scholarly journals Effect of Thermo-Mechanical Aging and Repressing on Fracture Resistance of Lithium Disilicate Crowns

2021 ◽  
Vol 24 (3) ◽  
Author(s):  
Amr El-Etreby ◽  
Mahmoud Metwally ◽  
Gihan EL-Nagar
Keyword(s):  
Glass Ceramic ◽  
Fracture Resistance ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Mean Value ◽  
Resistance Testing ◽  
Novel Approach ◽  
Significant Difference ◽  
Keywords Fracture ◽  
Mechanical Aging

Objective: The recycling of heat pressed lithium disilicate glass-ceramic leftover material has been reported to be done by dental laboratories. The effect of this procedure on the fracture resistance of single crowns is unknown, especially when it is functioning inside the oral cavity with subsequent exposure to temperature changes and cycles of mastication. Material and Methods: A total of 28 lithium disilicate glass-ceramic crowns (IPS emax Press) were constructed and randomly assigned into two groups (n = 14); Group (P): Included crowns fabricated from new e.max ingots. Group (R): Included crowns fabricated from repressed e.max buttons. Specimens of each group were divided into two equal subgroups (n = 7) according to whether the aging of specimens will be performed or not before fracture resistance testing. Subgroup (N), samples were subjected to fracture resistance without thermo-mechanical aging, while subgroup (A), samples were subjected to thermo-cycling and cyclic loading before being subjected to fracture strength testing. Different methods; SEM, XRD, EDAX were used to characterize the properties of lithium disilicate glass-ceramics before and after repressing. Results: The highest statistically significant fracture resistance value was recorded for the subgroup (RN) repressed/non-aged, followed by the subgroup repressed/aged (RA), while the lowest statistically significant mean value was recorded for the subgroup pressed/aged (PA). There was no significant difference between pressed/non-aged (PN) and repressed/aged (RA) subgroups. Conclusion: Repressing of leftover buttons may increase the fracture resistance of IPS emax Press crowns. Thermo-mechanical aging may negatively affect the fracture resistance of IPS emax Press crowns, yet Repressing may decrease this effect. Clinical implications: This is a novel approach that targets a point of research that has not been investigated before. It elaborates how repressing may decrease the effect of aging and increase the fracture resistance of lithium disilicate crowns. Thus, recycling of lithium disilicate glass ceramics might decrease its failure and prolong their serviceability.   Keywords Fracture resistance; Heat pressed; Lithium disilicate; Recycling; Repressing; Thermo-mechanical aging.

Influence of Ceramic Thickness and Ceramic Materials on Fracture Resistance of Posterior Partial Coverage Restorations

2015 ◽  
Vol 40 (2) ◽  
pp. 211-217 ◽  
Author(s):  
EM Bakeman ◽  
N Rego ◽  
Y Chaiyabutr ◽  
JC Kois
Keyword(s):  
Glass Ceramic ◽  
Fracture Resistance ◽  
Testing Machine ◽  
Lithium Disilicate ◽  
Ceramic Materials ◽  
Tooth Structure ◽  
Partial Coverage ◽  
Significant Difference ◽  
Ceramic Thickness ◽  
Ceramic Restorations

SUMMARY This study evaluated the influence of ceramic thickness and ceramic materials on fracture resistance of posterior partial coverage ceramic restorations. Forty extracted molars were allocated into four groups (n=10) to test for two variables: 1) the thickness of ceramic (1 mm or 2 mm) and 2) the ceramic materials (a lithium disilicate glass-ceramic [IPS e.max] or leucite-reinforced glass ceramic [IPS Empress]). All ceramic restorations were luted with resin cement (Variolink II) on the prepared teeth. These luted specimens were loaded to failure in a universal testing machine, in the compression mode, with a crosshead speed of 1.0 mm/min. The data were analyzed using two-way analysis of variance and the Tukey Honestly Significantly Different multiple comparison test (α =0.05). The fracture resistance revealed a significant effect for materials (p<0.001); however, the thickness of ceramic was not significant (p=0.074), and the interaction between the thickness of ceramic and the materials was not significant (p=0.406). Mean (standard deviation) fracture resistance values were as follows: a 2-mm thickness of a lithium disilicate bonded to tooth structure (2505 [401] N) revealed a significantly higher fracture resistance than did a 1-mm thickness of leucite-reinforced (1569 [452] N) and a 2-mm thickness of leucite-reinforced ceramic bonded to tooth structure (1716 [436] N) (p<0.05). There was no significant difference in fracture resistance values between a lithium disilicate ceramic at 1-mm thickness (2105 [567] N) and at 2-mm thickness. Using a lithium disilicate glass ceramic for partial coverage restoration significantly improved fracture resistance compared to using a leucite-reinforced glass ceramic. The thickness of ceramic had no significant effect on fracture resistance when the ceramics were bonded to the underlying tooth structure.

