Characterization of 3D printed composite for final dental restorations.

Objectives: This study evaluated the mechanical, optical, microstructural, surface, and adhesive behavior of a 3D printing resin comparing it with a machinable resin composite.

Materials And Methods: Specimens of different sizes and shapes were either printed (Vitality, Smart Dent) or machinable (Grandio Blocs, Voco GmbH) resin composites with similar composition were prepared. Surface and mechanical characterization were performed with Knoop hardness, flexural strength (three-point-bending), and elastic modulus tests.

Fatigue and failure mode analyses of glass infiltrated 5Y-PSZ bonded onto dentin analogues.

The purpose of this study was to evaluate the fatigue survival of 5Y-PSZ zirconia infiltrated with an experimental glass and bonded onto dentin analogues. Disc-shaped specimens of a 5Y-PSZ (Katana UTML Kuraray Noritake) were cemented onto dentin analogs (NEMA G10) and divided into four groups (n = 15): Zctrl Group (control, without infiltration); Zglz Group (Glaze, compression surface); Zinf-comp Group (Experimental Glass, compression surface); Zinf-tens Group (Experimental Glass, tension surface). Surface treatments were varied.

Borosilicate glass as a surface finishing alternative for improving the mechanical properties of third-generation zirconia.

Objective: This study evaluated the effect of an experimental borosilicate glass on the mechanical and optical behavior of 5Y-PSZ zirconia and comparing it to commercial glaze and as-sintered.

Methods: Disc-shaped specimens of a 5Y-PSZ (Zpex Smile) were prepared and sintered (1550 °C, 2 h). The zirconia discs were randomly divided according to the surface treatment: as-sintered (C), commercial glaze (G), and experimental borosilicate glass (SL).

Fatigue behavior of multilayer ceramic structures in traditional and reverse layering designs.

Purpose: This study evaluated the fatigue failure load (FFL) and the number of cycles for fatigue failure (CFF) of traditional (porcelain layer up) and reversed (zirconia layer up) designs of porcelain-veneered zirconia samples prepared with heat-pressing or file-splitting techniques.

Materials And Methods: Zirconia discs were prepared and veneered with heat-pressed or machined feldspathic ceramic. The bilayer discs were bonded onto a dentin-analog according to the bilayer technique and sample design: traditional heat-pressing (T-HP), reversed heat-pressing (R-HP), traditional file-splitting with fusion ceramic (T-FC), reversed file-splitting with fusion ceramic R-FC), traditional file-splitting with resin cement (T-RC), and reversed file-splitting with resin cement (R-RC).

Endocrown restorations in premolars: influence of remaining axial walls of tooth structure and restorative materials on fatigue resistance.

Objectives: To evaluate the effect of the remaining tooth structure and different CAD/CAM materials on the fatigue performance and failure mode of endodontically treated premolars restored with endocrowns.

Materials And Methods: Ninety maxillary premolars were endodontically treated and assigned into 6 groups (n = 15) according to the number of remaining axial walls (four, three, and two) and restorative materials (ultra-translucent zirconia 5Y-PSZ [KATANA UTML] and lithium disilicate [IPS e.max-CAD]).

Effect of resin cement elastic modulus on the biaxial flexural strength and structural reliability of an ultra-thin lithium disilicate glass-ceramic material.

Objectives: Photo- and dual-polymerized resin-based luting agent was evaluated for elastic moduli effects on ultra-thin lithium disilicate (LD) glass-ceramic strengthening, structural reliability, and stress distribution.

Materials And Methods: One hundred-sixty LD discs (IPS e.max CAD, Ivoclar/Vivadent) were produced in ultra-thin thicknesses (half with 0.

Effect of Resin Cement at Different Thicknesses on the Fatigue Shear Bond Strength to Leucite Ceramic.

Objectives:  This study was performed to evaluate fatigue survival by shear test in the union of leucite-reinforced feldspathic ceramic using different cement thicknesses.

Materials And Methods:  Leucite-reinforced glass ceramics blocks were sectioned in 2-mm thick slices where resin cylinders were cemented. The samples were distributed in two experimental groups ( = 20) according to the cement thickness (60 and 300 μm).

Determinants of COVID-19 Vaccine Acceptance among Dental Professionals: A Multi-Country Survey.

Purpose: This study sought to investigate the acceptance rate and associated factors of COVID-19 vaccines among dentists and dental students in seven countries.

Material And Methods: A structured questionnaire prepared and guided by the report of the SAGE Working Group on Vaccine Hesitancy was distributed among groups of dentists and dental students in seven countries across four continents.

