Indian Journal of Dental Research

: 2008  |  Volume : 19  |  Issue : 1  |  Page : 70--73

Two-rooted mandibular second premolars: Case report and survey

R Prakash, S Nandini, Suma Ballal, Sowmya N Kumar, D Kandaswamy 
 Department of Conservative Dentistry and Endodontics, Meenakshi Ammal Dental College and Hospitals, Chennai - 600 095, India

Correspondence Address:
S Nandini
Department of Conservative Dentistry and Endodontics, Meenakshi Ammal Dental College and Hospitals, Chennai - 600 095


Mandibular premolars have earned the reputation for having an aberrant anatomy. Literature is replete with reports of extra canals in mandibular second premolars, but reports about the incidence of extra roots in these teeth are quite rare. This paper attempts at explaining a rare case of successful endodontic management of a two-rooted mandibular second premolar with diagnostic, inter-operative and postoperative radiographic records along with a substantial data on the incidence of extra roots in these teeth. The standard method of radiographic appraisal was maintained as the criteria for determining the presence of extra roots. Totally, 600 patients were examined for a period of four months by three endodontists. Out of them, eight patients had an extra root in one of the mandibular second premolars and three patients showed a bilateral presence of two roots.

How to cite this article:
Prakash R, Nandini S, Ballal S, Kumar SN, Kandaswamy D. Two-rooted mandibular second premolars: Case report and survey.Indian J Dent Res 2008;19:70-73

How to cite this URL:
Prakash R, Nandini S, Ballal S, Kumar SN, Kandaswamy D. Two-rooted mandibular second premolars: Case report and survey. Indian J Dent Res [serial online] 2008 [cited 2022 Aug 17 ];19:70-73
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Full Text

A thorough understanding of root canal anatomy and morphology is required for achieving high levels of success in endodontic treatment. Failure to recognize variations in root or root canal anatomy can result in unsuccessful endodontic treatment. Hence, it is imperative that the clinician be well informed and alerted to the commonest possible variations. Hoen and Pink in their analysis on teeth requiring re-treatment, found a 42% incidence of missed roots or canals. [1]

Mandibular premolars have earned the reputation for having the most aberrant anatomy. Numerous reports of root canal variations in these teeth have been reported in the literature. [2],[3] Vertucci in his series of studies conducted on extracted teeth, reported 2.5% incidence of a second canal. [4] Zilich and Dawson reported 11.7% occurrence of two canals and 0.4% of three canals. [5] According to Ingle, mandibular second premolars have only 12% chance of a second canal, 0.4% of a third canal and Harty has reported 11% possibility of second canal. In most instances they have had one canal, but teeth with two or more canals have also been reported. [6],[7],[8],[9],[10]

A case of mandibular second premolar was referred to our postgraduate endodontic clinic, which on radiographic examination was found to have an unusual anatomy i.e. two roots. Successful endodontic management of the mandibular premolar with two roots was completed with proper precautions and planning. Routine radiographic examination of other patients in our department has often shown two-rooted mandibular second premolars. This led us to believe that, perhaps the incidence of two-rooted mandibular premolars in our population was really high. The purpose of this investigation was to study the presence of extra roots in mandibular premolars with a special emphasis on mandibular second premolars, reported to have notoriety for unusual root anatomy. Thus, this paper attempts to alert the dental fraternity on the presence of extra roots as a common feature in mandibular second premolar, which if left untreated, can contribute to failure of treatment.

 Case Report

A 45-year-old female patient was referred to our postgraduate endodontic department for management of lower right second premolar. History revealed that the patient had experienced sensitivity to cold drinks for the past six months and reported pain for the past two days. Pain was spontaneous in nature and aggravated on chewing and lying down. On intraoral clinical examination, there was a carious exposure of the pulp and the tooth was tender to percussion. The tooth was subjected to routine clinical tests and a provisional diagnosis of acute apical periodontitis was made. The patient was also found to have lost all lower molars in the right lower quadrant and first premolar, hence retaining the tooth was very critical for prosthetic rehabilitation of the patient.

On radiographic examination preoperative radiograph [Figure 1], the periodontal ligament outline suggested a rare anatomical feature and hence a second radiograph with a more mesial angulation was taken for a clear view (tube shift technique).

Two roots were found and were distinguished as buccal and lingual based on the Clark's SLOB rule [Figure 2], which states that if the object moves from its reference point towards the distal side, while the tube is shifted mesially, then the object lies on the buccal aspect and vice versa.

