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John W Nicholson - One of the best experts on this subject based on the ideXlab platform.

  • a review of glass ionomer cements for Clinical Dentistry
    Journal of Functional Biomaterials, 2016
    Co-Authors: S. K. Sidhu, John W Nicholson
    Abstract:

    This article is an updated review of the published literature on glass-ionomer cements and covers their structure, properties and Clinical uses within Dentistry, with an emphasis on findings from the last five years or so. Glass-ionomers are shown to set by an acid-base reaction within 2–3 min and to form hard, reasonably strong materials with acceptable appearance. They release fluoride and are bioactive, so that they gradually develop a strong, durable interfacial ion-exchange layer at the interface with the tooth, which is responsible for their adhesion. Modified forms of glass-ionomers, namely resin-modified glass-ionomers and glass carbomer, are also described and their properties and applications covered. Physical properties of the resin-modified glass-ionomers are shown to be good, and comparable with those of conventional glass-ionomers, but biocompatibility is somewhat compromised by the presence of the resin component, 2 hydroxyethyl methacrylate. Properties of glass carbomer appear to be slightly inferior to those of the best modern conventional glass-ionomers, and there is not yet sufficient information to determine how their bioactivity compares, although they have been formulated to enhance this particular feature.

  • The use of alginate impression material for the controlled release of sodium fusidate
    2015
    Co-Authors: Beata Czarnecka, John W Nicholson
    Abstract:

    Introduction. Alginate impression material has the potential to act as a controlled release material, either for transmucosal drug delivery, or for use as a self-disinfecting impression material in Clinical Dentistry. Aim of the study. To study whether sodium fusidate could be released from alginate impression material and, if so, to determine the release kinetics. Material and methods. Sodium fusidate was incorporated into alginate impression material at the mixing stage (2% by mass). The mixed material was pressed into a sheet and, once cured, discs (6 mm diameter x 2 mm thick) were cut out, and stored in water, one disc in a 5 ml volume. Small samples (20 I1l) were withdrawn at time intervals of 1, 2, 3, 4, 5, 24 h, 1, 2 and 3 weeks and analysed by HPLC. Results. Sodium fusidate was released from the impression material in a process that was shown to be diffusion based for the first 5 hours or so. The diffusion coefficient was 2.25 x 10–5 cm2 s-1, and the release corresponded to 36.0 ± 1.0% of the total loading. The system thus shows promise for Clinical application.

  • the biocompatibility of resin modified glass ionomer cements for Dentistry
    Dental Materials, 2008
    Co-Authors: John W Nicholson, Beata Czarnecka
    Abstract:

    Abstract Objectives The biological effects of resin-modified glass-ionomer cements as used in Clinical Dentistry are described, and the literature reviewed on this topic. Methods Information on resin-modified glass-ionomers and on 2-hydroxyethyl methacrylate (HEMA), the most damaging substance released by these materials, has been collected from over 50 published papers. These were mainly identified through Scopus. Results HEMA is known to be released from these materials and has a variety of damaging biological properties, ranging from pulpal inflammation to allergic contact dermatitis. These are therefore potential hazards from resin-modified glass-ionomers. However, Clinical results with these materials that have been reported to date are generally positive. Conclusions/significance Resin-modified glass-ionomers cannot be considered biocompatible to nearly the same extent as conventional glass-ionomers. Care needs to be taken with regard to their use in Dentistry and, in particular, dental personnel may be at risk from adverse effects such as contact dermatitis and other immunological responses.

