Unusal canal configuration in maxillary and mandibular second molars.

This clinical article describes three different case reports of maxillary and mandibular second molars with the unusual anatomy of single root with a single canal and their endodontic management. An unusual case of bilateralism is observed in the first two cases in the form of single-rooted second mandibular molars in both the quadrant of the same patient. The presence of maxillary second molar with single root and single canal in the third case is unusual.

Anatomical deviations in root canal morphology occur frequently, and the clinician must be familiar with the variation for a successful outcome. Multi-rooted teeth by way of its variation in root canal anatomy pose a persistent challenge for accurate prediction in the number of root canals during endodontic therapy.[1] Failure to recognize a root canal can lead to failure of endodontic treatment.[2] The current focus of many clinicians is to locate extra canals, apical ramifications, apical deltas, or lateral canals.[3] However, the possibility of the presence of single canal within a single root in a molar tooth should not be completely ignored.[4] Very few comparisons of unusual anatomy in contralateral pairs have been reported in the literature.[5] This article presents the case report of two patients with multiple teeth exhibiting single root with the single canal.

Case Reports

Case I and II

A 27-year-old male patient reported to the Ebenezar Multispecialty Dental Clinic, Chennai, with a chief complaint of pain in his lower left and right back teeth for the past 1 month. His medical and dental histories were noncontributory. On intraoral examination, tooth no 31 (Universal System) presented with a fractured restoration and 18 was grossly decayed. Electric, thermal, and cold tests were carried out to determine the pulpal status. Intraoral periapical radiographs of teeth no 31, 18 revealed pulpal involvement with the widening of the periodontal ligament space. Both the teeth were diagnosed as symptomatic irreversible pulpitis with apical periodontitis. Endodontic treatment was initiated and access opening of 18 was done under local anesthesia (Lignox *2% Adrenaline). Working length was determined as 20 mm with 25 size K-file (Mani, Tochigi, Japan) using an apex locator (Root Z × 2, Morito, Tokyo, Japan) and confirmed with a radiograph. Cleaning and shaping were done with step back technique and the master apical file was # 70. Irrigation was done copiously with 3% sodium hypochlorite (Prevest Denpro Limited, Jammu, India) followed by Ethylenediaminetetraacetic acid (EDTA) (Glyde™, Dentsply Maillefer, Ballaigues, Switzerland) in between each file size. Final rinse was done with chlorhexidine (Asep-RC, Steadman Pharmaceuticals Pvt. Ltd., Thiruporur, Tamil Nadu). After drying the canals with paper points, obturation was done with 0.02 tapered gutta-percha and AH plus sealer (De Trey DENTSPLY, Konstanz, Germany) by lateral compaction [Figure 1]. The access cavity was then sealed with cermet.

Figure 1

(a) Pre-operative radiograph, (b) Acess opening photograph, (c) Working length radiograph, (d) Master cone radiograph, (e) Obturation radiograph

Similarly, access opening of tooth no 31 was done under local anesthesia (Lignox *2%A). Working length was determined to be 23 mm with 30 size K-file using an apex locator (Root ZX2, Morito, Tokyo, Japan) and confirmed with a radiograph. Cleaning and shaping were done with step back technique and the master apical file was # 70. Irrigation was done copiously with 3% sodium hypochlorite followed by EDTA in between each file size. Final rinse was done with chlorhexidine. After drying the canals with paper points, obturation was done with 0.02 tapered gutta-percha and AH plus sealer by lateral compaction [Figure 1]. The access cavity was then sealed with cermet.

A postoperative panoramic radiograph was taken to check the obturation and the possibility of single rooted molar in the contralateral and maxillary region. Orthopantomograph reveals the presence of multiple single-rooted single canal molars in the maxilla also.

Case III

A 28-year-old male patient reported to the Ebenezar Multispecialty Dental Clinic, Chennai, with a chief complaint of pain in his upper left back tooth region for the past 1 month. His medical history and dental history were noncontributory. On intraoral examination, tooth no 15 was grossly decayed. It showed a delayed response to electric pulp testing and a lingering sensation to the thermal test when compared to its adjacent and contralateral teeth. Thus, a diagnosis of symptomatic pulpitis was made. Access opening of 15 was done under local anesthesia (Lignox *2% Adrenaline). Working length was determined as 18 mm with 35 size K-file (Mani, Tochigi, Japan) using radiographs and an apex locator (Root ZX2, Morito, Tokyo, Japan). Cleaning and shaping were done till size 70 K file with step back technique. Irrigation was done copiously with 3% sodium hypochlorite followed by EDTA in between each file size, and the final rinse was done with chlorhexidine. After drying the canals with paper points, obturation was done with 0.02 tapered gutta-percha and AH plus sealer by lateral compaction [Figure 1]. The access cavity was then sealed with cermet.

Discussion

The search for extra canals can sometimes lead to iatrogenic errors such as perforations and excessive loss of dentin. These errors can be avoided if the clinician possesses adequate knowledge about the location of the canals and the dimensions of the pulp chamber. A rational approach to study the relationships of the pulp chamber to the clinical crown has been put forth by Krasner and Rankow in the form of laws which are valuable aids to the clinician searching for elusive canals.[6] Although extra canals are more of a rule rather than an exception, the clinician should also be aware of the fact that in certain cases, there is a possibility of fused if not fewer canals than the normally presumed canal morphology.[4]

The important aspect to be considered in these cases is the presence of unusual anatomy in the maxillary and mandibular molars. Table 1 enumerates the various studies found in literature on the abnormalities and anatomic complexities in the second molar tooth. Very few authors have reported the incidence of the single canal in the maxillary first molar tooth.[417] Moreover, the incidence of the single canal in maxillary second and third molars is extremely rare in the literature.[5] However, the incidence of single canals in the mandibular second molar tooth is comparatively higher than their maxillary counterparts.[18] Mandibular second molar with a conical root and a wide single canal have been reported. According to Weine, mandibular second molar exhibits greater anatomical variations than all the other molar teeth. When one root is present, the root canal system may present a broad conical root canal, two canals that may or may not join or a c-shaped canal.[19]

Table 1

Abnormalities and anatomic deviations in the second molar tooth

The literature search for reports of the same anatomical variation assumes clinical significance as is evidenced in our case report. From a clinical perspective, when the initial radiograph shows the image of an unusual anatomic form, it is recommended to take a second radiograph with a mesial or distal angulation.[20] For additional information, it is also recommended to take a radiograph of the contralateral tooth. Sabala et al. stated that the more rare the aberration (<1%), the more probable that it was bilateral (90%) in the posterior teeth.[21] Hence, as anatomic discrepancies are increasingly being found, the clinician should suspect its presence on the contralateral pair as well.

Conclusion

Variations in root canal morphology need not be in the form of extra canals. It could also be in the form of fused or less number of canals. Clinicians should have adequate knowledge about root canal morphology and its possible anomalies. Radiographs are the most potent tool in daily clinical practice to detect abnormal variations in the root and root canal anatomy.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.