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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
Results - Discussion - References.



Results.
Of the151molars,16 (10.6%) exhibited C-shaped canals. Five molars presented a continuous C-shaped canal (category I), and three had a semicolon shape (category II) with a mesial canal located on the buccal or lingual side (depending on where the fusion occurred). In one instance, this canal swung back and merged with the distal canal, thus yielding a single foramen; in the other two cases, it remained distinctwith itsownportal of exit. The remaining eight were considered as category III, amongst those: two were subdivision I; two were subdivision II; and the remaining four were subdivision III.

Discussion.
Previously reported di!erences in the root-canal anatomy of mandibular second molars may be owing to the population fromwhich the teethwere chosen. If a Caucasian population were studied, then predominantly tworooted mandibular second molars could be expected (Ainamo & Loe 1968,Tamse & Ka!e 1981,Vertucci 1984, Weine et al. 1988), whereas if an Asian or Mongoloid population were examined then a higher number of teeth would be single-rooted (Kotoku 1985, Walker 1988). Single-rooted mandibular second molars have been reported less frequently (Kotoku 1985, Yang et al. 1988,Walker1988,Weine et al.1988), and the canal types have not been fully investigated.
A radiographic study (Weine et al. 1988) of three single- rooted specimens found one to have a single canal and two to be C-shaped, and photographs from another study (Walker 1988) of selected specimens that were cleared showed the complex anatomy characteristic of single-rooted specimens. In the current investigation, a variety of canal types was found, with category I representing almost one-third of the sample.
Cooke & Cox (1979) stated that it was impossible to diagnose C-shaped canals on the preoperative radiograph. In this study, almost all preoperative radiographs of category I, II, and III (subdivision I) showed common characteristics that provided a typical image and allowed identi¢cation of this anatomical condition. In fact,most radiographs revealed radicular fusionorproximity, a large distal canal, a narrow mesial canal, and a blurred image of a middle third canal (Fig. 3A).
Weine et al. (1988) advised placing ¢files inthe canals to determine canal configuration of the mandibular second molar. However, using a radiograph showing ¢les set to the canal terminus to diagnose and to determine canal morphology may not give the results expected. In some instances, it may be di⁄cult to distinguish between C-shaped canal or one with single or three canals joiningapically. Thus, itwas necessary to con¢rm the diagnosis by exploring the access cavity. Two types of root-canal orifices were observed.

  1. A complete C-shaped orifice located either on the buccal or lingual aspect of the £oor, that extended from the usual locationof the distal canal to the usual location of the mesial canals (Fig.7).
  2. Two or three orifices: a C-shaped orifice extending from distal to mesiobuccal ina buccal position separated with dentine from an independent mesiolingual orifice, or from distal to mesiolingual in a lingual positionwith an independent mesiobuccal orifice. Some teeth had onemesialand one distal orifice, and one orifice between the two (Fig. 8).

Figure 7. C-shaped chamber floor showing a complete C-shaped root-canal orifice in the formof a deep trough connecting the distal, mesiobuccal andmesiolingual canal orifices.

C-shaped chamber floor showing a complete C-shaped root-canal orifice in the formof a deep trough connecting the distal, mesiobuccal andmesiolingual canal orifices

Figure 8. C-shaped chamber ?floor of mandibular second molar with mesial, distal, andmidbuccal canal orifices are seen.

C-shaped chamber ?floor of mandibular second molar with mesial, distal, andmidbuccal canal orifices are seen

In the present study, all root canals that conformed to the general structure of a‘C’and occurred in a C-shaped root were described as C-shaped root canals, whether or not a separate canal or orificewas observed.The classi¢ cation system of canal types described by Melton et al. (1991) was modi¢ed and used to describe the canal system in C-shaped roots. In type I canal, a single canal is present fromorifice totheapex; thishasbeen described as a true C-shaped canal. Other more complex canal types were found in C-shaped roots; category III (subdivision III), the type with three canals, which did not necessarily combine, occurred most frequently.
The root-canal anatomyof teeth froma Chinese population with the C-shaped canals has been reported previously (Yang et al.1988), when ¢rst and second molars were examined using a transparent technique (Robertson et al. 1980). The C-shaped roots occurred in 31.5% of second molars. They found that roots with separate canal orifices formed separate canals as well as true Cshaped canals.The latter, which were described as roots having a C-shaped canal from the orifice to the apex, occurred in 7.4% of the sample of mandibular second molars. Manning (1990) found that, amongst 19 teeth, three (10%) had true C-shapes. Haddad et al. (1999) reported that true C-shaped canals with a single swath of canal were the exception rather than the rule. In the present study, from approximately the same number of teeth, ¢ve teeth exhibited this form.
In this study, all patients showing category III con¢- guration were under 40 years of age. This is in contrast to the observation of Manning (1990) that age-related deposition of dentine formed separate canals. Manning (1990) also reported that category III (subdivision III) systems occurredmost frequently,which is inagreement with this study. Melton et al. (1991) reported that the Cshaped canals had various configuration at di!erent root levels; this was particularly true in all category III canals.
The study of the incidence of C-shaped canals in the mandibular second molars using radiographic techniques might appear to have certain disadvantages. Only a 2D image of the tooth is seen and conceivably both roots and root canals can bemissed. However, clinically it remains the only noninvasive method available, and bystrictlyadhering to the radiographic criteria for determining the incidence of C-shaped canals in themandibular second molars, the ¢ndings of this study were in good accordwiththose of other recent studies using various techniques.
The frequency obtained in this investigation (10.6%) lies between the 31.5% frequency reported byYang et al. (1988) and the 2.7% frequency reported byWeine et al. (1988).The geographical position of Saudi Arabia in particular and theMiddle East, ingeneral,may be the explanation for this phenomenon. However, further studies would be necessary to con¢rm this phenomenon.

References.

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