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Petra C Guess - One of the best experts on this subject based on the ideXlab platform.
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load bearing properties of minimal invasive monolithic Lithium Disilicate and zirconia occlusal onlays finite element and theoretical analyses
Dental Materials, 2013Co-Authors: Petra C Guess, Yu ZhangAbstract:Abstract Objective The aim of this study was to test the hypothesis that monolithic Lithium Disilicate glass-ceramic occlusal onlay can exhibit a load-bearing capacity that approaches monolithic zirconia, due to a smaller elastic modulus mismatch between the Lithium Disilicate and its supporting tooth structure relative to zirconia. Methods Ceramic occlusal onlays of various thicknesses cemented to either enamel or dentin were considered. Occlusal load was applied through an enamel-like deformable indenter or a control rigid indenter. Flexural tensile stress at the ceramic intaglio (cementation) surface—a cause for bulk fracture of occlusal onlays—was rigorously analyzed using finite element analysis and classical plate-on-foundation theory. Results When bonded to enamel (supported by dentin), the load-bearing capacity of Lithium Disilicate can approach 75% of that of zirconia, despite the flexural strength of Lithium Disilicate (400 MPa) being merely 40% of zirconia (1000 MPa). When bonded to dentin (with the enamel completely removed), the load-bearing capacity of Lithium Disilicate is about 57% of zirconia, still significantly higher than the anticipated value based on its strength. Both ceramics show slightly higher load-bearing capacity when loaded with a deformable indenter (enamel, glass-ceramic, or porcelain) rather than a rigid indenter. Significance When supported by enamel, the load-bearing property of minimally invasive Lithium Disilicate occlusal onlays (0.6–1.4 mm thick) can exceed 70% of that of zirconia. Additionally, a relatively weak dependence of fracture load on restoration thickness indicates that a 1.2 mm thin Lithium Disilicate onlay can be as fracture resistant as its 1.6 mm counterpart.
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monolithic and bi layer cad cam Lithium Disilicate versus metal ceramic fixed dental prostheses comparison of fracture loads and failure modes after fatigue
Clinical Oral Investigations, 2013Co-Authors: Stefan Schultheis, Joerg R Strub, Thomas A Gerds, Petra C GuessAbstract:The authors analyzed the effect of fatigue on the survival rate and fracture load of monolithic and bi-layer CAD/CAM Lithium–Disilicate posterior three-unit fixed dental prostheses (FDPs) in comparison to the metal–ceramic gold standard. The authors divided 96 human premolars and molars into three equal groups. Lithium–Disilicate ceramic (IPS-e.max-CAD) was milled with the CEREC-3-system in full-anatomic FDP dimensions (monolithic: M-LiCAD) or as framework (Bi-layer: BL-LiCAD) with subsequent hand-layer veneering. Metal–ceramic FDPs (MC) served as control. Single-load-to-failure tests were performed before and after mouth-motion fatigue. No fracture failures occurred during fatigue. Median fracture loads in [N], before and after fatigue were, respectively, as follows: M-LiCAD, 1,298/1,900; BL-LiCAD, 817/699; MC, 1,966/1,818. M-LiCAD and MC FPDs revealed comparable fracture loads and were both significantly higher than BL-LiCAD. M-LiCAD and BL-LiCAD both failed from core/veneer bulk fracture within the connector area. MC failures were limited to ceramic veneer fractures exposing the metal core. Fatigue had no significant effect on any group. Posterior monolithic CAD/CAM fabricated Lithium–Disilicate FPDs were shown to be fracture resistant with failure load results comparable to the metal–ceramic gold standard. Clinical investigations are needed to confirm these promising laboratory results. Monolithic CAD/CAM fabricated Lithium–Disilicate FDPs appeared to be a reliable treatment alternative for the posterior load-bearing area, whereas FDPs in bi-layer configuration were susceptible to low load fracture failure.
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monolithic and bi layer cad cam Lithium Disilicate versus metal ceramic fixed dental prostheses comparison of fracture loads and failure modes after fatigue
Clinical Oral Investigations, 2013Co-Authors: Stefan Schultheis, Joerg R Strub, Thomas A Gerds, Petra C GuessAbstract:Objectives The authors analyzed the effect of fatigue on the survival rate and fracture load of monolithic and bi-layer CAD/CAM Lithium–Disilicate posterior three-unit fixed dental prostheses (FDPs) in comparison to the metal–ceramic gold standard.
