Lubricated Wear of Machinable Lithium Disilicate Glass Ceramic

An experimental investigation was performed to study the wear of a promising dental ceramic, i.e., machinable lithium disilicate glass ceramic, under lubrication conditions, in particular, to examine effects of the surface finish and applied load on wear. Our previous work has shown that a fine finish in a dry condition did not necessarily translate to the lowest wear volume due to changes in the dominant wear mechanisms. This study tested the ceramic specimens with four average surface roughness values of Sa = 143 nm, 217 nm, 353 nm, and 692 nm on a reciprocating sliding friction rig against alumina balls with two applied forces of 5 N and 25 N in a bath of distilled water. Comparing with the results obtained in the dry conditions, this study shows that surface roughness of approximately 200 nm may be suitable for surface preparation of crowns made from the material in the wet and dry wear conditions in the oral environment.

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Effects of surface roughness on the time-dependent wear performance of lithium disilicate glass ceramic for dental applications

Journal of the Mechanical Behavior of Biomedical Materials ◽

10.1016/j.jmbbm.2021.104638 ◽

2021 ◽

pp. 104638

Author(s):

M. Meng ◽

X.S. Wang ◽

K.Y. Li ◽

Z.X. Deng ◽

Z.Z. Zhang ◽

...

Keyword(s):

Surface Roughness ◽

Glass Ceramic ◽

Lithium Disilicate ◽

Time Dependent ◽

Wear Performance ◽

Dental Applications

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

Materials ◽

10.3390/ma13020381 ◽

2020 ◽

Vol 13 (2) ◽

pp. 381 ◽

Cited By ~ 6

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.

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Mechanical Wear and Surface Roughness of Glass and Hybrid Ceramics

Journal of Oral & Dental Health ◽

10.33140/jodh.03.02.16 ◽

2019 ◽

Vol 3 (2) ◽

Keyword(s):

Surface Roughness ◽

Weight Loss ◽

Wear Resistance ◽

Glass Ceramic ◽

High Surface ◽

Lithium Disilicate ◽

Mechanical Wear ◽

Roughness Change ◽

Before And After ◽

Ceramic Blocks

Aim: The purpose of this invitro study was to evaluate wear resistance and surface roughness of two hybrid ceramics in comparison to lithium disilicate glass ceramic before and after mechanical abrasion. Materials and Methods: Thirty samples were divided according to material of construction into three groups, group (1): Lithium disilicate glass ceramic (IPS e.max, n=10), group (2): Resin nanoceramic (Lava Ultimate, n=10), group (3): Polymer infiltrated ceramic (Vita Enamic, n=10). All samples were fabricated out of CAD CAM ceramic blocks, weighed and evaluated for surface roughness before and after mechanical wear. Results: Resin nanoceramic (Lava ultimate), showed significantly low weight loss and surface roughness change after mechanical wear than IPS e.max. The polymer infiltrated ceramic (Vita Enamic) showed significantly high surface roughness than Resin nanoceramic (Lava ultimate), while IPS e.max showed the highest weight loss and surface roughness change. Conclusion: Resin nanoceramics revealed highest mechanical wear resistance contributed by terms of weight loss and surface roughness change, while Lithium disilicate glass ceramic showed the least wear resistance.

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Influence of thermal and pH cycles on surface characteristics lithium disilicate glass-ceramic dental crowns milled with CAD/CAM process

World Journal of Engineering ◽

10.1108/wje-03-2021-0129 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Yajvinder Singh ◽

Vishal Gulati

Keyword(s):

Surface Roughness ◽

Glass Ceramic ◽

Research Work ◽

Surface Hardness ◽

Surface Characteristics ◽

Lithium Disilicate ◽

Content Type ◽

Cad Cam ◽

Group 3 ◽

Group 2

Purpose The paper aims to evaluate the influence of thermo-chemical cycles of oral fluids on the surface attributes (roughness and microhardness) of lithium disilicate glass-ceramic (LDC) crown restorations manufactured with CAD/CAM technology. Design/methodology/approach There have been 24 LDC crowns manufactured using the CAD/CAM process for their respective preparation dies ply methyl methacrylate (PMMA) of mandibular left second premolar tooth (n = 8 each group). The standard procedure was used to glaze 16 crown samples (Groups 2 and 3).Samples of Group 3 were aged with thermal (563°C and 5563°C) and pH (2–14) cycles. All 24 samples were tested with a Profilometer and a Vicker hardness tester was used for their surface roughness and hardness measurement, respectively. Findings In statistical examination on SPSS Statistics 20 (IBM) software, of surface roughness values (Ra) and Vicker hardness values from different groups, Tukey HSD test was executed in one-way ANOVA (a = 0.05). The means Ra for groups were accordingly Group 3 > Group1 > Group 2 (p < 0.001). Similarly, micro-hardness was in order of Group 2 > Group 1 > Group 3 (p < 0.001). Research limitations/implications The research work does not have any limitations. Originality/value Surrounding temperature and pH significantly impact the surface characteristics of lithium disilicate crown restoration. The study also reveals the inverse relationship between surface roughness and surface hardness parameters. The observed results and facts revealed well in agreement with the past research studies.

