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Year : 2016  |  Volume : 6  |  Issue : 2  |  Page : 87-91

Mandibular premolars with unusual root canal configuration: A report of two cases

1 Department of Dentistry, Dammam Medical Complex, Dammam, Saudi Arabia
2 Department of Dentistry, Prince Sultan Military Medical City, Riyadh, Saudi Arabia
3 Department of Dentistry, Al Wakra Hospital, Hamad Medical Corporation, Al Wakra, Qatar

Date of Web Publication18-Apr-2016

Correspondence Address:
Sarah Abdulla Essa Al-Mahroos
Department of Dentistry, Dammam Medical Complex, P.O. Box 369, Qatif 31911
Saudi Arabia
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1658-5984.180622

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Knowledge of the normal root canal morphology and its variation is essential to ensure a successful root canal therapy. The aim of this report is to describe the endodontic treatment of two mandibular premolars with aberrant root canal morphology with the aid of dental operating microscope. A 29-year-old Saudi male with three mandibular left premolars was referred by the Prosthodontic Department for endodontic evaluation prior to placement of final coronal restorations. The first premolar was diagnosed as having necrotic pulp while the third premolar was previously treated. Root canal treatment and nonsurgical root canal retreatment were performed for the first and third premolars, respectively. The first premolar had a C-shaped configuration and Vertucci's Type V (1-2) canal system while the third premolar had Type III configuration (1-2-1). One year later, the teeth were asymptomatic with normal periapical tissues radiographically. Root canal aberrations may occur in any tooth type, and the clinicians should always assume the presence of these aberrations and use all the available tools to detect and manage them.

Keywords: C-shaped canal, mandibular premolars, root canal configuration, Vertucci classification

How to cite this article:
Al-Mahroos SA, Al-Sharif AA, Ahmad IA. Mandibular premolars with unusual root canal configuration: A report of two cases. Saudi Endod J 2016;6:87-91

How to cite this URL:
Al-Mahroos SA, Al-Sharif AA, Ahmad IA. Mandibular premolars with unusual root canal configuration: A report of two cases. Saudi Endod J [serial online] 2016 [cited 2023 Mar 22];6:87-91. Available from: https://www.saudiendodj.com/text.asp?2016/6/2/87/180622

  Introduction Top

The major objectives of root canal treatment are to perform adequate biomechanical preparation and to fill the entire root canal system three-dimensionally. The clinicians should have a thorough understanding of root and root canal morphology of different teeth and their frequent variations to improve the predictability of endodontic therapy. [1] Inability to locate, prepare, or fill all roots and/or root canals may cause posttreatment disease of endodontically-treated teeth. [2],[3]

The external and internal anatomy of the mandibular premolars have been extensivley studied using a variety of in vivo and in vitro methods. In 2007, Cleghorn et al. reviewed studies that evaluated the morphology of first [4] and second [5] premolars. They found that although the majority of first (97.9%) and second (99.6%) premolars had one root, multiple root canals were evident in 24.2% and 9% of the first and second premolars, respectively. Another anatomical variation in the mandibular premolars is the C-shaped canal configuration and it has a prevalence of 1.1% to 29.7% in first premolars [6],[7],[8],[9],[10],[11],[12] and 0.6% to 1.9% in second premolars. [8],[10] The occurrence of these variations may partly explain the earlier finding of Slowey (1979), who suggested that mandibular premolars possess the greatest anatomical challenges of all teeth with regards to achieving successful root canal treatment. [13]

In the Saudi Arabian population, three clinical cases of multi-rooted and multi-canaled second premolars were reported. Two of them had two roots with three [14] and four [15] root canals while the third case had three roots with three root canals. [16] In addition, one study found that 10.6% of the mandibular second molars had a C-shaped canal configuration. [17] However, the later anatomical variation was not reported previously in mandibular premolars of the Saudi population. The aim of this paper is to illustrate the successful management of a patient having three mandibular left premolars and aberrant root canal morphology in two of them.

  Case report Top

A 29-year-old Saudi male with a noncontributory medical history was referred from the prosthodontic clinic to the endodontic clinic in Dammam Medical Complex, located in Dammam City, Saudi Arabia, for endodontic treatment of the left mandibular premolars. The clinical examination revealed the presence of three premolars while the contralateral side had only two premolars. The first premolar had a disto-occlusal carious lesion, the second premolar had a mesio-occluso-distal amalgam filling, and the third premolar had a mesio-occlusal amalgam filling [Figure 1]. The second premolar responded normally to cold test (Endo-Frost, Coltene Whaledent, Germany) while the first and third premolars did not respond. All premolars responded normally to percussion and palpation tests with no mobility and no periodontal involvement. Preoperative radiographs revealed large carious lesion in the first premolar [Figure 2]a and previous substandard root canal treatment in the third premolar with a missed root canal [Figure 3]a. All the three teeth had normal periapical tissues. Based on the clinical and radiographic examinations, the first premolar was diagnosed to have necrotic pulp with normal periapical tissues while the third premolar was diagnosed as previously treated with normal periapical tissues. Root canal treatment and nonsurgical root canal retreatment were planned for the first and third premolars, respectively. The second premolar was diagnosed as having a normal pulp and root canal treatment was not indicated. Endodontic treatment of the first and third premolars was carried out under rubber dam isolation with the aid of dental operating microscope (DOM) (Carl Zeiss Meditec AG, Jena, Germany).
Figure 1: An intraoral photograph showing three mandibular left premolars