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monolithic cad cam Lithium Disilicate versus veneered y tzp crowns comparison of failure modes and reliability after fatigue
International Journal of Prosthodontics, 2010Co-Authors: Petra C Guess, Ricardo Alexandre Zavanelli, Nelson R F A Silva, Estevam A Bonfante, Paulo G Coelho, Van P ThompsonAbstract:PURPOSE The aim of this research was to evaluate the fatigue behavior and reliability of monolithic computer-aided design/computer-assisted manufacture (CAD/CAM) Lithium Disilicate and hand-layer-veneered zirconia all-ceramic crowns. MATERIALS AND METHODS A CAD-based mandibular molar crown preparation, fabricated using rapid prototyping, served as the master die. Fully anatomically shaped monolithic Lithium Disilicate crowns (IPS e.max CAD, n = 19) and hand-layer-veneered zirconia-based crowns (IPS e.max ZirCAD/Ceram, n = 21) were designed and milled using a CAD/CAM system. Crowns were cemented on aged dentinlike composite dies with resin cement. Crowns were exposed to mouth-motion fatigue by sliding a WC-indenter (r = 3.18 mm) 0.7 mm lingually down the distobuccal cusp using three different step-stress profiles until failure occurred. Failure was designated as a large chip or fracture through the crown. If no failures occurred at high loads (> 900 N), the test method was changed to staircase r ratio fatigue. Stress level probability curves and reliability were calculated. RESULTS Hand-layer-veneered zirconia crowns revealed veneer chipping and had a reliability of < 0.01 (0.03 to 0.00, two-sided 90% confidence bounds) for a mission of 100,000 cycles and a 200-N load. None of the fully anatomically shaped CAD/CAM-fabricated monolithic Lithium Disilicate crowns failed during step-stress mouth-motion fatigue (180,000 cycles, 900 N). CAD/CAM Lithium Disilicate crowns also survived r ratio fatigue (1,000,000 cycles, 100 to 1,000 N). There appears to be a threshold for damage/bulk fracture for the Lithium Disilicate ceramic in the range of 1,100 to 1,200 N. CONCLUSION Based on present fatigue findings, the application of CAD/CAM Lithium Disilicate ceramic in a monolithic/fully anatomical configuration resulted in fatigue-resistant crowns, whereas hand-layer-veneered zirconia crowns revealed a high susceptibility to mouth-motion cyclic loading with early veneer failures.
Stefan Schultheis - One of the best experts on this subject based on the ideXlab platform.
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monolithic and bi layer cad cam Lithium Disilicate versus metal ceramic fixed dental prostheses comparison of fracture loads and failure modes after fatigue
Clinical Oral Investigations, 2013Co-Authors: Stefan Schultheis, Joerg R Strub, Thomas A Gerds, Petra C GuessAbstract:The authors analyzed the effect of fatigue on the survival rate and fracture load of monolithic and bi-layer CAD/CAM Lithium–Disilicate posterior three-unit fixed dental prostheses (FDPs) in comparison to the metal–ceramic gold standard. The authors divided 96 human premolars and molars into three equal groups. Lithium–Disilicate ceramic (IPS-e.max-CAD) was milled with the CEREC-3-system in full-anatomic FDP dimensions (monolithic: M-LiCAD) or as framework (Bi-layer: BL-LiCAD) with subsequent hand-layer veneering. Metal–ceramic FDPs (MC) served as control. Single-load-to-failure tests were performed before and after mouth-motion fatigue. No fracture failures occurred during fatigue. Median fracture loads in [N], before and after fatigue were, respectively, as follows: M-LiCAD, 1,298/1,900; BL-LiCAD, 817/699; MC, 1,966/1,818. M-LiCAD and MC FPDs revealed comparable fracture loads and were both significantly higher than BL-LiCAD. M-LiCAD and BL-LiCAD both failed from core/veneer bulk fracture within the connector area. MC failures were limited to ceramic veneer fractures exposing the metal core. Fatigue had no significant effect on any group. Posterior monolithic CAD/CAM fabricated Lithium–Disilicate FPDs were shown to be fracture resistant with failure load results comparable to the metal–ceramic gold standard. Clinical investigations are needed to confirm these promising laboratory results. Monolithic CAD/CAM fabricated Lithium–Disilicate FDPs appeared to be a reliable treatment alternative for the posterior load-bearing area, whereas FDPs in bi-layer configuration were susceptible to low load fracture failure.
