An evaluation by dental clinicians of cutting characteristics and haptic perceptions in 3D-printed typodont teeth: A pilot study.

Objectives: This study aimed to compare the haptic perception of clinicians to the cutting response of 3D-printed typodont teeth and commercial typodont teeth and human extracted teeth.

Methods: Twenty clinicians were asked to perform a Class I cavity preparation on commercial typodont teeth, 3D-printed typodont teeth, and human extracted teeth, while the forces were recorded via a three-axis load cell. The haptic perception of clinicians was also evaluated through a response questionnaire comparing commercial and 3D-printed typodont teeth.

Healing patterns of alveolar bone following ridge preservation procedures.

Objectives: Examine the histomorphometric bone composition, following alveolar ridge preservation techniques and unassisted socket healing.

Materials And Methods: Forty-two patients (42) requiring a single rooted tooth extraction were randomly allocated into three groups (n = 14 per group): Group 1: Guided Bone Regeneration (GBR) using deproteinised bovine bone mineral (DBBM) and a porcine collagen membrane; Group 2: Socket Seal (SS) technique using DBBM and a porcine collagen matrix; Group 3: Unassisted socket healing (Control). Trephined bone biopsies were harvested following a 4-month healing period.

Impairment of the Glial Phagolysosomal System Drives Prion-Like Propagation in a Model of Huntington's Disease.

Protein misfolding, aggregation, and spread through the brain are primary drivers of neurodegenerative disease pathogenesis. Phagocytic glia are responsible for regulating the load of pathological proteins in the brain, but emerging evidence suggests that glia may also act as vectors for aggregate spread. Accumulation of protein aggregates could compromise the ability of glia to eliminate toxic materials from the brain by disrupting efficient degradation in the phagolysosomal system.

Impairment of the glial phagolysosomal system drives prion-like propagation in a model of Huntington's disease.

Protein misfolding, aggregation, and spread through the brain are primary drivers of neurodegenerative diseases pathogenesis. Phagocytic glia are responsible for regulating the load of pathogenic protein aggregates in the brain, but emerging evidence suggests that glia may also act as vectors for aggregate spread. Accumulation of protein aggregates could compromise the ability of glia to eliminate toxic materials from the brain by disrupting efficient degradation in the phagolysosomal system.

Imaging a microfocus X-ray focal spot with a thin coded aperture.

Imaging of the focal spot size in X-ray generators can be achieved by means of a pinhole in a highly attenuating material, such as gold. For microfocus generators with spot sizes of only around 10 microns or less, the material must be very thin to avoid an impractical aspect ratio. With a 90 kV source, only 11% attenuation is attained with 5 µm gold.

An assessment of mineral concentration of dental enamel neighbouring hypothetical orthodontic brackets using X-ray microtomography.

Objectives: Differences in the mineral concentration (MC) level of dental enamel may represent a precursor of white spot lesions adjacent to fixed orthodontic brackets. The aim of the current in vitro study was to compare the MC level central, occlusal and cervical to orthodontic attachments.

Methods And Materials: A total of 16 enamel blocks were obtained from sound human premolar samples extracted for orthodontic reasons.

Development of two-dimensional beam hardening correction for X-ray micro-CT.

Background: Beam-hardening in tomography with polychromatic X-ray sources results from the nonlinear relationship between the amount of substance in the X-ray beam and attenuation. Simple linearisation curves can be derived with the use of an appropriate step wedge, however, this does not yield good results when different materials are present whose relationships between X-ray attenuation and energy are very different.

Objective: To develop a more accurate method of beam-hardening correction for two-phase samples, particularly immersed or embedded biological hard tissue.

Clinical and Radiographic Outcome of Non-Surgical Endodontic Treatment Using Calcium Silicate-Based Versus Resin-Based Sealers-A Systematic Review and Meta-Analysis of Clinical Studies.

The aim of this paper is to systematically analyse the effect of calcium silicate-based sealers in comparison to resin-based sealers on clinical and radiographic outcomes of non-surgical endodontic treatment in permanent teeth. Methods: The study was conducted according to the guidelines of the Cochrane Handbook for Systematic Reviews of Interventions and Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) statement. The literature search was performed using PubMed/MEDLINE, Cochrane Central Register of Controlled Trials, Web of Science, DOAJ and OpenGrey with no language restrictions.

Association of individual surgeon volume and postoperative outcome in esophagomyotomy for achalasia.

Background: Many surgical disciplines have demonstrated superior outcomes when procedures are performed at "high-volume". Esophagomyotomy is commonly performed for achalasia, however it's unclear what constitutes "high-volume" for this procedure, and if individual procedure volume and outcome are related. We identified physicians performing esophagomyotomy, stratified them by individual case volume, and examined their outcomes with the hypothesis that high-volume surgeons will be associated with improved outcomes as compared to low-volume surgeons.

Physico-Chemical Properties of Calcium-Silicate vs. Resin Based Sealers-A Systematic Review and Meta-Analysis of Laboratory-Based Studies.

Introduction: The aim of this systematic review is to analyse the effect of physico-chemical properties of calcium silicate-based sealers in comparison to epoxy resin sealers in permanent teeth using a single-cone obturation technique.

Methods: The study was conducted according to the guidelines of Cochrane Handbook for Systematic Reviews of Interventions and Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) statement. Literature search was performed using the PubMed/MEDLINE, Cochrane Central Register of Controlled Trials, Web of Science, DOAJ, Open Gray with no language restrictions until October 2020.

Unlocking history through automated virtual unfolding of sealed documents imaged by X-ray microtomography.

