* As is known to every dentist or even dental student , The pulp cavity is divided into two main portions: the pulp chamber, located in (or extending to just below) the anatomic crown of the tooth, and the root canal (or canals), found in the anatomic root. Other notable features are the pulp horns; accessory, lateral, and furcation canals; canal orifices; isthmus; fins; apical deltas; and apical foramina. The outline of the pulp cavity generally corresponds to the external contour of the tooth. However, factors such as physiologic aging, pathosis, trauma, and occlusion all can modify its dimensions through the production of dentin or reparative (irregular secondary, irritational, and tertiary) dentin .
In single-rooted teeth, pulp chamber extends to the most apical portion of the cervical margin of the crown; in double/multirooted teeth, it extends to the floor of chamber located in the coronal third of the root.
* ( Pulp horns ) :
The pulp horns are important because the pulp in them is often exposed by caries, trauma, or mechanical invasion, which usually necessitates vital pulp or root canal procedures. Also, the pulp horns undergo rapid mineralization, along with reduction of the size and shape of the pulp chamber because of the formation of reparative/irritational dentin over time.
** ( Morphology of root canal ) :
The root canal begins as a funnel-shaped canal orifice, generally at or just apical to the cervical line, and ends at the apical foramen (AF), which opens onto the root surface at or within 3 mm of the center of the root apex. Nearly all root canals are curved, particularly in a faciolingual direction, thereby posing problems during enlargement and shaping procedures because they are not evident on a standard two dimensional (2D) radiograph. In most cases, the number of root canals corresponds to the number of roots; however, an oval root may have more than one canal.
** ( Accessory canals ) :
Accessory canals are minute canals that extend in a horizontal, vertical, or lateral direction from the pulp space to the periodontium. In 74% of cases they are found in the apical third of the root, in 11% in the middle third, and in 15% in the cervical third. The diameter, length, shape, and undulation may vary among accessory canals. Apical deltas are multiple accessory canals that branch out from the main canal at or near the root apex . Accessory canals contain connective tissue and vessels but may not supply the pulp with sufficient circulation to form a collateral source of blood flow. They are formed by the entrapment of periodontal vessels in Hartwig's epithelial root sheath during mineralization.24 They may play a significant role in the communication of disease processes, serving as avenues for the passage of irritants, primarily from the pulp to the periodontium, although communication of inflammatory processes may occur from either tissue.
Accessory canals that are present in the bifurcation or trifurcation of multirooted teeth are referred to as furcation canals (or chamber canals). These channels form as a result of the entrapment of periodontal vessels during the fusion of the diaphragm, which becomes the pulp chamber floor. In mandibular molars, these canals occur in three distinct patterns. Pulpal inflammation can communicate to the periodontium via these canals and result in furcation lesions in the absence of demonstrable periodontal
disease. Likewise, the long-term presence of periodontal furcation lesions may influence the viability of the coronal or radicular pulp tissue when these aberrant channels are present .
To be continued in the next episode
ممكن فديو يوضح ليما مكان ال canals ف كل teeth ?!
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