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monolithic and bi layer cad cam Lithium Disilicate versus metal ceramic fixed dental prostheses comparison of fracture loads and failure modes after fatigue
Clinical Oral Investigations, 2013Co-Authors: Stefan Schultheis, Joerg R Strub, Thomas A Gerds, Petra C GuessAbstract:Objectives The authors analyzed the effect of fatigue on the survival rate and fracture load of monolithic and bi-layer CAD/CAM Lithium–Disilicate posterior three-unit fixed dental prostheses (FDPs) in comparison to the metal–ceramic gold standard.
Matthias Kern - One of the best experts on this subject based on the ideXlab platform.
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effect of fatigue loading on the fracture strength and failure mode of Lithium Disilicate and zirconia implant abutments
Clinical Oral Implants Research, 2018Co-Authors: Adham Elsayed, Sebastian Wille, Majed Alakhali, Matthias KernAbstract:Objective The aim of this study was to test five types of implant restorations using titanium, zirconia and Lithium Disilicate abutments after being subjected to long-term fatigue loading. Materials and methods Forty single-tooth implant restorations were assembled on titanium implants (FairTwo; FairImplant). The restorations differed only in the type of abutment used and were divided into five groups [Ti: titanium; Zr: zirconia with no metal base; ZrT: zirconia with titanium base; LaT: Lithium Disilicate abutment with titanium base; and LcT: Lithium Disilicate hybrid-abutment–crown with titanium base]. Specimens were subjected to dynamic load of 49 N up to 1,200,000 cycles using a dual-axis chewing simulator (Kausimulator; Willytech). The surviving specimens were subjected to quasi-static loading using a universal testing machine (Z010; Zwick) until the implant–abutment connection failed. The values of force (N) at which fracture or plastic deformation of the restoration occurred were calculated and the rate of deformation was analyzed. The data was then analyzed using Mann–Whitney tests. Results Groups Ti, ZrT, LaT and LcT withstood 1,200,000 fatigue load cycles and higher forces than physiological occlusal forces without fracture or debonding of the ceramic suprastructure. In group Zr, some specimen did not survive the chewing simulation and this group showed the lowest resistance to failure with a median of 198 N. Conclusions Within the limitations of this study, it could be concluded that Lithium Disilicate abutments and hybrid-abutment–crowns show promising durability and strength after long-term dynamic loading. The use of titanium base enhances the strength of the zirconia abutments.
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fracture strength of Lithium Disilicate crowns compared to polymer infiltrated ceramic network and zirconia reinforced Lithium silicate crowns
Journal of The Mechanical Behavior of Biomedical Materials, 2017Co-Authors: Kim Sieper, Sebastian Wille, Matthias KernAbstract:Abstract Objectives The aim of this study was to evaluate the fracture strength of crowns made from current CAD/CAM materials. In addition the influence of crown thickness and chewing simulation on the fracture strength was evaluated. Methods Crowns were fabricated from Lithium Disilicate, zirconia reinforced Lithium silicate (ZLS-ceramic) and a polymer-infiltrated ceramic-network (PICN) with an occlusal thickness of 1.0 mm or 1.5 mm, respectively (n=16). Crowns were cemented on composite dies. Subgroups of eight specimens were loaded with 5 kg in a chewing simulator for 1,200,000 cycles with thermal cycling. Finally, all specimens were loaded until fracture in a universal testing machine. Three-way ANOVA was used to detect statistical interaction. Differences regarding the materials were tested with two-way ANOVA, following one-way ANOVA and a post-hoc Tukey's-Test. Results All crowns survived the chewing simulation. The material had a significant influence on the fracture resistance (p≤0.05). Lithium Disilicate achieved the highest values of fracture strength in almost all groups followed by ZLS-ceramic. PICN achieved the lowest values of fracture strength. Chewing simulation increased the fracture strength of thick Lithium Disilicate crown significantly. Greater occlusal thickness of all crown materials resulted in higher crown fracture strength before chewing simulation. After chewing simulation occlusal thickness of Lithium Disilicate and PICN crowns had no significant influence on the fracture strength. Conclusions All crowns revealed fracture strength above the clinically expected loading forces. Therefore the durability of the tested CAD/CAM materials seems promising also in an occlusal thickness of 1.0 mm.
