Endotoxin and Gram-negative bacteria in the rat periapical lesions

Yamasaki, Masahiro; Nakane, Akinobu; Kumazawa, Masahiko; Hashioka, Kazuko; Horiba, Naoki; Nakamura, Hiroshi

doi:10.1016/s0099-2399(06)81351-8

Cited by 55 publications

(37 citation statements)

References 18 publications

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“…These events lead to an inflammatory reaction and bone resorption in the periapical region. These facts emphasize the important role of LPS in the pathogenesis of periapical lesions (4,9,10,11).…”

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confidence: 61%

Effect of Calcium Hydroxide on Bacterial Endotoxin In Vivo

Silva

Filho

Leonardo

et al. 2002

Journal of Endodontics

110

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The aim of this study was the histopathological evaluation of apical and periapical tissues in dog teeth that were submitted to bacterial endotoxin, associated or not with calcium hydroxide. After removal of the pulp from 60 premolars, the teeth were divided into four groups and were filled with bacterial endotoxin (group 1), bacterial endotoxin plus calcium hydroxide (group 2), saline solution (group 3), or had induced periapical lesions with no treatment (group 4). After 30 days, animals were killed and the teeth processed histologically. The inflammatory infiltrate, the thickness of the periodontal ligament, and the presence of resorption areas were similar for groups 1 and 4. Groups 2 and 3 were similar to each other. It can be concluded that the bacterial endotoxin caused a periapical lesion and that calcium hydroxide detoxified the lipopolysaccharides in vivo.Improvement in microbiology techniques for culture and identification has shown that root canals in teeth with pulp necrosis and a chronic periapical reaction have a predominance of anaerobic microorganisms (1, 2), especially Gram-negative ones (3). This polybacterial infection is present not only in the lumen of the root canal and dentinal tubules, but also in the apical craters and the entire root canal system (2). Gram-negative microorganisms not only have different virulent factors and produce toxic products and sub-products in apical and periapical tissues, but also contain endotoxin in their cell wall. Endotoxin, which consists of lipopolysaccharides (LPS), is liberated during bacterial cell multiplication or death and is responsible for a series of important biological effects (4, 5). Its action on macrophages (6) triggers the release of a series of inflammatory, bioactive, chemical mediators, or cytokines (5), such as tumor necrosis factor (TNF) (4, 5) and interleukins-1 (5, 7), -6, and -8 (7). Endotoxin also induces fever (8), is mitogenic to B lymphocytes (5), activates the complement system (8) and the metabolism of arachidonic acid (5), and irreversibly adheres to mineralized tissues. These events lead to an inflammatory reaction and bone resorption in the periapical region. These facts emphasize the important role of LPS in the pathogenesis of periapical lesions (4, 9, 10, 11).A survey of the medical literature over the last 10 yr produced 22,450 articles dealing with endotoxin; however only four articles in dentistry (9, 10, 12, 13) evaluated the effects of LPS on apical and periapical tissues using experimental animals.Treatment of root canals in teeth with pulp necrosis and a chronic periapical reaction should not only be concerned with bacterial death, but also the inactivation of endotoxin. Safavi and Nichols (14, 15), Barthel et al. (4), and Olsen et al. (16) studied, in vitro, the effect of calcium hydroxide on bacterial LPS, because LPS may remain in the root canals between intracanal dressing sessions. However, there are no in vivo studies reporting this problem.The purpose of this study was to evaluate histopathologically the ef...

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confidence: 61%

Effect of Calcium Hydroxide on Bacterial Endotoxin In Vivo

Silva

Filho

Leonardo

et al. 2002

Journal of Endodontics

110

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“…A fundamental role in the cause and maintenance of periapical lesions has been attributed to the bacterial endotoxin, lipopolysaccharide (LPS) (1)(2)(3). When released during bacterial multiplication or death, this endotoxin, composed of lipopolysaccharides, causes a series of important biological effects, which lead to an inflammatory reaction (4) and periapical bone resorption (2).…”

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confidence: 99%

“…When released during bacterial multiplication or death, this endotoxin, composed of lipopolysaccharides, causes a series of important biological effects, which lead to an inflammatory reaction (4) and periapical bone resorption (2).…”

mentioning

confidence: 99%

Radiographic Evaluation of the Effect of Endotoxin (LPS) Plus Calcium Hydroxide on Apical and Periapical Tissues of Dogs

Filho

Leonardo

Silva

et al. 2002

Journal of Endodontics

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The aim of this study was the radiographic evaluation of the apical and periapical region of dog teeth submitted to intracanal bacterial endotoxin (lipopolysaccharide, LPS), associated or not with calcium hydroxide. After removal of the pulp, 60 premolars were divided into four groups and were filled with bacterial endotoxin (group 1), bacterial endotoxin plus calcium hydroxide (group 2), saline solution (group 3), or periapical lesions were induced with no treatment (group 4), for a period of 30 days. Similar periapical lesions were observed in groups 1 and 4. The lamina dura was intact in groups 2 and 3. Bacterial endotoxin (LPS) caused radiographically visible periapical lesions, but when associated with calcium hydroxide, this endotoxin was detoxified.A fundamental role in the cause and maintenance of periapical lesions has been attributed to the bacterial endotoxin, lipopolysaccharide (LPS) (1-3). When released during bacterial multiplication or death, this endotoxin, composed of lipopolysaccharides, causes a series of important biological effects, which lead to an inflammatory reaction (4) and periapical bone resorption (2).During the past 20 yr, a high prevalence of Gram-negative anaerobic microorganisms (5, 6) and the chemical structure of bacterial endotoxin commonly found in root canals with radiographically visible periapical lesions has been reported (7). The types of microorganisms and the level of intracanal endotoxin have also been correlated with specific clinical findings (1, 8). However, little research has evaluated the effect on periapical tissues of the inoculation of endotoxin into root canals (9 -12).The medical and dental literature have emphasized research attempting to obtain a medication that could inactivate bacterial endotoxin: examples are caustic soda (9), formocresol (13), 1.2% chlorhexidine (14), and sodium hypochlorite (15). Use of most of these products is limited due to their lack of efficiency or high toxicity, which causes undesirable effects when in contact with tissue.During in vitro research, Safavi and Nichols (16,17), Barthel et al. (3), and Olsen et al. (18) modified the concept of intracanal dressings, showing that calcium hydroxide hydrolyzes lipid A, which is the toxic part of endotoxin. Recently, we reported the histopathological finding of inactivation of the toxic effects of bacterial endotoxin by calcium hydroxide, in vivo (19). However, there are no in vivo radiographic reports of this inactivation. Thus, the purpose of this study was to evaluate radiographically the effect of endotoxin and endotoxin plus calcium hydroxide on the apical and periapical region in dogs. MATERIAL AND METHODSThe methods used for this radiographic study were similar to those used for the histopathologic evaluation of the effect of endotoxin plus calcium hydroxide (19). In a laminar air flow, 100 mg of Escherichia coli endotoxin (lipopolysaccharide B, E. coli 055:B5-Lipid A, 9.2%; Difco, Bacto, Detroit, MI) was suspended in 10 ml of phosphate buffered saline. Half of the 10-mg/ml su...

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“…High level of LPS was obviously toxic to connective tissue and would result in tissue necrosis 40) . A significant correlation has been demonstrated between intracanal LPS contents and specific clinical symptomatology of pulp and periapical tissues [41][42][43] . There are increasing evidences that calcium hydroxide intracanal dressings may alter biological properties of LPS [18][19][20]44) .…”

Section: ⅳ Discussionmentioning

confidence: 96%