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Clinical and Experimental Dental... Dec 2022Tooth enamel has opalescence and fluorescence, which should be mimicked by esthetic dental restorations. The purpose of this study was to compare the effects of glazing...
OBJECTIVE
Tooth enamel has opalescence and fluorescence, which should be mimicked by esthetic dental restorations. The purpose of this study was to compare the effects of glazing and polishing on the opalescence and fluorescence of dental ceramics.
MATERIALS AND METHODS
Twenty-four discs were fabricated of feldspathic, IPS e.max, zirconia, and Enamic ceramics with 10 mm diameter and 0.5 and 1 mm thicknesses (n = 12). Of the discs fabricated with 0.5 and 1 mm thicknesses, half of them were glazed and the remaining half were polished (n = 6). Opalescence was calculated as the difference in yellow-blue (CIE ∆b*) and red-green (CIE ∆a*) color axes between the transmitted and reflected colors. The fluorescence of specimens was measured by a novel technique. Data were analyzed using two-way analysis of variance at a 0.05 level of significance.
RESULTS
In all groups (except for the Enamic ceramic), the mean opalescence of polished specimens (e.max = 2.704, feldspathic = 1.67, zirconia = 3.143) was higher than that of glazed specimens (e.max = 2.163, feldspathic = 1.016, zirconia = 2.690). The mean opalescence of glazed Enamic specimens (2.140) was higher than that of polished specimens (1.308). The fluorescence of glazed and polished specimens was not significantly different.
CONCLUSION
Surface treatment (glazing/polishing) affects the opalescence, but not the fluorescence of dental ceramics evaluated in this study.
Topics: Dental Polishing; Dental Porcelain; Iridescence; Surface Properties; Materials Testing; Ceramics
PubMed: 36245303
DOI: 10.1002/cre2.669 -
Revista Clinica Espanola Oct 2021
Topics: Aorta; Aortic Valve Stenosis; Dental Porcelain; Humans
PubMed: 34103277
DOI: 10.1016/j.rceng.2021.05.001 -
Compendium of Continuing Education in... Oct 2022Indirect ceramic restorations are commonly used to restore function and esthetics of vital and nonvital teeth as well as dental implants. With advancements in digital...
Indirect ceramic restorations are commonly used to restore function and esthetics of vital and nonvital teeth as well as dental implants. With advancements in digital dentistry and the massive adoption of computer-aided design/computer-aided manufacturing (CAD/CAM) systems, clinicians and dental assistants are now more involved in the manufacturing process of indirect ceramic restorations and need to understand the best clinical indication for each material and its respective adhesive protocols.
Topics: Ceramics; Computer-Aided Design; Dental Cements; Dental Implants; Dental Porcelain; Dental Prosthesis Design; Esthetics, Dental
PubMed: 36227133
DOI: No ID Found -
The Journal of Prosthetic Dentistry Oct 2021Lithium disilicate (LD) is a popular dental ceramic and has been a focus of dental research. Nevertheless, a quantified literature analysis focusing on the research of... (Review)
Review
STATEMENT OF PROBLEM
Lithium disilicate (LD) is a popular dental ceramic and has been a focus of dental research. Nevertheless, a quantified literature analysis focusing on the research of lithium disilicate is lacking.
PURPOSE
The purpose of this bibliometric analysis was to review the progress of research into lithium disilicate in dentistry, including the identification of contributing researchers, organizations, countries or regions, journals, and the analysis of high-impact keywords and research trending.
MATERIAL AND METHODS
The search was carried out within the topic field of the Web of Science (WoS) database, collecting publications related to LD from between 1996 and 2019. Metadata including the titles, abstracts, keywords, authors, affiliations, countries or regions, and references were extracted. Bibliometric indicators in terms of documents, authors, journals, and keywords were analyzed.
