The aim of this systematic review is to determine the effectiveness of self-etching primers in comparison to the conventional protocol with hydrofluoric acid and silane treatment for bonding lithium ...disilicate ceramics.
The formulated PICO question for this research was: "Does self-etching silane primer surface treatment in lithium disilicate ceramics present a similar bond strength value compared to conventional hydrofluoric acid and silane treatment?". Combinations of words and appropriate truncations were adapted for each database. For the selection, duplicate articles were systematically eliminated using Mendeley software. The Cohen's Kappa statistic was then computed, RoBDEMAT questions were addressed, and the meta-analyses were conducted using RevMan 5.4, at a significance level of 5%.
Two independent reviewers conducted a blind and independent analysis of 190219 articles from PubMed, Scopus, Web of Science, and OpenGrey. Subsequently, they extracted data from 21 studies for the systematic review and in 16 the meta-analysis. In all in vitro studies, the most frequently cited concentration of hydrofluoric acid was 5%. In the meta-analysis, no statistical differences were observed between the two treatments concerning bond strength.
Self-etching silane primers demonstrate promising results in lithium disilicate bonding, suggesting their potential as an alternative surface treatment to hydrofluoric acids + silane.
Lithium disilicate, Hydrofluoric acid, Dental Porcelain, Ceramics, Silanes.
The surface treatment of glass-ceramic-based materials, namely, lithium disilicate glass (IPS e.max CAD), feldspar porcelain (VITABLOCS Mark II), and a polymer-infiltrated ceramic network (VITA ...ENAMIC), using aqueous fluoride solutions and their influence on luting agent bonding were investigated. Six experimental aqueous fluoride solutions were applied to these materials, and their effects were assessed by surface topological analysis. The obtained results were compared using non-parametric statistical analyses. Ammonium hydrogen fluoride (AHF) etchant demonstrated the greatest etching effect. Subsequent experiments focused on evaluating different concentrations of the AHF etchant for the bonding pretreatment of glass-ceramic-based materials with a luting agent (PANAVIA V5). AHF, particularly at concentrations above 5 wt%, effectively roughened the surfaces of the materials and improved the bonding performance. Notably, AHF at a concentration of 30 wt% exhibited a more pronounced effect on both etching and bonding capabilities compared to hydrofluoric acid.
•Occlusal veneers can be reliably produced by 3D-printing with the Lithography-based Ceramic Manufacturing process.•3D-printed zirconia, milled zirconia and heat-pressed lithium disilicate can be ...recommended as material for ultra-thin occlusal veneers.•These materials exhibit a fracture toughness surpassing the suggested values for posterior restorations if bonded to dentin.
The load-bearing capacity of ultra-thin occlusal veneers made of 3D-printed zirconia were compared to the ones obtained by fabricating these reconstructions by CAD/CAM milling zirconia or heat-pressing lithium-disilicate.
On 60 extracted human molars, the occlusal enamel was removed and extended into dentin. Occlusal veneers of 0.5 mm thickness were digitally designed. The specimens were divided into 3 groups (n = 20 each) differing in the restorative material and the fabrication technique of the occlusal veneer. (1) 3DP: 3D-printed zirconia (Lithoz); (2): CAM: milled zirconia (Ceramill Zolid FX); (3) HPR: heat-pressed lithium disilicate (IPS e.max Press). After conditioning procedures, the restorations were adhesively bonded onto the conditioned tooth. Thereafter, all specimens were aged in a chewing simulator by exposure to cyclic fatigue and temperature variations. Subsequently the specimens were statically loaded and the load which was necessary to decrease the maximum load by 20% and initiate a crack (Finitial) and the load which was needed to fracture the specimen (Fmax) were measured. Differences between the groups were compared applying the Kruskal-Wallis (KW) test and the Wilcoxon-Mann-Whitney-Test (WMW: p < 0.05).
The median Finitial values for the groups 3DP, CAM and HPR were 1’650 N, 1’250 N and 500 N. The differences between all three groups were statistically significant (KW: p < 0.0001). The median Fmax values amounted to 2’026 N for the group 3DP, 1’500 N for the group CAM and 1’555 N for the group HPR. Significant differences were found between 3DP and CAM (WMW: p = 0.0238).
