topics: Bronchi; Bronchoscopy; Female; Humans; Lung; Radiography; Tomography, X-Ray Computed
PubMed: 35851790
DOI: 10.3897/folmed.64.e60500 -
Journal of Vision Jul 2020When judging the optical properties of a translucent object, humans often look at sharp geometric features such as edges and thin parts. An analysis of the physics of...
When judging the optical properties of a translucent object, humans often look at sharp geometric features such as edges and thin parts. An analysis of the physics of light transport shows that these sharp geometries are necessary for scientific imaging systems to be able to accurately measure the underlying material optical properties. In this article, we examine whether human perception of translucency is likewise affected by the presence of sharp geometry, by confounding our perceptual inferences about an object's optical properties. We use physically accurate simulations to create visual stimuli of translucent materials with varying shapes and optical properties under different illuminations. We then use these stimuli in psychophysical experiments, where human observers are asked to match an image of a target object by adjusting the material parameters of a match object with different geometric sharpness, lighting, and three-dimensional geometry. We find that the level of geometric sharpness significantly affects perceived translucency by observers. These findings generalize across a few illumination conditions and object shapes. Our results suggest that the perceived translucency of an object depends on both the underlying material's optical parameters and the three-dimensional shape of the object. We also find that models based on image contrast cannot fully predict the perceptual results.
Topics: Female; Form Perception; Humans; Imaging, Three-Dimensional; Light; Male; Materials Testing; Orientation, Spatial; Psychophysics; Surface Properties; Young Adult
PubMed: 32663255
DOI: 10.1167/jov.20.7.10 -
Nano Letters Nov 2018Transparent/translucent glass ceramics (GCs) have broad applications in biomedicine, armor, energy, and constructions. However, GCs with improved optical properties...
Transparent/translucent glass ceramics (GCs) have broad applications in biomedicine, armor, energy, and constructions. However, GCs with improved optical properties typically suffer from impaired mechanical properties, compared to traditional sintered full-ceramics. We present a method of obtaining high-strength, translucent GCs by preparing ZrO-SiO nanocrystalline glass ceramics (NCGCs) with a microstructure of monocrystalline ZrO nanoparticles (NPs), embedded in an amorphous SiO matrix. The ZrO-SiO NCGC with a composition of 65%ZrO/35%SiO (molar ratio, 65Zr) achieved an average flexural strength of 1 GPa. This is one of the highest flexural strength values ever reported for GCs. ZrO NPs bond strongly with SiO matrix due to the formation of a thin (2-3 nm) amorphous Zr/Si interfacial layer between the ZrO NPs and SiO matrix. The diffusion of Si atoms into the ZrO NPs forms a Zr-O-Si superlattice. Electron tomography results show that some of the ZrO NPs are connected in one direction, forming in situ ZrO nanofibers (with length of ∼500 nm), and that the ZrO nanofibers are stacked in an ordered way in all three dimensions. The nanoarchitecture of the ZrO nanofibers mimics the architecture of mineralized collagen fibril in cortical bone. Strong interface bonding enables efficient load transfer from the SiO matrix to the 3D nanoarchitecture built by ZrO nanofibers and NPs, and the 3D nanoarchitecture carries the majority of the external load. These two factors synergistically contribute to the high strength of the 65Zr NCGC. This study deepens our fundamental understanding of the microstructure-mechanical strength relationship, which could guide the design and manufacture of other high-strength, translucent GCs.
Topics: Biomimetic Materials; Ceramics; Glass; Nanoparticles; Silicon Dioxide; Zirconium
PubMed: 30335389
DOI: 10.1021/acs.nanolett.8b03220