scholarly journals Effect of Nd:YAG Laser with/without Graphite Coating on Bonding of Lithium Disilicate Glass-Ceramic to Human Dentin

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Amjad Abu Hasna ◽  
Stephanie Semmelmann ◽  
Fernanda Alves Feitosa ◽  
Danilo De Souza Andrade ◽  
Franklin R Tay ◽  
...  
Keyword(s):  
Bond Strength ◽  
Glass Ceramic ◽  
Nd:Yag Laser ◽  
Testing Machine ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Resin Cement ◽  
Cylindrical Shape ◽  
Universal Testing ◽  
Human Dentin

This study evaluated the effect of different surface treatments on the tensile bond strength between lithium disilicate glass-ceramics, resin cement, and dentin. Fifty truncated cone-shape glass-ceramics were divided into five groups (n = 10): G1, control: 10% hydrofluoric acid (HF); G2, Nd:YAG laser + silane; G3, Sil + Nd:YAG laser; G4, graphite + Nd:YAG laser + Sil; and G5, graphite + Sil + Nd:YAG laser. Fifty human third-molars were cut to cylindrical shape and polished to standardize the bonding surfaces. The glass-ceramic specimens were bonded to dentin with a dual-cured resin cement and stored in distilled water for 24 h at 37ºC. Tensile testing was performed on a universal testing machine (10 Kgf load cell at 1 mm/min) until failure. The bond strength values (mean ± SD) in MPa were G1 (9.4 ± 2.3), G2 (9.7 ± 2.0), G3 (6.7 ± 1.9), G4 (4.6 ± 1.1), and G5 (1.2 ± 0.3). Nd:YAG laser and HF improve the bond strength between lithium disilicate glass-ceramics, resin cement, and dentin. The application of a graphite layer prior to Nd:YAG laser irradiation negatively affects this bonding and presented inferior results.

scholarly journals LED and Halogen Light Transmission through a CAD/CAM Lithium Disilicate Glass-Ceramic

2015 ◽  
Vol 26 (6) ◽  
pp. 648-653 ◽  
Author(s):  
Carolina Nemesio de Barros Pereira ◽  
Cláudia Silami de Magalhães ◽  
Bruno Daleprane ◽  
Rogéli Tibúrcio Ribeiro da Cunha Peixoto ◽  
Raquel da Conceição Ferreira ◽  
...  
Keyword(s):  
Regression Model ◽  
Glass Ceramic ◽  
Light Transmission ◽  
Light Attenuation ◽  
Lithium Disilicate ◽  
Strong Negative Correlation ◽  
Halogen Light ◽  
Significant Difference ◽  
Cad Cam ◽  
Ceramic Thickness

