Clinical assessments of dental amalgam restorations.

In assessing the performance of amalgam restorations in most clinical studies, the significant factor to evaluate is marginal fracture. The clinical relevance of marginal fracture is reflected in its relationship to the presence of secondary caries. Furthermore, whereas most other failures can be avoided by proper operator technique, marginal fracture is an inherent deficiency of amalgam restorations.

Marginal fracture of amalgam: effect of type of tooth and restoration class and size.

In this study of the marginal fracture of clinical amalgam restorations, it was found that restoration class or size did not influence fracture behavior, and a contralateral pair design was not found to be necessary. However, a slight effect was found for tooth type.

A predictive model for the clinical marginal fracture of amalgam.

The relationship of clinical marginal fracture to creep and zinc content of amalgam alloys was examined. Using multiple regression analysis, a predictive equation was found which produced an excellent fit to the experimental data (R2 = .944).

Clinical performance of a gold-containing amalgam.

In this study, the clinical performance (marginal fracture) of a gold-containing amalgam was compared to five traditional gamma 2-containing amalgams and one non-gamma 2 amalgam. The results showed that the performance of this gold-containing amalgam was bettered by the non-gamma 2 amalgam and four of the five gamma 2-containing amalgams. A microprobe evaluation of a five-year-old clinical restoration made from this alloy revealed an unusual corrosion pattern.

The effect of time on the marginal fracture behaviour of amalgam.

In this study the effect of time on the marginal fracture behaviour of amalgam was determined. Six alloys in clinical service for up to 6 years were used as a data base and occlusal photographs were categorized according to a standard set of photographs depicting varying degrees of marginal fracture. The standard set of photographs was assigned a linear numerical scale, and the index of extent of fracture was considered to be an arithmetic mean based on this linear scale.

The effect of the operator on the clinical performance of amalgam.

In this study, the effect of the operator on the clinical performance of amalgam was examined by evaluating the marginal fracture characteristics of four alloys placed by four operators. The results were as follows: --Marginal fracture was influenced by the operator. Therefore, careful attention should be given to the cavity design and the placement technique.

Creep versus microstructure of gamma2-containing amalgams.

An analysis of the relationship between creep and microstructural characteristics of several gamma2-containing amalgams showed the grain size of the Ag-Hg phase (gamma1) to be a predominant factor influencing creep. When gamma1 grain size is increased, creep is reduced.

Cortisol and GH responses to D- and L-amphetamine in monkeys.

Equimolar doses of D-amphetamine and L-amphetamine, and a water placebo were injected intravenously on different days into rhesus monkeys, and their plasma cortisol and GH responses were determined over a 3-hour period. D- and L-amphetamine (but not the placebo) equally suppressed plasma cortisol concentration and equally increased plasma GH concentration. Pretreatment of the monkeys with large doses of pimozide, a specific dopamine receptor blocker, did not appear to block the hormonal responses to either isomer of amphetamine.

Vinblastine-induced precipitation of microtubule protein.

Vinblastine quantitatively precipitates a protein from supernatants obtained from high-speed centrifugation of homogenates of HeLa cells and of pig brain. This protein migrates as a single band on gel electrophoresis, has a mobility identical to that of purified microtubule protein, and-like microtubule protein-binds colchicine. The precipitation is partially inhibited by 0.

Induction in vitro of microtubular crystals by vinca alkaloids.

The addition of vinblastine or vincristine to solutions of pure microtubule protein or to supernatants from high-speed centrifugation of rabbit-brain homogenates results in the formation of a fine precipitate. Examination of this precipitate by electron microscopy reveals ordered structures with areas of ladder-like configuration.