Management of C Shaped Root Canal in the Mandibular Second Molar an Endodontic Challenge

INTRODUCTION

Normally, mandibular molar have two roots, mesial and distal and three roots canals, but sometimes mandibular molars presents with variations in its internal anatomy of canal configuration. The commonest among the unusual anatomy is C shaped canals, The C shaped canal configuration presents a ribbon shaped orifices looks like 180 0 arcs, usually starts from mesiolingual line angle of the chamber sweeps around buccally and finally ends at the distal aspect. The occurrence of C shaped canal in the mandibular molar was first documented by Cooke and Cox in 1979.¹ In mandibular second molars prevalence of C shaped canals ranges from 2.7 % to 44.5 %.³ Apart from high occurrence rate in mandibular second molar, it is also observed in maxillary third molar [4.7 %], mandibular third molar [3.5 to 4 %], mandibular first and second premolar [1%], mandibular and maxillary first molar [0.12 %] and rare occurrence in maxillary lateral incisor.^4,7-11 The bilateral occurrence of C configuration canal ranges from 70 to 81%.^15,16 It is believed that failure of fusion of Hertwigs Epithelial Root Sheath on the buccal or lingual root surfaces results in the formation of C shaped canals.² Another reason stated by Manning is that deposition of cementum due to aging results in the formation of C shaped canal.^5,6 Incomplete debridement of this complex anatomy results in treatment failure. This case report presents the successful detection and management of C shaped canal by conventional radiographic and obturation techniques.

CASE REPORT

A 22 year old male patient referred to department of conservative dentistry and endodontics with the chief complaint of pain in his lower right back tooth region for past 2 days. His medical history was non contributory and clinical examination of tooth 47 revealed dental caries and tooth was tender to percussion. Radiographic examination revealed dental caries involving pulp with widening of periodontal ligament space. It is also noted that single root outline till the apex. Thermal test and electric pulp test gives exaggerated response in comparison with control tooth. Based on clinical and radiographic evaluation diagnosis was made as symptomatic apical periodontitis and root canal therapy was initiated.
After administration of local anaesthesia, tooth was isolated with rubber dam. Access cavity was prepared with Endo access and Endo Z bur [DENTSPLY, Switzerland]. The floor of the pulp chamber was examined carefully. The presence of single canal, curved in a semicircular manner without separate orifice was seen. The canal was negotiated with 10 no K file. Working length was determined using electronic apex locator [Canalpro, Coltene] and confirmed with intraoral periapical radiograph, which showed single fused root canal system. The cleaning and shaping was done using protaper rotary files up to F3. Irrigation was done using 5.25 % NAOCL and then with copious amount of normal saline. The activation of NAOCL by endoactivator for better removal of debris from the canal was used. The canals were dried with paper points and obturation was done by cold lateral condensation technique using sealapex sealer. The cavity was restored with permanent restoration.

DISCUSSION

The commonest anatomical variation in the mandibular second molar is C shaped canal and its occurrence ranges from 2.7 % to 44.5 %. The management of this complex root canal needs proper clinical and radiographic evaluation, advanced techniques for cleaning, shaping and obturation. Magnification devices such as dental loupes, dental operating microscope is helpful in managing these complex structures. Conventional periapical radiographs is useful to know the root outline, but main disadvantage is, it’s a two dimensional view. An advanced imaging technique includes Computed Tomography and Cone Beam Computed Tomography is more accurate in diagnosing C shaped canal.³ Proper access cavity preparation and careful clinical evaluation of the pulp chamber gives clue in identifying the different types of C shaped canal, which was classified by Melton and Fan et al. Fan et al concluded that most of the C shaped canal is the orifice with an uninterrupted semicircle C shaped configuration.¹⁸ Continuous C shaped canal [MB-D] should be negotiated with three or more initial K files No 8 and 10, which decreases the chance of missing canal. The cleaning and shaping of the canal includes Niti rotary files using anticurvature filing method, which prevents strip perforations. The use of sonic and ultrasonic activators for irrigation provides better removal of debris from these irregular complex root canals.²⁰ Obturation techniques include lateral compaction of gutta percha starting from distal side to mesial gives better result. Thermo plasticized gutta percha technique provides effective obturation of the root canals. By having proper knowledge about common occurrence of this abnormal internal anatomy and use of proper instruments and techniques facilitates long term success of endodontic treatment.

CONCLUSION

The treatment of mandibular second molar with this complex C shaped anatomy poses an endodontic challenge to every clinician. Thorough knowledge about abnormal anatomic variations and proper clinical and preoperative radiographic evaluation helps in early detection of C shaped root canals. Early detection of these canals and use of advanced instruments and proper application of cleaning and obturation techniques will results in successful management of C shaped canals.

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