RESULTS
Between 1996 and 2019, the dental research on LD trended upward. Scholars in the United States, Germany, Switzerland, and Brazil actively participated in the research on LD, and publications from the United States had the most citations. The Journal of Prosthetic Dentistry and Dental Materials were the major contributing journals. High-impact terms could be categorized into types of restorative material, types of prostheses, and properties or techniques of materials. Co-occurrence and relative normalized citation analysis of keywords highlighted several research interests, such as comparison studies between LD and zirconia, computer-aided design and computer-aided manufacturing (CAD-CAM) techniques, and the performance of complete coverage LD restorations.
CONCLUSIONS
With the global upsurge in research on lithium disilicate, extensive collaborations and citations have been noted among authors, institutions, and countries or regions. Research hotspots include types of restorative material, types of prostheses, and properties or techniques of materials.
Topics: Bibliometrics; Ceramics; Computer-Aided Design; Crowns; Dental Porcelain; Materials Testing
PubMed: 33008629
DOI: 10.1016/j.prosdent.2020.08.012 -
Journal of Dentistry Jul 2024To give a comprehensive review of advancement in dental ceramics, fabrication methods, and the challenges associated with clinical application. (Review)
Review
OBJECTIVES
To give a comprehensive review of advancement in dental ceramics, fabrication methods, and the challenges associated with clinical application.
DATA, SOURCES AND STUDY SELECTION
Researches on chemical composition, biomechanical behaviors, optical properties, bonding strategies and fabrication methods were included. The search of articles was independently conducted by two authors in the PubMed, Scopus, Medline and Web of Science.
CONCLUSIONS
Dental ceramics have shown significant advancements in terms of esthetics and function. However, improving fracture toughness without compromising optical properties remains a challenge. Repairing fractured zirconia or glass-matrix ceramic prostheses with the same material is difficult due to the sintering process. Developing innovative bonding techniques that provide strong and long-lasting bonding strength between ceramics and tooth structures poses a recurring obstacle.
CLINICAL SIGNIFICANCE
Despite the emergence of dental ceramics and fabrication techniques, certain limitations such as susceptibility to brittleness and fracture still exist. Therefore, the current review provided valuable information around the advanced dental ceramics in tooth repair. The laboratory test data and the clinical outcome are also presented in details, aiming to guide clinicians in making informed decisions regarding ceramic restorations.
Topics: Humans; Ceramics; Zirconium; Dental Materials; Dental Bonding; Dental Porcelain; Esthetics, Dental; Materials Testing; Dental Prosthesis Design
PubMed: 38729288
DOI: 10.1016/j.jdent.2024.105053 -
Dental Materials : Official Publication... May 2024Lithium silicate-based glass ceramics have evolved as a paramount restorative material in restorative and prosthetic dentistry, exhibiting outstanding esthetic and... (Review)
Review
OBJECTIVES
Lithium silicate-based glass ceramics have evolved as a paramount restorative material in restorative and prosthetic dentistry, exhibiting outstanding esthetic and mechanical performance. Along with subtractive machining techniques, this material class has conquered the market and satisfied the patients' needs for a long-lasting, excellent, and metal-free alternative for single tooth replacements and even smaller bridgework. Despite the popularity, not much is known about the material chemistry, microstructure and terminal behaviour.
METHODS
This article combines a set of own experimental data with extensive review of data from literature and other resources. Starting at manufacturer claims on unique selling propositions, properties, and microstructural features, the aim is to validate those claims, based on glass science. Deep knowledge is mandatory for understanding the microstructure evolution during the glass ceramic process.
RESULTS
Fundamental glass characteristics have been addressed, leading to formation of time-temperature-transformation (TTT) diagrams, which are the basis for kinetic description of the glass ceramic process. Nucleation and crystallization kinetics are outlined in this contribution as well as analytical methods to describe the crystalline fraction and composition qualitatively and quantitatively. In relation to microstructure, the mechanical performance of lithium silicate-based glass ceramics has been investigated with focus on fracture strength versus fracture toughness as relevant clinical predictors.
CONCLUSION
Fracture toughness has been found to be a stronger link to initially outlined manufacturer claims, and to more precisely match ISO recommendations for clinical indications.