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tensile bond strength of different universal adhesive systems to Lithium Disilicate ceramic
Journal of the American Dental Association, 2015Co-Authors: Nicole Passia, Frank Lehmann, Sandra Freitagwolf, Matthias KernAbstract:Abstract Background Today, many adhesive systems with different coupling agents for tooth structures and restorative materials are available. The purpose of this in vitro study was to evaluate the tensile bond strength (TBS) of different universal adhesive systems to etched Lithium Disilicate ceramic. Methods The authors etched and bonded 96 disk-like Lithium Disilicate ceramic specimens (IPS e.max CAD, Ivoclar Vivadent) with 4 different adhesive bonding systems to Plexiglas tubes filled with a composite resin. The authors stored the specimens in water at 37°C for 3 days without thermal cycling or for 30 or 150 days with 7,500 or 37,500 thermal cycles between 5°C and 55°C, respectively. Then, all specimens underwent TBS testing. The authors performed statistical analysis by using Kruskal-Wallis and Wilcoxon tests with a Bonferroni-Holm correction for multiple testing. Results Initially, all adhesive systems exhibited considerable TBS, but some showed a significant reduction after 30 days of storage. After 3, 30, and 150 days, the Monobond Plus and Multilink Automix (Ivoclar Vivadent) silane-containing adhesive system showed significantly higher bond strengths to Lithium Disilicate ceramic than did the other universal adhesive systems, some of which do not contain silanes. Conclusions The bond strength to Lithium Disilicate ceramic is affected significantly by the adhesive bonding system used. Practical Implications Universal adhesive systems that do not contain a silane should be avoided for bonding Lithium Disilicate ceramic restorations because of their inferior bond strength.
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ten year outcome of three unit fixed dental prostheses made from monolithic Lithium Disilicate ceramic
Journal of the American Dental Association, 2012Co-Authors: Matthias Kern, Martin Sasse, Stefan WolfartAbstract:ABSTRACT Background The authors conducted a prospective study to evaluate the long-term outcome of crown-retained fixed dental prostheses (FDPs) made from monolithic Lithium Disilicate ceramic (IPS e.max Press, Ivoclar Vivadent, Schaan, Liechtenstein). Methods Faculty dentists at the Department of Prosthodontics, Propaedeutics and Dental Materials, School of Dentistry, Christian-Albrechts University at Kiel, Germany, placed 36 three-unit FDPs in 28 patients to replace six anterior and 30 posterior teeth. The proximal connector size (height and width) was 4 × 3 millimeters for anterior FDPs and 4 × 4 mm for posterior FDPs. FDPs were cemented either conventionally with glass ionomer cement (n = 19) or adhesively with resin-based composite (n = 17). Patients made annual recall visits. Results The mean (standard deviation) observation period was 121 (12.8) months. FDPs' survival rate (survival being defined as remaining in place either with or without complications) was 100 percent after five years and 87.9 percent after 10 years, and their success rate (success being defined as remaining unchanged and free of complications) was 91.1 percent after five years and 69.8 percent after 10 years. The cementation method did not affect the outcome. Conclusion Three-unit FDPs made from monolithic Lithium Disilicate ceramic showed five- and 10-year survival and success rates that were similar to those of conventional metal-ceramic FDPs. Clinical Implications If the manufacturer's recommendations are followed, three-unit FDPs made from monolithic Lithium Disilicate ceramic may be a safe alternative to metal-ceramic FDPs regardless of the cementation method used.
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the effect of storage conditions contamination modes and cleaning procedures on the resin bond strength to Lithium Disilicate ceramic
Journal of Adhesive Dentistry, 2009Co-Authors: Karsten Klosa, Frank Lehmann, Stefan Wolfart, Hansjurgen Wenz, Matthias KernAbstract:Purpose The purpose of this in-vitro study was to evaluate the resin bond strength to pre-etched Lithium Disilicate ceramic using different cleaning methods after two contamination modes (saliva or saliva and silicone). Materials and methods Plexiglas tubes filled with composite resin (MultiCore Flow) were bonded to etched and silanized ceramic disks made of Lithium Disilicate ceramic (IPS e.max Press) using a luting resin (Multilink Automix). Either etched or unetched ceramic surfaces were contaminated with saliva or with saliva followed by a disclosing silicone. Groups of 16 specimens each were bonded after pretreatment using 4 surface cleaning agents (37% phosphoric acid, 5% hydrofluoric acid, 96% isopropanol, air polishing device with sodium bicarbonate) in different combinations. Before measuring tensile bond strength, specimens were stored for 3 or 150 days with thermocycling. Results After 150 days of storage, etching of saliva-contaminated surfaces with 5% hydrofluoric acid and/or 37% phosphoric acid provided statistically significantly higher bond strengths (37.9 to 49.5 MPa) than the other cleaning methods (1.7 to 15.5 MPa). After saliva and silicone contamination, etching with 5% hydrofluoric acid provided statistically significantly higher bond strengths (44.5 to 50.3 MPa) than all other cleaning methods (0.3 to 13.5 MPa). Conclusion Ceramic cleaning methods after try-in procedures have a significant influence on the resin bond strength and are dependent on the type of contamination. Re-etching Lithium Disilicate ceramic with 5% hydrofluoric acid is most effective in removing contamination with saliva and/or a silicone disclosing medium.
