ABSTRACT
A new laboratory technique has been developed in an effort to simulate the deterioration processes occurring in dental amalgam restorations while they are exposed to attack by the oral environment and simultaneously subjected to biting forces during mastication. This combined mechanical wear and corrosion action may be one of the major contributors to the degradation of dental amalgam restorations. The technique provides the capability of varying and measuring electrochemical and mechanical parameters during a sliding-wear process in a corrosive environment. A high-copper dental amalgam was selected and tested to demonstrate the applicability of the method in evaluating and studying the effects of the combined action of wear and corrosion processes on dental materials. For the particular amalgam material tested in the present study, it was found that sliding-wear significantly lowered its corrosion potential and increased corrosion rates by at least one order of magnitude.
Subject(s)
Dental Amalgam , Copper , Corrosion , Dental Stress Analysis/methods , Materials Testing/methodsABSTRACT
Volatile short-chain fatty acids (SCFA) in synovial fluid from 80 patients were quantified by gas-liquid chromatography (GLC). Characteristic patterns of volatile SCFA could not be associated with septic, nonseptic inflammatory, or noninflammatory groups. Mean concentrations of pentanoic and hexanoic acids were similar in all groups studied. In the septic arthritis group 3 of 4 patients with acetic acid and of 3 of 3 with 3-methyl butanoic acid had culture-proved staphylococcal infections. In patients with synovial fluid findings consistent with septic arthritis, including markedly raised leucocyte count, decreased glucose level, or detectable succinic acid, the detection of acetic and 3-methyl butanoic acids by GLC analysis may increase the suspicion that Staphylococcus aureus is the cause of the septic arthritis.
Subject(s)
Arthritis, Infectious/metabolism , Fatty Acids, Volatile/analysis , Synovial Fluid/analysis , Arthritis/metabolism , Arthritis, Infectious/microbiology , Caproates/analysis , Chromatography, Gas , Humans , Pentanoic Acids/analysis , Synovial Fluid/microbiologyABSTRACT
Nonvolatile short-chain fatty acids from 80 synovial fluids were quantified by gas-liquid chromatography. Succinic acid was detectable in all 23 septic synovial fluids infected with either gram-positive or gram-negative organisms and in only 5 of 57 nonseptic synovial fluids. Lactic acid was present in all of the effusions but was correlated with septic arthritis only when present in concentrations greater than 250 mg%. Neither short-chain fatty acid was more sensitive than high white blood cell counts (greater than 50,000 mm3) or depressed glucose concentration (less than 40 mg/dl) in diagnosing septic arthritis before antibiotic therapy; however, the detection of succinic acid was helpful in identifying patients with septic arthritis who had been given antibiotic treatment before arthrocentesis. Thus, gas-liquid chromatography, a rapid and sensitive method for the detection of short-chain fatty acids, may complement the currently available methods used to diagnose septic arthritis.