Topics: Ceramics; Silicates; Materials Testing; Glass; Surface Properties; Dental Materials; Crystallization; Lithium Compounds; Dental Porcelain
PubMed: 38580561
DOI: 10.1016/j.dental.2024.03.006 -
Dental Materials : Official Publication... Apr 2022To assess accuracy of reflectance reconstruction and color estimation of different dental materials with varying thicknesses using Principal Component Analysis (PCA).
OBJECTIVE
To assess accuracy of reflectance reconstruction and color estimation of different dental materials with varying thicknesses using Principal Component Analysis (PCA).
METHOD
A1, A2, A3, A3.5, B2, C2 and D2 shades and 5 thicknesses (within 0.5-2.5 mm range) of Vita Suprinity (VS-PC) and Vitapan Dentine (VD), were used. Reflectance measurements were performed over black background using a non-contact spectroradiometer with CIE 45∕0 geometry. A PCA based algorithm was proposed to reconstruct spectral data and color of samples, using both extrapolation and interpolation approaches. Root Mean Square Error (RMSE), Goodness of Fit (GFC), correlation coefficient (R) as well as ΔE with corresponding 50:50% acceptability and perceptibly thresholds (AT and PT) were used as performance assessment.
RESULTS
The interpolation approach provided an average RMSE = 0.01 and GFC > 0.999 when comparing predicted and measured spectral reflectances for both materials, while for the extrapolation approach RMSE = 0.02 and GFC > 0.999. Interpolation approach also resulted in lower overall mean color difference ΔE = 0.8 (ΔE = 0.9 for VS-PC and ΔE = 0.7 for VD), while using extrapolation approach resulted in higher overall mean color difference ΔE = 1.6, although below the AT (ΔE = 1.8 for VS-PC and ΔE = 1.5 for VD). Correlation values between predicted and measured spectral reflectances of R = 0.987 and R = 0.993 were globally obtained for VS-PC and VD, respectively.
SIGNIFICANCE
The proposed PCA-based algorithm is able to efficiently predict reflectance spectrum and color of monolithic samples of different dental materials with varying thickness. It can be used to optimize dental materials manufacturing processes and to improve chromatic accuracy of clinical dental restorations.
Topics: Ceramics; Color; Dental Porcelain; Materials Testing
PubMed: 35034772
DOI: 10.1016/j.dental.2021.12.140 -
Journal of Environmental Management Aug 2019The use of waste glass as a raw material for whitewares is a subject that has been investigated for many years. This residue could be used in whitewares formulations as... (Review)
Review
The use of waste glass as a raw material for whitewares is a subject that has been investigated for many years. This residue could be used in whitewares formulations as a fluxing agent for partial or total substitution of one of the natural raw materials, commonly alkaline feldspar and brings the opportunity to improve sustainability. The majority of the studies in this field are related to the production of porcelain tile, but there are also investigations about hard porcelain and sanitarywares. As a general result, the reviewed articles show that waste glass reduces the firing temperature of whitewares, and alters some properties, such as phase crystallization, microstructure, and mechanical strength. In addition, the presence of waste glass also changes some processing properties which have not been adequately highlighted yet. The present article presents a review of the waste glass in its composition and uses in whitewares formulations, as well as its influence on formulation dosage, milling parameters, conformation and firing processes, besides the alterations on mechanical strength, toughness, resistance to deep abrasion and thermal expansion coefficient. Based on the findings, indications are provided to determine the ideal amount of waste glass in a formulation, which may be related to the desired properties. The key findings are that waste glass can replace feldspar with technical and environmental advantages: reaching the desired properties required for commercial whitewares, with lower firing temperature, but with a few adjustments in the processing.
Topics: Ceramics; Crystallization; Dental Porcelain; Glass; Hardness; Materials Testing
PubMed: 31121503
DOI: 10.1016/j.jenvman.2019.05.038 -
The Journal of Prosthetic Dentistry Dec 2022Polyetheretherketone (PEEK) is a high-performance polymer that is increasingly used in dentistry, for example, as a framework for implant-supported fixed complete...
