Optical properties and color stability of a translucent zirconia: effects of finishing after grinding.

This study evaluated the effect of grinding and finishing treatments (polishing or glaze) on the color stability, translucency and opalescence of a translucent zirconia (3Y-TZP) after immersion in red wine. Discs (Ø= 12 mm; thickness 0.8 mm) of 3Y-TZP (Zenostar T, Ivoclar AG) were randomly allocated (n= 8) according to the surface treatment factor: Ctrl - as-sintered; Gr - grinding with diamond bur #4219; Gr + Pol - grinding followed by polishing; Gr + Gl - grinding followed by glaze.

Effect of ZrO2 paste, surface treatments, and storage on Weibull characteristics and resin bond strength to zirconia.

The objective is to evaluate the effect of different surface treatments and storage on the shear strength of ultratranslucent zirconia. 36 blocks of ultra-translucent zirconia were fabricated (7x7x2mm) and sintered. Then, divided into 12 groups according to the "surface treatment" (C -Primer; Al -Sandblasting with Al2O3 + Primer; Si -Silicate + Primer; Gl -Glaze + HF + Primer; Z -Zirlink; Zp -Zirlink + Primer) and "storage" factors (ST-with 150 days/37º and without).

Tooth discoloration induced by endodontic sealers and cervical limit: 1-year in vitro evaluation.

This laboratory study aimed to evaluate the influence of endodontic sealer and cervical limit of root filling on the discoloration of root canal treated teeth. Bovine incisors were randomly distributed into six experimental groups and control (n=21/group), according to the endodontic sealer used [AH Plus (AP); MTA Fillapex (MF) and Sealer Plus BC (SPB)] and the cervical limit of root filling [dental cervix (DC) or 2 mm in apical direction (2mm-AD)]. Tooth discoloration (ΔE) was evaluated by a digital spectrophotometer using the CIED2000 method.

Advanced lithium disilicate: A comparative evaluation of translucency and fatigue failure load to other ceramics for monolithic restorations.

The aim of this in vitro study was to evaluate the surface roughness, translucency, fatigue failure load (FFL), and number of cycles for fatigue failure (CFF) of a recently released lithia-based material called advanced lithium disilicate and three other ceramics indicated for monolithic restorations. First, ALD (advanced lithium disilicate, CEREC Tessera, Dentsply Sirona), LD (lithium disilicate, IPS e. max CAD, Ivoclar), LS (lithium silicate-disilicate, Suprinity, Vita Zahnfabrik), and 4Y-PSZ (Yttria-stabilized zirconia, IPS e.

The loss of resin cement adhesion to ceramic influences the fatigue behavior of bonded lithium disilicate restorations.

When partial and/or non-retentive preparation, such as those for occlusal veneers, is indicated, a proper and stable adhesion is essential. Therefore, the aim of this in vitro study was to evaluate the effect of loss of adhesion in different regions of the bonding interface on the fatigue behavior of simplified lithium disilicate restorations. For this, lithium disilicate (IPS e.

Surface properties and flexural fatigue strength of an advanced lithium disilicate.

The aim of this study was to evaluate the surface properties and fatigue mechanical behavior of an advanced lithium disilicate ceramic in comparison to lithium disilicate and zirconia. First, discs (n = 15, diameter = 13.5 mm and thickness = 1.

Resin cement coating reverts the machining damage on the flexural fatigue strength of lithium disilicate glass-ceramic.

This study evaluated the effect of resin cement coating with high and low viscosities on the flexural fatigue strength of machined lithium disilicate glass-ceramic. Discs (IPS e.max CAD; Ivoclar Vivadent) were prepared and divided according to the surface condition (machining [M]-CEREC inLab; and polishing [P]-laboratory procedures), resin cement coating (with or without), and cement viscosity (high [H] and low [L]).

Adhesive application after ceramic surface treatment is detrimental to load-bearing capacity under fatigue of a lithium disilicate glass-ceramic.

Objective: To evaluate whether an adhesive application after surface treatment on a lithium disilicate ceramic (LD) has an influence on its load-bearing capacity under fatigue.

Methods: LD discs (Ø= 10 mm; thickness= 1 mm) were allocated into 8 groups (n= 15), considering 3 factors: "ceramic surface treatment" - HF: hydrofluoric acid + universal primer application; or MEP: single-component ceramic primer; "adhesive application" - with or without; and "aging protocol" - baseline: 24 h to 7 days; or aging: 180 days of storage + 25,000 thermal cycles. The LD discs were adhesively bonded to glass fiber-reinforced epoxy resin discs (Ø= 10 mm; thickness= 2 mm) and stored according to the condition and each group.

Biaxial flexure strength and physicochemical characterization of a CAD/CAM lithium disilicate ceramic: effect of etching time, silane, and adhesive applications.

Objective: To evaluate the effect of different acid etching time and bonding agent (silane and/or adhesive system) on biaxial flexural strength and physico-chemical properties of a lithium disilicate ceramic.

