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Azerbaycan Saytlari

 »  Home  »  Endodontic Articles 6  »  C-shaped root canals in mandibular second molars in a Saudi Arabian population
C-shaped root canals in mandibular second molars in a Saudi Arabian population

K. S. Al-Fouzan
Dental Department, King Fahad National Guard Hospital, Riyadh, Kingdomof Saudi Arabia.

Athorough knowledge of the anatomy of teeth involved in root-canal treatment is essential for successful debridement and obturation of the root-canal system. Recognition of unusual canal configurations and variations are paramount, because it has been established that the rootwith a single tapering canal and apical foramen is the exception rather than the rule (Abou-Rass et al. 1980).
Of particular interest is the canal configuration of the mandibular second molar as a great deal of variation can occur, C-shaped canals are common (Cooke & Cox 1979) with the presence of a thin ¢n connecting the root canals being the main anatomical feature (Barril et al. 1989). Once recognized, the C-shaped canal provides a challenge with respect to debridement and obturation, especially because it is unclear whether the C-shaped orifice found on the £oor of the pulp chamber actually continues to the apical third of the root.
The shape and the number of roots are determined by Hertwig’s epithelial sheath, which bends in a horizontal plane below the amelocemental junction and fuses in the centre leaving openings for roots (Orban & Mueller 1929). Fused rootsmay formeither bycoalescenceowing to cementum deposition with time, or as a result of failure of Hertwig’s epithelial sheath to develop or fuse in the furcation area (Pederson 1949). A C-shaped canal appears when fusion of either the buccal or lingual aspect of the mesial and distal roots occurs. This fusion remains irregular, and the two roots stay connected by an interradicular ribbon (Barnett 1986, Barril et al. 1989).The pulp chamber has a single ribbon-shaped ori- ¢cewitha1808arc fromthe distal tomesial canal (Cohen & Burns 1994). The £oor of the pulp chamber is deep and has an unusual anatomical appearance (Barnett 1986).Two or three canals may be found inthe C-shaped groove, or the C-shape may be continuous throughout the length of the root.
The mandibular second molars with C-shaped canals vary in their configuration (Yang et al. 1988, Melton et al.1991). Clearly, the recognition of these configurations facilitates cleaning, shaping, and obturation (Rice & Gilbert 1987). Preoperative radiographs demonstrate close fused roots or images of two distinct roots. This occurs when the ¢n is thin and thus, not visible on the X-ray and makes clinical recognition of the C-shaped canal unlikely until access to the pulp chamber has been achieved (Barril et al. 1989). Radiographs takenwhilst negotiating the root-canal systemmay suggest suchanatomyas theycanreveal two characteristics: instruments tending to converge at the apex (Rice & Gilbert 1987) or instruments appearing both clinically and radiographically to be centered and appearing to be exiting the furcation (Fig.1).This cancause confusion and initiate a search for a perforation (Barril et al. 1989, Melton et al.1991).
The C-shaped canals were ¢first documented by Cooke & Cox (1979) in three case reports. Similar reports have since been published (Wells & Bernier 1984, Rabie 1985, Barnett 1986). Endodontic textbooks state that the Cshaped canal is not uncommon (Walton & Torabinejad 1996) and this is con¢rmed by studies in which frequencies ranging from 2.7 to 8% have been reported (Cooke & Cox 1979,Weine et al.1988). Although it is not speci¢- cally stated, these ¢gures probably relate to teeth of Caucasoid origin with an absence (Ainamo & Loe 1968, Tamse&Ka!e1981,Vertucci1984)ornearabsence (Weine etal.1988) of C-shaped canals. Investigations of the rootcanal anatomy of mandibular second molars conducted onJapanese (Kotoku1985), Chinese (Yang et al.1988) and Hong Kong Chinese (Walker 1988) populations showed a high incidence of C-shaped canals (31.5%). It has thus been established that this particular anatomy is more frequent in Asians than inother racial groups (Manning 1990).No dataareavailable onthe incidence of this canal configuration in the Saudi Arabian population.
This study was undertaken to provide information on the distribution of C-shaped canal anatomy, to establish a classi¢cation for the most common configurations, and to determine its frequency in a sample representing the Saudi population.

Figure 1. Radiographwith instruments in root canals for working length determination. (A) Instruments tend to converge at the apex and (B) instruments appear to perforate the furcation.

Radiographwith instruments in root canals for working length determination