Saudi Endodontic Journal

: 2012  |  Volume : 2  |  Issue : 3  |  Page : 156--160

Bilateral mandibular second premolars with three separate roots

Raed Hakam Mukhaimer 
 Department of Conservative Dentistry and Endodontics, Dental School, Arab American University, Jenin, Palestine

Correspondence Address:
Raed Hakam Mukhaimer
Department of Conservative Dentistry and Endodontics, Dental School, Arab American University, PO Box 240, Jenin


The mandibular second premolar is usually described as a single-rooted tooth with a single root canal. However, three root canals may be found but the occurrence of three separate roots is extremely rare. This report describes the case of a patient with bilateral mandibular second premolar with three roots and three root canals. The pre-operative radiograph of the right premolar revealed the presence of three roots, while the radiograph of the left premolar looked unusual and showed two roots. The access cavity preparation was extended and three orifices leading to three roots were found. All root canals were cleaned, shaped, and obturated. The post-operative radiograph showed a satisfactory root canal filling. Clinicians should always consider the presence of anatomical variations in the teeth during endodontic treatments. Despite the low prevalence, variations may occur in the number of roots and root canals of mandibular second premolars, as demonstrated in this case report.

How to cite this article:
Mukhaimer RH. Bilateral mandibular second premolars with three separate roots.Saudi Endod J 2012;2:156-160

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Mukhaimer RH. Bilateral mandibular second premolars with three separate roots. Saudi Endod J [serial online] 2012 [cited 2021 Oct 22 ];2:156-160
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Successful endodontic treatment requires thorough knowledge regarding the basic root canal morphology and the possible variations of root canal anatomy. This is followed by effective cleaning, shaping, and three-dimensional obturation. Lack of understanding and underestimation of the root canal morphology had been considered as a major cause of endodontic treatment failures. [1]

The incidence of the number of roots and root canals of the mandibular second premolar had been investigated by some anatomical studies. [2],[3],[4] These studies had reported a single root in 99.6% of the cases. Two roots were found in only 0.3% of the teeth. Three-rooted teeth (0.1%) were extremely rare. A single canal was found in 91% of the teeth studied, whereas, 9% had two or more canal systems.

Recent anatomical studies reported higher incidence of mandibular second premolars with more than two canals. In a study of a Jordanian population, 42% of mandibular first premolars and 28% of mandibular second premolars possessed more than two canals. [5] Sert and Bayirli's study had evaluated the root canal configuration of teeth by gender in a Turkish population and found an incidence of two or more canals in 29% of the cases. [6]

Although uncommon, possible morphological anomalies reported in the literature include mandibular second premolars with two canals and two roots, [7] two roots and four canals, [8] three roots and three canals, [9] and four canals in one root. [10] With the aid of spiral computed tomography, Sachdeva et al., [11] reported a case of mandibular second premolar with four roots and four root canals.

The aim of the present case was to discuss the endodontic management of bilateral mandibular second premolars with three separate roots. The dental operating microscope (DOM) was not used, which made the endodontic management of this case a great challenge. Moreover, bilateral cases had never been previously reported in the endodontic literature. This is of interest because this very extreme rare case must be taken into consideration when endodontically treating the mandibular second premolar. Knowledge of this anatomical variation can aid location and negotiation of canals as well as their subsequent management.