Luiz Felipe Valandro - One of the best experts on this subject based on the ideXlab platform.
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how does hydrofluoric acid etching affect the cyclic load to failure of Lithium Disilicate restorations
Journal of The Mechanical Behavior of Biomedical Materials, 2018Co-Authors: Catina Prochnow, Marco C Bottino, Maite Munhoz Scherer, Andressa Borin Venturini, Gabriel Kalil Rocha Pereira, M P Rippe, Cornelis J Kleverlaan, Luiz Felipe ValandroAbstract:Abstract This study investigated the effect of etching with distinct hydrofluoric (HF) acid concentrations on the cyclic load-to-failure (CLf) of simplified Lithium Disilicate glass-ceramic restorations adhesively cemented to a dentin analogue (n = 20): non-etched/control (CTRL), or etched for 20 s with HF acid at 3% (HF3), 5% (HF5), or 10% (HF10). A silane coating was then applied onto the ceramic surfaces. Fatigue tests followed the staircase approach (initial load= 720 N; step-size= 70 N; 500,000 cycles per sample; 20 Hz) using a hemispheric stainless-steel piston (O= 40 mm) under water. The CLf data were analyzed using Dixon and Mood method. Topographic and fractographic analyses were conducted. CLf (in N) of HF3 (1355 ± 32.0) and HF5 (1335 ± 58.8) groups were the highest and statistically similar; HF10 presented intermediate CLf (1175 ± 132.9), while the non-etched group had the lowest one (965 ± 145.0). Topographical analysis showed that the higher the HF acid concentration, the more pronounced the topographical changes. All failures (radial cracks) started from the inner surface of the ceramic discs. Topographical changes promoted by intermediate HF acid concentrations (3% and 5%) may improve fatigue performance for adhesively-cemented Lithium Disilicate restorations.
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hydrofluoric acid concentrations effect on the cyclic load to failure of machined Lithium Disilicate restorations
Dental Materials, 2018Co-Authors: Thiago A L Burgo, Marco C Bottino, Catina Prochnow, Andressa Borin Venturini, Gabriel Kalil Rocha Pereira, Luis Felipe Guilardi, Cornelis J Kleverlaan, Luiz Felipe ValandroAbstract:Abstract Objectives To evaluate the effects of the etching with different hydrofluoric acid (HF) concentrations on the cyclic load-to-failure ( C L f ) of machined Lithium Disilicate crowns cemented to dentin analogue material. Methods Pairs of dentin analogue prosthetic preparations and Lithium Disilicate ceramic crowns with simplified and standardized designs were machined (n = 18). The preparations were etched with 10% HF (60 s), followed by primer application. The intaglio surface of the ceramic crowns was treated as follows: non-etched (control, CTRL); or etched for 20 s with different HF concentrations — 3% (HF3), or 5% (HF5), or 10% (HF10). A silane coating was then applied onto the treated ceramic surfaces, and they were adhesively cemented to the preparations. To perform the fatigue tests (staircase approach), a hemispheric stainless-steel piston (O = 40 mm) applied cyclic loads in the center of the crowns under water (initial load: 720 N; step-size: 70 N; cycles: 500,000; frequency: 20 Hz). Additionally, topographic, fractographic, and fractal analyses were carried out. The fatigue data were analyzed using the Dixon and Mood method. Results Although the topographic and fractal analyses depicted the action of HF etching altering the superficial complexity and topography, the preponderant topography pattern was established by machining on CAD/CAM. All groups showed similar CLf (in N) (CTRL = 805.00 ± 91.23; HF3 = 781.25 ± 29.87; HF5 = 755.00 ± 154.49; HF10 = 833.75 ± 100.74). Significance Etching with different HF acid concentrations did not promote a deleterious effect on the cyclic load-to-failure of machined Lithium Disilicate crowns.