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Effect of hydrofluoric acid etching duration on the roughness and flexural strength of a lithium disilicate-based glass ceramic

Brazilian Dental Journal ◽

10.1590/s0103-64402011000100008 ◽

2011 ◽

Vol 22 (1) ◽

pp. 45-50 ◽

Cited By ~ 79

Author(s):

Lucas Villaça Zogheib ◽

Alvaro Della Bona ◽

Estevão Tomomitsu Kimpara ◽

John F. Mccabe

Keyword(s):

Surface Roughness ◽

Flexural Strength ◽

Glass Ceramic ◽

Hydrofluoric Acid ◽

Lithium Disilicate ◽

Bending Test ◽

Acid Etching ◽

Etching Time ◽

Control Group ◽

The Mean

The aim of this study was to examine the effect of different acid etching times on the surface roughness and flexural strength of a lithium disilicate-based glass ceramic. Ceramic bar-shaped specimens (16 mm x 2 mm x 2 mm) were produced from ceramic blocks. All specimens were polished and sonically cleaned in distilled water. Specimens were randomly divided into 5 groups (n=15). Group A (control) no treatment. Groups B-E were etched with 4.9% hydrofluoric acid (HF) for 4 different etching periods: 20 s, 60 s, 90 s and 180 s, respectively. Etched surfaces were observed under scanning electron microscopy. Surface profilometry was used to examine the roughness of the etched ceramic surfaces, and the specimens were loaded to failure using a 3-point bending test to determine the flexural strength. Data were analyzed using one-way ANOVA and Tukey's test (?=0.05). All etching periods produced significantly rougher surfaces than the control group (p<0.05). Roughness values increased with the increase of the etching time. The mean flexural strength values were (MPa): A=417 ± 55; B=367 ± 68; C=363 ± 84; D=329 ± 70; and E=314 ± 62. HF etching significantly reduced the mean flexural strength as the etching time increased (p=0.003). In conclusion, the findings of this study showed that the increase of HF etching time affected the surface roughness and the flexural strength of a lithium disilicate-based glass ceramic, confirming the study hypothesis.

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Effect of Surface Preparation with Nd:YAG and Er,Cr:YSGG Lasers on the Repair Bond Strength of Lithium Disilicate Glass Ceramic to a Silorane-based Composite Resin

Journal of Dental Research Dental Clinics Dental Prospects ◽

10.15171/joddd.2018.003 ◽

2018 ◽

Vol 12 (1) ◽

pp. 12-17 ◽

Cited By ~ 4

Author(s):

Mohammad Esmaeel Ebrahimi Chaharom ◽

Fatemeh Pournaghi Azar ◽

Narmin Mohammadi ◽

Rezvan Nasiri

Keyword(s):

Bond Strength ◽

Glass Ceramic ◽

Composite Resin ◽

Surface Preparation ◽

Lithium Disilicate ◽

Effect Of Surface

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Contact Analysis of Tire Tread Rubber on Flat Surface with Microscopic Roughness3

Tire Science and Technology ◽

10.2346/1.2346375 ◽

2006 ◽

Vol 34 (4) ◽

pp. 237-255 ◽

Cited By ~ 2

Author(s):

M. Kuwajima ◽

M. Koishi ◽

J. Sugimura

Keyword(s):

Surface Roughness ◽

Finite Element ◽

Sliding Friction ◽

Tangential Force ◽

Partial Slip ◽

Real Contact Area ◽

Element Analysis ◽

Real Contact ◽

Local Slip ◽

Tread Rubber

Abstract This paper describes experimental and analytical studies of the dependence of tire friction on the surface roughness of pavement. Abrasive papers were adopted as representative of the microscopic surface roughness of pavement surfaces. The rolling∕sliding friction of tire tread rubber against these abrasive papers were measured at low slip velocities. Experimental results indicated that rolling∕sliding frictional characteristics depended on the surface roughness. In order to examine the interfacial phenomena between rubber and the abrasive papers, real contact length, partial slip, and apparent friction coefficient under vertical load and tangential force were analyzed with two-dimensional explicit finite element analysis in which slip-velocity-dependent frictional coefficients were considered. Finite element method results indicated that the sum of real contact area and local partial slip were larger for finer surfaces under the same normal and tangential forces. In addition, the velocity-dependent friction enhanced local slip, where the dependence of local slip on surface roughness was pronounced. It proved that rolling∕sliding friction at low slip ratio was affected by local frictional behavior at microslip regions at asperity contacts.

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Friction Force and Stresses Analysis for Contact of Assembled Details

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.113.334 ◽

2006 ◽

Vol 113 ◽

pp. 334-338

Author(s):

Z. Dreija ◽

O. Liniņš ◽

Fr. Sudnieks ◽

N. Mozga

Keyword(s):

Mechanical Properties ◽

Surface Roughness ◽

Plastic Deformation ◽

Friction Force ◽

Sliding Friction ◽

Friction Model ◽

Contact Interface ◽

Finite Element Program ◽

Elastic Plastic ◽

Element Program

The present work deals with the computation of surface stresses and deformation in the presence of friction. The evaluation of the elastic-plastic contact is analyzed revealing three distinct stages that range from fully elastic through elastic-plastic to fully plastic contact interface. Several factors of sliding friction model are discussed: surface roughness, mechanical properties and contact load and areas that have strong effect on the friction force. The critical interference that marks the transition from elastic to elastic- plastic and plastic deformation is found out and its connection with plasticity index. A finite element program for determination contact analysis of the assembled details and due to details of deformation that arose a normal and tangencial stress is used.

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