Inquiry

Apical periodontitis

Background

Studies find that apical periodontitis is caused by microbial agents from an infected root canal system. Treatments have been developed to counter these agents, but because of the diversity of the endodontic microbiota and the current poor understanding about specific bacterial species, the role of these organisms remains a mystery. A review was undertaken to summarize the state of knowledge about the microorganisms that contribute to apical periodontitis, identify targets for future research,

Methods

The Dentistry and Oral Sciences Source (EBSCO) and Medline electronic databases were searched for English language articles published between 1995 and 2015 dealing with apical periodontitis and its microbiological ties. A hand search of articles was also conducted. The results of the search were divided into etiologic concerns and identification of species, pathogenesis of apical periodontitis, and treatment implications.

Etiologic Concerns and Identification of Species

Various studies in animals have confirmed that the role of microorganisms in the development of apical periodontitis is essential. The pathogenicity of the species involved is enhanced when more than one is present.

The specific bacteria dwelling in root canal infections were predominantly anaerobic, with facultative anaerobes found in the more coronal aspect of the system and obligate anaerobes found apically. The survival of these species depends on the availability of nutrients, oxygen level,

Pathogenesis of Apical Periodontitis

Complex interactions between the microbial factors and host defenses responding to the bacterial invasion produce apical periodontitis. The specific pathogenicity of the invading species is modified by bacterial interactions, host evasive actions, the release of lipopolysaccharides (LPS), and the production of proteolytic enzymes.

Microbes grow and avoid detection until the community is large enough to cause host destruction by interfering with host defenses. Porphyromonas gingivalis appears

Treatment Implications

The primary aim of endodontic therapy is the eradiation or reduction of microbial organisms. Recent research has focused on how efficacious disinfection of the root canal is. Proper shaping, disinfection, and obturation of the entire length of each canal are important in reducing the number of bacterial species present. Apical enlargement improves bacterial reduction, but weakens roots, causes difficulty with obturation, and introduces problems related to excessive loss of radicular dentin