The effect of thickness, shade and translucency of CAD/CAM lithium disilicate glass-ceramic on light transmission of light-emitting diode (LED) and quartz-tungsten-halogen units (QTH) were evaluated. Ceramic IPS e.max CAD shades A1, A2, A3, A3.5, high (HT) and low (LT) translucency were cut (1, 2, 3, 4 and 5 mm). Light sources emission spectra were determined. Light intensity incident and transmitted through each ceramic sample was measured to determine light transmission percentage (TP). Statistical analysis used a linear regression model. There was significant interaction between light source and ceramic translucency (p=0.008) and strong negative correlation (R=-0.845, p<0.001) between ceramic thickness and TP. Increasing one unit in thickness led to 3.17 reduction in TP. There was no significant difference in TP (p=0.124) between shades A1 (ß1=0) and A2 (ß1=-0.45) but significant reduction occurred for A3 (ß1=-0.83) and A3.5 (ß1=-2.18). The interaction QTH/HT provided higher TP (ß1=0) than LED/HT (ß1=-2.92), QTH/LT (ß1=-3.75) and LED/LT (ß1=-5.58). Light transmission was more effective using halogen source and high-translucency ceramics, decreased as the ceramic thickness increased and was higher for the lighter shades, A1 and A2. From the regression model (R2=0.85), an equation was obtained to estimate TP value using each variable ß1 found. A maximum TP of 25% for QTH and 20% for LED was found, suggesting that ceramic light attenuation could compromise light cured and dual cure resin cements polymerization.

scholarly journals Effect of Thermocycling, Surface Treatments and Microstructure on the Optical Properties and Roughness of CAD-CAM and Heat-Pressed Glass Ceramics

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 381 ◽  
Author(s):  
Roxana-Diana Vasiliu ◽  
Sorin Daniel Porojan ◽  
Mihaela Ionela Bîrdeanu ◽  
Liliana Porojan
Keyword(s):  
Surface Roughness ◽  
Optical Properties ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Ceramic Materials ◽  
Surface Treatments ◽  
Lithium Silicate ◽  
Before And After ◽  
Cad Cam

Dental ceramic restorations are widely spread nowadays due to their aesthetics and biocompatibility. In time, the colour and structure of these ceramic materials can be altered by aging processes. How does artificial aging affect the optical and surface roughness of ceramics? This study aims to assess the effect of thermocycling, surface treatments and microstructure upon translucency, opalescence and surface roughness on CAD-CAM and heat-pressed glass-ceramic. Forty-eight samples (1.5 mm thickness) were fabricated from six types of A2 MT ceramic: heat-pressed and milled glass-ceramic (feldspathic, lithium disilicate and zirconia reinforced lithium silicate). The samples were obtained respecting the manufacturer’s instructions. The resulted surfaces (n = 96) were half glazed and half polished. The samples were subjected to thermocycling (10,000 cycles) and roughness values (Ra and Rz), colour coordinates (L*, a*, b*) and microstructural analyses were assessed before and after thermocycling. Translucency (TP) and opalescence (OP) were calculated. Values were statistically analysed using ANOVA test (one way). TP and OP values were significantly different between heat-pressed and milled ceramics before and also after thermocycling (p < 0.001). Surface treatments (glazing and polishing) had a significant effect on TP and OP and surface roughness (p < 0.05). The heat-pressed and milled zirconia reinforced lithium silicate glass-ceramic experienced a loss in TP and OP. Ra and Rz increased for the glazed samples, TP and OP decreased for all the samples after thermocycling. Microstructural analyse revealed that glazed surfaces were more affected by the thermocycling and especially for the zirconia reinforced lithium silicate ceramic. Optical properties and surface roughness of the chosen ceramic materials were affected by thermocycling, surface treatments and microstructural differences. The least affected of the ceramics was the lithium disilicate ceramic heat-pressed polished and glazed.

scholarly journals Feldspathic and Lithium Disilicate Onlays with a 2-Year Follow-Up: Split-Mouth Randomized Clinical Trial

2021 ◽  
Vol 32 (2) ◽  
pp. 53-63
Author(s):  
Guilherme de Siqueira Ferreira Anzaloni Saavedra ◽  
João Paulo Mendes Tribst ◽  
Nathália de Carvalho Ramos ◽  
Renata Marques de Melo ◽  
Vinícius Anéas Rodrigues ◽  
...  
Keyword(s):  
Clinical Performance ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Ceramic Materials ◽  
Significant Difference ◽  
Term Trial ◽  
Cad Cam ◽  
Age Range ◽  
Postoperative Sensitivity