Material And Methods: One hundred twenty ceramic discs were made and divided into 8 groups (n = 15) according to factors "etching time" (20 and 120 s) with hydrofluoric acid (HF) and "bonding agent" (C, no bonding agent; S, silane, A, adhesive; and SA, silane + adhesive). After surface treatment, a resin cement layer was applied to the surface and all specimens were subjected to biaxial flexural strength (BFS) test with treated surfaces loaded in tension (1 mm/min).

Influence of testing environment on static fatigue behavior of a glass and a polycrystalline ceramic.

It aims on evaluate the effect of the test environment on static fatigue behavior of lithium disilicate-based (LD), and yttrium oxide-stabilized zirconia (YSZ) ceramics. Specimens of LD (IPS e.max CAD, Ivoclar Vivadent) and YSZ (IPS e.

Residual stresses explaining clinical fractures of bilayer zirconia and lithium disilicate crowns: A VFEM study.

Objective: To understand the stress development in porcelain-veneered zirconia (PVZ) and porcelain-veneered lithium disilicate (PVLD) crowns with different veneer/core thickness ratios and cooling rates. To provide design guidelines for better performing bilayer restorations with the aid of Viscoelastic Finite Element Method (VFEM).

Methods: The VFEM was validated by comparing the predicted residual stresses with experimental measurements.

Extended glaze firings for porcelain-veneered zirconia: Effects on the mechanical and optical behavior.

Objective: This study evaluated the effect of dwell time (conventional or extended) and cooling protocol (fast or slow) of self-glaze firings on the mechanical (flexural strength and crack propagation) and optical (color and translucency) properties of a porcelain-veneered zirconia system.

Methods: Bilayer disc-shaped samples were prepared (Vita VM9 + In-Ceram YZ) and divided according to the final thermal treatment: glaze firing followed by slow cooling (furnace opening at 200 °C) (G-S) or fast cooling (furnace opening at 600 °C) (G-F, manufacturer-recommended protocol), extended glaze firing (15 min of dwell time) followed by slow cooling (EG-S) or fast cooling (EG-F), or no thermal treatment (CTRL). Porcelain roughness (Ra and Rz) was measured before and after glaze firings.

Effect of milling, fitting adjustments, and hydrofluoric acid etching on the strength and roughness of CAD-CAM glass-ceramics: A systematic review and meta-analysis.

Statement Of Problem: Whether procedures performed before the cementation of computer-aided design and computer-aided manufacturing (CAD-CAM) glass-ceramic restorations, including milling, fitting adjustment, and hydrofluoric acid etching introduce defects on the ceramic surface that affect the mechanical and surface properties is unclear.

Purpose: A systematic review and meta-analysis were conducted to assess the effect of milling, fitting adjustments, and hydrofluoric acid etching (HF) on the flexural strength and roughness (Ra) of CAD-CAM glass-ceramics.

Material And Methods: Literature searches were performed up to June 2020 in the PubMed/MEDLINE, Web of Science, and Scopus databases, with no publication year or language limits.

Step-stress vs. staircase fatigue tests to evaluate the effect of intaglio adjustment on the fatigue behavior of simplified lithium disilicate glass-ceramic restorations.

The aim of the study was to compare the outcomes for the fatigue mechanical behavior of bonded simplified lithium disilicate restorations, with and without an internal adjustment by grinding with diamond bur in running two fatigue tests: Staircase and Step-stress testing approaches. Ceramic discs (IPS e.max CAD) were prepared (Ø = 10 mm; thickness = 1.

Effect of resin cement space on the fatigue behavior of bonded CAD/CAM leucite ceramic crowns.

This study evaluated the influence of occlusal resin cement space on the fatigue performance of bonded-leucite crowns to a dentin-analogue material. Leucite anatomical crowns were adhesively cemented to dentin-like preparations having distinct occlusal cement space (50, 100 and 300 μm) (n = 18), and subjected to step-stress fatigue testing (150 N - 350 N; step-size: 25 N; 20,000 cycles/step; 20 Hz). Fatigue data (load and number of cycles for failure) were analyzed using Kaplan-Meier and Mantel-Cox (log-rank) tests (p <0.

High load frequency at 20Hz: Its effects on the fatigue behavior of a leucite-reinforced glass-ceramic.

Considering the long time spent in low frequency cyclic fatigue tests, this study aimed to evaluate the influence of loading frequency (2 Hz and 20 Hz) on the flexural fatigue strength (FFS) and on the time and number of cycles to failure of a leucite-reinforced glass-ceramic. Disc-shaped specimens were produced using leucite-reinforced glass-ceramic CAD/CAM blocks (IPS Empress CAD), according to ISO 6872/2015. Two fatigue tests were performed.

Grinding the intaglio surface of yttria partially- and fully-stabilized zirconia polycrystals restorations: Effect on their fatigue behavior.

