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Biomedical subjects

N W Rupp

Publications and source records attributed to N W Rupp.

At least 19 recordsLinked to original sources
PubMed1989

Comparison of microleakage of experimental and selected commercially available bonding system.

The microleakages of composite restorations bonded with two commercial and two experimental systems were observed. A high-viscosity condensable composite and a low-viscosity composite were used as the restorative materials. The bonding systems used were two widely accepted commercial brands and two experimental systems, one containing ferric oxalate and the other aluminum oxalate. Restorations were placed in cavities prepared in extracted human teeth and treated with the various bonding systems. These restorations were stored in 37 degrees C water for 24 hours and then polished. The restored teeth were subjected to seven days of thermocycling (5 degrees C-55 degrees C for 540 cycles per day). Microleakage was detected and scored from 0-4 according to the degree of stain penetration. The experimental systems had lower scores than the commercial systems. The high-viscosity composite restorations had microleakage scores higher than those of the lower-viscosity composite restorations.

Composite Resins↗
PubMed1989

Pulpal and micro-organism responses to two experimental dental bonding systems.

Several new bonding systems have been reported that promote strong adhesion. This in vivo study involves treatment with two experimental bonding systems of Class V cavity preparations in the teeth of three Macaca fascicularis primates and reports the pulpal responses and degree of micro-organism invasion associated with each treatment. In each monkey, the teeth in the upper left quadrant were treated with the experimental solution, containing 2.5% aluminum nitrate + 1.5% oxalic acid + 4.9% NPG, followed by application of PMDM and Silux XL composite. The lower right quadrant was treated with the experimental solution, containing 5.7% NPG + 2.4% nitric acid, followed by PMDM and Silux XL composite. The upper right and lower left quadrants were treated with clinical materials to establish positive and negative controls. After four, 25, and 59 days, the teeth were removed and underwent routine histological and bacteriological evaluation. Slight pathological conditions were noted for superficial and deep responses, but all values approached 0.0 by the 59th day. Micro-organisms were seen under only 12% of the restorations. Both experimental systems appear to be safe for human clinical trials.

Animals↗
PubMed1989

Clinical biocompatibility of an experimental dentine-enamel adhesive for composites.

Previous studies have shown that sequential application of an acidified solution of ferric oxalate, N-phenylglycine and PMDM (the reaction product of pyromellitic dianhydride and hydroxyethyl methacrylate) yields strong adhesive bonding of composite resins to both dentine and enamel. The purpose of this study was to evaluate the clinical characteristics and the biocompatibility of this system in human teeth scheduled for extraction in the course of orthodontic treatment. Controls were light-cured Scotch-bond or ZOE in contralateral teeth. Evaluation criteria, which included clinical feasibility, patient acceptability, retention, margin aesthetics and human pulp response, were met. Within the 4-241 day observation periods, there was no postoperative sensitivity, pain, loss of retention, staining or discolouration. All pulp responses (double-blind pulp analysis including all teeth) were acceptable. With mean (+/- SD) remaining dentine thickness (RDT) of 0.67 +/- 0.35 mm, all indicators of pulp inflammation (displacement, superficial response, deep response etc.) averaged between none and slight, under 1 on a 0-4 scale. Both controls gave similar results. Linear regression analysis indicated low responses at all RDTs. The experimental material is safe and effective; further unrestricted clinical evaluations in teeth to be retained are indicated.

Adhesives↗
PubMed1988

Wear and microhardness of a silver-sintered glass-ionomer cement.

Knoop Hardness and pin-and-disc-wear measurements were made on a commercial silver-sintered glass-ionomer cement. The objective was to determine whether the incorporation of a bonded-metal-to-glass filler would enhance durability as determined by the above measurements. As with the previous work on conventional (non-metalized) glass-ionomer cements, the specimens were preconditioned at 37 degrees C in air, water, 0.02 mol/L lactic acid (pH 2.67), and heptane. The influence of these media on the microhardness of the silver-sintered material was about the same as that on the conventional materials. Storing in air produced dehydration, which increased the hardness considerably. Heptane storage increased the hardness less, but this increase is attributed to continued curing during storage. After storage in water, the hardness was essentially unchanged; the influence of increased cure is believed to be offset by softening or plasticization from water uptake. Lactic acid produced a decrease in hardness from chemical dissolution as seen from the SEM observations. In most cases, in particular for the air-stored specimens, the wear resistance was enhanced markedly over that of the conventional materials evaluated previously. The exception was the lactic acid-stored specimens for which little, or no, improvement was observed during early periods of wear. The incorporation of silver appeared to provide lubrication, thus reducing wear. However, catastrophic failure from brittle fracture was still a problem, but its occurrence was less frequent.

Cermet Cements↗
PubMed1987

Bond strength of a luting composite to dentin with different bonding systems.

This study evaluated the tensile bond strength of Conclude luting composite to dentin under different environmental conditions with Scotchbond dental adhesive, the FNP system, and unfilled BIS-GMA resin used as bonding agents. Although the bonding systems reportedly yield high tensile bond values to enamel, large differences were observed in this study for bond values to dentin. Only the FNP bonding system produced consistently high tensile load values to dentin under the three environmental conditions tested.

Adhesives↗
PubMed1987

Wear and microhardness of glass-ionomer cements.

Pin-and-disc wear and Knoop Hardness measurements were made on three commercial glass-ionomer cements having slightly different compositions. The specific objective was to determine whether these cements have potential for use in posterior teeth, and, if not, what modifications in composition and structure would be appropriate to enhance their performance. The specimens were pre-conditioned in air, water, or lactic acid at 37 degrees C for one week prior to being wear-tested. Although differences among the samples were noted, some common trends were observed. From changes in hardness, before and after storage, two opposing trends were observed. One trend involved continued cross-linking and possible dehydration, resulting in a substantial increase in hardness. The other trend involved softening from penetrant liquid absorption and a concomitant decrease in hardness. The wear resistances compared favorably with those for resin-based composites except for the lactic-acid-stored specimens, for which changes in microstructure were revealed by SEM. All specimens were very brittle, and catastrophic failure during wear was frequent. Although our conclusion is that glass-ionomer cements with composition similar to those evaluated here are not acceptable for posterior occlusal application, some compositional changes may enhance their performance in stress-bearing applications.

Air↗
PubMed1983

Detecting margin leakage of dental composite restorations.

The degree of microleakage between a restoration and the cavity wall is difficult to quantify objectively. A silver-staining method is used and compared to the radioisotope method with results that indicate a superior definition and more accurate evaluation of microleakage. In addition to the accuracy, two advantages are presented: (1) scoring of the leakage can be refined and divided into more precise numbers, and (2) teeth can be observed directly in a microscope without resorting to the indirect interpretation of film or photograph.

Calcium Radioisotopes↗