Radiographic and histologic evaluation of the effect of endotoxin on the periapical tissues of the cat

doi:10.1016/S0099-2399(81)80265-8

Journal of Endodontics

Volume 7, Issue 1, 1981, Pages 31-35

https://doi.org/10.1016/S0099-2399(81)80265-8 Get rights and content

The periapical tissue reaction to three concentrations of Escherichia coli endotoxin solutions, to three detoxified E coli endotoxin solutions, and to a sterile saline control solution was examined in ten adult cats. The maxillary and mandibular canines were isolated with a rubber dam, and the pulps were extirpated. The solutions were deposited in the root canals of each cat, and the access cavities were sealed. The periapical tissues were examined histologically and radiographically at 2, 4, and 6 weeks. The radiographic and histologic results indirectly suggest that endotoxins have a part in initiating and perpetuating periapical inflammatory lesions in man.

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Cited by (39)

Local Immunomodulatory Effects of Intracanal Medications in Apical Periodontitis
2022, Journal of Endodontics
Citation Excerpt :
The highly orchestrated interaction between the 2 immune systems ensures an appropriate and effective immune response. Periapical inflammation occurs in response to the egress of bacterial toxins (eg, lipopolysaccharide [LPS] and lipoteichoic acid) and noxious microbial metabolic by-products from the root canal system into the periapical tissues52–54. The innate immune system is activated after the recognition of pathogen-associated molecular patterns (PAMPs) as well as damage-associated molecular pattern molecules (DAMPs) (eg, apoptotic cells and their by-products) via the immune cell pattern recognition receptors, thus initiating an inflammatory cascade by triggering several transcription factors, such as nuclear factor kappa B (NF-kB), with subsequent production of proinflammatory mediators55–58.
The immune system is an extremely complex biological network that plays a crucial role in the hemostasis of periapical tissue, pathogenesis of apical periodontitis (AP), and periapical tissue healing. The successful elimination of microbial infections remains a significant challenge, mostly because of the ever-growing development of antimicrobial-resistant pathogens. The bacterial endurance in the root canal system contributes to features ranging from altered posttreatment healing to exacerbation of chronic periradicular immune response, which compromise the outcome of endodontic treatment. A highly effective strategy for combating infectious diseases and the associated inflammation-mediated tissue damage is to modulate the host immune response in conjunction with antimicrobial therapy. There are several medications currently used in endodontic treatment; however, they suffer various levels of microbial resistance and do not deliver all the required characteristics to simultaneously address both intracanal bacteria and periapical inflammation. The interaction of antimicrobial agents with the immune system can impact its function, leading to immune-suppressive or immune-stimulatory effects. The group of nonconventional antimicrobial medications, such as antimicrobial peptides, propolis, and nanomaterials, are agents that provide strong antimicrobial effectiveness and concomitant immunomodulatory and/or reparative effect without any host tissue damages. In this review, we provide an overview of local immune modulation in AP and a comprehensive review of the immunomodulatory effect of antimicrobial intracanal medications applied in endodontics with specific emphasis on the antimicrobial nanomaterial-based approaches that provide immunomodulatory potential for successful clinical deployment in endodontics.
Pathobiology of the Periapex
2010, Cohen's Pathways of the Pulp, Tenth Edition
Immunologic Reactions and Endodontics: An Online Study Guide
2008, Journal of Endodontics
The Editorial Board of the Journal of Endodontics has developed a literature-based study guide of topical areas related to endodontics. This study guide is intended to give the reader a focused review of the essential endodontic literature and does not cite all possible articles related to each topic. Although citing all articles would be comprehensive, it would defeat the idea of a study guide. This section will cover potential immunological reactions, endotoxin, and cysts versus granulomas.
In vitro effects of endodontic irrigants on endotoxins in root canals
2007, Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontology
Citation Excerpt :
However, treatment of root canals in teeth with pulp necrosis should not only be concerned with bacterial death, but also the inactivation of endotoxin.11,12 Endotoxin has an important role in the inflammatory and immunologic responses of pulpal and periradicular tissues, including bone resorption.7,9,13 The presence of endotoxin in teeth with vital or necrotic pulps has already been proven by many researchers1,17,29; however, few studies have evaluated the effects of irrigation solutions on LPS using teeth as a model system.
The objective of this study was to evaluate the effects of endodontic irrigants on endotoxins in root canals.