Abstract The present study was a prospective, controlled, randomized, clinical short-term trial aiming to evaluate the clinical performance of adhesively luted, lithium disilicate and feldspathic glass-ceramics onlays over a period up to 2 years. A total of 11 patients (7 female, 4 male; age range: 18-60 years, mean age: 39 years) were selected for this study. Each patient received a maximum of two restorations per group in a split-mouth-design. LD: Eleven onlays, performed with lithium disilicate-based ceramic (IPS e.max CAD, Ivoclar Vivadent, Schaan, Liechtenstein), and FP: Eleven onlays, performed with feldspathic ceramic (Vita Mark II, Vita Zanhfabrik, Bad Säckingen). Recalls were performed at 2 weeks (baseline = R1), 1 year (R2) and 2 years (R3) after the cementation by three calibrated blinded independent investigators using mirrors, magnifying eyeglasses, probes and bitewing radiographs. The postoperative sensitivity, secondary caries, marginal integrity, marginal discoloration, color match, surface roughness, tooth integrity, and restoration integrity were evaluated. The Friedman test was used to determine if there was a statistically significant difference in time-to-time comparison of the parameters in the ceramics restorations. A total of 95.4% of the restorations were clinically acceptable at the 2-year recall, without a difference for any evaluation parameter for both ceramic materials. Based on the 2-year data, the CAD-CAM onlays manufactured with feldspathic and lithium-disilicate based ceramics showed similar clinical performance.

scholarly journals Fracture Resistance of New Metal-Free Materials Used for CAD-CAM Fabrication of Partial Posterior Restorations

Medicina ◽  
2020 ◽  
Vol 56 (3) ◽  
pp. 132
Author(s):  
Georgina García-Engra ◽  
Lucia Fernandez-Estevan ◽  
Javier Casas-Terrón ◽  
Antonio Fons-Font ◽  
Pablo Castelo-Baz ◽  
...  
Keyword(s):  
Hybrid Materials ◽  
Fracture Resistance ◽  
Lithium Disilicate ◽  
Lithium Silicate ◽  
Control Group ◽  
Test Machine ◽  
Occlusal Wear ◽  
Significant Difference ◽  
Computer Aided ◽  
Cad Cam

Background and Objectives: To evaluate in vitro the fracture resistance and fracture type of computer-aided design and computer-aided manufacturing (CAD-CAM) materials. Materials and Methods: Discs were fabricated (10 × 1.5 mm) from four test groups (N = 80; N = 20 per group): lithium disilicate (LDS) group (control group): IPS e.max CAD®; zirconium-reinforced lithium silicate (ZRLS) group: VITA SUPRINITY®; polymer-infiltrated ceramic networks (PICN) group: VITA ENAMIC®; resin nanoceramics (RNC) group: LAVA™ ULTIMATE. Each disc was cemented (following the manufacturers’ instructions) onto previously prepared molar dentin. Samples underwent until fracture using a Shimadzu® test machine. The stress suffered by each material was calculated with the Hertzian model, and its behavior was analyzed using the Weibull modulus. Data were analyzed with ANOVA parametric statistical tests. Results: The LDS group obtained higher fracture resistance (4588.6 MPa), followed by the ZRLS group (4476.3 MPa) and PICN group (4014.2 MPa) without statistically significant differences (p < 0.05). Hybrid materials presented lower strength than ceramic materials, the RNC group obtaining the lowest values (3110 MPa) with significant difference (p < 0.001). Groups PICN and RNC showed greater occlusal wear on the restoration surface prior to star-shaped fracture on the surface, while other materials presented radial fracture patterns. Conclusion: The strength of CAD-CAM materials depended on their composition, lithium disilicate being stronger than hybrid materials.

Influence of Different Diameters and Materials of Posts on the Fracture Resistance of Endodontically Treated Teeth

2014 ◽  
Vol 633 ◽  
pp. 286-289
Author(s):  
Li Xian Zhang ◽  
Yu Xiao Liu ◽  
Ya Li Liu ◽  
Qiong Rong
Keyword(s):  
Fracture Resistance ◽  
Resistance Testing ◽  
Fiber Post ◽  
Endodontically Treated Teeth ◽  
Significant Difference ◽  
Group A ◽  
Group B ◽  
Different Diameters ◽  
Group D ◽  
Titanium Post

