Scientific Aspects of Dental Materials

Fraunhofer, Von

doi:10.1111/j.1365-2591.1976.tb01236.x

Cited by 20 publications

(10 citation statements)

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“…It has been pointed out by JORGENSEN Sc SAITO (1970) atid JORGENSEN (1972 and by a tiumber of other investigators that the most cotTodible phase is y^ or the tintiiercury phase. After packing and carving tfie surface layer of an atrtalgam filling is likely to contain tnore of the y2 phase than tlie body of the filling (FRAUNHOFER 1975). Tfiis is the probable explanation for tfie fact that the single recent amalgam filling in the experitnental material had the lowest potetitial value, -520 tnV.…”

Section: Soremark Freedman Goldin 8cmentioning

confidence: 99%

Potential and polarization measurements in vivo of oral galvanism

Bergman

Ginstrup

Nilner

1978

European J Oral Sciences

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abstract— Galvanic currents within the oral cavity may have harmful effects on biological tissues. In the present work 16 patients with different kinds of oral and other discomfort and pain which they attributed to oral galvanism were investigated. The potential and polarization of each metal restoration within reach of a platinum probe were measured versus a reference electrode. A recording of these measured values permits a calculation of the currents which may pass between the teeth. A control group of patients with no subjective symptoms of galvanism in the oral cavity was also investigated. The results of the electrochemical measurements showed that conditions for oral galvanism existed within the individuals of the patient group as well as within the control group. One remarkable observation was that the metallic restorations often consisted of different electrically isolated areas with different electrochemical properties. This and other factors influencing oral galvanism are discussed.

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Section: Soremark Freedman Goldin 8cmentioning

confidence: 99%

Potential and polarization measurements in vivo of oral galvanism

Bergman

Ginstrup

Nilner

1978

European J Oral Sciences

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“…Then, the variation of specimen weight with time (day) was examined, and from the water absorption-time curve obtained, the equilibrium moisture content and the diffusion coefficient of water were determined. The determination of the diffusion coefficient (D) was calculated using the following equation (Crank, 1970;von Fraunhofer, 1975):…”

Section: Methodsmentioning

confidence: 99%

Viscoelastic properties of denture base resins obtained by underwater test

Hiromori

Fujii

Inoue

2000

J of Oral Rehabilitation

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The viscoelastic properties of denture base polymers, such as poly(methylmethacrylate) (PMMA), polycarbonate (PC), polysulfone (PSF) and polyethersulfone (PES) which have been used in current clinical dentistry were investigated. In addition, water absorption, diffusion coefficient of water into material, cubical expansion, specific volume and residual monomer were also determined. From the results of this study, the viscoelastic behaviours of the denture base polymers in water have been discussed. The relaxation modulus (Er(5)) which was calculated using a stress at 5 s from the start of measurement for the specimen which reached an equilibrium moisture content (wet specimen), decreased from 23.1 to 25.5% compared with that of PMMA stored in a desiccator (37 degrees C) for 1 week (dry specimen). In contrast, this decreasing ratio was 7.0 to 10.0% for PC, PSF and PES. It is suggested that this phenomenon is caused by the increase of specific volume (cm3/g) with water absorption in each material. The water absorption of the PMMA group was relatively large in comparison with other material and was 1.81-1.85%. This value was within the range from 0.38 to 1.74% for PC, PSF and PES. The diffusion coefficients of water for PC, PSF and PES increased by approximately 1.5-2.7 times that of PMMA. Furthermore, the coefficient of cubical expansion of the wet specimen was larger than that of the dry specimen. The increasing ratio was 1.03-1.10 times for the PMMA group and 1. 18-2.38 times for PC, PSF and PES. The variation of Er(5) of the PMMA group with temperature in water was larger than those of PC, PSF and PES.

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“…The measurement of water absorption was carried out using an electronic balance § § and was continued for 30 days. The diffusion coefficient (D) was determined using the following equation (von Fraunhofer, 1975):…”

Section: Measurement Of Water Absorptionmentioning

confidence: 99%

Dynamic viscoelastic properties of photo-activated composite resins containing short glass fibres

Kanayama¹,

Kanie²,

Inoue³

2000

J Oral Rehabil

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The dynamic shear modulus in torsion (G'), water absorption, thermal expansion and residual monomer of the reinforced materials produced by adding four short glass fibres (19 microm in mean diameter and 86.1--763 microm in mean length) and one spherical E glass (11.1 microm in mean diameter) were examined and discussed in comparison with those of the materials without filler. G' of short fibre reinforced composites increased with fibre length and reached a maximum value near 382 microm for a dry specimen and near 156 microm for a wet one. In addition, the coefficient of thermal expansion of the fibre reinforced composites and the amount of residual monomer decreased considerably compared with those of composites containing spherical glass. There was no significant difference in water absorption between the fibre reinforced composites and the composites containing spherical glass. Therefore, it was concluded that the reinforcement method of adding short glass fibres is favourable for improving the viscoelastic properties of the materials.

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Scientific Aspects of Dental Materials

Cited by 20 publications

References 0 publications

Potential and polarization measurements in vivo of oral galvanism

Potential and polarization measurements in vivo of oral galvanism

Viscoelastic properties of denture base resins obtained by underwater test

Dynamic viscoelastic properties of photo-activated composite resins containing short glass fibres

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