Author: Dr Ankita Garg, Dr Varun Goel.
Urban Estate, Karnal, Haryana, India.



Introduction:
The aim of endodontic treatment is the elimination of infection from the root canal and the prevention of reinfection (Sjogren et al. 1990). However, root canal treatment may fail because of factors including persistent infection of the root canal, unsatisfactory intracanal procedures that may lead to poor canal preparation, broken instruments and incomplete root canal fillings. Morphological features of the tooth may also adversely affect endodontic procedures1 (Nair et al 1990).

In most cases, mandibular canines present only one root (Green D 1973, Vertucci FJ 1984, Ouellet R 1995). The occurrence of two roots and even more, two root canals is rare, ranging from 1% to 5% (Ouellet R 1995).

Similarly, morphology of mandibular incisors is not as simple as it may appear to be on standard periapical radiographs, and that it may be complicated by the presence of bifurcated and lateral canals. As reported, more than 40% of mandibular incisors have two root canals and more than 1% have two separate apical foramina (Carrotte P 2004). Many of the second, accessory and lateral canals are detected only by means of a stereomicroscope after the teeth have been extracted, decalcified and cleared. Most of them are very small and can not be identified in vivo during endodontic treatment or on periapical radiographs.

The purpose of these case reports is to illustrate the outcome of endodontic treatment of the patients who had two separate root canals in one root in mandibular canines and mandibular central incisor.    

Case report 1:
A 38 years old female reported to the department of conservative dentistry and endodontics after treatment of a facial trauma in a road side accident. The patient had lost her central and lateral incisors in both the arches bilaterally. A fixed prosthesis was planned after intentional root canal treatment of the canines of both maxillary and mandibular arches. Pre operative IOPA radiographs were taken of all the four canines. The radiographs did not reveal any sign of presence of extra canal and/or root.

The teeth were anaesthetised with an infiltration of 2.0 ml of 2% Lidocaine with 1:80,000 epinephrine (Xylocaine; Astra Zeneca Pharma, Bangalore, India).

Endodontic access cavity was prepared with a round diamond bur and the pulp chamber was explored under dental operating microscope (Moller denta 300; Haag Streit International, Koniz, Switzerland). The pulp chamber of lower right canine was found to be having an unusually large size and a second root canal was found in the lingual portion of the pulp chamber (fig 1) which was further confirmed by IOPA radiograph(fig 2). Biomechanical preparation was done using ProTaper rotary files (Dentsply/Maillefer).  Calcium Hydroxide dressing was given for one week. In the next appointment, the instrumented root canals were obturated with ProTaper gutta percha cones and an epoxy resin based (Sealer 26; Dentsply/Maillefer). The final radiograph showed two well obturated canals(fig 3).

Taking into consideration the bilateral incidence of two canals, the left mandibular canine was also explored thoroughly but no second canal was found. Similarly, the maxillary canines were also explored thoroughly, but no other canal was found.

Case report 2:
Another case of a fifty six year old female reported to the department of Conservative Dentistry and Endodontics. The patient was already having prostheses (porcelain fused to metal crowns) in both upper and lower arches. The patient was having pain in lower left anterior region. All the crowns were placed on vital teeth and now the patient was complaining of pain in left mandibular canine and lateral incisor. The teeth were tender to percussion. So, non- surgical endodontic treatment was planned after removal of the prostheses over these two teeth.

The teeth were anaesthetised with an infiltration of 2.0 ml of 2% Lidocaine with 1:80,000 epinephrine (Xylocaine; Astra Zeneca Pharma, Bangalore, India). Root cnal treatment of the lateral incisor and canine were started as in previous case. While exploring the pulp chamber of the mandibular canine, it was found to be having an unusually large size and a second root canal was found in the lingual portion of the pulp chamber. The presence of extra canal was confirmed with the help of IOPA x ray (fig 4). Biomechanical preparation was done using ProTaper rotary files (Dentsply/Maillefer).  The lateral incisor was also explored thoroughly under dental operating microscope for presence of any other canal but no second canal was found.

Calcium Hydroxide dressing was given in both teeth and the patient was recalled. On the second appointment, after one week, patient was completely asymptomatic and relieved of pain. The instrumented root canals were obturated with ProTaper gutta percha cones and an epoxy resin based (Sealer 26; Dentsply/Maillefer). Three months follow up revealed that patient was asymptomatic.

fig-1	fig-2	fig-3

Case report 3:
A 53 year old man reported to the department of Conservative Dentistry and Endodontics. The patient was asymptomatic and was not having pain or any other problem. The patient wanted a fixed prostheses in the lower anterior region as the lower three anterior teeth (42, 41, 31) were missing. So, intentional RCT was planned for the remaining three anterior teeth (43, 32 and 33) as they had marked abrasion in the incisal and cervical regions. There had been gingival and bone recession of at least 3mm from the cementoenamel junction, but no deep periodontal pockets were present. The pre-operative periapical radiograph did not reveal any sign of two roots or two canals.