This study evaluated the effects of diamond bur grinding the intaglio surface of second (yttria partially-stabilized zirconia polycrystals, PSZ) and third-generation zirconia (fully-stabilized zirconia polycrystals, FSZ) adhesively cemented to dentin analogue substrate on the fatigue failure load, cycle number until failure, surface micromorphology and phase transformation. Disc-shaped specimens were produced from second (Katana ML-HT, Kuraray) and third-generation zirconia (Katana STML, Kuraray) and randomly allocated (n = 15) into two groups according to the intaglio surface treatment: Control - Ctrl (without grinding); Grinding - Gr (grinding at the center of the intaglio surface). The ceramic discs were adhesively cemented (Multilink Automix System) onto dentin analogue discs.

Do thermal treatments affect the mechanical behavior of porcelain-veneered zirconia? A systematic review and meta-analysis.

Objectives: A systematic review of in vitro studies was conducted to assess the effect of thermal treatments on flexural strength or critical load to failure of porcelain-veneered zirconia (PVZ).

Sources: Literature searches were performed up to June 2018 in PubMed/MEDLINE, Scopus and Web of Science databases, with no publication year or language limits.

Data: From 393 relevant studies, 21 were selected for full-text analysis, from which 7 failed to meet the inclusion criteria.

File-splitting multilayer vs monolithic Y-TZP: Fatigue flexural strength and loading stresses by finite element analysis.

Objective: To compare file-splitting multilayer (fused and cemented) with monolithic Y-TZP on the fatigue flexural strength and finite element analysis (FEA) stresses. Additionally, to verify the effect of the material under tension in multilayer Y-TZP.

Methods: Disc-shaped (diameter: 14.

The effect of extended glaze firing on the flexural fatigue strength of hard-machined ceramics.

Statement Of Problem: It is unclear whether an extended glaze firing could improve the long-term mechanical performance of densely sintered CAD-CAM ceramics.

Purpose: The purpose of this in vitro study was to analyze the effect of an extended glaze firing on the flexural fatigue strength (FFS) of densely sintered milled (hard-machined) leucite-based (LEU) and lithium disilicate-based (DIS) ceramics.

Material And Methods: Disks were machined from ceramic blocks and divided into 6 groups (n=20) according to the material, LEU or DIS, and to the applied glaze firing: manufacturer-recommended glaze (G group), extended glaze (EG group), and control/no firing (C group).

Internal adjustments decrease the fatigue failure load of bonded simplified lithium disilicate restorations.

Objective: To investigate the effect of intaglio surface adjustment of simplified lithium disilicate ceramic restorations adhesively cemented to a dentin-like material on its fatigue behavior.

Methods: Ceramic discs (IPS e.max CAD) were prepared and an in-Lab simulation of machining roughness was performed by grinding with SiC paper (#60).

Does veneering technique affect the flexural strength or load-to-failure of bilayer Y-TZP? A systematic review and meta-analysis.

Statement Of Problem: Causes of failures of bilayer yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) restorations include the processing technique and the properties of the veneer ceramic. The effect of the veneering method on the mechanical behavior of veneered Y-TZP remains unclear.

Purpose: The purpose of this systematic review was to assess the effect of the veneering method on the flexural strength and failure load of bilayer Y-TZP.

Impact of machining on the flexural fatigue strength of glass and polycrystalline CAD/CAM ceramics.

Objectives: To assess the effect of machining on the flexural fatigue strength and on the surface roughness of different computer-aided design, computer-aided manufacturing (CAD/CAM) ceramics by comparing machined and polished after machining specimens.

Methods: Disc-shaped specimens of yttria-stabilized polycrystalline tetragonal zirconia (Y-TZP), leucite-, and lithium disilicate-based glass ceramics were prepared by CAD/CAM machining, and divided into two groups: machining (M) and machining followed by polishing (MP). The surface roughness was measured and the flexural fatigue strength was evaluated by the step-test method (n=20).

Fatigue failure load of feldspathic ceramic crowns after hydrofluoric acid etching at different concentrations.

Statement Of Problem: Hydrofluoric acid etching modifies the cementation surface of ceramic restorations, which is the same surface where failure is initiated. Information regarding the influence of hydrofluoric acid etching on the cyclic loads to failure of ceramic crowns is lacking.

Purpose: The purpose of this in vitro study was to evaluate the influence of different hydrofluoric acid concentrations on the fatigue failure loads of feldspathic ceramic crowns.

Color stability of ceramic laminate veneers cemented with light-polymerizing and dual-polymerizing luting agent: A split-mouth randomized clinical trial.

Statement Of Problem: The color stability of luting agents influences the esthetics of ceramic laminate veneers. Clinical studies that have evaluated the color changes of veneers cemented to enamel with light- and dual-polymerizing resin cement are lacking.

Purpose: The purpose of this split-mouth randomized clinical trial was to evaluate the color change and marginal discoloration of dual- and light-polymerizing cement used for cementation of ceramic laminate veneers.