Graphene composites with dental and biomedical applicability.

Pure graphene in the form of few-layer graphene (FLG) - 1 to 6 layers - is biocompatible and non-cytotoxic. This makes FLG an ideal material to incorporate into dental polymers to increase their strength and durability. It is well known that graphene has high mechanical strength and has been shown to enhance the mechanical, physical and chemical properties of biomaterials.

An approach to understanding tribological behaviour of dental composites through volumetric wear loss and wear mechanism determination; beyond material ranking.

Objective: To investigate the fundamental wear mechanisms of six resin-based composite (RBC) formulations during short-term in vitro wear testing.

Materials: RBC materials were condensed into rectangular bar-shaped specimens and light irradiated using the ISO 4049 specimen manufacture and irradiation protocol. Wear testing (n=10 specimens for each RBC) was performed on a modified pin-on-plate wear test apparatus and wear facets were analysed for wear volume loss using a white light profilometer.

Data acquisition variability using profilometry to produce accurate mean total volumetric wear and mean maximum wear depth measurements for the OHSU oral wear simulator.

Objective: To identify the minimum data acquisition variables in the x- and y-planes required when using three-dimensional (3D) profilometry to produce accurate mean total volumetric wear and mean maximum wear depth measurements for a range of wear facets produced by an oral wear simulator.

Methods: The Oregon Health Science University (OHSU) oral wear simulator was employed to wear an experimental resin-based composite formulation from 25,000 to 400,000 wear cycles. Mean total volumetric wear and mean maximum wear depth were determined using a contact profilometry at a measurement speed of 1mm/s.

Assessment of wear facets produced by the ACTA wear machine.

Objective: To investigate the use of a three-dimensional (3D) digital scanning method in determining the accuracy of the wear performance parameters of resin-based composites (RBCs) determined using a two-dimensional (2D) analogue methodology following in-vitro testing in an Academisch Centrum for Tandheelkunde Amsterdam (ACTA) wear machine.

Methods: Specimens compatible with the compartments of the ACTA wear machine specimen wheel (n=10) were prepared from one commercial and four experimental RBCs. The RBC specimens were rotated against an antagonist wheel in a food-like slurry for 220,000 wear cycles.

A discriminatory mechanical testing performance indicator protocol for hand-mixed glass-ionomer restoratives.

Objectives: To identify a reproducible and discriminatory mechanical testing methodology to act as a performance indicator for hand-mixed glass-ionomer (GI) restoratives.

Methods: Groups of 20 (five batches of four) cylinders (6.0±0.

The reliability of Little's Irregularity Index for the upper dental arch using three dimensional (3D) digital models.

Aim: To investigate the inter-examiner variability of contact point displacement measurements (used to calculate the overall Little's Irregularity Index (LII) score) from digital models of the maxillary arch by four independent examiners.

Methods: Maxillary orthodontic pre-treatment study models of ten patients were scanned using the Lava(tm) Chairside Oral Scanner (LCOS) and 3D digital models were created using Creo(®) computer aided design (CAD) software. Four independent examiners measured the contact point displacements of the anterior maxillary teeth using the software.

Can the intra-examiner variability of Little's Irregularity Index be improved using 3D digital models of study casts?

Objectives: To compare contact point displacement measurements, used to determine the Little's Irregularity Index (LII) score on study casts and digital models of study casts by an independent examiner.

Methods: The contact point displacement measurements of the six maxillary anterior labial teeth were measured on ten study casts using digital callipers and their associated digital models using Creo Parametric software on five occasions following scanning using a LAVA Chairside Oral Scanner (LCOS) three-dimensional (3D) intra oral scanner. Means, standard deviations and coefficients of variation (CoV) were determined, data analyses (Pearson's correlation coefficients (PCCs) and Intraclass correlation coefficients (ICCs)) and statistical analyses (three and two-way analyses of variance (ANOVAs) and Independent Sample Student's t-tests) were carried out (p<0.

Hertzian indentation testing of glass-ionomer restoratives: A reliable and clinically relevant testing approach.

Objectives: To investigate the load to failure of encapsulated posterior glass-ionomer (GI) restoratives tested under Hertzian indentation and to explore the validity and reproducibility of the test results achieved for consideration of inclusion as an ISO testing protocol.