 Case Report

A 21-year-old Palestinian male with a noncontributory medical history attended my private endodontic clinic suffering from severe pain at his lower right and left quadrants. The chief complaint of the patient was "Sharp lingering pain upon cold stimulus, the pain was spontaneous and awakened him at night". The pain was bilateral. Clinical examination revealed an extensive amalgam restoration of the occlusal surface of the right mandibular second premolar and a very deep distal carious lesion affecting the left mandibular second premolar. Both teeth were tender to percussion. There was no mobility, and probing with a periodontal probe did not reveal any periodontal pocket. Vitality tests (cold, electric pulp test [EPT]) on the involved teeth showed abnormal responses (lingering pain to cold, increased reaction at EPT). Pre-operative radiographs were taken digitally (Dr. Suni, San Jose, California, USA). The radiograph for the right second premolar [Figure 1] revealed recurrent caries underneath the amalgam restoration, which was very close to the pulp chamber. Careful examination of the radiograph revealed the unusual anatomy of the second premolar having three separate roots. There was no radiographic evidence of apical periodontitis. On the pre-operative radiograph of the left second premolar [Figure 2], two roots were distinguished (mesial and distal). The clear lamina dura outlines were not clearly identified suggesting a third root or a root canal. The diagnosis of irreversible pulpitis was made for the right and left second premolars, and nonsurgical root canal treatment was scheduled for both teeth. The root canal treatment was initiated first for the right second premolar. After the administration of the local anesthetic (2% Lignocaine with 1:100,000 epinephrine), under rubber dam isolation, the amalgam restoration and caries were removed and the pulp chamber was accessed. To gain sufficient access to the canals, the conventional access opening was modified into one that was wider bucco-lingually and mesiodistally. On entry into the pulp chamber, three main orifices were found: One lingually, one buccaly, and one mesially. Coronal flaring was done using Sx file of the ProTaper system (Dentsply, Maillefer, Ballaigues, Switzerland). Initial scouting of all the root canals was carefully done with K-file number 10 (Dentsply, Maillefer, Baillaigues, Switzerland), one by one, and the patency of root canals was established. The working length of the located canals was established with the use of an apex locator (Root ZX; J Morita Co, Kyoto, Japan) and verified by taking a radiograph. All three canals were instrumented to an apical size 20 by hand files to create a glide path. Individual canal flaring was performed with ProTaper (Dentsply, Maillefer, Ballaigues, Switzerland) rotary NiTi files. During instrumentation, copious irrigation was performed with 2.5% sodium hypochlorite. All canals were prepared till an F2 file. After completion of the chemomechanical preparation, root canals were dried with sterile paper points and then obturated using System B (Analytic technology, Redmont, WA, USA) and Obtura III (Obtura Corporation, Fenton, MO, USA). AH plus (Dentsply DeTrey, Konstanz, Germany) was used as a sealer. A post- operative radiograph was taken [Figure 3], which showed a satisfactory obturation. Root canal treatment for the left second premolar was performed the next day. The same clinical steps were performed but when the pulp chamber was accessed, only two main orifices were found: Lingual and buccal. The two canals were carefully scouted with K-file number 10. Working length was determined using the electronic apex locator. To confirm the working length, K- files number 10 were placed in the two canals and a radiograph was taken. Surprisingly, a third root was obvious on the radiograph [Figure 4]. Careful inspection of the pulpal floor with endodontic explorer (DG-16, Dentsply, Gloucester, UK) revealed a small orifice in the middle of the mesial wall that could be negotiated with K- file number 8. Three K- files were placed and another X-ray was exposed that revealed three separate roots ending into three separate foramina [Figure 5]. All canals were prepared till F2 ProTaper file (Dentsply, Maillefer, Ballaigues, Switzerland). Copious irrigation with 2.5% sodium hypochlorite was used. After full cleaning and shaping, the canals were obturated with System B and Obtura III devices using AH plus as a sealer. A post- operative radiograph was taken [Figure 6], which showed a satisfactory obturation. Both treated teeth were restored with amalgam and plans were set for future crowning. At six month follow-up examination, teeth were completely asymptomatic and functional [Figure 7].{Figure 1}{Figure 2}{Figure 3}{Figure 4}{Figure 5}{Figure 6}{Figure 7}


Successful outcomes of endodontic treatment depends on the identification of all root canals which in turn guarantees complete extirpation of pulp tissue, proper chemo-mechanical cleaning and shaping and three dimensional obturation of the root canal system with an inert filling material. Normal and aberrant anatomy of root canals should be identified prior to and during endodontic treatment. It is generally accepted that a major cause of root canal treatment failure is an inability to locate and adequately treat all of the canals of the root canal system. [12] In a statistical analysis of re-treatment cases, Allen et al., [13] analyzed a total of 1300 endodontic subjects for factors that may have contributed to the failure of the original treatment and reported that untreated canals were responsible for failure in 114 cases, with an 8.8% prevalence. In another investigation, Hoen and Pink found that, missed canals were the main cause of endodontic re-treatment in 42% of cases studied. [14]

