Successful root canal treatment depends on the thorough management of the canal anatomy.
The use of periapical radiographs is essential to identify and monitor the canal's morphological variations. The C-shaped single canaled man-dibular 2nd molar probably requires a different regimen of treatment from the two rooted, three canaled version, as it is rare.
Because of the importance of its true diagnosis and treatment, a comprehensive review of published information and investigations about it in addition to approaches for its treatment is necessary. Int J Clin Pediatr Dent ;7 1 The C-shaped canal, which was first documented in endodontic literature by Cooke and Cox in , is so named for the cross-sectional morphology of the root and root canal.
Below the orifice level, the root structure can harbor a wide range of anatomic variations.
These can be classified into two basic groups: 1 those with a single, ribbon-like, C-shaped canal from orifice to apex and 2 those with three or more distinct canals below the C-shaped orifice. Fortunately, C-shaped canals with a single swath of canal are the exception rather than the rule.
The shape and the number of roots are determined by Hertwig's epithelial sheath, which bends in a horizontal plane below the cementoenamel junction and fuses in the center leaving openings for roots. Melton et al in proposed the following classification of C-shaped canals based on their cross-sectional shape Fig. Category I : Continuous C-shaped canal running from the pulp chamber to the apex defines a C-shaped outline without any separation.
Category II : The semicolon-shaped orifice in which dentine separates a main C-shaped canal from one mesial distinct canal. Subdivision I : C-shaped orifice in the coronal third that divides into two or more discrete and separate canals that join apically.
Subdivision II : C-shaped orifice in the coronal third that divides into two or more discrete and separate canals in the midroot to the apex. Subdivision III : C-shaped orifice that divides into two or more discrete and separate canals in the coronal third to the apex.
Fan et al 8 in modified Melton's method of classi-fication into the following categories Fig. Category V C5 : No canal lumen could be observed which is usually seen near the apex only. Fan et al classified C-shaped roots according to their radio-graphic appearance into three types Figs 3A to C :.
Type I : Conical or square root with a vague, radiolucent longitudinal line separating the root into distal and mesial parts.
C shaped canal pdf merge
There was a mesial and a distal canal that merged into one before exiting at the apical foramen foramina. Type II : Conical or square root with a vague, radiolucent longitudinal line separating the root into distal and mesial parts. There was a mesial and a distal canal, and the two canals appeared to continue on their own pathway to the apex.
Type III : Conical or square root with a vague, radio-lucent longitudinal line separating the root into distal and mesial parts. There was a mesial and a distal canal, one canal curved to and superimposed on this radiolucent line when running toward the apex, and the other canal appeared to continue on its own pathway to the apex.
The frequency of C-shaped canals varies greatly among different ethnicities. Gulabivala et al, in , using a canal staining and tooth clearing technique, reported the incidence of At the same time, Al-Fauzan indicated the incidence of Endodontic textbooks state that the C-shaped canal is not uncommon and this is confirmed by studies in which frequencies ranging from 2.
This configuration is a significant ethnic variation in the incidence of C-shaped molars. It is seldom found in white people and is much more common in Asians than in whites.
This variation may occur in mandibular first molars, maxillary molars, mandibular first premolars, and even in maxillary lateral incisors, but it is most commonly found in mandibular second molars 2 Fig. The preoperative awareness of a C-shaped canal configuration before treatment can facilitate effective management.
The latter sometimes may resemble a perforation of the furcation.
This radiographic appearance is more likely to occur in category I continuous. Recent research used a spiral computed tomography Fig. Although the radiographic contrast medium can enhance the radiopacity of target tissue images against other surrounding tissues, sometimes the enhancement is insufficient to make those thin, fine, or small structures discernible. The pulp chamber in teeth with C-shaped canals may be large in the occlusoapical dimension with a low bifurcation.
Alternatively, the canal can be calcified, disguising its C-shape. At the outset, several orifices may be probed that link up on further instrumentation Fig. In a true C-shaped canal, it is possible to pass an instrument from mesial to distal aspect without obstruction. The access cavity for teeth with a C-shaped root canal system varies considerably and depends on the pulp morphology of the specific tooth. Initial canal-system recognition occurs after achievement of routine endodontic access and removal of tissue from the pulp chamber.
If a C-shaped root is present, two of Melton's three categories category I and II should be evident in category III, two or three separate canals may appear initially as a typical three-canal orifice mandibular molar. In all categories, the mesiobuccal and distal canal spaces usually can be prepared normally. Also, Gates-Glidden burs should not be used to prepare the mesiobuccal and buccal isthmus areas.