Methods: Groups of 20 disc-shaped specimens (10.0±0.

The in vitro wear behavior of experimental resin-based composites derived from a commercial formulation.

Objective: To investigate the short- and long-term in vitro wear resistance of experimental resin-based composites (RBCs) derived from a commercial formulation.

Methods: Six experimental RBCs were manufactured by manipulating the monomeric resin composition and the filler characteristics of Grandio (Voco GmbH, Cuxhaven, Germany). The Oregon Health Sciences University (OHSU) oral wear simulator was used in the presence of a food-like slurry to simulate three-body abrasion and attrition wear for 50,000, 150,000 and 300,000 cycles.

Influence of resin-based composite restoration technique and endodontic access on cuspal deflection and cervical microleakage scores.

Objectives: To assess cuspal deflection and cervical microleakage of mesio-occlusal-distal cavities in standardised premolar teeth restored incrementally with resin-based composite (RBC) placed horizontally or obliquely and with endodontic access cavities (with and without gutta percha and epoxy resin sealer obturation).

Materials And Methods: Thirty-two teeth were allocated to four groups (n=8) and RBC restored in eight horizontal (Group A) or oblique increments (Groups B-D) using a quartz-tungsten-halogen light curing unit. The dependent variable for Groups B-D was endodontic access (none (Group B), obturated without (Group C) and with gutta percha and epoxy resin sealer (Group D)).

Using Little's Irregularity Index in orthodontics: outdated and inaccurate?

Objectives: Little's Irregularity Index (LII) was devised to objectively score mandibular incisor alignment for epidemiological studies but has been extended to assess the relative performance of orthodontic brackets, retainer or treatment modalities. Our aim was to examine the repeatability and precision of LII measurements of four independent examiners on the maxillary arch of orthodontic patients. The hypothesis was that the reproducibility of individual contact point displacement measurements, used to calculate the LII score, are inappropriate.

The influence of monomeric resin and filler characteristics on the performance of experimental resin-based composites (RBCs) derived from a commercial formulation.

Objective: To explore experimental RBCs derived from a successful commercially available RBC (Grandio) to investigate resin monomer blend and filler parameters (volume fraction, density and diameter) on RBC performance.

Method: Six experimental RBCs modified from a commercial RBC were tested. The three-point flexure strength (σ(3)) and modulus (E) data was determined for groups of 20 bar-shaped specimens, prepared in a custom-made knife-edge split aluminum mold and irradiated using a modification of the ISO 4049 protocol.

The crushing truth about glass ionomer restoratives: exposing the standard of the standard.

Objectives: The compressive fracture strength (CFS) test is the only strength test for glass ionomers (GIs) in ISO 9917-1: 2003. The CFS test was the subject of much controversy in 1990 and has been challenged over its appropriateness and reproducibility and the study aimed to revisit the suitability of the CFS test for GIs.

Methods: Groups of 20 (four batches of n=5) cylinders (6.

Improving the standard of the standard for glass ionomers: an alternative to the compressive fracture strength test for consideration?

Objectives: Three strength tests (compressive, three point flexure and biaxial) were performed on three glass ionomer (GI) restoratives to assess the most appropriate methodology in terms of validity and reliability. The influence of mixing induced variability on the data sets generated were eliminated by using encapsulated GIs.

Methods: Specimen groups of 40 (eight batches of n=5) cylinders (6.

Can poly(acrylic) acid molecular weight mixtures improve the compressive fracture strength and elastic modulus of a glass-ionomer restorative?

Objectives: To optimize the compressive fracture strength (σ) and elastic modulus (E) of a glass-ionomer (GI) restorative using poly(acrylic) acid (PAA) weight average molecular weight (M(w)) mixtures.

Methods: 174 PAA solutions were prepared (four control PAA M(w)s at three PAA concentrations (25, 35 and 45%) (n=12) and six M(w) mixtures (Groups A-F at nine blend ratios and three PAA concentrations (n=162))). The viscosity (η) of each PAA solution was determined using a digital viscometer.

The influence of poly(acrylic) acid number average molecular weight and concentration in solution on the compressive fracture strength and modulus of a glass-ionomer restorative.

Objectives: The aim was to investigate the influence of number average molecular weight and concentration of the poly(acrylic) acid (PAA) liquid constituent of a GI restorative on the compressive fracture strength (σ) and modulus (E).