Access was gained to the pulp chamber after administration of local anesthesia, under rubber dam isolation. To gain sufficient access to the canals, the conventional access opening was modified into one that was wider bucco-lingually as the roots were bucco-lingually oriented. Orifice location was not easy as the coronal pulp chamber was unusually long and the separation of the roots was from the middle third of the root. After careful inspection, two canal orifices were located and patency was ascertained using a small size K-file. To distinguish between the two roots and canals, one H-file and one K-file was inserted into each of the canals, before radiographic exposure. Then the working length radiograph was taken and measured [Figure 3].

Gates-Glidden drills 4,3,2 with a brushing motion, in a crown down fashion was used to enlarge the orifices to achieve a straight line access to the apex. The canal were sequentially irrigated using 5.25% Sodium hypochlorite and 17% EDTA during the cleaning and shaping procedure. Calcium hydroxide intracanal medicament was placed inside the canals as inter appointment dressing and sealed with IRM. Calcium hydroxide was removed from the canals with ultrasonic activation of 17% EDTA and 5.25% Sodium hypochlorite. The canals were thoroughly dried and obturation was done using standardized Gutta-percha and Zinc Oxide Eugenol sealer by means of lateral condensation. Occlusal access opening was sealed with temporary filling material and a final radiograph was taken. The two roots of the second premolar can be appreciated well in this post-obturation radiograph [Figure 4].

The patient was reviewed for two weeks and the post-endodontic permanent restoration was completed with composite and was referred to the department of Prosthodontia for further management.


It was the purpose of this investigation to study the root canal morphology of mandibular premolars with special emphasis on the prevalence of two or more roots in second premolars. Six hundred patients in a period of four months, who reported to our postgraduate clinic, were subjected to radiographs of mandibular second premolars with their prior written consent. The radiographs were taken with a standardized paralleling technique, using a film holder and focus film distance of approximately 16 inches. The radiographs were obtained at 70 kV using Kodak Ultra-speed films. A fixed schedule was used for the exposure times and films were developed under standardized conditions. The radiographs were examined with a magnifying viewer by three examiners and if the presence of any unusual morphology was suspected by the majority of them, then the patients were subjected for further radiographs of the area, in different angulations for confirmation.

The criteria for determining the presence of more than one canal were the standard methods of radiographic appraisal. In a single-rooted tooth, a radiograph taken straight or without proximal angulation of the X-ray cone, occasionally shows an obvious change in the density of the root canal space. According to Amos, this always indicates the presence of extra canals or a root. [11] Other landmarks to suggest the presence is the second periodontal ligament contour and root furcations.

While strictly adhering to the radiographic criteria for determining the number of roots, the findings of the study were in good accordance with recent studies using various techniques. The presence of two distinct roots could be observed and appreciated clearly in the radiographs presented in our study [Figure 5],[Figure 6],[Figure 7],[Figure 8],[Figure 9],[Figure 10],[Figure 11],[Figure 12].

Our survey reported a high incidence of about 1.33% of two roots and almost half among that population showed bilateral presence of two roots in mandibular second premolars. In less then 10 studies on mandibular premolars in the literature, nearly all of them reported more than 20% incidence of extra canals. However, there are only three incidental reports on the presence of extra roots, among them one was reported from our Indian population. [12] Apart from Amos and Trope, no other studies have reference to race. Our study was conducted among the South Indian population, who visit our hospital for treatment. Care was taken to ascertain the racial past of the patient and if there were any history of mix-up they were omitted from the study.


The presence of extra roots or canals in mandibular premolars is undoubtedly an endodontic challenge. A collection of previous studies have been tabulated for better understanding [Table 1].

Clearly, these findings are clinically important, as in a study at the University of Washington assessing the results of endodontic therapy, the mandibular premolars showed the highest failure rate of all types of teeth. [13] Conceivably, these findings could be due to the complex root canal anatomy of a large number of these teeth. A wide range of opinions are reported in the literature regarding the number of root canals, but there are very few reports on the variations in the number of roots that occur in the mandibular second premolars. [12],[14]

These discussions also validate an important consideration that must not be overlooked i.e. the anatomic position of the mental foramen and the neurovascular structures that pass through it, in close proximity to the apices of the mandibular second premolar. There are reports in the literature, of flare-ups in mandibular second premolars with associated parasthesia of the inferior alveolar and mental nerves. [15] Failure to recognize the presence of extra root or canals can often lead to acute flare-ups during treatment and subsequent failure of endodontic therapy.


The clinician should be astute enough to identify the presence of unusual numbers of roots and their morphology. A thorough knowledge of root canal anatomy and its variations, careful interpretation of the radiograph, close clinical inspection of the floor of the chamber and proper modification of access opening are essential for a successful treatment outcome.


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