Comparison of the performance on prosthodontic criteria of several alternative alloys used for fixed crown and partial denture restorations: Department of Veterans Affairs Cooperative Studies project 147.

In a 10-year, multicenter, double-blind clinical trial, comparisons of the clinical behavior of crown and fixed partial denture restorations were made between a gold alloy and four less costly alternative alloys. The endpoints of interest were (1) the development of unacceptable ratings on any of 11 individual prosthodontic criteria and an overall rating, (2) the removal of the restoration, and (3) an event combining unacceptable overall rating and restoration removal. Each of 630 patients had two restorations completed, one from gold-palladium alloy and the other from one of four alternative alloys. The patients were enrolled during a period of 3 1/2 years, with some patients followed up as long as 10 years after restoration. Analysis of the endpoints showed that one of the alternative alloys was significantly poorer than the other materials for certain criteria.

Effect of acute ethanol on esophageal motility in cat.

In man, acute ethanol administration decreases lower esophageal sphincter pressure (LESP), prolongs the duration, and lowers the amplitude of esophageal contractions. These changes may contribute to gastroesophageal reflux and esophagitis. To evaluate the underlying mechanisms of these changes an animal model is needed. Hence, we studied the effect of various doses of ethanol on esophageal motility in cats, an animal with an esophagus similar to man's. Similar to man, intravenous administration of ethanol significantly decreased LESP and amplitude of lower (smooth muscle portion) esophageal contractions. It also prolonged the duration of lower esophageal contractions, even through it had no effect on contraction velocity. The effect of ethanol on upper (striated muscle portion) esophagus was different. Ethanol had no effect on the amplitude of contractions, whereas it prolonged their duration and decreased their velocity. The effect of acute ethanol on LESP in four withdrawing alcoholic cats was similar to controls. However, the acute effect of ethanol on the esophageal contractions was less marked in alcoholics. Bilateral cervical vagotomy and intravenous injection of the neurotoxin tetrodotoxin before the administration of ethanol did not prevent the effect of ethanol on LESP. This data suggests that cat esophagus is a good model for studying the underlying mechanisms of the effects of acute ethanol because its response is similar to the esophagus of man, and the acute effect of ethanol on LESP is not neurally mediated but is the result of its direct effect on muscle.