Edge-bevel fracture resistance of three direct-filling materials.

Edge strength is defined in this study as the resistance to fracture of the beveled extension normally located at the cavosurface margin of a dental restoration. The edge strength of direct-filling alloy restorations plays an important role in maintaining the integrity of margins at tooth-alloy interfaces during functional loading. The purpose of this study was to determine the relative strength of an experimental consolidated silver material in comparison to other direct filling materials. The method used was designed as a simulation for relative edge-strength clinical properties. Stainless steel dies were formed from disks 5 mm thick, each with a centered hole tapered (1/48) toward the bottom side of the disk. A 41 degrees bevel, 0.5 mm wide as viewed from above, was placed on the top-side of the disk. Dispersalloy (D) or Unison (U) amalgam, Z-100 composite (C), hand-consolidated silver powder (HAg), or pneumatically consolidated silver powder (PAg) was used to fill the die opening. Excess was polished from both sides of the disk with 600-grit abrasive paper. The sample was loaded from the beveled side with a 3 mm-in-diameter flat-ended plunger at a rate of 1.0 mm/minute until failure. Failure load and total energy to failure were recorded and compared. Tukey's multiple comparison test (p < 0.05) ranked the materials (U) > (HAg) > (D) > (PAg) > (C) for fracture strength and (HAg) > (D) > (U) > (PAg) > (C) for fracture energy.

Ma1, a novel neuron- and testis-specific protein, is recognized by the serum of patients with paraneoplastic neurological disorders.

The identification of antineuronal antibodies has facilitated the diagnosis of paraneoplastic neurological disorders and the early detection of the associated tumours. It has also led to the cloning of possibly important neuron-specific proteins. In this study we wanted to identify novel antineuronal antibodies in the sera of patients with paraneoplastic neurological disorders and to clone the corresponding antigens. Serological studies of 1705 sera from patients with suspected paraneoplastic neurological disorders resulted in the identification of four patients with antibodies that reacted with 37 and 40 kDa neuronal proteins (anti-Ma antibodies). Three patients had brainstem and cerebellar dysfunction, and one had dysphagia and motor weakness. Autopsy of two patients showed loss of Purkinje cells, Bergmann gliosis and deep cerebellar white matter inflammatory infiltrates. Extensive neuronal degeneration, gliosis and infiltrates mainly composed of CD8+ T cells were also found in the brainstem of one patient. In normal human and rat tissues, the anti-Ma antibodies reacted exclusively with neurons and with testicular germ cells; the reaction was mainly with subnuclear elements (including the nucleoli) and to a lesser degree the cytoplasm. Anti-Ma antibodies also reacted with the cancers (breast, colon and parotid) available from three anti-Ma patients, but not with 66 other tumours of varying histological types. Preincubation of tissues with any of the anti-Ma sera abrogated the reactivity of the other anti-Ma immunoglobulins. Probing of a human complementary DNA library with anti-Ma serum resulted in the cloning of a gene that encodes a novel 37 kDa protein (Mal). Recombinant Mal was specifically recognized by the four anti-Ma sera but not by 337 control sera, including those from 52 normal individuals, 179 cancer patients without paraneoplastic neurological symptoms, 96 patients with paraneoplastic syndromes and 10 patients with non-cancer-related neurological disorders. The expression of Mal mRNA is highly restricted to the brain and testis. Subsequent analysis suggested that Mal is likely to be a phosphoprotein. Our study demonstrates that some patients with paraneoplastic neurological disorders develop antibodies against Mal, a new member of an expanding family of 'brain/testis' proteins.

Paraneoplastic anti-Hu serum: studies on human tumor cell lines.

Patients with low titers of anti-Hu, the paraneoplastic encephalomyelitis/sensory neuronopathy (PEM/PSN) antibody, have a better tumor prognosis that those who do not harbor these antibodies. Accordingly, we examined the effects of serum from patients with anti-Hu antibodies on human tumor cell lines, in order to determine: (1) if the serum was toxic (growth inhibition or cytolysis) to tumor cells with or without complement, and (2) if anti-Hu antibodies contributed to tumor toxicity. The serum of 14 patients with anti-Hu associated PEM/PSN, 22 patients with small-cell lung cancer (SCLC) without anti-Hu antibodies, and 20 normal individuals were studied. Three cell lines (NT-2, BE(2)-C, and SH.SY5Y) that express Hu proteins, and one cell line (SAOS-2) that does not, were studied. We examined the effects of whole serum, IgG-depleted serum, and purified IgG in the presence or absence of complement. A higher percentage of anti-Hu sera were toxic (71%) compared with sera from anti-Hu negative SCLC patients (23%) (p < 0.0001). No correlation existed between the titer of anti-Hu antibodies and toxicity. The toxic effects were observed in all tumor cell lines including the cell line that does not express Hu antigens. Toxicity persisted in serum depleted of IgG. Purified anti-Hu IgG in the presence and absence of complement, was not toxic. Our findings indicate that anti-Hu serum is toxic for human tumor cell lines, but this toxicity does not appear to be mediated by anti-Hu antibodies.

The indirect aesthetic inlay/onlay.

Tooth-colored inlays and onlays for posterior restorations have gained in popularity, replacing time-honored amalgam or cast gold restorations in patients with high aesthetic concerns. This article discusses the available types of indirect inlay/onlay systems and compares them in relation to their marginal integrity, wear, and overall esthetics. A basic preparation outline is discussed.

Comparison of casting ability of castable ceramic and type III gold.

This study compared the property of castability of a castable ceramic to an American Dental Association-certified type II casting alloy. A wax pattern was made with a manifold-type structure from which monofilament lines projected approximately 5 to 6 mm. The diameter of the nylon lines ranged from 132 micron to 1270 micron. Each pattern was invested and cast according to the manufacturer's specifications. Each casting was divested and measured for length of casting of the monofilament on a measuring microscope. The castable ceramic and type II gold cast completely at diameters of 1270 micron, and 724 micron, but only type II gold cast completely at the 152 micron and 132 micron diameters.

Intracoronal pressure during crown cementation.

A model system was developed which recorded the intracoronal pressure during crown cementation at three locations simultaneously. Peak pressures and residual pressures were greatest with zinc phosphate cement. The zinc oxide-eugenol cement generated the smallest amount of peak and residual pressures. The polycarboxylate cement exhibited an intermediate pressure intensity. The uneven intracoronal pressure in the cement suggests a complex flow pattern capable of developing the separation of phases that earlier work reported. However, the small residual pressure indicates that these internal back pressures appear to play a limited role in preventing a complete seating of a crown.

The relationship of bevels to the adaptation of intracoronal inlays.

The elongation of Types II and III gold alloys ranges from 20 to 35 per cent. It has therefore been proposed that a nonbeveled margin could be "pulled" (elongation) to close the margin. However, in clinical practice, it is difficult to pull gold over an unsupported space to close the margin. Furthermore, the thin area of gold that would be pulled toward the margin could easily be sheared or abraded during finishing. Malleting or swaging a beveled margin is a more sucessful technique of adapting cast gold to the cavosurface angles.