Objectives: To characterize the prevalence of normal microorganisms on complete upper dentures on successive weeks after insertion reaching a stable condition. Also, to find out the effect of the microwave curing system on the periodic microbiological growth on complete upper dentures and compare them with the results obtained from the water-bath curing method.
Materials and Methods: Ten healthy fully edentulous patients were selected. A comparative micro flora on acrylic resin samples cured by two ways: the water-bath curing method and microwave curing energy. The samples fixed in the fitting surface of complete upper denture. The micro flora were studied during four experimental periods starting from zero time, the time just before the insertion of new complete dentures till the 6th week of denture insertion. The data were analyzed using SPSS software with T-test, and the differences were considered statistically significant at P<0.05.
Results: Various microorganism species isolated from both samples, include streptococci, staphylococci, Gram-positive rods, Gram-negative rods and cocci.
The microwave samples appeared to support significantly more aerobic Gram-positive rods and anaerobic Gram-negative rods, but less aerobic and anaerobic streptococci, Gram-negative cocci, and aerobic staphylococci. No candida growth could be identified before and after denture insertion. In spite of oscillate population of the bacteria, it has been noted it tends to stabilize on two subjects at the 10th week.
Conclusions: It was difficult to decide which one of the either methods of curing acrylic resin is better in harboring fewer microorganisms. The number of both aerobic and anaerobic microorganisms significantly increased as the period of wearing denture is prolonged. Early plaque contains different kinds of bacteria; the majority was Gram-positive rods. No candida growth was detected.
It was considered that the fall in lung function seen after exposure to cotton dust may be attributable in part to the activity of arachidonic acid metabolites, such as leucotrienes as well as to the more established release of histamine by cotton dust. However, we found that cotton and barley dusts elicited poor release of arachidonic acid from an established macrophage like cell line compared with that observed with other organic dusts.In the experimental animal, pulmonary cellular responses to both cotton and barley dust were similar to those evoked by moldy hay and pigeon dropping dusts, although after multiple doses a more severe response was seen to cotton and barley. Since both moldy hay and pigeon droppings elicit a greater arachidonic acid release than cotton or barley, a role for arachidonic acid in inducing the cellular response is less likely than other factors.There are limitations to our conclusions using this system, i.e., the arachidonic acid may be released in a nonmetabolized form, although it is noted that the two dusts with the greatest arachidonic acid release produce their clinical responses in humans largely by hypersensitivity mechanisms.
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