Pathogenesis of Apical Periodontitis and the Causes of Endodontic Failures

Abstract

Apical periodontitis is a sequel to endodontic infection and manifests itself as the host defense response to microbial challenge emanating from the root canal system. It is viewed as a dynamic encounter between microbial factors and host defenses at the interface between infected radicular pulp and periodontal ligament that results in local inflammation, resorption of hard tissues, destruction of other periapical tissues, and eventual formation of various histopathological categories of apical periodontitis, commonly referred to as periapical lesions. The treatment of apical periodontitis, as a disease of root canal infection, consists of eradicating microbes or substantially reducing the microbial load from the root canal and preventing re-infection by orthograde root filling. The treatment has a remarkably high degree of success. Nevertheless, endodontic treatment can fail. Most failures occur when treatment procedures, mostly of a technical nature, have not reached a satisfactory standard for the control and elimination of infection. Even when the highest standards and the most careful procedures are followed, failures still occur. This is because there are root canal regions that cannot be cleaned and obturated with existing equipments, materials, and techniques, and thus, infection can persist. In very rare cases, there are also factors located within the inflamed periapical tissue that can interfere with post-treatment healing of the lesion. The data on the biological causes of endodontic failures are recent and scattered in various journals. This communication is meant to provide a comprehensive overview of the etio-pathogenesis of apical periodontitis and the causes of failed endodontic treatments that can be visualized in radiographs as asymptomatic post-treatment periapical radiolucencies.

Apically extruded debris in filling removal of curved canals using 3 NiTi systems and hand files

“…However, complete bone healing may not occur even in a well-done endodontic treatment (1). In these cases, as simulated in the present investigation, removing the well-condensed filling material is more laborious and instrument deformation or fracture may occur.…”

“…Cases of unresolved post-treatment periapical radiolucency are referred to as "endodontic failures" (1). Even when the highest standards of canal disinfection and filling are met, failures can occur because of the anatomical complexity of the root canal system (2).…”

Avaliação do metabolismo epitelial em cistos radiculares pela técnica de AgNORS

“…As periodontites apicais se originam pela colonização progressiva de microrganismos e seus produtos nos tecidos periapicais, provenientes da infecção e da necrose pulpar em decorrência da cárie dentária 2,3 . Os CRs são os mais comuns dos cistos maxilares 1 e representam de 6% a 55% das periodontites apicais 4 .…”

“…Dentre estes fatores, podem-se citar citocinas inflamatórias, como as interleucinas 1 e 6 (IL-1a, IL-1b, IL-6), e o Fator de Necrose Tumoral (TNF) 3 . Devido a isso, a primeira linha de tratamento para os CR é o tratamento endodôntico, para eliminar a inflamação presente e permitir a involução da lesão [4][5][6][7] .…”

Mesenchymal Stem Cells from Periapical Lesions Upregulate the Production of Immunoregulatory Cytokines by Inflammatory Cells in Culture / Mezenhimske matične ćelije iz periapeksnih lezija stimulišu produkciju imunoregulacijskih citokina od strane inflamacijskih ćelija u kulturi

“…As a result of descending bacterial invasion and inflammation, necrosis of dental pulp arises followed by spreading the inflammatory process to periapical dental tissues and generation of periapical lesions (PLs) (1). Chronic PLs stand for granulomatous inflammation, where the process of exacerbation (symptomatic PLs) and their restriction (asymptomatic PLs) are present (2).…”