Non surgical endodontic treatment was planned. Left mandibular lateral incisor and canine were opened after giving an infiltration of 2.0 ml of 2% Lidocaine with 1:80,000 epinephrine (Xylocaine; Astra Zeneca Pharma, Bangalore, India) and access cavities were prepared. The pulp chamber of the lateral incisor was noted as an unusually large size buccolingually. The pulp chamber was explored under dental operating microscope and two root canal orifices were found- one on labial and other on lingual side. Both the right and left mandibular canines were found to have one canal only. Working length x-ray (fig 5) was taken and it was found to be a 2 in 1 configuration.

Chemomechanical preparation of the canals was completed using a combination of K files and NiTi ProTaper (Dentsply/ Maillefer) rotary files while copiously irrigating with 5.25% NaOCl and 1% EDTA gel. The root canals were then obturated with ProTaper gutta percha and AH Plus as sealer (fig 6). The access cavities were sealed temporarily with glass ionomer cement. The patient reported no symptoms following endodontic treatment and the prosthetic part of treatment was completed successfully.

fig-4	fig-5	fig-6

Discussion:
It is essential that clinicians know the clinical and radiographic signs that suggest the presence of extra canals. Clinically, the presence of continuous bleeding in teeth with pulpitis or normal pulps despite complete instrumentation can suggest the presence of such canals (Iqbal et al 2005).  In cases with necrotic pulps or when the canals are pulpless, the presence of an apical rarefaction on the lateral side of the root may suggest the presence of an extra canal. Some of the other indications could be the eccentric location of an endodontic file on a radiograph during working length determination, inconsistent apex locator readings, a sinus tract that traces laterally away from the main canal, or the feeling of a ‘catch’ on the canal wall during instrumentation of a wide and unobstructed main canal.

Careful interpretation of the radiographic features is essential in order that root canals are not overlooked. This depends on the availability of good and accurate periapical radiographs and, ideally, periapical radiographs taken from two different horizontal angulations. In the presented cases, there were no signs of the second root canals on the panoramic radiographs and the periapical radiographs taken with standard (‘straight on’) angles were not sufficient to detect the second canals in each tooth.

The initial radiograph is extremely important because it allows for the identification or suspicion of root and root canal anatomical variations. Bifurcations in the cervical and middle thirds may be observed radiographically when the x-ray incidence angle does not cause superimposition of images. In mandibular canines, bifurcations at these sites has been shown to occur in 43.1% of the situations (Sharma et al 1998).

As in the presented case reports, the mandibular canine was not treated endodontically previously and the patient had pain and tenderness and a periapical pathology was evident on periapical radiograph. After access opening and biomechanical preparation, there were no symptoms. So, endodontists should always search for two canals in mandibular canine during endodontic treatment, even in single rooted teeth. Green et al(1973) observed two canals in a single root in 13 out of 100 mandibular canines observed. This is consistent with the findings of Hess W 1925, who observed two canals in 15% of the cases. Vertucci (1974) reported the presence of two canals in 18% of mandibular canines.  Laurichesse et al (1986) reported that 2% of mandibular canines presented with one root and two canals and that 1% had two roots and two root canals. Heling et al (1995) described a rare case of a root canal retreatment in a mandibular canine with two roots and three canals.

A common reason for not locating a second canal in mandibular incisors is an inadequate access preparation into the tooth which leaves a lingual shelf of dentine over the second (usually the lingual) canal Benjamin et al (1974). These authors recommended that when entering mandibular incisors in order to perform endodontic treatment, clinicians should always initially assume that two root canals exist. Therefore, clinicians should always prepare an access cavity with the appropriate size and location, and then thoroughly search for the canals. Only after such a search fails to reveal a second canal should clinicians be satisfied that the tooth has only one root canal.

Conclusion:
Thus, these case reports highlight the importance of having a thorough knowledge of all possible root canal irregularities. In some cases, it is very difficult to identify additional root canals by radiographic examination and therefore visualisation and deep probing during initial endodontic treatment is essential for the location of all canals. With advances in modern endodontic techniques, most teeth with complex root canal anatomies can be successfully treated without surgical intervention.

References:

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