Fate of the Tissue in Lateral Canals and Apical Ramifications in Response to Pathologic Conditions and Treatment Procedures

By Ricucci D, Siqueira J

Date: 10/2011
Journal: JOE

•Lateral and apical ramifications are formed after a localized fragmentation of epithelial root sheath develops, and a small gap is left in place. Also when blood vessels running from the dental sac through the dental papilla persistently.

•Can be seen throughout the root but most commonly seen in the apical third in posterior teeth

73.1% seen in apical third overall

•Lateral canals are not usually filled during RCT.  Filling of lateral canals is not always necessary for a successful root canal treatment. (Camps and Lambruschini, 1991)

•No study revealed any relationship between unfilled lateral canals and status of PA inflammation (Barthel et al 2004). However, lateral canals and apical ramifications have been implicated to cause RCT failure if they are sufficiently large to harbor enough bacteria and provide access to the periradicular are. (Seltzer et al , 1967)

•Therefore, disinfection of lateral canals and apical ramification sin cases of pulpal necrosis and apical and/or lateral periodontitis should be considered. Forcing materials into these canals and sealing them is still debatable, and there is no evidence yet to support it.

Considerations based on clinical observations:

•Lateral and apical ramifications are not visible on pre-operative radiographs and their presence can only be assumed through different observations. i.e. localized thickening of PDL laterally, presence of lateral periodontitis, after RCT when sealer flows into lateral canals.

•Lateral canals foramina’s are usually 2-3 times smaller than the major apical foramen (average up to #20). Therefore, a definite lateral lesion indicates the presence of a significantly large lateral canal with sufficient necrotic tissue to give rise to periodontitis.

•Lateral lesions have been observed to heal after RCT. This is attributed to the fact that thee bacterial content of the main canal has been removed. This interrupts the aggression caused to the tissue in ramification and accumulation of bacterial products flow through lateral canals up to the PDL. (Fig.2)

Histopathologic and histobacteriologic observations:

•N = 493 human teeth screened for the presence of lateral canals and/or apical ramifications

•Sample included intact, carious, restored teeth and apical periodontal lesion was still attached

•Overall frequency of lateral canals and/or apical ramifications was 75%, and up to 80% in molars and maxillary premolars

Considerations based on histopathologic observations:

•In vital teeth, lateral canals remained vital as long as the main canal was vital even in cases of carious pulp exposure. (Fig.4)

•Pulp exposure to bacteria aggravates inflammation, vascular events take place including vasodilation and increased permeability. This results in exudation which leads to edema and increase in tissue pressure. Stagnation of blood flow promotes increased viscosity and impairs removal of waste products leading to cell death and tissue necrosis.

•When pulp necrosis reached the level of entrance of lateral canals and apical ramifications, tissue within was partially or completely necrotic. Interestingly, the PDL at the exit of these canals was free from inflammation.

•In periodontal disease cases, when subgingival biofilm reached a lateral canal, the corresponding microcirculation was severed but inflammation of the adjacent pulp tissue was minimal. When subgingival biofilm reached main apical foramen, the whole pulp became necrotic.

Teeth subjected to Endodontic procedures:

•Chemo-mechanical preparations partially removed necrotic tissue from the entrance of the ramifications. Adjacent tissue remained inflamed and associated with lateral and/or apical disease.

•In cases with long standing pulp necrosis and complex internal anatomy, necrotic tissue and bacteria in ramifications remained untouched.

•For vital cases, lateral canals and ramifications was never removed by chemo-mechanical preparation and appeared free of inflammation most of the time.

Root canal treated teeth:

Vital Cases: •Canals were not filled. Tissue within remained vital. No significant influence on the outcome. (Fig.11)

• Canals were not actually filled, despite the RG appearance, and had damaged and inflamed tissue around and adjacent to filling material.

Necrotic Cases:

•Canals that were not filled showed necrotic tissue

•Canals that were filled showed them actually not filled, and necrotic debris with varying degrees of inflammation ere present.

•Filled canals: histologic sections shows the lateral canal not actually filled, with islands of residual tissue. (Fig.12)

Conclusion:

1.Tissue within ramifications remain relatively unaffected by instruments and irrigants after chemo-mechanical preparation, regardless of the preoperative pulp conditions

2.In cases with vital pulp, forcing obturation materials into lateral canals caused unnecessary damage to the tissue, with consequent inflammation

3.Material that radiographically appears in the lateral canals and apical ramifications was forced into these areas, but this by no means indicates that the ramification is sealed or disinfected

4.Because bacteria located in large ramifications might reach sufficient numbers to cause or maintain disease, strategies other than finding a technique that better squeezes sealer or gutta-percha within ramifications should be pursued to effectively disinfect these regions and optimize the treatment outcome.