Regarding their load-bearing capacity, 3D-printed or milled zirconia as well as heat-pressed lithium disilicate can be recommended as restorative material for ultra-thin occlusal veneers to prosthetically compensate for occlusal tooth wear. Despite statistically significant differences between the restoration materials, all load-bearing capacities exceeded the clinically expected normal bite forces.
The surfaces of four lithium disilicate glass ceramics (LDGC) were characterized at the nanolevel. The goal was to detect the chemical alteration of the surface on etching with hydrofluoric acid ...(HF). The four LDGC tested were Celtra Duo, IPS e.max CAD, Straumann n!ce and Vita Suprinity. Four blocks of each LDGC were sectioned to ∼ 1 mm thicknesses. The requirement for firing, or not, was carried out following the manufacturer’s recommendations. The samples were then divided into two groups: a control and an etched group. Etching was carried out using a solution of 5% HF for 20 s, rinsed for 20 s and dried for 10 s, using an air jet. The atomic percentages of the first atomic layers were probed using X-ray photoelectron spectroscopy (XPS) in the survey mode (n = 12). The oxygen and silicon peaks (O1s and Si2p) were then analyzed in the high resolution mode. The samples were also characterized using scanning electronic microscopy at high magnification (60 k). XPS showed the amounts of the major elements, Si, O and Li, were changed on etching. For all samples, trace elements, such as P, Zn, Y, Na and Sr, disappeared on glassy phase dissolution. Zr and Al percentages varied, based on the LDGC analyzed. High resolution spectra of the O1s and Si2p peaks showed that the chemical environments were qualitatively different in all samples. Acid etching, using 5% HF for 20 s, modified not only the topographic structure, but also the chemical composition of the LDGC surface.
•In all tested ceramics, the surface chemical composition at the nanolevel differs from the bulk composition.•HF acid etching modifies the concentrations of O, Si, Li on the surfaces of all samples.•LDGCs with high concentrations of Zr or Al are more affected by etching.•Except for n!ce, a crystalline phase of SiO2 was detected in the control group for all LDGCs.
Zirconia-reinforced lithium silicates (ZLS) are a novel generation of aesthetic, lithium-based ceramics intended for use in dental restorations at high loads due to their enhanced fracture strength ...compared to the previous lithium disilicate (LS2) materials. However, under severe dental conditions, material durability in service may be limited by wear from repetitive, frictional contacts. Here, a comparison is made between commercial ZLS and LS2 dental ceramics of their severe wear behavior under sliding contact against hard zirconia antagonists by means of in-vitro pin-on-disk tests. Specific wear rates greater than 10−6 mm3/N⋅m are obtained. The mechanisms responsible for material removal are a combination of deformation and fracture. Results are discussed in terms of the materials’ microstructure and mechanical properties. In combination with analytical modelling, ZLS dental ceramics are estimated to be up to 5 times less durable than LS2 under conditions modelling heavy chewing/bruxism. Finally, implications for the microstructural design of novel lithium silicate/disilicate materials with improved durability are considered.
•Wear tests on lithium-based dental materials are conducted with a view to assessing durability under severe chewing conditions.•Wear behavior depends on material microstructure and mechanical properties. Results are analyzed using contact mechanics.•Zirconia-reinforced lithium silicate is estimated to be 5x less durable than lithium disilicate under severe conditions.•Implications for the microstructural design of novel lithium-based dental materials with improved durability are discussed.
The aim of this study was to evaluate the load-bearing capacity of monolithic lithium disilicate (LiDi - IPS e.max CAD) and novel ultra-translucent zirconia restorative systems of various ...compositions: 5Y-PSZ (5 mol% yttria-partially-stabilized zirconia) and 4Y-PSZ (4 mol% yttria-partially-stabilized zirconia); relative to a 3Y-TZP (3 mol% yttria-stabilized zirconia) control.
Experiments were carried out with 10 disc specimens (Ø12 ×1 mm) per ceramic material. The zirconia intaglio surface (as machined) was sandblasted (50 µm Al
O
at 2 bar), while LiDi was etched with 5% HF for 20 s. The ceramic discs were then adhesively bonded onto a dentin-like substrate (G10, a high-pressure fiberglass material) using Multilink Automix cement and Monobond Plus primer, producing a ceramic/cement/dentin-like substrate trilayer structure. The bonded specimens were stored in water for 3 days at 37 °C prior to a Hertzian indentation flexural radial fracture test. The plate-on-foundation theory was used to validate the load-bearing capacity of the trilayer systems based on the flexural tensile stress at the ceramic intaglio (cementation) surface-a cause for bulk fracture of ceramic onlays.
