Abstract
New knowledge of the structure and biological activity of endotoxins (LPS) has revolutionized concepts concerning their mechanisms of action and forms of inactivation. Since the 1980's, technological advances in microbiological culture and identification have shown that anaerobic microorganisms, especially Gram-negative, predominate in root canals of teeth with pulp necrosis and radiographically visible chronic periapical lesions. Gram-negative bacteria not only have different factors of virulence and generate sub-products that are toxic to apical and periapical tissues, as also contain endotoxin (LPS) on their cell wall. This is especially important because endotoxin is released during multiplication or bacterial death, causing a series of biological effects that lead to an inflammatory reaction and resorption of mineralized tissues. Thus, due to the role of endotoxin in the pathogenesis of periapical lesions, we reviewed the literature concerning the biological activity of endotoxin and the relevance of its inactivation during treatment of teeth with pulp necrosis and chronic periapical lesion.
Highlights
Bacterial endotoxin (LPS) has been amply studied
Interest in knowledge concerning the structure of bacterial endotoxin, its mechanism of action, and forms of inactivation in both the clinical and laboratory studies is obvious by the fact that in the past 10 years, a total of 28.100 articles have been reported on Medline
In Dentistry, much research using different in vivo and in vitro methodologies has emphasized the importance of anaerobic bacteria and endotoxin in the etiology of chronic periapical lesions[3,9,13,19,21,25,36,42,52,57,63]
Summary
Bacterial endotoxin (LPS) has been amply studied. interest in knowledge concerning the structure of bacterial endotoxin, its mechanism of action, and forms of inactivation in both the clinical and laboratory studies is obvious by the fact that in the past 10 years, a total of 28.100 articles have been reported on Medline Considering the discussed above, the major objective of the dental professional during treatment of root canals of permanent teeth with pulp necrosis and chronic periapical lesion should not be only bacterial death, and the inactivation of lipid A, which is the toxic portion of endotoxin. This objective is not reached by using root canal antibacterial dressings, which only kill the bacteria remaining in the root canal system after biomechanical preparation. The action of laser on periapical bacterial biofilm has been tested[2], its use is limited by the fact that there is no free access to the sites where the endotoxin is present, the root canal system of infected teeth, except when apical surgery is performed
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