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Biomedical subjects

J W Robbins

Publications and source records attributed to J W Robbins.

At least 37 records · Page 2Linked to original sources
PubMed1986

The placement of bases beneath amalgam restorations: review of literature and recommendations for use.

On the basis of the literature, it can be concluded that there are no absolute rules regarding the placement of bases under amalgam restorations. The following recommendations are offered: A base should not be used unless its use is indicated clearly. When a base is indicated, it should be used with the minimum thickness necessary to achieve the desired result. Lost dentin should not be replaced with a base in an attempt to simulate an ideal preparation. A stronger base should not be placed over a weaker base, for strength. The entire base is only as strong as the weakest component. Covering the entire pulpal floor with a base should be avoided. Sound dentin surrounding the base should be left so that the amalgam restoration is supported by dentin as much as possible.

Calcium Hydroxide↗
PubMed1980

Success of overdentures and prevention of failure.

Placement of dentures over selected retained teeth has become a commonly used treatment in dentistry. The relationship between the overdenture and the areas of periodontal, endodontic, restorative, and prosthodontic diagnosis and treatment has been discussed. Within each area, aspects of treatment that are crucial to success of the overdenture have been identified. It is suggested that the two most important concerns are adequate diagnosis and maintenance. The combination of a properly diagnosed case and a motivated patient, along with extreme attention to detail during treatment, will enhance the prospect of success.

Dental Abutments↗
PubMed1976

Potash guar gum--a source of halophilic bacteria.

Moderate and extreme halophilic microorganisms have been isolated from guar gum solutions dissolved in potash brine for use in sylvite froth flotation. Tentative identifications have been made of vibrio, Halobacterium, and Halococcus species. Reinoculation of these isolates into guar gum solutions has shown that they are not carbohydrate-utilizing strains, but instead metabolize the contaminating proteins present in guar.

Halobacteriaceae↗
PubMedDate not supplied

The production of recombinant beta-galactosidase in Escherichia coli in yeast extract enriched medium.

The productivity of Escherichia coli biomass and recombinant beta-galactosidase was increased in Luria broth (LB) enriched with yeast extract. In flask culture under conditions of LB limitation, yeast extract supplementation gave the highest biomass (strain HB101/pRW756) stimulation per unit of component added compared with supplementation by various amounts of amino acids, vitamins, minerals, purines/pyrimidines, tryptone, casamino acids, casein peptone or gelatin peptone. The biomass production of E. coli HB101/pRW756, XL-1 Blue/puc118, XL-1 Blue FF/puc118 and TB-1/p1034 cells was stimulated in fermentor-scale experiments with additional yeast extract in LB. Total beta-galactosidase production from plasmid genes in fermentor-scale experiments was increased 105.4% in XL-1 blue/puc118 cells, 365.5% in XL-1 blue FF/puc118 cells and 421.4% in TB-1/p1034 cells by 0.5%, 1% and 1% weight per volume of additional yeast extract in LB, respectively. Depending on different strains, the increase of the enzyme production was obtained either by increased biomass, or the combination of enhanced gene expression and increased biomass. Neither the biomass nor beta-galactosidase production was stimulated in N4830/p1034 cells by the increase in yeast extract concentration in the medium.

Culture Media↗
PubMedDate not supplied

Fracture resistance of reinforced glass ionomer as a buildup material.

This study in vitro investigated the fracture resistance of two reinforced glass ionomers and amalgam when used as core-buildup materials. Four-pin buildups using the three materials were placed in human molar teeth and prepared for gold crowns. The crowns were cemented and the teeth were compressed at 45 degrees to failure. There was no significant difference found in the fracture resistance of the three materials.

Dental Amalgam↗
PubMedDate not supplied

Effect of distribution of resistance features in complex amalgam restorations.

This study measured fracture resistance of complex amalgam restorations when pins or amalgapins were either distributed around the preparation or concentrated in one area of the preparation. The occlusal surfaces of 80 extracted molars were ground flat to 2 mm occlusal to the cementoenamel junction (CEJ). Roots were notched and embedded. Teeth were sized and distributed equally into eight groups (n = 10). Resistance features, four TMS stainless steel Regular pins or four amalgapin channels, were inserted into each molar. Resistance features were either distributed at the four line angles of each molar or clustered at two line angles. Matrices were applied, and amalgam was mechanically condensed into the matrices. Restorations were adjusted to a 4 mm vertical height and flat occlusal surfaces. A load was applied to each restoration at either a 45 degrees or a 90 degrees angle to the long axis of the tooth. Distributed pins provided significantly more resistance than clustered pins in groups tested at 90 degrees. Resistance to fracture in all groups loaded at 45 degrees and in amalgapin groups was not significantly affected by distribution of resistance features. Pins provided significantly more resistance than amalgapins at both angles of testing.

Analysis of Variance↗
PubMedDate not supplied

Shear bond strength of composite resin to microetched metal with five newer-generation bonding agents.

The purpose of this study was to determine the shear bond strength of a hybrid composite resin to a nickel-chrome-beryllium (Ni-Cr-Be) alloy, using five of the newer-generation bonding agents: Optibond, All-Bond 2, Prisma Universal Bond 3, Restobond 4, and Amalgambond Plus with HPA. For each bonding system 10 samples of metal were microetched with 50-micron aluminum oxide prior to the placement of the bonding agent and resin. The shear bond strength was tested, and the results showed that Amalgambond Plus with HPA developed the strongest bond at 18.81 +/- 3.924 MPa, followed by All-Bond 2 at 14.33 +/- 3.408, Optibond at 13.97 +/- 1.508, Prisma Universal Bond 3 at 12.51 +/- 1.845, and Restobond 4 at 10.29 +/- 1.407.

Aluminum Oxide↗
PubMedDate not supplied

In vitro comparison of filled and unfilled universal bonding agents of amalgam to dentin.

In this study, four different adhesive amalgam systems were compared(Amalgambond Plus, Amalgambond Plus with HPA, All-Bond 2, and All-Bond 2 with Liner-F) regarding their ability to bond amalgam to freshly prepared dentinal surfaces. The two groups that yielded the highest mean bond strengths, Amalgambond Plus with HPA and All-Bond 2 with Liner-F, were the only two groups in comparison that were not statistically different (P > 0.05). The use of the filled resin bonding agents created significantly higher bond strengths between tooth and freshly triturated amalgam than the unfilled resin bonding agents. Further study is required to determine: a) the exact nature and mechanism of the bonds, and b) clinical in vivo presence and longevity of the bonds.

Analysis of Variance↗