STATEMENT OF PROBLEM
Polyetheretherketone (PEEK) is a high-performance polymer that is increasingly used in dentistry, for example, as a framework for implant-supported fixed complete dentures. One protocol calls for individual lithium disilicate crowns to be cemented on preparation-shaped retentive elements on the framework. However, the flexibility and strength of the bonded system is unclear.
PURPOSE
The purpose of this in vitro study was to compare the flexibility and strength of bonded lithium disilicate to PEEK with the bond between lithium disilicate and zirconia.
MATERIAL AND METHODS
Fifteen PEEK (JUVORA Dental Disc), 15 zirconia (ArgenZ HT+), and 30 lithium disilicate (IPS e.max CAD) beam-shaped specimens (12.5×2×2 mm) were prepared. The ends of the PEEK beams were conditioned with 50-μm aluminum oxide airborne-particle abrasion, followed by primer (visio.link) and light-activated polymerization. Zirconia specimens were prepared with airborne-particle abrasion and primer (Monobond Plus). Lithium disilicate specimens were etched with 4.5% hydrofluoric acid (IPS Ceramic Etching Gel) and primed (Monobond Plus). The lithium disilicate specimens were cemented (Multilink Automix) to the PEEK and zirconia specimens. Light- and chemical-activated polymerization were used. Monolithic specimens of PEEK and zirconia (25×2×2 mm) were also prepared. All specimens were stored overnight in distilled water and submitted to a 4-point bend test in a universal testing machine at 0.5 mm/min crosshead speed until fracture, and the flexural modulus and strength were calculated. Differences among groups were statistically tested by using 1-way analysis of variance followed by the Student-Newman-Keuls post hoc test (α=.05).
RESULTS
All bonded specimens fractured at their adhesive interface. Zirconia bonded to lithium disilicate specimens (29.7 ±8.8 MPa) were approximately 3 times stronger than PEEK bonded to lithium disilicate specimens (10.4 ±2.7 MPa) and approximately 12 times more rigid (78.5 ±6.7 GPa and 6.5 ±1.8 GPa, respectively). The flexure of monolithic PEEK was such that it did not fracture when loaded at 0.5 mm/min, while zirconia fractured at 413.9 ±38.5 MPa. Monolithic PEEK was approximately 37 times more flexible than monolithic zirconia (4.3 ±0.3 GPa and 157.2 ±7.2 GPa, respectively). All values were statistically significantly different except between the flexural moduli of monolithic PEEK and PEEK bonded to lithium disilicate.
CONCLUSIONS
The bond strength between PEEK and lithium disilicate was significantly weaker than between zirconia and lithium disilicate. Monolithic zirconia was significantly stiffer than monolithic PEEK.
Topics: Humans; Resin Cements; Materials Testing; Dental Porcelain; Zirconium; Ceramics; Dental Stress Analysis; Surface Properties
PubMed: 33846011
DOI: 10.1016/j.prosdent.2021.02.025 -
Dental Materials Journal Sep 2023The purpose of the study was the investigation of the polymerization of a preheated composite resin beneath lithium disilicate. First, lithium disilicate discs in two...
The purpose of the study was the investigation of the polymerization of a preheated composite resin beneath lithium disilicate. First, lithium disilicate discs in two shades (HT A2 and HT A4) and three different thicknesses (2, 4, and 6 mm) were bonded on dentine with preheated composite resin that was photo-polymerized for 20 s. The composite resin microhardness, the double bond conversion (DC) and their correlation were estimated. Second, standardized occlusal veneers of two shades and two different thicknesses (4 and 6 mm) were bonded with preheated composite resin and photopolymerized for 60 or 270 s. A microhardness line profiling was performed on the cross-section of each specimen and the correspondence DC was calculated. Shade and thickness of lithium disilicate were found to have a significant impact on micro-hardness and DC of the composite resin. Beneath standardized occlusal veneers DC can reach clinically acceptable level if photopolymerization duration is extended properly.
Topics: Composite Resins; Dental Veneers; Materials Testing; Dental Porcelain; Resin Cements; Ceramics
PubMed: 37661372
DOI: 10.4012/dmj.2023-057