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Figure 2: Mandibular left first premolar. (a) Preoperative radiograph showing large carious lesion and presence of multiple root canals. (b) An occlusal photograph of the access cavity showing C-shaped canal configuration. (c) Working length radiograph showing the presence of Type V (1-2) canal configuration. (d) Postoperative radiograph

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Figure 3: Mandibular left third premolar. (a) Preoperative radiograph showing a previously treated tooth and large amalgam restoration. (b) Working length radiograph showing the presence of Type III (1-2-1) canal configuration. (c) Postoperative radiograph

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Mandibular left first premolar

After tooth was isolated, all caries was excavated, and the access cavity was modified using an Endo-Z bur (Dentsply Maillefer, Ballaigues, Switzerland). Examination under DOM revealed the presence of C-shaped canal configuration in the middle third of the root. Two root canals (one mesial and one distal) were detected [Figure 2]b and they were negotiated with size 10 K-files (Dentsply Maillefer, Ballaigues, Switzerland). The working length was determined using an electronic apex locator (EAL) (Root ZX, J. Morita, Tokyo, Japan). The EAL was inconclusive and giving different readings. A working length radiograph was taken to confirm the length and it revealed a Vertucci Type V (1-2) canal system [Figure 2]c. The canals' orifices were enlarged with size 2 and 3 Gates Glidden drills (Dentsply Maillefer, Ballaigues, Switzerland) using a brushing motion, and the canals were instrumented with manual K-files and profile rotary system (Dentsply Maillefer, Ballaigues, Switzerland) to size 30/0.04. Copious amount of 5.25% sodium hypochlorite (NaOCl) was used as irrigant, and it was activated with EndoActivator system (Dentsply Tulsa Dental Specialties, Tulsa, OK, USA) to maximize its effect. [18] The canals were dried with sterile paper points, and the access cavity was sealed with Cavit (ESPE, Seefeld, Germany). At the second visit, the canals were irrigated with NaOCl, dried and obturated with gutta-percha cones and AH Plus sealer (De Trey Dentsply, Konstanz, Germany) using continuous wave compaction technique. Postspace was prepared by removing the gutta-percha up to the level where the C-shaped configuration started. Finally, the access cavity was double sealed with Cavit and self-cure glass ionomer restorative material (Riva self-cure, SDI, Victoria, Australia) [Figure 2]d.

Mandibular left third premolar

The tooth was isolated and the amalgam restoration and underlying caries were removed prior to accessing the pulp chamber. The access was modified using an Endo-Z bur and gutta percha was removed from the distal canal manually using H-files (Dentsply Maillefer, Ballaigues, Switzerland). Careful clinical examination revealed the presence of Vertucci Type III (1-2-1) canal configuration. The canals were enlarged with Gates Glidden drills, and the working length was determined with EAL and confirmed radiographically [Figure 3]b. The canals were prepared by K-files and profile rotary system to size 35/0.04. The distal canal was considered the main canal and instrumented to the full working length while the mesial canal was instrumented just to the contact point with the distal canal. Copious amount of 5.25% NaOCl was used and activated with EndoActivator. The canals were dried with sterile paper points, and the access cavity was sealed with Cavit. At the second visit, the canals were irrigated with NaOCl, dried and obturated with gutta-percha cones and AH plus sealer using the continuous wave compaction technique. The gutta-percha was cut up to the level of canals bifurcation. Finally, the access cavity was double sealed with Cavit and glass ionomer restoration [Figure 3]c. The patient was referred to the prosthodontic clinic to restore the teeth. The first premolar was restored with a fiber post (EasyPost, Dentsply Maillefer, Ballaigues, Switzerland) and composite build-up (Herculite XRV Ultra, Kerr, Bioggio, Switzerland), the second premolar was restored with a composite filling and the third premolar was built up with composite and restored with a full ceramic crown.

At the 1 year recall visit, the patient was clinically asymptomatic and the soft tissues were within normal limits. Radiographically, all teeth had normal periapical tissues [Figure 4].
Figure 4: One year recall (a and b) intraoral photograph showing the final restorations of the mandibular left premolars (c and d) Periapical radiographs showing normal periapical tissues of all treated teeth

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  Discussion Top

Supernumerary teeth are usually associated with syndromes and their presence in a nonsyndromic patient is a rare occurrence. The prevalence of supernumerary permanent teeth is between 0.08% and 0.26% and supernumerary premolars account for only 10% of all the supernumerary cases. [19] Supernumerary premolars occur more commonly in the mandible [20] and male patients are more prone to supernumerary premolars than females. [21] Surgical removal of supernumerary teeth is indicated if they have already caused complications to the surrounding structures or if their presence may cause complications later on. [22] Clinical and radiographic examination for the patient in this report revealed the presence of three mandibular left premolars that are fully erupted, well aligned and none of them was indicated for extraction.