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fatigue failure load of an adhesively cemented Lithium Disilicate glass ceramic conventional ceramic etching vs etch prime one step primer
Dental Materials, 2018Co-Authors: Maite Munhoz Scherer, Thiago A L Burgo, Catina Prochnow, Andressa Borin Venturini, Gabriel Kalil Rocha Pereira, M P Rippe, Luiz Felipe ValandroAbstract:Abstract Objectives To evaluate the effect of different glass-ceramic surface treatments and aging on the fatigue failure load of a Lithium Disilicate glass-ceramic adhesively cemented to a dentin analogue material. Methods One hundred and twenty (120) disc-shaped Lithium Disilicate specimens (O = 10 mm, thickness = 1.5 mm) were produced and randomly allocated (n = 20) into 6 groups, considering 2 study factors: “surface treatment” in 3 levels (SIL—silane application only; HF5+SIL—5% hydrofluoric acid etching and silane application; MEP aging—storage for 90 days + 12,000 thermal cycles). Ceramic discs were adhesively cemented to discs of a dentin analogue material (O = 10 mm, thickness = 2.0 mm) following the manufacturers’ instructions. The fatigue failure load was determined by the staircase approach (250,000 cycles; 20 Hz; initial load = 1050 N [∼70% of mean load-to-failure]; step size = 52.5 N [5% of initial load]). Micro-morphologic, fractographic, and atomic force microscope analysis were also performed. Fatigue failure load data were evaluated by one-way ANOVA, Bonferroni and t-tests for independent samples. Results HF5+SIL presented higher fatigue failure load in both conditions (baseline and aging); ME&P presented intermediary mean values, while the SIL group presented the worst performance. All groups had a statistically significant decrease in the fatigue performance after aging. Significance Hydrofluoric acid followed by silane application showed the best fatigue performance for an adhesively-cemented Lithium Disilicate ceramic. Aging negatively influenced the fatigue performance for all tested groups.
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fatigue failure load of Lithium Disilicate restorations cemented on a chairside titanium base
Journal of Prosthodontics, 2018Co-Authors: Peerapat Kaweewongprasert, Kamolphob Phasuk, John A Levon, George J Eckert, Sabrina Alves Feitosa, Luiz Felipe Valandro, Marco C Bottino, Dean MortonAbstract:PURPOSE To evaluate the fatigue failure load of distinct Lithium Disilicate restoration designs cemented on a chairside titanium base for maxillary anterior implant-supported restorations. MATERIALS AND METHODS A left-maxillary incisor restoration was virtually designed and sorted into 3 groups: (n = 10/group; CTD: Lithium Disilicate crowns cemented on custom-milled titanium abutments; VMLD: monolithic full-contour Lithium Disilicate crowns cemented on a chairside titanium-base; VCLD: Lithium Disilicate crowns bonded to Lithium Disilicate customized anatomic structures and then cemented onto a chairside titanium base). The chairside titanium base was air-abraded with aluminum oxide particles. Subsequently, the titanium base was steam-cleaned and air-dried. Then a thin coat of a silane agent was applied. The intaglio surface of the ceramic components was treated with 5% hydrofluoric acid (HF) etching gel, followed by silanization, and bonded with a resin cement. The specimens were fatigued at 20 Hz, starting with a 100 N load (5000× load pulses), followed by stepwise loading from 400 N up to 1400 N (200 N increments) at a maximum of 30,000 cycles each. The failure loads, number of cycles, and fracture analysis were recorded. The data were statistically analyzed using one-way ANOVA, followed by pairwise comparisons (p < 0.05). Kaplan-Meier survival plots and Weibull survival analyses were reported. RESULTS For catastrophic fatigue failure load and the total number of cycles for failure, VMLD (1260 N, 175,231 cycles) was significantly higher than VCLD (1080 N, 139,965 cycles) and CDT (1000 N, 133,185 cycles). VMLD had a higher Weibull modulus demonstrating greater structural reliability. CONCLUSION VMLD had the best fatigue failure resistance when compared with the other two groups.
