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Endodontic management of radix entomolaris in a mandibular third molar

A wide array of anatomical variations present to dentists from time to time. The mandibular third molars are not far away in this context. Many a time, extraction remains the choice of treatment because of their most posterior location and unpredictable anatomy. In terms of anatomy, an extra distolingual root (radix entomolaris) poses a serious challenge, and it is very rare as well. Hence, the identification and management of radix entomolaris is an essential goal for the successful root canal treatment. The aim of this article is to present article the successful endodontic management of a mandibular third molar with three roots and four root canals.


INTRODUCTION
It is important to save the third molar if it is serving as a support for future replacements of missing teeth in the adjacent vicinity rather than extraction. [1] In such cases, third molar teeth should be provided with proper and thorough endodontic treatment.
Such a variant is a characteristic feature in mandibular first molar, rare in mandibular third molar with least occurrence in the mandibular second molar. The highest occurrence of radix entomolaris (RE) was found among the Mongolian race, including Chinese, Taiwanese, and Koreans. However since it is uncommon among the Caucasians (3.4% -4.2%) it is considered as an unusual or dysmorphic root morphology. [2] Mandibular third molar exhibits major anatomical and morphological variations as compared to other teeth such as may have one or four roots. Till date, the extra roots in mandibular third molar have been identified in vitro by clearing technique; [ Table 1] only, very limited case reports have been documented [ Table 1].
The diagnosis and management of RE are of paramount importance from the point of endodontic success. This case report further emphasizes the rare occurrence and successful management of radix in mandibular third molars and that one should attempt to see the unseen.

CASE REPORT
A 22-year-old male patient reported with spontaneous pain in his right lower back region of the jaw the past 1 week. Clinical and radiographical examination revealed that the pulp was exposed by deep caries, and the tooth was symptomatic to vertical pressure. Pulp vitality tests (cold and electric pulp tests) confirmed the diagnosis of pulp necrosis and symptomatic apical periodontitis [ Figure 1a]. Radiograph revealed an additional root. Another radiograph has been taken with same lingual opposite buccal. Patient's consent was taken following which access preparation Endodontic management of radix entomolaris in a mandibular third molar was started using local anesthesia (2% lignocaine with 1:100,000 epinephrine) under rubber dam. To locate an extra canal, the conventional opening was redefined. After careful inspection and examination under operating loupes × 3.5 (Zumax), it revealed the presence of four root canals orifices. All together four root canal orifices were identified, i.e. mesiobuccal, mesiolingual, distobuccal, and distolingual [ Figure 1b]. The caries were removed from the coronal walls, and the working length was established using an apex locator (Root ZX, J. Morita Inc.,) and further by radiographs [ Figure 1c]. Chemomechanical preparation was completed in all the canals till X2 Protaper Next (Dentsply Maillefer, Switzerland) along with copious use of 3% sodium hypochlorite followed by 17% ethylenediaminetetraacetic
The patient reported after 2 weeks and was totally asymptomatic. The temporary filling was removed; canals were irrigated and thereafter dried with paper points. The corresponding gutta-percha points were placed, and a radiograph was obtained [ Figure 1d]. Root canal filling was thereafter completed, and the postendodontic permanent restoration was performed with nanohybrid composite (Tetric N-Ceram) [ Figure 2a]. The patient came after a 3-month follow-up and was found to be asymptomatic [ Figure 2b].

DISCUSSION
Endodontic treatment of third molars are considered an ordeal owing to their most posterior location, unpredictable internal anatomy, bizarre occlusal anatomy and aberrant eruption patterns. [18] Although the extraction of third molars is often the treatment of choice, few clinical situations might demand the retention of these teeth. Third molars might serve as an abutment for removable partial denture of fixed prosthesis, where second molars are lost. Moreover, the principle of endodontics is directed at the preservation of each and every functional component of the dental arch. The anatomical variations confronted in third molars range from extra root (RE), curved roots, bayonet roots, fused canals, C-shaped canals, dilacerations, etc., The exact cause of RE is still not known. Some authors say that it may be due to disturbance during odontogenesis or may be due to an atavistic gene. Incidence varies from 5% to 30% and also among different populations. [2] To achieve a correct diagnosis, minimum of two diagnostic radiographs are necessary using buccal object rule. Even the presence of an extra cusp may sometimes indicate the presence of RE.
Access cavity preparation should be modified usually from a triangular to trapezoidal shape. The modification should be done following the dentinal map. Advanced diagnostic aids help in the better identification and visualization of all the canals.
Some of the common problems encountered during the treatment of RE in mandibular third molar are as follows: 1. Difficulty in radiographic interpretation 2. Inability to locate the fourth canal because of limited space 3. Proximity to inferior alveolar nerve 4. Confusion in working length determination 5. Difficulty in rubber dam placement.
Apart from these difficulties, clinicians are prone to commit some iatrogenic errors such as straightening of a root canal, resulting in loss of working length, ledge formation, zipping, transportation or even perforation, and instrument separation due to limited mouth opening. Hence, these factors should be kept in mind before embarking the treatment of mandibular third molar.
CONCLUSION RE in mandibular third molar is very rare, and it was possible to detect same through radiographic techniques and enhanced magnification aids. There is limited literature avaliable regarding the successful endodontic management of RE in mandibular third molar with a 3-month follow-up.

Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship
Nil.

Conflicts of interest
There are no conflicts of interest.