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Biomedical subjects

K J Reinhardt

Publications and source records attributed to K J Reinhardt.

34 records · Page 2Linked to original sources
PubMed1979

[The problem of standards for composites].

The bending strenght to the breakage point was determined for five different composites. The testing instrument was set up in accordance with standard specifications under application of pressure. It could be established that the bending strength to the breakage point depends on the intensity and duration of the force. Values were 10% to 20% higher than with polymerized samples without pressure. Long-term studies carried out approximately 24 hours after the sample had been produced showed the highest values for bending strength to the breakage point. These values dropped about 20% during the course of 8 to 10 days. The influence of storage conditions was also determined. In these tests, the bending strength to the breakage point dropped 20% to 30% after 24 hours.

Composite Resins↗
PubMed1979

[A comparison of light-hardened and UV-polymerizable sealants and composites].

Ultraviolet irradiation has been used for the photopolymerization of composites and sealers. As new initiators were developed, the effectivity of this system was extended into the visible spectral region. Photo-sensitivity probably only limits the processing period slightly, at least under these conditions relevant for the dental practice. One important advantage is the extension of the maximal tempering depth (2 to 3 times, compared to ultraviolet polymerization). The improved penetrability of the dental substance with increasing wave lengths also reduces the risk of portions of the undercuts not being polymerized.

Composite Resins↗
PubMed1979

[A scanning electromicroscopic determination of the depth of penetration of dental enamel adhesives in the etched enamel].

The surface tension of the liquid preservative was held responsible for the loss of plastic tags in the penetration zone between sealer and enamel due to the preparation. This loss is demonstrable with fluorescence, interference, and polarization microscopy. With the help of freeze-drying procedures, tags of approximately 200 mum could be exposed and photographed with the scanning electron microscope.

Acid Etching, Dental↗
PubMed1978

[Relationship between hardness, abrasion and bending strength of UV-polymerizable adhesives].

These experiments were undertaken to explore the influence of hardening on bending and bending strength of photopolymerisable adhesives. It was shown that light sources at present in use only influence the bending strength to a small degree but enable 40% variation in bending. The use of more intensive light sources not yet in commercial use led to further improvements.

Biomechanical Phenomena↗
PubMed1978

[Effect of oxygen and humidity on UV-polymerizable sealing materials].

The influence of humidity, oxygen and protecting gases on the wetting capacity of UV polymerisable adhesives is examined by means of border-angle measurements. The thickness of the upper layer not polymerisable through the presence of oxygen is determined and its effect on the surface structure of compounds is clarified by scanning electron microsc-investigations. For solution the use of a protecting gas is discussed.

Bicuspid↗
PubMed1978

[Thermic behavior of dental enamel, dentin and selected dental materials].

The linear coefficient of expansion of enamel, dentin as well as selected dental working materials is estimated by means of holographic-interferometric measurements. A good correlation was found between hard dental texture and a phosphate glass envisaged for use with lasers. The possible effects of the greatly increased coefficient of expansion of tested composites is discussed.

Biophysical Phenomena↗
PubMed1978

[Physical properties of highly polishable filling materials compared to composites].

Physical characteristics of three highly polishable filling materials (Estic R Microfill, Isopast and Superlux) were compared with those of current composites (Concise, Adaptic). It was shown that the materials with improved polishing qualities exhibit lower bending strength. Critical comments of practical importance are based on special temperature measurements of the material as well as of the pulp cavity. Aspects of testing and preparing the material are mentioned. Tests were further performed on the abrasion behaviour of the dental materials mentioned and the reciprocal changeable influence of the granularity of the abrasive and the quality of the working material is debated.

Dental Materials↗
PubMed1977

[Hardening of photopolymerizable sealing materials in variously deep enamel zones (in vitro)].

The effect of irradiation times of various lengths on the resulting Vickers-hardness and polymerisation of adhesives (Estilux glaze, Nuva Seal) was estimated for varying UV light sources. Secondary effects depending on position were found in the polymerisation, the progress of which could be estimated. The results of the polymerisation experiments, irradiating caries-containing and healthy enamel sections, using appropriate UV light sources, show polymerisation of adhesives with definable Vickers-hardness in enamel zones of various depths.

Dental Cements↗
PubMed1977

[Studies on silicate-containing and silicate-free adhesives compared to composite materials II].

The photo-polymerisable adhesive Estilux glaze and its successor product Estiglaze microfill as well as a compound from the same firm were subjected to comparative investigations. Maximal polymerisable thickness of the named materials were ascertained by means of variable intensive light sources. Electron-microscopic investigations were carried out on the matrices in order to estimate the wetting behaviour. No generally valid connection between hardness and abrasion of comparative materials could be observed, but Estiglaze microfill, containing filling-substance shows reduced abrasiveness to the factor 2.5 in comparison to products free from filling substance.

Composite Resins↗
PubMedDate not supplied

Self-etching primer vs phosphoric acid: an alternative concept for composite-to-enamel bonding.

The purpose of this in vitro study was (1) to investigate the composite-to-enamel bond strength and (2) to analyze the marginal adaptation of resin composite restorations in class 2 cavities using three self-etching priming agents in comparison to conventional phosphoric acid etching and bonding application. In the first part of the study 24 extracted bovine incisors were embedded in acrylic resin and ground flat with 800-grit paper. The following three self-etching priming agents/composite resins were applied to the enamel surfaces of six teeth each: Clearfil Liner Bond 2/Clearfil AP-X (Group I), Etch & Prime 3.0/Degufill mineral (Group II), Resulcin AquaPrime + MonoBond/Ecusit (Group III). In Group IV Ecusit-Mono/Ecusit was used after enamel etching with phosphoric acid (37%). Shear bond strength values measured on a T22 K testing machine at a crosshead speed of 1 mm/min were: 24.2 +/- 3.0 MPa (Group I), 21.9 +/- 1.4 MPa (II), 34.0 +/- 3.6 MPa (III), and 26.3 +/- 1.8 MPa (IV). ANOVA revealed significant (P < 0.05) differences in shear bond strength between groups, except comparison of Group I and II, and Group I and IV. In the second part of the study 24 standardized class 2 cavity preparations with the approximal box extending 1 mm above the CEJ were prepared in extracted human molars. Enamel margins were beveled and the teeth were divided into four groups of six teeth each. Cavities were restored using the self-etching priming agents Clearfil Liner Bond 2 (Group I), Etch & Prime 3.0 (Group II), and Resulcin AquaPrime + MonoBond (Group III). In Group IV composite resin restorations were placed after 37% phosphoric acid etching and bonding application (Ecusit-Mono). Quantitative SEM analysis of the marginal adaptation of the restorations after thermocycling (5-55 degrees C, 2500 cycles) and mechanical loading (100 N, 500,000 cycles) revealed excellent, gap-free margins in 91.2% (Group I), 93.0% (Group II), 92.0% (Group III), and 92.5% (Group IV) of the restorations' approximal area. There were no statistically significant differences between the four groups (P < 0.05). In conclusion, results of the present in vitro study indicate that use of self-etching primers may be an alternative to conventional phosphoric acid pre-treatment in composite-to-enamel bonding restorative techniques.

Acid Etching, Dental↗