Hard machining, glaze firing and hydrofluoric acid etching: Do these procedures affect the flexural strength of a leucite glass-ceramic?

Objective: To evaluate the effects of hard machining, glaze firing and hydrofluoric acid etching on the biaxial flexural strength and roughness of a CAD/CAM leucite glass-ceramic; to investigate if ceramic post-machining surface roughness is influenced by the machining order and by the pair of burs used for it.

Methods: A hundred forty four discs were machined by six nominally identical pairs of burs and divided into groups (n=24): (1) machining-M, (2) machining and glaze firing-MG, (3) machining and hydrofluoric acid etching-MA, (4) machining, glaze firing and hydrofluoric acid etching-MGA, (5) machining followed by polishing, as a control-MP, (6) machining, polishing and hydrofluoric acid etching-MPA. The roughness after each treatment (Ra and Rz) was measured.

Effect of random/aligned nylon-6/MWCNT fibers on dental resin composite reinforcement.

The aims of this study were (1) to synthesize and characterize random and aligned nanocomposite fibers of multi-walled carbon nanotubes (MWCNT)/nylon-6 and (2) to determine their reinforcing effects on the flexural strength of a dental resin composite. Nylon-6 was dissolved in hexafluoropropanol (10 wt%), followed by the addition of MWCNT (hereafter referred to as nanotubes) at two distinct concentrations (i.e.

Antimicrobial Effects of Novel Triple Antibiotic Paste-Mimic Scaffolds on Actinomyces naeslundii Biofilm.

Introduction: Actinomyces naeslundii has been recovered from traumatized permanent teeth diagnosed with necrotic pulps. In this work, a triple antibiotic paste (TAP)-mimic scaffold is proposed as a drug-delivery strategy to eliminate A. naeslundii dentin biofilm.

Influence of insertion techniques for resin cement and mechanical cycling on the bond strength between fiber posts and root dentin.

Purpose: To evaluate the effect of the insertion technique for resin cement and mechanical cycling on the bond strength between fiber posts and root dentin.

Materials And Methods: Sixty-four single-rooted bovine teeth were endodontically prepared to receive glass-fiber posts. The insertion of cement into the root canal was performed using one of the following techniques: POS, insertion with the post; LEN, the use of a lentulo-type drill; EXP, insertion with a straight-tip explorer; or CEN, the use of a Centrix syringe.

Effect of composite surface treatment and aging on the bond strength between a core build-up composite and a luting agent.

Objective: The purpose of this study was to assess the influence of conditioning methods and thermocycling on the bond strength between composite core and resin cement.

Material And Methods: Eighty blocks (8×8×4 mm) were prepared with core build-up composite. The cementation surface was roughened with 120-grit carbide paper and the blocks were thermocycled (5,000 cycles, between 5°C and 55°C, with a 30 s dwell time in each bath).

Effects of ciprofloxacin-containing scaffolds on enterococcus faecalis biofilms.

Introduction: Antibiotic-containing polymer-based nanofibers (hereafter referred to as scaffolds) have demonstrated great potential for their use in regenerative endodontics from both an antimicrobial and cytocompatibility perspective. This study sought to evaluate in vitro the effects of ciprofloxacin (CIP)-containing polymer scaffolds against Enterococcus faecalis biofilms.

Methods: Human mandibular incisors were longitudinally sectioned to prepare radicular dentin specimens.

Halloysite nanotube incorporation into adhesive systems—effect on bond strength to human dentin.

Objectives: This study aimed to evaluate the effect of Halloysite® aluminosilicate clay nanotube (HNT) incorporation into a two-step etch-and-rinse (ER) and a one-step self-etch (SE) adhesive on human dentin shear bond strength (SBS).

Materials And Methods: Ten groups (n = 12) were prepared according to the adhesive system (i.e.

Physicomechanical and antibacterial properties of experimental resin-based dental sealants modified with nylon-6 and chitosan nanofibers.

This study aimed to develop and evaluate resin-based experimental dental sealants containing electrospun nylon-6 (N6) and chitosan (CH) fibers in an attempt to improve the physicomechanical properties and provide an antibacterial protective effect, respectively. Electrospun N6 and CH mats were immersed into a resin mixture, light-cured, and then cryomilled to obtain micron-sized resin-modified fiber particles. Different levels of the novel cryomilled particles (i.

Influence of zirconia surface treatment on veneering porcelain shear bond strength after cyclic loading.

Statement Of Problem: The influence of yttria-stabilized tetragonal zirconia polycrystal surface treatment on veneering porcelain shear bond strength after cyclic loading is not fully understood.

Purpose: The purpose of this study was to investigate the influence of yttria-stabilized tetragonal zirconia polycrystal surface treatment on veneering porcelain shear bond strength and cyclic loading on the shear bond strength between the 2 materials.