  • polyacid modified composite resins compomers and their use in Clinical Dentistry
    Dental Materials, 2007
    Co-Authors: John W Nicholson
    Abstract:

    Abstract Objectives This paper describes the chemistry and properties of polyacid-modified composite resins (“compomers”) designed for use in Clinical Dentistry, and reviews the literature in this area. Methods Information has been obtained from over 50 published articles appearing in the dental and biomaterials literature, with studies being principally identified through MedLine. Results Published work shows that polyacid-modified composite resins constitute a discrete class of polymeric repair material for use in Dentistry. Their distinction is that they contain hydrophilic components, and these cause water to be drawn into the material following cure. This triggers an acid–base reaction, and gives the materials certain Clinically-desirable properties (fluoride release, buffering capability) that are also associated with glass-ionomer cements. The water uptake leads to a decline in certain, though not all, physical properties. However, Clinical studies have shown these materials to perform acceptably in a variety of applications (Class I, Class II and Class V cavities, as fissure sealants and as orthodontic band cements), especially in children's teeth. Conclusions/significance Polyacid-modified composite resins constitute a versatile class of dental repair material, whose bioactivity confers Clinical advantages, and which are particularly useful in children's Dentistry.

William M Johnston - One of the best experts on this subject based on the ideXlab platform.

  • color accuracy of commercial digital cameras for use in Dentistry
    Journal of Prosthetic Dentistry, 2007
    Co-Authors: Alvin G Wee, Delwin T Lindsey, Shanglun Kuo, William M Johnston
    Abstract:

    Objectives The use of calibrated, commercial digital cameras for dental applications is promising. The color accuracy of various calibration models were evaluated as applied to three commercial digital cameras for use in dental color matching. Methods CIE LAB values of 264 color patches and 65 shade tabs were measured with a spectroradiometer. Digital images of the samples were taken with the Nikon D100, Canon D60 and Sigma SD9 cameras. Four regression models were formulated from the color patch CIE LAB and the digital image values. Shade tab CIE LAB colors were predicted by applying the digital image values into the calibration models and were compared to the measured CIE LAB values. The Wilcoxon Rank-Sum test determined if the 12 camera/calibration models differed significantly from the color measurement setup. Results Every camera/calibration model (Δ E 's ranging from 1.79 to 5.25) showed a statistically significant difference from the color measurement setup. Significance Commercial SLR digital cameras when combined with the appropriate calibration protocols showed potential for use in the color replication process of Clinical Dentistry.— Reprinted with permission of Elsevier Publishing.

  • color accuracy of commercial digital cameras for use in Dentistry
    Dental Materials, 2006
    Co-Authors: Alvin G Wee, Delwin T Lindsey, Shanglun Kuo, William M Johnston
    Abstract:

    Summary Objectives The use of calibrated, commercial digital cameras for dental applications is promising. The color accuracy of various calibration models were evaluated as applied to three commercial digital cameras for use in dental color matching. Methods CIE LAB values of 264 color patches and 65 shade tabs were measured with a spectroradiometer. Digital images of the samples were taken with the Nikon D100, Canon D60 and Sigma SD9 cameras. Four regression models were formulated from the color patch CIE LAB and the digital image values. Shade tab CIE LAB colors were predicted by applying the digital image values into the calibration models and were compared to the measured CIE LAB values. The Wilcoxon Rank-Sum test determined if the 12 camera/calibration models differed significantly from the color measurement setup. Results Every camera/calibration model (Δ E 's ranging from 1.79 to 5.25) showed a statistically significant difference from the color measurement setup. Significance Commercial SLR digital cameras when combined with the appropriate calibration protocols showed potential for use in the color replication process of Clinical Dentistry.

Alvin G Wee - One of the best experts on this subject based on the ideXlab platform.