Results: A total of 1527 subjects (850 dentists and 677 dental students) participated in this survey.

Effect of Porcelain-to-Zirconia Ratio and Bonding Strategy on the Biaxial Flexural Strength and Weibull Characteristics of a Stress-Free Bilayer CAD/CAM Ceramic System.

Purpose: To evaluate the biaxial flexural strength of different porcelain-to-zirconia thickness ratios and bonding strategies of a stress-free bilayer CAD/CAM ceramic system.

Materials And Methods: A total of 60 zirconia discs (diameter: 15 mm; thickness: 0.3 or 0.

Design Equations for Mixed-Mode Fracture of Dental Ceramic-Cement Interfaces Using the Brazil-Nut-Sandwich Test.

Dental interfaces are subject to mixed-mode loading. This study provides practical guidance for determining interfacial fracture toughness of dental ceramic systems. We address interfacial fracture of a composite resin cement sandwiched between two dental ceramic materials.

Fatigue strength of 5Y-FSZ: glazing and polishing effects.

Objective: The aim of this study was to evaluate the effect of four different finishing procedures on the fatigue strength of a fully stabilized zirconia (5Y-FSZ) material.

Materials And Methods: Disc-shaped specimens of a 5Y-FSZ (Katana UTML, Kuraray Noritake) were made (ISO 6872-2015), grinded with 600- and 1200-grit silicon carbide paper, sintered as recommended, and randomly assigned into four groups according to the finishing technique: C (control, as-sintered), P (polished with polishing rubbers), G (glaze application - powder/liquid technique), and PG (polished with polishing rubbers + glaze application - powder/liquid). Then fatigue strength (staircase method), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses were performed.

A Global Survey of COVID-19 Vaccine Acceptance Among Healthcare Workers.

Objectives: Even though several effective vaccines are available to combat the COVID-19 pandemic, wide disparities in vaccine distribution, and vaccine acceptance rates between high- and low-income countries appear to be major threats toward achieving population immunity. Our global descriptive study aims to inform policymakers on factors affecting COVID-19 vaccine acceptance among healthcare workers (HCWs) in 12 countries, based on income index. We also looked for possible predictors of vaccine acceptance among the study sample.

Mechanical behavior and microstructural characterization of different zirconia polycrystals in different thicknesses.

Purpose: To characterize the microstructure of three yttria partially stabilized zirconia ceramics and to compare their hardness, indentation fracture resistance (IFR), biaxial flexural strength (BFS), and fatigue flexural strength.

Materials And Methods: Disc-shaped specimens were obtained from 3Y-TZP (Vita YZ HT), 4Y-PSZ (Vita YZ ST) and 5Y-PSZ (Vita YZ XT), following the ISO 6872/2015 guidelines for BFS testing (final dimensions of 12 mm in diameter, 0.7 and 1.

Effect of finishing/polishing techniques and aging on topography, C. albicans adherence, and flexural strength of ultra-translucent zirconia: an in situ study.

Objective: To investigate the influence of different finishing/polishing techniques and in situ aging on the flexural strength (σ), surface roughness, and Candida albicans adherence of 5 mol% yttria-stabilized zirconia (ultratranslucent zirconia).

Materials And Methods: A total of 120 zirconia bars (Prettau Anterior, Zirkonzahn) with dimensions of 8 × 2 × 0.5 mm were divided into 8 groups (n = 15) according to two factors: "in situ aging" (non-aged and aged (A)) and "finishing/polishing" (control (C), diamond rubber polishing (R), coarse grit diamond bur abrasion (B), and coarse grit diamond bur abrasion + diamond rubber polishing (BR)).

Stress Concentration of Endodontically Treated Molars Restored with Transfixed Glass Fiber Post: 3D-Finite Element Analysis.

The loss of dental structure caused by endodontic treatment is responsible for a decrease in tooth resistance, which increases susceptibility to fracture. Therefore, it is important that minimally invasive treatments be performed to preserve the dental structure and increase the resistance to fracture of endodontically treated posterior teeth. To evaluate under axial loads, using the finite element method, the stress distribution in endodontically treated molars restored with both transfixed or vertical glass fiber posts (GFP) and resin composite.

In-lab simulation of CAD/CAM milling of lithium disilicate glass-ceramic specimens: Effect on the fatigue behavior of the bonded ceramic.