Material And Methods: A total of 48 cylinder-shaped yttria-stabilized tetragonal zirconia polycrystal specimens were fabricated with computer-aided design and computer-aided manufacturing (CAD/CAM), sintered for 8 hours at 1500°C, ground with 320-grit diamond paper, and divided into 4 groups (n = 12) according to surface treatment as follows: no treatment/control; heat treatment of 650°C to 1000°C at 55°C/min; airborne-particle abrasion with 50-μm alumina at 0.

Effects of aging procedures on the topographic surface, structural stability, and mechanical strength of a ZrO2-based dental ceramic.

Objective: To determine the effects of different aging methods on the degradation and flexural strength of yttria-stabilized tetragonal zirconia (Y-TZP) METHODS: Sixty disc-shaped specimens (∅, 12mm; thickness, 1.6mm) of zirconia (Vita InCeram 2000 YZ Cubes, VITA Zahnfabrik) were prepared (ISO 6872) and randomly divided into five groups, according to the aging procedures (n=10): (C) control; (M) mechanical cycling (15,000,000 cycles/3.8Hz/200N); (T) thermal cycling (6,000 cycles/5-55°C/30s); (TM) thermomechanical cycling (1,200,000 cycles/3.

Bimix antimicrobial scaffolds for regenerative endodontics.

Introduction: Eliminating and/or inhibiting bacterial growth within the root canal system has been shown to play a key role in the regenerative outcome. The aim of this study was to synthesize and determine in vitro both the antimicrobial effectiveness and cytocompatibility of bimix antibiotic-containing polydioxanone-based polymer scaffolds.

Methods: Antibiotic-containing (metronidazole [MET] and ciprofloxacin [CIP]) polymer solutions (distinct antibiotic weight ratios) were spun into fibers as a potential mimic to the double antibiotic paste (DAP, a MET/CIP mixture).

Carbon film coating of abutment surfaces: effect on the abutment screw removal torque.

Purpose: To evaluate the effect of diamond-like carbon (DLC) coating of prefabricated implant abutment on screw removal torque (RT) before and after mechanical cycling (MC).

Materials And Methods: Fifty-four abutments for external-hex implants were divided among 6 groups (n = 9): S, straight abutment (control); SC, straight coated abutment; SCy, straight abutment and MC; SCCy, straight coated abutment and MC; ACy, angled abutment and MC; and ACCy, angled coated abutment and MC. The abutments were attached to the implants by a titanium screw.

Finite element analysis of the influence of geometry and design of zirconia crowns on stress distribution.

Purpose: To evaluate the influence of the geometry and design of prosthetic crown preparations on stress distribution in compression tests, using finite element analysis (FEA).

Materials And Methods: Six combinations of 3D drawings of all-ceramic crowns (yttria-stabilized zirconia framework and porcelain veneer) were evaluated: F, flat preparation and simplified crown; FC, flat preparation and crown with contact point; FCM, flat preparation and modified crown; A, anatomical preparation and simplified anatomical crown framework; AC, anatomical preparation and crown with contact point; and ACM, anatomical preparation and modified crown. Bonded contact types at all interfaces with the mesh were assigned, and the material properties used were according to the literature.

The effect of mechanical loading on the cusp defection of premolars restored with direct and indirect techniques.

Aim: This study assessed the effect of fatigue load cycling on human premolars restored with MOD restorations (direct and indirect approaches) on cuspal defection, compared to intact teeth (unprepared) and unrestored teeth with an inlay preparation.

Materials And Methods: MOD inlay preparations were performed on sixty premolars with their roots embedded in acrylic resin. These teeth were divided into six groups (n = 10): (1) intact teeth; (2) unrestored and prepared teeth; (3) teeth restored with direct composite resin; (4) teeth restored with an indirect composite resin; (5) teeth restored with injected ceramic inlays (IPS Empress 2 (Ivoclar); (6) teeth restored with CAD/CAM inlays made of feldspathic ceramic (Vita Mark II).

A microstrain comparison of passively fitting screw-retained and cemented titanium frameworks.

Statement Of Problem: An imprecise fit between frameworks and supporting dental implants in loaded protocols increases the strain transferred to the periimplant bone, which may impair healing or generate microgaps.

Purpose: The purpose of this study was to investigate the microstrain between premachined 1-piece screw-retained frameworks (group STF) and screw-retained frameworks fabricated by cementing titanium cylinders to the prefabricated framework (group CTF). This procedure was developed to correct the misfit between frameworks and loaded implants.

Antimicrobial effects of drug-containing electrospun matrices on osteomyelitis-associated pathogens.

Purpose: To synthesize polydioxanone (PDS)-based drug delivery systems (hereafter referred to as "matrices") containing vancomycin (VANC) and/or rifampicin (RIF) and investigate their effect on the inhibition of biofilm growth containing osteomyelitis (OM)-associated pathogens.

