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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 -
Materials (Basel, Switzerland) Dec 2023Dental zirconias have been broadly utilized in dentistry due to their high mechanical properties and biocompatibility. Although initially introduced in dentistry as an... (Review)
Review
Dental zirconias have been broadly utilized in dentistry due to their high mechanical properties and biocompatibility. Although initially introduced in dentistry as an infrastructure material, the high rate of technical complications related to veneered porcelain has led to significant efforts to improve the optical properties of dental zirconias, allowing for its monolithic indication. Modifications in the composition, processing methods/parameters, and the increase in the yttrium content and cubic phase have been presented as viable options to improve zirconias' translucency. However, concerns regarding the hydrothermal stability of partially stabilized zirconia and the trade-off observed between optical and mechanical properties resulting from the increased cubic content remain issues of concern. While the significant developments in polycrystalline ceramics have led to a wide diversity of zirconia materials with different compositions, properties, and clinical indications, the implementation of strong, esthetic, and sufficiently stable materials for long-span fixed dental prostheses has not been completely achieved. Alternatives, including advanced polycrystalline composites, functionally graded structures, and nanosized zirconia, have been proposed as promising pathways to obtain high-strength, hydrothermally stable biomaterials. Considering the evolution of zirconia ceramics in dentistry, this manuscript aims to present a critical perspective as well as an update to previous classifications of dental restorative ceramics, focusing on polycrystalline ceramics, their properties, indications, and performance.
PubMed: 38138684
DOI: 10.3390/ma16247541 -
Materials (Basel, Switzerland) Jul 2023The clinical success of porcelain laminate veneers (PLVs) depends on many clinical and technical factors, from planning to execution, among which adhesive cementation is... (Review)
Review
The clinical success of porcelain laminate veneers (PLVs) depends on many clinical and technical factors, from planning to execution, among which adhesive cementation is of significant importance. This procedure carries many risk factors if not optimally executed. The objective of this study was to document the clinical parameters affecting successful cementation procedures with a focus on the adhesive strength, integrity, and esthetics of the PLVs. A literature search was conducted through MEDLINE, complemented by a hand search using predefined keywords. Articles published in English between 1995 and 2023 were selected. According to this review, the success and longevity of PLVs rely in great part on the implementation of a precise cementation technique, starting from field isolation, adequate materials selection for adhesion, proper manipulation of the materials, the seating of the veneers, polymerization, and elimination of the excess cement. Several clinical steps performed before cementation, including treatment planning, preparation, impression, and adequate choice of the restorative material, could affect the quality of cementation. Scientific evidence suggests careful implementation of this process to achieve predictable outcomes with PLVs. The short- and long-term clinical success of adhesively luted PLVs is tributary to a deep understanding of the materials used and the implementation of clinical protocols. It is also contingent upon all the previous steps from case selection, treatment planning, and execution until and after the cementation.
PubMed: 37512206
DOI: 10.3390/ma16144932 -
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 -
Maxillofacial Plastic and... Aug 2023This study aimed to analyze the clinical outcome and complications of narrow-diameter dental implants (NDIs) (diameter ≤3.5 mm).
BACKGROUND
This study aimed to analyze the clinical outcome and complications of narrow-diameter dental implants (NDIs) (diameter ≤3.5 mm).
METHODS
The 274 NDIs that met the selection criteria from 2013 to 2018 were included in the retrospective study, and the survival rates (SVR) were compared. Mechanical complications included screw loosening and fractures of the implant components, such as the implant fixture, abutment, and prosthesis. In addition, marginal bone loss (MBL) was measured immediately after surgery and 1 year after loading.
RESULTS
The 3-year cumulative SVR was 92.4%. Nineteen fixtures failed during the follow-up. The failure rate was significantly higher (OR=4.573, p<0.05) in smokers and was significantly higher in osteoporosis patients (OR=3.420, p<0.05). The vertical and horizontal values of MBL were 0.33±0.32 mm and 0.18±0.17 mm, respectively. Mechanical complications included screw loosening (5.5%) and porcelain fracture (2.2%), but no fractures of the fixture or components were observed. The choice of titanium and zirconium (TiZr) alloy implant was significantly more frequent in the posterior region. Bone graft was significantly more frequently done in the anterior region.
CONCLUSIONS
According to the high SVR and stability of NDIs, the findings of the study suggest that NDIs may be a replacement for regular diameter dental implants (RDIs) and the use of TiZr alloy could extend the indication of NDIs. In the esthetic area, contour augmentation may be a reason for increasing the frequency of bone grafts.