Methods: Series of PAA solutions for eight experimental PAAs with molecular weights ranging from 5000 to 200,000 were prepared at concentrations ranging from 10 to 60%. The PAA number average molecular weights were determined using gel permeation chromatography and the viscosity at each concentration was determined using a digital viscometer.

Percutaneous localisation of pulmonary nodules prior to video-assisted thoracoscopic surgery using methylene blue and TC-99.

The widespread use of computed tomography (CT) scans for evaluating patients has resulted in the detection of many small solitary pulmonary nodules of uncertain significance. Workup of these nodules can be expensive and emotionally draining, especially in patients who have an established diagnosis of malignancy. Since the early 1990s, video-assisted thoracoscopic surgery (VATS) has become a procedure of choice in the workup and therapy of small lung lesions.

Are encapsulated anterior glass-ionomer restoratives better than their hand-mixed equivalents?

Objectives: The performance of encapsulated anterior GI restoratives were compared with their hand-mixed equivalents for the range of powder to liquid mixing ratios routinely encountered clinically. The clinically induced variability of powder to liquid mixing variations of an anhydrous GI restorative formulation was also compared with conventional GI restorative formulations that contained a polyalkenoic acidic liquid.

Methods: Mean compressive fracture strengths, mean elastic moduli and mean total volumetric wear were determined for the encapsulated anterior GI restoratives mechanically mixed in a Capmix or Rotomix machine and the hand-mixed GI restoratives prepared with powder contents reduced from that recommended by the manufacturer (100%) in 10% increments to 50% for a constant weight of liquid.

Is encapsulation of posterior glass-ionomer restoratives the solution to clinically induced variability introduced on mixing?

Objectives: Three GI restorative systems were evaluated to determine if encapsulated GI restoratives performed more favorably than the hand-mixed equivalents prepared with powder contents progressively decreased from that recommended by manufacturers in 10% increments for a constant weight of liquid which are routinely employed in clinical practice.

Methods: Mean compressive fracture strengths, associated Weibull moduli and mean elastic moduli were determined for series of 30 nominally identical cylindrical specimens for three hand-mixed GI restoratives prepared with 100-50% of the recommended powder content for a constant weight of liquid and the equivalent encapsulated GI restoratives mechanically mixed in the Capmix or Rotomix machines.

Results: Decreasing the powder content of the three hand-mixed GI restoratives for a constant weight of liquid from that recommended by the manufacturers resulted in a progressive deterioration of the mean compressive fracture strengths and the mean elastic modulus.

The impact of montmorillonite clay addition on the in vitro wear resistance of a glass-ionomer restorative.

Objectives: The in vitro wear resistance of a glass-ionomer (GI) restorative ChemFil Superior (Dentsply DeTrey, Kanstanz, Germany) reinforced with either a pristine calcium montmorillonite (Ca-MMT) or an organically modified 12-amino-dodecanoicacid treated montmorillonite (ADA-MMT) clay was evaluated to investigate the potential of MMT reinforced GI restoratives as posterior filling materials.

Methods: The wear resistance of a GI restorative reinforced with 0.5-2.

The influence of montmorillonite clay reinforcement on the performance of a glass ionomer restorative.

Objectives: A pristine calcium montmorillonite (Ca-MMT) and an organically modified 12-amino-dodecanoicacid treated montmorillonite (ADA-MMT) clay were evaluated to determine the reinforcement effect on the performance of a glass ionomer (GI) restorative ChemFil Superior (Dentsply DeTrey, Kanstanz, Germany) to assess the potential as a posterior filling material.

Methods: Mean compressive fracture strengths and standard deviations were determined for groups of 30 cylindrical specimens with 0.5-2.

Pituitary adenoma detected on FDG positron emission tomography in a patient with mucosa-associated lymphoid tissue lymphoma.

A 52-year-old woman with a history of treated non-Hodgkin's lymphoma, B-cell type, was examined for a right eyelid mass proved on excision to be a mucosa-associated lymphoid tissue lymphoma. She was referred for F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging of the whole body, including the brain, to identify the possible presence or recurrence of lymphoma. The FDG-PET images revealed focal marked FDG uptake in the pituitary gland but no evidence of abnormal metabolic sites in the rest of the body, including the orbital regions.