Materials And Methods: PDS matrices were prepared by electrostatic spinning, and the drugs were incorporated as follows: group (G)1, 5wt%VANC; G2, 10wt%VANC; G3, 5wt%RIF; G4, 10wt%RIF; G5, 5wt%VANC+RIF; and G6, 10wt%VANC+RIF. A control group of pure PDS was also electrospun (G7).

Effect of ceramic thickness and shade on mechanical properties of a resin luting agent.

Purpose: This study aimed to investigate the influence of ceramic thickness and shade on the Knoop hardness and dynamic elastic modulus of a dual-cured resin cement.

Materials And Methods: Six ceramic shades (Bleaching, A1, A2, A3, A3.5, B3) and two ceramic thicknesses (1 mm, 3 mm) were evaluated.

Stem cell-derived tissue-engineered constructs for hemilaryngeal reconstruction.

Objectives: As an initial step toward our goal of developing a completely tissue-engineered larynx, the aim of this study was to describe and compare three strategies of creating tissue-engineered muscle-polymer constructs for hemilaryngeal reconstruction.

Methods: Cartilage-mimicking polymer was developed from electrospun poly(D,L-lactide-co-ε-caprolactone) (PCL). Primary muscle progenitor cell cultures were derived from syngeneic F344 rat skeletal muscle biopsies.

Biodegradable nanofibrous drug delivery systems: effects of metronidazole and ciprofloxacin on periodontopathogens and commensal oral bacteria.

Objectives: The purposes of this study were to fabricate biodegradable polydioxanone (PDS II®) electrospun periodontal drug delivery systems (hereafter referred to as matrices) containing either metronidazole (MET) or ciprofloxacin (CIP) and to investigate the effects of antibiotic incorporation on both periodontopathogens and commensal oral bacteria.

Materials And Methods: Fibrous matrices were processed from PDS polymer solution by electrospinning. Antibiotic-containing PDS solutions were prepared to obtain four distinct groups: 5 wt.

Population epidemiological study on the prevalence of dizziness in the city of São Paulo.

Unlabelled: The epidemiology of dizziness is essential in clinical practice.

Objective: To establish the prevalence of dizziness in the adult population of São Paulo, its clinical characteristics and level of discomfort.

Method: A prospective cross-sectional study ran from April to October of 2012 by a field questionnaire, totaling 1,960 interviews.

Improved adhesion of Y-TZP ceramics: a novel approach for surface modification.

The aim of this study was to evaluate the effect of novel surface treatments of Y-TZP ceramics on initial shear bond strengths to resin cement. Eighty-four samples (7 x 6 x 5 mm) were randomly divided into 6 groups (n=14): Group1 (G1), no treatment; Group 2 (G2), air-borne particle abrasion with silica-coated aluminum oxide particles; Group 3 (G3), vitreous application 1 + etching with hydrofluoric acid; Group 4 (G4), vitreous application 1 + tribosilicatization; Group 5 (G5), vitreous application 2 + etching; Group 6 (G6), vitreous application 2 + tribosilicatization. Surface roughness (Ra) evaluation was performed by optical profilometry, scanning electron microscopy, and X-ray spectroscopy.

Influence of air-particle deposition protocols on the surface topography and adhesion of resin cement to zirconia.

Objectives: This study evaluated the influence of air-particle abrasion protocols on the surface roughness (SR) of zirconia and the shear bond strength (SBS) of dual-polymerized resin cement to this ceramic.

Materials And Methods: Sintered zirconia blocks (n = 115) (Lava, 3M ESPE) were embedded in acrylic resin and polished. The specimens were divided according to the 'particle type' (Al: 110 µm Al2O3; Si: 110 µm SiO2) and 'pressure' factors (2.

Effect of finish line on marginal fit of sintered gold copings.

The aim of this study was to evaluate the vertical marginal gap of sintered gold copings and metal-ceramic crowns with different finish line preparations: a beveled round shoulder (BRS) and a beveled long chamfer (BLC), testing the null hypotheses that there are no differences in marginal gap regardless of finish line and phase of restoration (coping or crown). Stainless steel master models were fabricated to simulate tooth preparation for metal-ceramic crowns with different finish lines (BRS and BLC). Ten dies were obtained from each model.

Low-temperature degradation of a Y-TZP ceramic after surface treatments.

The purpose of this study was to evaluate the influence of zirconia surface treatments on low-temperature degradation (LTD). Disc-shaped specimens were subjected to one of four surface treatments, denoted as C (control-no surface treatment), Si (air abrasion with 30 µm silica-modified alumina particles), Al (air abrasion with 30 µm alumina particles), and Gr (grinding with 120 grit diamond discs). Half of the samples were submitted to autoclave treatment for 12 h (127°C, 1.