PubMed: 37526800
DOI: 10.1186/s40902-023-00394-6 -
Materials Today. Proceedings Sep 2023Studies have reported challenges of debonding of dental zirconia crowns to from luting cement and prepared teeth. The aim of the study was to explore the application of...
Studies have reported challenges of debonding of dental zirconia crowns to from luting cement and prepared teeth. The aim of the study was to explore the application of dental glazing systems for enhancing the bonding of zirconia dental ceramics to luting resin cement. Commercial glaze powder and liquid (Vita Akzent) and experimental mica-based glaze powders were used for the study. X-ray diffraction analysis of the glaze powders (XRD) and Fourier Transform InfraRed Spectroscopy (FTIR) was done on the glaze liquid. Sandblasted sintered dental zirconia (Katana, Noritake) were the control samples. Glazed zirconia samples were coated with commercial glaze and experimental glaze powders which were further etched with 5% hydrofluoric acid. Shear bond strengths of sandblasted and glazed zirconia samples to resin composites were evaluated. XRD of commercial and experimental glaze powders revealed a broad peak confirming the amorphous nature of glass and FTIR analysis of the glaze liquid revealed symmetrical stretching (CH-CH) of the alcohol group indicating a mixture of -butane and ethanol. Glazed and etched zirconia showed significantly higher shear bond strength to resin cement compared to sand-blasted zirconia. The study confirms the glassy nature of dental glaze powders and the presence of ethanol-based mixtures in the commercial glaze liquid. Glazing systems have the potential to be explored for enhancing the bonding of non-etchable zirconia ceramics to resin cement and tooth substrates.
PubMed: 38590583
DOI: 10.1016/j.matpr.2023.04.308 -
Journal of Dental Sciences Jul 2023The simulated color of restorations plays an important role in improving patient satisfaction. The aim of this study was to test a new intelligent colorimetric solution...
BACKGROUND/PURPOSE
The simulated color of restorations plays an important role in improving patient satisfaction. The aim of this study was to test a new intelligent colorimetric solution using the Advanced Reflectionless Technology (ART) monitor and compare them using commercially available shade systems.
MATERIALS AND METHODS
Six participants' right maxillary central incisors were tested with three devices, including the AUO Display Plus (Group A), a Canon single-lens reflex camera with eLAB's polar eyes filter (Group E), and the VITA Easyshade V (Group V). Each porcelain tooth was divided into three areas, and was assigned a CIELAB L∗a∗b∗ value by using the VITA Easyshade V. The original data were compared with the CIELAB L∗a∗b∗ obtained using the VITA Easyshade V. A prosthodontist compared the color of the porcelain veneers by eyes and gave the scores from 1 to 3.
RESULTS
For the ΔE, the three areas of Group A had the smallest differences between the color of the fabricated teeth and that of the original teeth. Colorimetric analysis indicated that Groups A and V did not differ much in the color of the three areas of the tooth. Groups E and A exhibited significant differences between the cervical third and middle third of the tooth, and Groups E and V exhibited significant differences between the middle third and incisal third of the tooth.
CONCLUSION
Compared with traditional monitors, ART is closer to real images in terms of color, contrast, and detail grayscale. Technicians are able to produce realistic and pleasing colors.
PubMed: 37404640
DOI: 10.1016/j.jds.2023.04.003 -
European Oral Research Sep 2023This study aimed to investigate the discoloration of four types of dental porcelain systems (feldspathic, monolithic zirconia, lithium disilicate, and leucite...
PURPOSE
This study aimed to investigate the discoloration of four types of dental porcelain systems (feldspathic, monolithic zirconia, lithium disilicate, and leucite glassceramic) with various surface treatments (glazed and mechanically polished) after undergoing chewing simulation against a natural tooth antagonist.
MATERIALS AND METHODS
Disc-shaped porcelain groups (9x3mm) were produced for the following categories: feldspathic glazed (FG), feldspathic mechanically polished (FM), zirconia glazed (ZG), zirconia mechanically polished (ZM), lithium disilicate glazed (ExG), lithium disilicate mechanically polished (ExM), leucite glass-ceramic glazed (EG), and leucite glass-ceramic (EM). In vitro chewing simulation was conducted on all porcelain groups, and a spectrophotometer was used to compare the color changes between their initial states.