Thorough knowledge of the internal and external root and root canal anatomy is essential for proper shaping, cleaning, and obturation that are mandatory for successful endodontic treatment. Variations in the canal configuration should be recognized since having a single tapering canal and apical foramen is the exception rather than the rule. [23]

The C-shaped canal is an anatomical variation that could be faced during the treatment of posterior teeth, most commonly in mandibular second molars. It has been also observed in other mandibular and maxillary molars as well as in mandibular premolars. [23] The awareness of the key anatomical features of the C-shaped canals before starting the treatment will enhance the biomechanical instrumentation, obturation, and restoration of the involved teeth. In recent years, the internal and external morphology of C-shaped mandibular premolars were evaluated using micro-computed tomography. [9],[11],[24] Fan et al. 2008 [24] classified these premolars according to their cross sections into six categories [Table 1]. They noticed that the canal shape of C-shaped premolars might vary along the length of the root. At the coronal third, there was usually a single canal (C4b or C4c), the incidence of canal configurations C1, C2, or C3 would increase observably at the middle third whereas the majority of the canal shapes in the apical third were C2 or C3. Fan et al. 2012 [9] studied the location and length of the C-shaped part in 97 mandibular first premolars. They found that the average length of the C-shaped part was 4.64 mm, located 6.34 mm from cementoenamel junction (CEJ) and 2.92 mm from the apex. In another study, Gu et al. 2013 [11] demonstrated that C-shaped canals were frequently located between 6 and 11 mm below the CEJ. They also found that the mesial walls of C-shaped mandibular premolars had the minimal thickness of all walls, especially at the lingual sites. The authors concluded that clinicians should be conservative during canal instrumentation and postspace preparation procedures to avoid the risk of root perforation at danger zones of C-shaped canals. According to Fan's classification, the mandibular first premolar in the current report had a C1 cross-section in the coronal half (about 6 mm below the CEJ) and C3 cross section in the remaining length of the root. The postspace was prepared carefully in the coronal 6 mm of the canal away from the mesial wall to avoid root perforation.
Table 1: Classification of C-shaped mandibular premolars

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The intraoral periapical radiographs are the primary diagnostic tools used to evaluate the tooth morphology in the clinical setup. The major limitation of these radiographs is that they provide a two-dimensional representation of three-dimensional anatomic structures. Exposing radiographs from different horizontal angles may help to overcome the superimposition of structures in the bucco-lingual dimension. In addition, the use of advance imaging techniques such as computed tomography and cone-beam computed tomography (CBCT) enhances the three-dimensional understanding of the root canal system. CBCT is a noninvasive technique that can be used to visualize the dentition, the maxillofacial skeleton, and the relationship of anatomic structures in three dimensions. However, this technique has some limitations including a possible higher radiation dose to the patient, potential for artifact generation and high levels of scatter and noise. [25],[26] The American Association of Endodontists and the American Academy of Oral and Maxillofacial Radiology advised the clinicians to use CBCT "only when the need for imagining cannot be met by lower dose two-dimensional radiography." [26] In teeth with complex root canal system, as the premolars in the present report, CBCT is recommended to facilitate their detection and management. However, unfortunately, CBCT was not used since it was not available at our center at the time of treatment.

The DOM is another important adjunct in the contemporary endodontic practice and is gaining popularity among endodontists. Kersten et al. 2008 [27] reported that the use of the DOM by endodontists increased from 52% in 1999 to 90% in 2007. The main advantages of DOM are; it improves visualization, quality and precision of treatment, enhances ergonomics, allows for digital documentation and communication ability through integrated videos. [28] In the current case, the use of DOM allowed the early recognition of the C-shaped canal system in the first premolar, the detection of the missed root canal in the third premolar and facilitated the biomechanical instrumentation and obturation of these two teeth.

The current case report illustrated the clinical management of a mandibular first premolar with C-shaped canal configuration. Further studies using advanced techniques such as the CBCT and microcomputed tomography are warranted to give more information regarding the prevalence of this anatomical variation in the Saudi Arabian population.

  Conclusions Top

The mandibular premolars may have complex root and root canal morphology. The clinicians should be aware of the morphological variations in different teeth types and use all the available tools to detect and manage them.


The authors would like to thank Dr. Maymoona Badahdah for her help and support.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

  [Table 1]

This article has been cited by
1 Management of mandibular premolars with various C-shaped root canal configurations: A case series
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Saudi Endodontic Journal. 2022; 12(3): 322
[Pubmed] | [DOI]


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