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Biomedical subjects

N Ewoldsen

Publications and source records attributed to N Ewoldsen.

9 recordsLinked to original sources
PubMed2001

A review of orthodontic cements and adhesives.

Dental cements and resins are used intraorally to secure fixed orthodontic devices. Although cements are still used, the popularity of resin and resin-cement hybrid materials is increasing because of their improved physical properties and low solubility in oral fluids. Some cements bond chemically to enamel, but bond strengths are low because cements are brittle and fracture cohesively. Resin adhesives penetrate micropores in etched enamel and mechanical retentions in orthodontic devices, resulting in higher bond strengths because resins are more fracture resistant than cements. Resins, however, do not bond well in the presence of moisture, and their attachment to surfaces is primarily mechanical. Hybridized materials combine the advantages of cements and resins but also have certain disadvantages. Optimal material selection and application require an understanding of the chemical differences and physical limitations of today's orthodontic cements, resins, and hybrid materials.

Acid Etching, Dental↗
PubMed1998

Wiropress SL: a multipurpose dental pressure vessel with transparent chamber.

Pneumatic vessels used in dentistry provide a pressurized environment to enhance the outcome of many laboratory procedures. A pressurized environment directs volume loss associated with polymerization shrinkage, minimizes air inclusions in powder/liquid mixtures, raises the boiling point of liquids, and facilitates flow of impression and replication materials, improving surface detail. The following report illustrates the usefulness of a reliable pneumatic vessel during denture base repair resin processing and replication of pattern details.

Acrylic Resins↗
PubMed1998

Decay-inhibiting restorative materials: past and present.

Clear differences exist in the fluoride release characteristics and setting reactions of glass-ionomer cements and compomers. Differences in decay inhibition associated with specific materials are less clear. Furthermore, resin added to glass ionomer cement formulations and acids added to composite resins make it difficult to distinguish composite resins from compomers and glass ionomer cements, all of which have reported fluoride release. Optimal fluoride release from a dental restorative depends on several conditions, including oral flora, saliva, diet, mineral content of the dental tissues, and marginal seal of the restoration. Presently, in vitro and in vivo studies suggest that materials which behave similarly to silicate cements in their setting reactions and hydration characteristics will behave as decay-inhibiting restoratives. Until optimal fluoride release from dental restoratives can be quantified, dental clinicians are encouraged to consider clinical outcomes as the best test for decay inhibition. Nearly a century of clinical findings support the anticariogenicity of silicate cements. This article reviews fluoride release and anticariogenicity of restorative materials using silicate cement as a model with a well-defined mechanism for preventing secondary caries. The behavior of newer materials is compared to silicate cement for predicting decay inhibition.

Cariostatic Agents↗
PubMed1996

Using a resin-modified glass ionomer as an occlusal sealant: a one-year clinical study.

The authors compared the retention and clinical performance of a resin-modified glass ionomer, or RMGI, restorative and a light-cured resin sealant. The first permanent molars on one side of the dental arch in 50 children were sealed with an RMGI, and the same teeth on the other side were sealed with a resin sealant. At baseline, six months after placement and one year after placement, examiners documented sealant retention, secondary caries, marginal discrepancy and marginal staining. In general, the RMGI appeared to wear markedly. At one year, the retention of the RMGI was significantly less than the resin, but the RMGI had significantly fewer marginal discrepancies. There were no significant differences in caries development or marginal discoloration.

Bisphenol A-Glycidyl Methacrylate↗
PubMedDate not supplied

The physical and adhesive properties of dental cements used for atraumatic restorative treatment.

Atraumatic restorative treatment (ART), a recently reported field dentistry technique, involves removal of carious debris using only hand instruments and placement of a glass-ionomer cement (GIC) restoration. While small ART-GIC restorations are effective short-term replacements for lost tooth form, many larger ART-GIC restorations are defective after two years. Presently, resin-modified GICs (R-M GIC) are available which require no special activation equipment and handle easily in field settings. This study measured the compressive, tensile, and shear bond strengths to enamel and dentin of a conventional ART-GIC (Fuji IX) and two R-M GICs (Fuji Plus and Advance) at a powder-to-liquid ratio of 3.6:1. The compressive strengths of the GICs tested were significantly different. Fuji IX had the highest compressive strength, and Advance had the lowest strength (p < 0.05). The tensile strength of the R-M GICs was greater than that of the ART-GIC. Fuji Plus showed the highest shear bond strength to enamel and dentin and was significantly different from both Fuji IX and Advance. A clinical protocol is presented followed by case reports where the ART technique was used for management of acute caries in a modern dental setting.

Acute Disease↗