RESULTS
The ΔE values (discoloration) of all porcelain samples were statistically different (p <0.05), and the ΔE values of the glazed samples were higher than those of the mechanically polished samples.
CONCLUSION
All the glazed samples are more likely to show more color change than the mechanically polished sample groups.
PubMed: 37929221
DOI: 10.26650/eor.20231033050 -
Journal of Applied Biomaterials &... 2024Despite the development of implant-supported prostheses, there are still patients for whom conservative treatments such as resin-bonded fixed dental prostheses (RBFDPs)... (Review)
Review
Despite the development of implant-supported prostheses, there are still patients for whom conservative treatments such as resin-bonded fixed dental prostheses (RBFDPs) are more appropriate. This study's objective was to analyze the available research on full-ceramic RBFDPs. In this study, Web of Science, MEDLINE/PubMed, Scopus, Embase, Cochrane Library, and Google Scholar databases were searched for articles published in English between 2010 and 2020. A total of 14 studies were reviewed based on the eligibility criteria. The results showed that using a cantilever design with one abutment had an advantage over two abutments. Additionally, it was proposed that preparations designed with retentive aids, such as a proximal box, groove, and pinhole, could improve RBFDP survival rates. IPS e.max ZirCAD, In-Ceram alumina, and zirconia CAD/CAM were the most commonly used framework materials. Most studies used air abrasion, salinization, or hydrofluoric acid for surface treatment. Adhesive resin cements were the most frequently used type of cement. The survival rate of In-Ceram ceramics (85.3%-94.8%) was lower than that of In-Ceram zirconia and IPS e.max ZirCAD. Debonding, followed by framework fracture, was the leading cause of failure. Following 3-10 years follow-up, the survival percentage of all-ceramic RBFDPs ranged from 76% to 100%. Although RBFDPs have demonstrated satisfactory success as a conservative treatment, long-term follow-ups and higher sample sizes in clinical research are required to gain more reliable outcomes on the clinical success rate of various RBFDP designs.
Topics: Humans; Ceramics; Resin Cements; Dental Porcelain; Dental Prosthesis, Implant-Supported; Denture, Partial, Fixed, Resin-Bonded; Zirconium
PubMed: 38706266
DOI: 10.1177/22808000241250118 -
Journal of the Mechanical Behavior of... Dec 2023This study investigated the impact of preparation design and material types on fracture strength in maxillary premolars endocrowns after thermodynamic aging.
PURPOSE
This study investigated the impact of preparation design and material types on fracture strength in maxillary premolars endocrowns after thermodynamic aging.
MATERIALS AND METHODS
Eighty two-rooted maxillary premolar crowns underwent endodontic treatment (N = 80, n = 10). The teeth were categorized into ten groups (4-mm deep with no intracanal extension lithium disilicate glass ceramic & multilayer zirconia endocrowns (LE0 & ZE0); 4-mm deep with 4-mm intracanal extension in one canal (LE1 & ZE1); 4-mm deep with 2-mm intracanal extensions in both canals (LE2 & ZE2); flat overlays with no endocore (LO & ZO); glass fiber reinforced post & core and crown (LC & ZC)). After cementation, all specimens were subjected to 1500 thermocycles and 1,200,000 chewing cycles with an axial occlusal load of 49 N. A static loading test was performed at a non-axial 45° loading using a universal testing machine and failure modes (Type I: restoration debonding; Type II: restoration fracture; Type III: restoration/tooth complex fracture above bone level; Type IV: restoration/tooth complex fracture below bone level) were evaluated using a stereoscope. Data were ananalzed using 2-way ANOVA and Tukey's tests (alpha = 0.05).
RESULTS
The endocrowns manufactured from multilayered zirconia and pressed lithium disilicate glass ceramic exhibited a fracture load ranging between 1334 ± 332 N and 756 ± 150 N, with ZC presenting the highest and LE2 the lowest values. The differences were not statistically significant (p > 0.05).
CONCLUSION
All endocrowns tested in this study performed similar considering the different designs and materials tested. The distribution of fracture modes did not differ significantly depending on the design of the restoration and the type of material used.
Topics: Humans; Flexural Strength; Materials Testing; Computer-Aided Design; Zirconium; Ceramics; Dental Porcelain; Tooth Fractures; Dental Stress Analysis; Dental Restoration Failure
PubMed: 37839334
DOI: 10.1016/j.jmbbm.2023.106184