Ninety-eight single-root human teeth were used. Escherichia coli endotoxin was inoculated into 84 root canals. All root canals were enlarged and assigned to 7 groups (n = 14), according to solution used. Group 1 (G1): 2.5% NaOCl; G2: 5.25% NaOCl; G3: 2% chlorhexidine; G4: 0.14% calcium hydroxide; G5: polymyxin B; G6: positive control, saline solution; G7: negative control (no endotoxin). Two samplings of root canal were accomplished: immediate and after 7 days. Detoxification of endotoxin was evaluated by Limulus assay and antibody production in B-lymphocyte culture. Results were analyzed by Kruskal-Wallis/Dunn and ANOVA/Tukey.
At the immediate and second samplings, groups G4, G5, and G7 presented the best results, significantly different from groups G1, G2, G3, and G6 (P < .05).
Calcium hydroxide and polymyxin B detoxified endotoxin in root canals and altered properties of LPS to stimulate the antibody production by B-lymphocytes. Sodium hypochlorite and chlorhexidine did not detoxify endotoxin.
Root Canal Irrigants
2006, Journal of Endodontics
Local wound debridement in the diseased pulp space is the main step in root canal treatment to prevent the tooth from being a source of infection. In this review article, the specifics of the pulpal microenvironment and the resulting requirements for irrigating solutions are spelled out. Sodium hypochlorite solutions are recommended as the main irrigants. This is because of their broad antimicrobial spectrum as well as their unique capacity to dissolve necrotic tissue remnants. Chemical and toxicological concerns related to their use are discussed, including different approaches to enhance local efficacy without increasing the caustic potential. In addition, chelating solutions are recommended as adjunct irrigants to prevent the formation of a smear layer and/or remove it before filling the root canal system. Based on the actions and interactions of currently available solutions, a clinical irrigating regimen is proposed. Furthermore, some technical aspects of irrigating the root canal system are discussed, and recent trends are critically inspected.
In vitro effects of calcium hydroxide and polymyxin B on endotoxins in root canals
2005, Journal of Dentistry
To evaluate the effects of intracanal medicaments on endotoxins in root canals.
Seventy-five freshly extracted maxillary incisors were used in this study. The crowns of teeth were sectioned near the CEJ in order to standardize the root length to 14 mm. The root canals were instrumented to an apical size #50 file and irrigated with 1% sodium hypochlorite solution and sterilized with 60 Co gamma irradiation. Standardized suspension containing Escherichia coli endotoxin was inoculated into the 60 root canals. The specimens were randomly assigned to 5 groups (n=15), according to the intracanal medicament used: (G1) calcium hydroxide; (G2) polymyxin B; (G3) combination neomycin–polymyxin B-hydrocortisone; (G4) positive control (no intracanal medicament); (G5) negative control (no endotoxin and no intracanal medicament). After 7 days, the detoxification of endotoxin was evaluated by Limulus lysate assay and antibody production in B-lymphocytes culture.
Groups 1, 2 and 5 presented the best results by Limulus lysate and were significantly different to groups 3 and 4 (p<0.05). Stimulation of antibodies production in cell culture by groups 1 and 6 was smaller and statistically different than groups 2, 3, 4 and 5 (p<0.05). Groups 2 and 5 induced a small increase in the antibodies production in relation to the groups 1 and 6. Groups 3 and 4 induced a significant increase of antibodies production (p<0.05).
The calcium hydroxide and polymyxin B intracanal medicaments detoxified endotoxin in root canals and altered the properties of LPS to stimulate the antibody production by B-lymphocytes. The combination neomycin–polymyxin B-hydrocortisone did not detoxified endotoxin.

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¹: Dr. Dwyer was a graduate student in endodontics, Loma Linda University, School of Dentistry, and is currently practicing endodontics in Upland, Calif.

²: Dr. Torabinejad is associate professor and coordinator of graduate endodontic research, Department of Endodontics, School of Dentistry, Loma Linda University, Loma Linda, Calif 92350.

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Radiographic and histologic evaluation of the effect of endotoxin on the periapical tissues of the cat

J Endod

Release of endotoxin in a experimental model simulating the dental root canal. Oral Surg

Biological effects of bacterial endotoxins in man

J Infect Dis

Biology of endotoxin

Ann Rev Med

and Syverton, J

Effects on monkeys of introduction of hemolytic streptococci into root canals. J Dent Res

Experimental study on focal infection in rabbits by prolonged sensitization through dental pulp canals

Arch Oral Biol

Periapical destructions caused by experimental pulpal inoculation of Streptococcus mutans in rats

Oral Surg

Antibody formation in primates following introduction of antigens into the root canal

J Dent Res

Systemic distribution of lead from root canal fillings

J Endod