The experiment data showed that, when bonded to and supported by a dentin-like substrate, the load-bearing capacity of LiDi (872 N) is superior to the 5Y-PSZ (715 N) and can even reach that of 4Y-PSZ (864 N), while 3Y-TZP still holds the highest load-bearing capacity (1195 N). Theoretical analyses agree with experimental observations. The translucency of 5Y-PSZ approaches that of LiDi, which are superior to both 4Y-PSZ and 3Y-TZP.
When adhesively bonded to and supported by dentin, lithium disilicate exhibits similar load-bearing properties to 4Y-PSZ but much better than 5Y-PSZ.
Objectives
To compare the strength and translucency of CAD/CAM zirconia blocks, with traditional and high‐speed sintering, to lithium disilicate.
Materials and Methods
Three zirconia materials ...(Katana STML Block, Prettau Anterior, and Zpex Smile) were tested with either traditional (7 hours) or high‐speed (18 or 30 minutes in a SpeedFire furnace) sintering. A lithium disilicate material (IPS e.max CAD) was tested as a reference. Three‐point bend flexural strength specimens (16 mm × 4 mm × 1.2 mm, n = 10) were tested on 14‐mm‐separated supports and loaded to failure at 1 mm/min. Specimens (1 mm thick, n = 10) were measured in a Color‐i7 spectrophotometer against a black and white background to calculate translucency parameter. Zirconia specimens were thermally etched and a grain structure was observed with scanning electron microscopy. Data were analyzed with 1‐way ANOVA and Tukey's post hoc analysis (α = 0.05).
Results
There were significant differences between materials for flexural strength, translucency parameter, and grain size (P < .001). Grains became significantly larger and pores were present when two of the zirconia materials (Prettau Anterior and Zpex Smile) were sintered with a high‐speed sintering program.
Conclusions
Two of the zirconia materials (Prettau Anterior and Zpex Smile) became less translucent and less strong using a high‐speed sintering program, whereas another (Katana STML Block) was unaffected.
The primary aim of this in vitro study was to compare the load-bearing capacity of lithium disilicate occlusal veneers, fabricated via different manufacturing processes. Secondary objectives included ...assessing internal accuracy and production time-efficiency.
Four fabrication methods for ultra-thin lithium disilicate occlusal veneers on extracted human molars with simulated erosive defects were compared (n = 20/group): CAM: milled lithium disilicate (IPS e.max CAD); HPR: heat-pressed lithium disilicate (IPS e.max Press) out of a milled PMMA template (Ddpmma CAST); 3DP: 3D-printed lithium disilicate (experimental lithium disilicate); PTE: heat-pressed lithium disilicate (IPS e.max Press) out of a 3D-printed template (SilaPrint cast). Internal accuracy was measured prior to thermo-mechanical aging, followed by static loading to measure the load-bearing capacity (Fmax). Fabrication time (time-efficiency) was also recorded. Statistical analysis was performed using the Kruskal-Wallis (KW) test.
No statistically significant differences were found in median load-bearing capacities (Fmax) between the groups (KW p = 0.5902): CAM 1821 N, HPR 1896 N, 3DP 2003 N, PTE 1687 N. Significant differences were found in internal accuracy between the groups that employed printing processes (3DP, PTE) and all other groups in margins (p < 0.001), cusps (p < 0.0018), and fossae (p < 0.0346). The time-efficiency measurements indicated an increase in fabrication time, starting from CAM 67.2 ± 5.8 min, followed by HPR 200.8 ± 33.0 min, PTE 289.2 ± 38.7 min, and peaking with the highest duration observed for 3DP 701.6 ± 8.1 min.
The fabrication method of ultra-thin lithium disilicate occlusal veneers does not significantly impact their load-bearing capacity, but affects the clinical fit and adaptation of the veneers.
•All fabrication methods exhibited high load-bearing capacities, with no significant differences between the groups.•Milled or heat-pressed restorations demonstrated minimal marginal discrepancies and high internal accuracy.•3D-printed restorations showed larger marginal gaps but superior internal accuracy in the cusp and fossa regions.•Direct milling was the most time-efficient; 3D-printing the most time-consuming, and procedures involving methacrylate-based templates were intermediate.
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