  • color accuracy of commercial digital cameras for use in Dentistry
    Journal of Prosthetic Dentistry, 2007
    Co-Authors: Alvin G Wee, Delwin T Lindsey, Shanglun Kuo, William M Johnston
    Abstract:

    Objectives The use of calibrated, commercial digital cameras for dental applications is promising. The color accuracy of various calibration models were evaluated as applied to three commercial digital cameras for use in dental color matching. Methods CIE LAB values of 264 color patches and 65 shade tabs were measured with a spectroradiometer. Digital images of the samples were taken with the Nikon D100, Canon D60 and Sigma SD9 cameras. Four regression models were formulated from the color patch CIE LAB and the digital image values. Shade tab CIE LAB colors were predicted by applying the digital image values into the calibration models and were compared to the measured CIE LAB values. The Wilcoxon Rank-Sum test determined if the 12 camera/calibration models differed significantly from the color measurement setup. Results Every camera/calibration model (Δ E 's ranging from 1.79 to 5.25) showed a statistically significant difference from the color measurement setup. Significance Commercial SLR digital cameras when combined with the appropriate calibration protocols showed potential for use in the color replication process of Clinical Dentistry.— Reprinted with permission of Elsevier Publishing.

  • color accuracy of commercial digital cameras for use in Dentistry
    Dental Materials, 2006
    Co-Authors: Alvin G Wee, Delwin T Lindsey, Shanglun Kuo, William M Johnston
    Abstract:

    Summary Objectives The use of calibrated, commercial digital cameras for dental applications is promising. The color accuracy of various calibration models were evaluated as applied to three commercial digital cameras for use in dental color matching. Methods CIE LAB values of 264 color patches and 65 shade tabs were measured with a spectroradiometer. Digital images of the samples were taken with the Nikon D100, Canon D60 and Sigma SD9 cameras. Four regression models were formulated from the color patch CIE LAB and the digital image values. Shade tab CIE LAB colors were predicted by applying the digital image values into the calibration models and were compared to the measured CIE LAB values. The Wilcoxon Rank-Sum test determined if the 12 camera/calibration models differed significantly from the color measurement setup. Results Every camera/calibration model (Δ E 's ranging from 1.79 to 5.25) showed a statistically significant difference from the color measurement setup. Significance Commercial SLR digital cameras when combined with the appropriate calibration protocols showed potential for use in the color replication process of Clinical Dentistry.

Theodore P Croll - One of the best experts on this subject based on the ideXlab platform.

  • glass ionomer restorative cement systems an update
    Pediatric Dentistry, 2015
    Co-Authors: Joel Berg, Theodore P Croll
    Abstract:

    : Glass ionomer cements have been used in pediatric restorative Dentistry for more than two decades. Their usefulness in Clinical Dentistry is preferential to other materials because of fluoride release from the glass component, biocompatibility, chemical adhesion to dentin and enamel, coefficient of thermal expansion similar to that of tooth structure, and versatility. The purpose of this paper was to review the uses of glass ionomer materials in pediatric Dentistry, specifically as pit and fissure sealants, dentin and enamel replacement repair materials, and luting cements, and for use in glass ionomer/resin-based composite stratification tooth restoration (the sandwich technique). This article can also be used as a guide to research and Clinical references regarding specific aspects of the glass ionomer systems and how they are used for young patients.

Pekka K Vallittu - One of the best experts on this subject based on the ideXlab platform.

  • high aspect ratio fillers fiber reinforced composites and their anisotropic properties
    Dental Materials, 2015
    Co-Authors: Pekka K Vallittu
    Abstract:

    Abstract Objectives To present an overview of fiber-reinforced composites (FRCs) that are a group of non-metallic dental biomaterials used in several fields of Dentistry. Methods A range of relevant publications from the past half century are surveyed, with emphasis upon recent publications. Results FRCs vary according to the type of fiber fillers and orientation of fibers, the latter being responsible for several properties which can vary from isotropic to anisotropic. The length of the fibers, i.e. the aspect ratio of the filler, is another factor or variable that contributes to the properties and the development of new types of composite resins for restorative and prosthetic Dentistry, as well as to reconstructive medicine. Significance Understanding the anisotropic nature of FRCs from the perspective of dental applications has increased in recent years. This review describes some fiber orientation related anisotropic properties of FRCs which contribute to the increased use of FRCs in Clinical Dentistry.