The aim of this study was to evaluate the effect of in-lab simulation procedures performed on a lithium disilicate ceramic luted to a dentin-analogue material regarding the fatigue performance and topographic changes. Lithium disilicate ceramic (IPS e.max CAD) discs (Ø = 13.

Cleaning and Surface Treatment Protocols for Repair of Aged Y-TZP with Composite Resin.

The purpose of this study was to evaluate the cleaning and surface treatment techniques in the repair of aged and contaminated yttrium oxide-stabilized tetragonal polycrystalline zirconia (Y-TZP). From a total of 80 specimens of Y-TZP, 60 were subjected to aging simulation in a buccal environment with degradation in an autoclave for 24 hours (127°C/1.5 bar) and contaminated with Streptococcus mutans.

Degradation kinetics of high-translucency dental zirconias: Mechanical properties and in-depth analysis of phase transformation.

This study aimed to evaluate the effects of low temperature degradation (LTD) on commercial dental zirconias (conventional and high-translucent - HT) with different microstructures, as well as on their mechanical properties and t-m phase transformation. The amount of monoclinic zirconia in different depths was quantified using X-ray diffraction (XRD) with different anode tubes (Cr, Co and Cu). XRD was also used to measure the residual stress of the materials at 0 h, 26 h and 140 h aging times.

Short communication: Influence of retainer configuration and loading direction on the stress distribution of lithium disilicate resin-bonded fixed dental prostheses: 3D finite element analysis.

The present study elucidates the mechanical performance of different designs of resin-bonded fixed dental prostheses made of lithium disilicate simulating masticatory loads of anterior or canine guidance. A three-dimensional model of maxilla was constructed containing central incisor and canine teeth, with edentulous space of the lateral incisor. Three designs of prosthesis were created: retained in central incisor (1-I), retained in canine (1-C) and fixed in both teeth (2-IC).

Short communication: Influence of restorative material and cement on the stress distribution of posterior resin-bonded fixed dental prostheses: 3D finite element analysis.

The goal of this study was to compare the mechanical response of resin-bonded fixed dental prosthesis (RBFDP) made in zirconia, metal, lithium disilicate and composite resin cemented using resin cements with different elastic modulus. For the finite element analysis, a three-dimensional model of partial right maxilla was used to create a model with edentulous space in the second premolar and the cavity's preparation on the first pre-molar and first molar to receive a RBFDP. The model was imported to the analysis software in which they were divided into mesh composed by nodes (371,101) and tetrahedral elements (213,673).

Strength of a Zirconia-Reinforced Lithium Silicate Ceramic: Acid-Etching Time and Resin Cement Application Effects.

This study aimed to evaluate the effect of hydrofluoric (HF)-acid-etching time and the impact of a resin-cement layer on the biaxial flexural strength and structural reliability of a zirconia-reinforced lithium silicate (ZLS) glass ceramic. Disc-shaped specimens (n = 15) were divided according to: etching time (conditioning with 10% HF acid for 20, 40, and 60 seconds), and application of a resin-cement layer. Biaxial flexural, contact angle, and roughness analyses were performed.

Sequential usage of diamond bur for CAD/CAM milling: Effect on the roughness, topography and fatigue strength of lithium disilicate glass ceramic.

The aim of this study was to evaluate the effect of sequential usage (milling order) of CAD/CAM diamond burs on the surface roughness, topography and fatigue performance of a lithium disilicate glass-ceramic. Seventy-two (72) ceramic discs (Ø= 13.5 mm; thickness= 1.

The performance of sol-gel silica coated Y-TZP for veneered and monolithic dental restorations.

Objectives: The purpose of the study was to characterize the microstructure, constituents, and mechanical properties of mono and bilayered zirconia specimens infiltrated with silica by the sol gel method.

Methods: 180 zirconia discs (14-mm diameter) were divided in 3 groups (n = 60) according to thickness (1.2, 0.

A Powdering Technique for Veneering Zirconia and Its Effect on the Flexural Strength of Ceramic Bilayers.

The aim of this study was to assess the powdering technique and its effects on the flexural strength of bilayered zirconia. Bars made of zirconia partially stabilized by yttrium (Y-TZP) received porcelain by the following techniques (n = 10 per group): (1) L: VM9 application; (2) P: powdering technique + VM9 application; (3) C: Y-TZP coloring before sintering + Y-TZP sintering + VM9 application; or (4) CP: Y-TZP coloring before sintering + Y-TZP sintering + powdering technique + VM9 application. The powdering technique consisted of the application of VM9 margin powder followed by sintering.