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.

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.

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.

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.

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.

Mapping the spatial and temporal progression of human dental enamel biomineralization using synchrotron X-ray diffraction.

Objective: The complex biological, physicochemical process of human dental enamel formation begins in utero and for most teeth takes several years to complete. Lost enamel tissue cannot regenerate, therefore a better understanding of the spatial and temporal progression of mineralization of this tissue is needed in order to design improved in vivo mineral growth processes for regenerative dentistry and allow the possibility to grow a synthetic whole or partial tooth.

Method: Human dental enamel samples across a range of developmental stages available through archaeological collections have been used to explore the spatial and temporal progression of enamel biomineralization.

Quantitative high contrast X-ray microtomography for dental research.

Objectives: X-ray microtomography (XMT or micro-CT) is a miniaturized version of medical CT and has been used extensively for in vitro dental research. The technique allows three-dimensional analyses of both structure and density (or concentration), the latter requiring some a priori knowledge of composition. The aim of this paper is to demonstrate the capabilities of an XMT scanner specifically designed for dental research, especially that requiring high contrast resolution or accurate mineral concentration quantification.

Quantification of residual dentine thickness following crown preparation.

Objectives: Pulpal response to tooth preparation is a major concern in fixed prosthodontics. Research has suggested that 2mm or more of remaining dentine is critical in protecting the pulp following tooth preparation. However, clinicians have no means of knowing dentine thickness either before or after preparation and therefore lack feedback about this important aspect of preparation quality.

Diffusive transport within dentinal tubules: an X-ray microtomographic study.

The hydrodynamic theory of dentine hypersensitivity proposes that external stimuli cause dentinal fluid movement within dentinal tubules thereby triggering mechanosensitive nerves and eliciting a pain response. The aim of this study was to employ X-ray microtomography (XMT) to monitor diffusion of caesium acetate through dentine to investigate the extent to which transport occurs within the primary tubules compared to that through branched microtubules believed to run perpendicular to the direction of the primary dentinal tubules. 2.

Three-dimensional study of human dental fissure enamel by synchrotron X-ray microtomography.

The three-dimensional morphology of human tooth fissures and the quantification of mineral distribution in fissure enamel are pertinent to the development and diagnosis of caries. Synchrotron X-ray microtomography was used to measure linear attenuation coefficients (at 25 keV) at high spatial resolution with a volume-imaging element (cubic voxel) of 4.9x4.

Dentin exposure in tooth preparations for porcelain veneers: a pilot study.

Statement Of Problem: The various clinical techniques available for even reduction of a tooth surface to receive a porcelain veneer restoration do not produce a consistently even conservative reduction. In addition, it is not known which technique is most conservative of enamel.

Purpose: The purpose of this pilot study was to assess the effectiveness of 3 clinical techniques, namely, dimple, depth groove, and freehand, in producing an intraenamel preparation.

Non-destructive studies of tissue-engineered phalanges by magnetic resonance microscopy and X-ray microtomography.

One of the intents of tissue engineering is to fabricate biological materials for the augmentation or replacement of impaired, damaged, or diseased human tissue. In this context, novel models of the human phalanges have been developed recently through suturing of polymer scaffolds supporting osteoblasts, chondrocytes, and tenocytes to mimic bone, cartilage, and tendon, respectively. Characterization of the model constructs has been accomplished previously through histological and biochemical means, both of which are necessarily destructive to the constructs.

Modulation of mastication during experimental loosening of complete dentures.

Purpose: Suction is achieved when complete dentures are first fitted, but it fades during the months following insertion, when it is increasingly complemented by muscular denture control. The aim of this study was therefore to investigate the extent to which patterns of mastication are altered by experimental failure of physical retention.

Materials And Methods: Seven edentulous volunteers had maxillary replica dentures made, with fine tubes incorporated so that alternating positive and negative air pressure could be generated under the fitting surface.