Because of the large volumetric capacity of the C-shaped canal system, housing transverse anastomoses and irregularities and continuous circumferential fling along the periphery of the C canal is irrigated with copious amounts of 5. If hemorrhaging persists, then ultrasonic removal of tissue or placement of calcium hydroxide may be used between appointments to enhance tissue removal and control hemorrhage. Alternative canal cleaning techniques, such as those that use ultrasonics, would be more effective.
An increased volume of irrigant and deeper penetration with small instruments using sonics or ultrasonics may allow for more cleansibility in fan-shaped areas of the C-shaped canal.
Obturation of C-shaped canals may require technique modifications. The mesiolingual and distal canal spaces can be prepared and obturated as standard canals.
However, sealing the buccal isthmus is difficult if lateral condensation is the only method used. Because this isthmus may not be prepared with a sufficient fare to permit deep placement of the spreader, application of thermoplasticized gutta-percha is more appropriate.
The clinician must be aware of the impact this anatomy has when surgical endodontics is indicated. The absence of furca contraindicates hemisection or root amputation. The intercanal communications or fins visualized on the serial sections reinforce the difficulty the clinician would encounter after apicoectomy with the retropreparation and eventual retrofilling.
Technique modification may be required for restoration of C-shaped roots. If post placement for a crown core is desired, use of only the distal canal should be considered. Proper post-canal adaptation and stress distribution is more likely to result in the tubular distal canal. Placement of posts or antirotational pins in the mesiolingual and mesiobuccal areas of C-shaped root invites perforation. Also, post width should be minimized.
It should be remembered that there is a higher risk of root perforation at the thinner lingual walls of C-shaped canals during shaping and post space preparation procedures. Both buccal and lingual canal walls are frequently narrower at mesial locations. Restorations with failure in the furca have a poor prognosis.
If the failure results from an apical etiology and apical surgery is not possible, viable options include extraction, extraoral retrofilling and replantation. Because C-shaped roots generally are conical, they are easy to extract without fracture.
Anatomic and Diagnostic Challenges of C-Shaped Root Canal System
When sound principles of cleaning and shaping, obturation and restoration are followed, the long-term prognosis for the C-shaped root retention equals that of other molars, but cautious optimism would seem most appropriate when prognosticating the success of the root canal treatment of a C-shaped canal.
The early recognition of these configurations facilitates cleaning, shaping and obturation of the root-canal system. It should be noted that using a radiograph showing files set to the canal terminus to diagnose and to determine canal morphology may not give the results expected. In some instances, it may be difficult to distinguish between C-shaped canal or one with single or three canals joining apically.
Thus, it is necessary to confirm the diagnosis by exploring the access cavity. Knowledge and recognition of canal configuration facilitates more effective canal identification and unnecessary removal of healthy tooth structure in an attempt to search for missing canals.
All the cases were treated in multiple sittings to rule out the possibility of a missed canal.
endodontic treatment c shaped and confluence canal mandibular molar perforation MTA one curve
National Center for Biotechnology Information , U. Int J Clin Pediatr Dent.
Published online Apr Author information Article notes Copyright and License information Disclaimer. Corresponding author. Received Sep 3; Accepted Sep This work is licensed under a Creative Commons Attribution 3.
Keywords: Tooth anatomy, C-shaped canal, Mandibular 2nd molar, Root canal treatment. ETIOLOGY The shape and the number of roots are determined by Hertwig's epithelial sheath, which bends in a horizontal plane below the cementoenamel junction and fuses in the center leaving openings for roots.
Open in a separate window. Classification of C-shaped root canal configuration according to melton.
Fan's Classification Radiographic Classification 9 Fan et al classified C-shaped roots according to their radio-graphic appearance into three types Figs 3A to C :. Figs 3A to C. Clinical appearance of a C-shaped canal configuration in mandibular second molar. Figs 5A and B.
Radiographic appearance of a C-shaped canal configuration in mandibular second molar. CBCT image of C-shaped canal system in both mandibular left and right molar teeth. Footnotes Source of support : Nil Conflict of interest : None. Root canal configuration and the prevalence of C-shaped canals in mandibular second molars in an Iranian population.
J Oral Sci. The C-shaped root canal configuration: A review.
J Endod. Orban B, Mueller E. The development of bifurcation of multi-rooted teeth. J Am Dent Assoc.