Objective: To evaluate the fracture resistance of endodontically treated teeth reinforced with cast titanium posts and prefabricated glass-fiber posts with different diameters. Materials and Methods: 50 recently extracted human maxillary central incisors were endodontically treated and randomly divided into 5 groups of 10 specimens each: Group A: 1.35mm diameter of cast titanium post; Group B: 1.5mm diameter of cast titanium post; Group C: 1.375mm diameter of prefabricated fiber post; Group D: 1.5mm diameter of prefabricated fiber post; Group E: resin restoration. All specimens were subjected to fracture resistance testing in a universal testing machine, statistical analysis was performed and the fracture modes were analyzed. Results: The mean fracture resistance of five groups as follows: 404.22±73.92N for group A, 488.17±78.68N for group B, 280.32±45.23N for group C, 317.53±50.87N for group D, 222.76±38.67N for group E. The fracture resistance of restored teeth between group C and group D had no significant difference (P>0.05). The fracture resistance of the rest pairwise group comparisons had significant difference (P<0.05). Most of cast post samples fractured at the root middle or apical portion, while most of the fiber post samples fractured at the root cervical or post fracture, which could be retreated. Conclusion: Human maxillary central incisors restored with cast posts could bear higher fracture load and fiber post could protect the root from fracture preferably.

scholarly journals Fracture behaviors of monolithic lithium disilicate ceramic crowns with different thicknesses

RSC Advances ◽  
2017 ◽  
Vol 7 (41) ◽  
pp. 25542-25548 ◽  
Author(s):  
Tao Yu ◽  
Fu Wang ◽  
Yan Liu ◽  
Tao Wu ◽  
Zaixi Deng ◽  
...  
Keyword(s):  
Fracture Resistance ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Fracture Behaviors ◽  
Ceramic Crowns

The present in vitro study assessed the fracture resistance of monolithic ceramic crowns, made from two lithium disilicate glass ceramics with different thicknesses.

scholarly journals The Effect of Different Surface Treatment Protocols on the Shear Bond Strength to Repressed Lithium Disilicate Glass Ceramics

2021 ◽  
Vol 24 (3) ◽  
Author(s):  
Amr El-Etreby ◽  
Osama AlShanti ◽  
Gihan El-Nagar
Keyword(s):  
Bond Strength ◽  
Surface Treatment ◽  
Glass Ceramic ◽  
Hydrofluoric Acid ◽  
Shear Bond Strength ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Resin Cement ◽  
Treatment Protocols ◽  
X Ray

Objective: The present study aimed to evaluate the effect of repressing and different surface treatment protocols on the shear bond strength of lithium disilicate glass-ceramics. Material and Methods: A total of 52 lithium disilicate glass-ceramic discs (IPS emax Press, Ivoclar Vivadent) were fabricated using the heat-press technique. The discs were divided into two groups; group (P): discs fabricated from new e.max ingots (n=26), group (R): discs fabricated from reused e.max buttons (n=26). Each group was subdivided into subgroup (E): discs were etched with hydrofluoric acid (9.5%) (n=13), subgroup (S): discs were air-abraded with 110 µm alumina particles. All specimens were subjected to X-ray Diffraction analysis, Scanning Electron Microscope, Energy Dispersive X-Ray, Thermo-Cycling, and Shear Bond Strength Testing. Results: Repressed Etched subgroup (RE) recorded the statistically highest shear bond strength value, followed by the Pressed Etched subgroup (PE), while the statistically lowest shear bond strength value was recorded for the Pressed Air-Abraded subgroup (PS) and Repressed Air-Abraded subgroup (RS). Conclusion: Repressing the leftover buttons for the construction of new lithium disilicate glass-ceramic restorations has no adverse effect on the bond strength of the resin cement to the ceramic. Hydrofluoric acid surface treatment improves the shear bond strength and durability of resin cement bond to both pressed and repressed lithium disilicate glass-ceramic. Air-abrasion cannot be considered as a reliable surface treatment when bonding to lithium disilicate glass-ceramics. Keywords Heat pressed; Lithium disilicate glass-ceramics; Repressing; Shear bond strength; Surface treatment.

Sign in / Sign up

Export Citation Format

Share Document