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Biomedical subjects

M H Reisbick

Publications and source records attributed to M H Reisbick.

At least 19 recordsLinked to original sources
PubMed1992

Cement luting thickness beneath porcelain veneers made on platinum foil.

Porcelain laminate veneers were made using a platinum foil matrix and were subsequently cemented to mandibular anterior Cymel teeth. Cement film thickness was measured in six predetermined locations. Repeated measures analysis of variance and single degree of freedom contrasts delineated a significant difference between marginal openings at the incisal edge where foil is folded and in four of the other vertical areas (132 versus 74.1 microns). Marginal cement film thickness of veneers made on platinum foil is less than that reported for veneers made on a refractory investment.

Analysis of Variance↗
PubMed1990

Prosthetic and surgical management of osteogenic sarcoma of the maxilla.

Maxillary surgical defects resulting from resection of oral neoplasms vary in size from small perforations of the hard and soft palate to complete removal of these structures. Osteogenic sarcoma is of unknown etiology and is a rapidly growing tumor that may produce pain, paresthesia, and anesthesia. The recommended treatment of radical resection often results in defects that produce significant orofacial disfigurement. These defects, regardless of size, present significant functional disability, with compromised esthetics, mastication, and deglutition. Restoration with a maxillary obturator prosthesis can reestablish the physical separation between oral and nasal cavities and, in soft palate defects, enable normal palatopharyngeal function. Most patients can be rehabilitated successfully with restoration of speech and swallowing to normal levels and significant improvement in appearance.

Deglutition Disorders↗
PubMed1990

Occlusal accuracy of casts made and articulated differently.

This study evaluated the occlusal accuracy of gypsum casts constructed from irreversible hydrocolloid and selected nonaqueous elastomeric materials. Master metal casts were attached to a vertically moving apparatus that allowed their occlusal surfaces to produce repeatable contacts. Impressions were made with irreversible hydrocolloid, polysulfide, and vinylsiloxane. Resulting maxillary casts were mounted with a constant positioning device and mandibular casts were mounted with zinc oxide-eugenol paste records or by maximum intercuspation. Four specific master occlusal contacts were compared with contacts generated from the mounted gypsum casts; a perfect score was 40 (four contacts x 10 casts). A chi-square linear model for category data was used to compare groups. Results indicated that casts made from irreversible hydrocolloid should not be articulated with the use of a zinc oxide-eugenol paste but are best articulated by using maximum intercuspation (32/40 contacts).

Chi-Square Distribution↗
PubMed1988

The effects of a liquid dispersing agent and a microcrystalline additive on the physical properties of type IV gypsum.

This study evaluated the effects of a liquid dispersing agent (LDA) and a microcrystalline additive (MCA) on selected physical properties of type IV gypsum. Working consistency, setting time, setting expansion, and compressive strength (1 hour and 7 days) were determined, following ADA Specification No. 25, on a standard, LDA (0.5, 1, 1.5, and 2 mL), MCA (21.1, 24.1, and 27.1 gm), and combination (LDA 0.75 mL + MCA 12.05 gm) mixes per 300 gm of gypsum. Results indicate that the additives affect the consistency of the mix, but consistency can be kept close to that of the standard by lowering the water/powder ratio. Statistical analysis of the data indicated that the additives significantly affected the setting time, setting expansion, and both the 1-hour and the 7-day compressive strengths. SEM examination of fractured surfaces of test mixes indicated improved crystal packing. The properties of type IV gypsum can be improved by optimizing the amount of LDA and MCA additives.

Calcium Sulfate↗
PubMed1979

The effect of nonionic surfactants on bubble entrapment in elastomeric impression materials.

The incorporation of certain nonionic surfactants into silicone and polysulfide elastomers increases their wettability by gypsum products and consequently results in less bubble entrapment in poured casts. The choice of the most effective surfactant is critical and differs not only between types of elastomer, but also between brands of a single type. The beneficial effect of the optimal surfactant is not reduced by rinsing the impression prior to pouring. While the working time of silicone is increased by surfactant additions, that of polysulfide is essentially unaffected, as are the dimensional accuracies and permanent deformations of both materials.

Air↗
PubMed1977

Loading rate and temperature as variables in amalgam bending.

Three commercial dental amalgams of known dissimilar clinical properties were evaluated in pure blending at widely different loading rates and temperatures. Comparative data of fracture stress at 140 F rank these alloys according to their clinical fracture resistance; the phenomenon of creep may account for early marginal fracture prior to corrosion-induced fracture.

Dental Amalgam↗
PubMed1977

The effect of added particles on the properties of Ag3 Sn-additive amalgams.

Physical and chemical properties of amalgam alloys containing varying amounts of copper were evaluated. Evidence presented refutes the theory of physical strengthening due to the addition of silver-copper by its eutectic. Results suggest that reactive copper could be more advantageously added to the system by using fewer copper additive particles; these particles may need to have a greater copper content that those used in Dispersalloy.

Chemical Phenomena↗
PubMed1977

Improving the fracture resistance of dental ceramic.

A time-temperature sequence for optimally strengthening dental ceramic by ion exchange was investigated. Stress relaxation occurs at higher temperatures and/or longer times. Improved strenghts are obtained in a reasonable period of time that could be used for clinical application.

Dental Porcelain↗
PubMed1977

Amalgam containing nickel or tungsten dispersions. I.

Wetting tests were conducted to determine compatability between select dispersion powders and Ag3Sn. Subsequently, a method was perfected for incorporating nickel or tungsten powder into the Ag3 Sn ingot. Initial studies reveal good distributions of the dispersed phase in the ingots and the comminuted alloys, after amalgamation, appear to retain their normal working characteristics.

Chemical Phenomena↗
PubMed1977

Amalgam containing nickel or tungsten dispersions. II.

The technique of injecting dispersed phase particles into an Ag-Sn melt followed by rapid quenching was utilized. Results of this investigation show that a marked improvement of the brittle amalgam alloy occurs.

Chemical Phenomena↗
PubMed1977

A flexural method for evaluation of metal-ceramic bond strengths.

A test technique is presented for evaluating metal-ceramic bond strengths. The test piece consists of a four-point loaded metal beam with porcelain bonded to the central tension side of the beam. The test produced failures at predictable locations and was able to differentiate between metal surface treatments.

Dental Alloys↗
PubMed1975

Preceramic and postceramic solder joints.

This investigation evaluated preceramic and postceramic soldering procedures. Three gap spaces and two soldering methods were evaluated. Wider gaps produced stronger joints. The strongest joints were achieved by using wider gaps and the oven soldering technique. Very wide gaps (0.76 mm.) are not recommended because of possible distortion through excessive solder shrinkage. However, in practice, many solder joints exceed the 0.31 mm. recommended minimum; these joints will not show decreased strength.

Ceramics↗