Computational flattening algorithms have been successfully applied to X-ray microtomography scans of damaged historical documents, but have so far been limited to scrolls, books, and documents with one or two folds. The challenge tackled here is to reconstruct the intricate folds, tucks, and slits of unopened letters secured shut with "letterlocking," a practice-systematized in this paper-which underpinned global communications security for centuries before modern envelopes. We present a fully automatic computational approach for reconstructing and virtually unfolding volumetric scans of a locked letter with complex internal folding, producing legible images of the letter's contents and crease pattern while preserving letterlocking evidence.

Mineral exchange within restorative materials following incomplete carious lesion removal using 3D non-destructive XMT subtraction methodology.

Objectives: The objective of this study was to quantify the changes in mineral and selected element concentrations within residual carious dentine and restorative materials following incomplete carious lesion removal (ICLR) using different cavity liners, with non-destructive subtraction 3D-X-ray Microtomography (XMT, QMUL, London, UK).

Materials And Methods: A total of 126 extracted teeth with deep dental caries were assessed using International Caries Risk and Assessment (ICDAS). Eight teeth were subsequently selected after radiographic evaluation.

Fabrication of Porous Bone Scaffolds Using Alginate and Bioactive Glass.

Porous composite scaffold using an alginate and bioactive glass ICIE16M was synthesized by a simple freeze-drying technique. The scaffold was characterized using compression testing, Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), X-ray microtomography (XMT) and scanning electron microscopy (SEM). The bioactivity of the scaffold was evaluated by its ability to form apatite on its surface in simulated body fluid (SBF).

Crystallographic texture and mineral concentration quantification of developing and mature human incisal enamel.

For human dental enamel, what is the precise mineralization progression spatially and the precise timing of mineralization? This is an important question in the fundamental understanding of matrix-mediated biomineralization events, but in particular because we can use our understanding of this natural tissue growth in humans to develop biomimetic approaches to repair and replace lost enamel tissue. It is important to understand human tissues in particular since different species have quite distinct spatial and temporal progression of mineralization. In this study, five human central incisors at different stages of enamel maturation/mineralization were spatially mapped using synchrotron X-ray diffraction and X-ray microtomography techniques.

Virtual Recovery of Content from X-Ray Micro-Tomography Scans of Damaged Historic Scrolls.

There is a large body of historical documents that are too fragile to be opened or unrolled, making their contents inaccessible. Recent improvements in X-ray scanning technology and computer vision techniques make it possible to perform a "virtual" unrolling of such documents. We describe a novel technique to process a stack of 3D X-ray images to identify the surface of parchment scrolls, unroll them, and create a visualization of their written contents.

Estimating age using permanent molars and third cervical vertebrae shape with a novel semi-automated method.

Estimating chronological age accurately in young adults is difficult and additional methods are required to increase the accuracy. This study explored a new semi-automated method to assess shape change of third cervical vertebra (C3) with age in the living; comparing this as a method to determine whether individuals could be categorised into being less than 18 years of age (<18), or at least 18 years of age (≥18) with tooth formation of the second and third mandibular molars (M2 and M3). The sample was panoramic and lateral skull radiographs of 174 dental patients (78 males, 96 females aged 15-22 years).

Comparison of efficacy of dental varnish containing fluoride either with CPP-ACP or bioglass on root caries: Ex vivo study.

Objectives: To compare the efficacy of fluoride varnishes either casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) or bioglass particles on the severity index of root caries.

Methods: Visual-tactile assessments including lesion hardness was carried out to categorise the severity index of 80 extracted teeth with primary root caries. These teeth were randomly divided into four groups; CPP-ACP and fluoride, bioglass and fluoride, fluoride only, and no treatment.

In vitro and in vivo study of commercial calcium phosphate cement HydroSet™.

The commercial calcium phosphate cement, HydroSet™, was investigated in vitro, studying phase formation, compressive strength and setting time, followed by an ovine in vivo study to measure osseointegration, bone apposition and bone-to-graft contact. The X-ray diffraction and P Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) results showed the initial formation of octacalcium phosphate and hydroxyapatite at one hour. Over 7 days the octacalcium phosphate transformed to apatite, which was the only crystalline phase of the cement at 28 days.

Real-time observations of tooth demineralization in 3 dimensions using X-ray microtomography.

Objectives: The immediate aim of this study was to develop and test a method to record, visualize and quantify real-time demineralization (or remineralization) of teeth in vitro using X-ray microtomography (XMT or micro-CT). The longer term objective is to improve understanding of demineralization processes, allowing the creation of better artificial models of dental caries and better quantification of the efficacy of caries treatment and prevention regimes.

Methods: For demineralization studies, the tooth is mounted in a plastic container through which the demineralizing solution is circulated during simultaneous repeated scanning.

Body wall structure in the starfish Asterias rubens.

The body wall of starfish is composed of magnesium calcite ossicles connected by collagenous tissue and muscles and it exhibits remarkable variability in stiffness, which is attributed to the mechanical mutability of the collagenous component. Using the common European starfish Asterias rubens as an experimental animal, here we have employed a variety of techniques to gain new insights into the structure of the starfish body wall. The structure and organisation of muscular and collagenous components of the body wall were analysed using trichrome staining.

Microscopic study of dental hard tissues in primary teeth with Dentinogenesis Imperfecta Type II: Correlation of 3D imaging using X-ray microtomography and polarising microscopy.

Objectives: The aim of this study was to examine the histological appearance of dental hard tissues in primary teeth from children with DI using conventional polarised light microscopy and correlate that with 3D imaging using X-ray microtomograpy (XMT) to gain a further understanding of the dentine structure of teeth diagnosed with dentinogenesis imperfecta.

Design: Undecalcified sections of primary teeth from patients diagnosed with Dentinogenesis Imperfecta Type II were examined using polarised light microscopy. XMT was employed for 3D-imaging and analysis of the dentine.