The frequency and risk of missed anatomy are strictly linked with the complexity of the root canal system. Mandibular premolars have gained a reputation for having aberrant anatomy. Slowey [1] reported that mandibular premolars were probably the most difficult teeth to treat endodontically because of wide variations in root canal morphology. Serman and Hasselgren [15] examined full mouth series of radiographs of 547 patients and found that 15.7% of patients had at least one mandibular first premolar with either a divided canal or a root. The incidence of second premolars in this study was 7%. Trope et al., [16] compared the root and the root canal morphology in African American and Caucasian patients and found a 4.8% incidence of two roots in second premolar teeth in African American and a 1.5% incidence in Caucasian patients. The incidence of three distinctly separated roots in mandibular premolars is extremely rare, appearing to range from 0% to 0.4%. [2] Bilateral occurrence of mandibular second premolar is being reported in this clinical report, a case which has never been reported in the endodontic literature.

Detection of root canals is best achieved with sound knowledge of the anatomical variations of the tooth in concern and proper use of available armamentarium. This includes careful evaluation of two or more high quality diagnostic periapical radiographs taken with different angles. [17] These radiographs provide much needed information about root canal morphology. Martinez-Lozano et al., [18] found that by varying the horizontal angle of about 20 and 40 degrees, the number of root canals observed coincided with the actual number of canals present. In a case report of a mandibular molar with five root canals, Friedman et al., [19] emphasized the critical importance of pre-operative radiograph in identifying the complex canal morphology and stated that any attempt to develop techniques that require fewer radiographs runs the risk of missing information, which may be significant for the success of therapy.

In the presented case, unusual root shape was observed in the pretreatment radiograph of the mandibular right second premolar, which recommended the possibility of extra roots and canals. The working length determination radiograph of the mandibular left second premolar provided valuable information on the presence and position of the extra root as the third root was not discovered on the preoperative radiograph most probably because of the superimposition of roots.

Although the dental operating microscope (DOM) was not used in this clinical case, its use is recommended in routine endodontic practice as it offers an excellent illumination and magnification to the operating field and provides a tremendous advantage in locating and treating 'extra' canals as it brings minute details into clear view. Several studies and case reports have shown that the DOM significantly increases the dentist's ability to locate and negotiate canals. [8],[20],[21] Baldassari-Cruz et al., [20] demonstrated an increase in the number of second mesio-buccal canals (MB2) located from 51% with the naked eye to 82% with the DOM. Coelho de Carvalho and Zuolo [21] concluded that the DOM made canal location easier by magnifying and illuminating the grooves in the pulpal floor and differentiating the color differences between the dentin of the floor and the walls. The DOM had enabled them to locate 8% more canals in mandibular molars.

A proper access cavity preparation represents the most important step in locating and negotiating the orifices of the root canals. This mechanical step requires good knowledge of the pulp chamber anatomy and a careful study of pre-operative radiographs.

Careful tactile examination of the pulpal floor with sharp endodontic explorer is essential for locating additional canals. [22] An extra canal should be suspected clinically when the pulp chamber does not appear to be aligned in its expected bucco-lingual relationship. Moreover, if the pulp chamber appears to deviate from normal configuration and seems to be too large in a mesiodistal plane, more than one canal should be expected. [8] In the pulp chamber floor of the mandibular premolars with three canals, many authors reported one orifice in the lingual side and two in the buccal. [23],[24] However, in the present case, three separate orifices were found, one buccally, one lingually, and the third one was located mesially. In conclusion, the diagnosis and management of extra roots in mandibular premolars are undoubtedly an endodontic challenge. In the current cases, if the additional roots would have been missed, it could lead to persistence of clinical symptoms and subsequent failure of the endodontic treatment.


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