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effect of resin cement type on the microtensile bond strength to Lithium Disilicate ceramic and dentin using different test assemblies
Journal of Adhesive Dentistry, 2013Co-Authors: Susana Maria Salazar Marocho, Mutlu Ozcan, Regina Amaral, Marco Antonio Bottino, Luiz Felipe ValandroAbstract:PURPOSE: This study evaluated the microtensile bond strength (µTBS) of 3 different resin cements to Lithium-Disilicate ceramic using two assemblies: ceramic-cement-ceramic (CCC) and ceramic-cement-dentin (CCD). MATERIALS AND METHODS: The bonding surfaces of Lithium Disilicate ceramic blocks (5 × 5 × 4 mm) (Nblock = 90) were etched with 4% hydrofluoric acid for 20 s and silanized. Flat dentin surfaces of human third molars were conditioned according to the respective manufacturer's specifications for three types of resin cements (ML: Multilink, Ivoclar-Vivadent; PF: Panavia F, Kuraray; SB: Super Bond CB and aging condition (AC - thermocycling 12,000 times + water storage for 150 days). The µTBS bond strength test was performed using a universal testing machine (1 mm/min). After debonding, the substrate and adherent surfaces were analyzed using a scanning electron microscope to categorize the failure types. The data were statistically evaluated using 2-way ANOVA and Tukey's test (5%). RESULTS: While the mean µTBS of CCC assemblies were significantly influenced by the cement type (p 0.05). Without aging (DC), the mean µTBS (MPa) of SB (26.9) and PF (26.9) were significantly higher than ML (18.5) (p 0.05). In both CCC and CCD assemblies, pre-test failures were the least with SB cement. Regardless of the resin cement type employed and storage conditions, adhesive failures ranged between 35.3% and 88.9%, cohesive failures in cement between 2.3% and 35.3%, and cohesive failures in ceramic between 3.3% and 6.8%. CONCLUSION: SB resin cement demonstrated the highest bond strength to a Lithium Disilicate ceramic in both tests assemblies with and without aging conditions.
Thomas A Gerds - One of the best experts on this subject based on the ideXlab platform.
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monolithic and bi layer cad cam Lithium Disilicate versus metal ceramic fixed dental prostheses comparison of fracture loads and failure modes after fatigue
Clinical Oral Investigations, 2013Co-Authors: Stefan Schultheis, Joerg R Strub, Thomas A Gerds, Petra C GuessAbstract:The authors analyzed the effect of fatigue on the survival rate and fracture load of monolithic and bi-layer CAD/CAM Lithium–Disilicate posterior three-unit fixed dental prostheses (FDPs) in comparison to the metal–ceramic gold standard. The authors divided 96 human premolars and molars into three equal groups. Lithium–Disilicate ceramic (IPS-e.max-CAD) was milled with the CEREC-3-system in full-anatomic FDP dimensions (monolithic: M-LiCAD) or as framework (Bi-layer: BL-LiCAD) with subsequent hand-layer veneering. Metal–ceramic FDPs (MC) served as control. Single-load-to-failure tests were performed before and after mouth-motion fatigue. No fracture failures occurred during fatigue. Median fracture loads in [N], before and after fatigue were, respectively, as follows: M-LiCAD, 1,298/1,900; BL-LiCAD, 817/699; MC, 1,966/1,818. M-LiCAD and MC FPDs revealed comparable fracture loads and were both significantly higher than BL-LiCAD. M-LiCAD and BL-LiCAD both failed from core/veneer bulk fracture within the connector area. MC failures were limited to ceramic veneer fractures exposing the metal core. Fatigue had no significant effect on any group. Posterior monolithic CAD/CAM fabricated Lithium–Disilicate FPDs were shown to be fracture resistant with failure load results comparable to the metal–ceramic gold standard. Clinical investigations are needed to confirm these promising laboratory results. Monolithic CAD/CAM fabricated Lithium–Disilicate FDPs appeared to be a reliable treatment alternative for the posterior load-bearing area, whereas FDPs in bi-layer configuration were susceptible to low load fracture failure.
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monolithic and bi layer cad cam Lithium Disilicate versus metal ceramic fixed dental prostheses comparison of fracture loads and failure modes after fatigue
Clinical Oral Investigations, 2013Co-Authors: Stefan Schultheis, Joerg R Strub, Thomas A Gerds, Petra C GuessAbstract:Objectives The authors analyzed the effect of fatigue on the survival rate and fracture load of monolithic and bi-layer CAD/CAM Lithium–Disilicate posterior three-unit fixed dental prostheses (FDPs) in comparison to the metal–ceramic gold standard.