Successful root canal treatment requires adequate knowledge regarding morphologic variations in root canal system of teeth. This report describes a six-canalled mandibular first molar with four mesial root canals requiring endodontic retreatment. The two additional canals in the mesial root were found during retreatment with the aid of illumination and magnification. In conclusion, the possibility of atypical morphology and additional canals should never be over looked

Aminsobhani, Mohsen

Bolhari, Behnam

Ghabraei, Sholeh

Ghorbanzadeh, Abdollah

Shokouhinejad, Noushin

English

PubMed

Mohsen Aminsobhani

Noushin Shokouhinejad

Sholeh Ghabraei

Behnam Bolhari

Abdollah Ghorbanzadeh

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 138  IEJ -Volume 5, Number 3, Summer 2010 Retreatment of a 6-canalled mandibular first molar with four mesial canals: A case report   Mohsen Aminsobhani P1P DDS, MS, Noushin Shokouhinejad P1*P DDS, MS, Sholeh Ghabraei P2P DDS, MS, Behnam Bolhari P2P DDS, MS, and Abdollah Ghorbanzadeh P2P DDS, MS  1. Assistant Professor of Endodontics, Dental School/Dental Research Center, Tehran University of Medical Sciences, and member of Iranian Center for Endodontic Research, Tehran, Iran.  2. Assistant Professor of Endodontics, Dental School/Dental Research Center, Tehran University of Medical Sciences, Tehran, Iran.  Abstract   Successful root canal treatment requires adequate knowledge regarding morphologic variations in root canal system of teeth. This report describes a six-canalled mandibular first molar with four mesial root canals requiring endodontic retreatment. The two additional canals in the mesial root were found during retreatment with the aid of illumination and magnification. In conclusion, the possibility of atypical morphology and additional canals should never be overlooked. [Iranian Endodontic Journal 2010;5(3):138-40]  Keywords: First mandibular molar, Four root canal, Mesial root.  Received February 2010; accepted May 2010 *Correspondence: Dr. Noushin Shokouhinejad, Endodontic Department, School of Dentistry, Tehran University of Medical Sciences, Ghods Ave., Enghelab St., Tehran, Iran. E-mail: shokouhinejad@yahoo.com Introduction One of the most important prerequisites for successful endodontic treatment is adequate knowledge and understanding of root canal anatomy. Numerous in vitro and in vivo studies have investigated the root canal morphology of mandibular first molars. Most of them had two roots, with two canals in the mesial root and one canal or two canals in the distal root (1-3). The incidence of mesial roots with three root canals in mandibular molars has been reported to range between 1-15% (3-10). Very few articles have demonstrated four canals in the mesial root of mandibular first molars (11-13). This case report describes a six-canalled mandibular first molar with four canals in the mesial root, and two in the distal; this tooth had previously received incomplete root canal treatment.   Case Report A 30 year old female with a non-contributory medical history was referred to our private office with severe spontaneous pain and tenderness to percussion in the right mandibular region. The patient reported that the tooth #30 had been root treated one month ago. She had experienced localized swelling and pain since then.  Clinical examination revealed extensive amalgam restoration in the mandibular molar; however no swelling or sinus tract was present. Tooth #30 was sensitive to palpation and percussion. There was no mobility and probing did not reveal the presence of a periodontal pocket. The adjacent teeth responded normally to thermal and electrical pulp testing, and to palpation, and percussion. Radiographic examination revealed a large radiolucency associated with the mesial root of tooth #30 (Figure 1A). A diagnosis of secondary or exacerbating apical periodontitis associated with incomplete root canal treatment was made. Therefore, endodontic re-treatment was indicated.  Local anesthesia with inferior alveolar nerve block using lidocaine (Daroupakhsh, Iran) was performed. After removing the coronal filling material and carious tooth structure, a prefabricated post was removed from the distal root. The tooth was isolated with a rubber dam and an adequately sized access cavity preparation was created. The floor of the pulp chamber was explored under magnification and illumination with the aid of    139  6-canalled molar IEJ -Volume 5, Number 3, Summer 2010     Figure 1. A) Preoperative radiograph B) Four root canal orifices can be observed: mesiobuccal 1 (MB1), mesiobuccal 2 (MB2), mesiolingual 1 (ML1), and mesiolingual 2 (ML2) C) Four gutta-percah master cones in four mesial canals D) Length confirmation of radiograph demonstrating four root canals in  mesial root E) A radiograph after completion of retreatment. F) Postoperative radiograph showing four mesial canals in mesial root  a HEINE 2.5× HR Binocular Loupe and 3S LED HeadLight® (HEINE Optotechnik GmbH & Co. Herrsching, Germany). Two mesial and two distal root canal orifices had been inadequately treated during the first root canal treatment. Root filling materials were removed from the root canals with the aid of hand and rotary files. The unusually wide space between the two mesial orifices clinically and the radiographic appearance of the root canals indicated possible additional canal(s) in the mesial root. Moreover, during exploration of the groove with a sharp explorer and file, a sticky groove was felt. Two additional canals were located between the two previously discovered mesial orifices (Figure 1B). The working lengths of the root canals were determined using an electronic apex locator (ProPex™, Dentsply Maillefer, Montigny le Bretonneux, Switzerland) and were then confirmed with a digital radiography (Kodak RVG 5100 Digital Radiography System, Eastman Kodak Co., Trophy Radiology, Marne-la-Vallée, France). Root canal instrumentation was performed with ProTaper series Ni-Ti instruments (Dentsply Maillefer, Ballaigues, Switzerland) and EDTA gel (MD-ChelCream, Meta Biomed Co., Ltd., Cheongju City, Chungbuk, Korea). The root canals were irrigated with 2.5% sodium hypochlorite during instrumentation. Afterwards, the root canals were dressed with calcium hydroxide paste (Calcipex II, NISHIKA, Shimonoseki, Japan) and coronally sealed with a temporary filling material (Zonalin, Kemdent, UK). At the next appointment (after 10 days), the tooth was asymptomatic. After completion of the chemomechanical preparation and radiographs with gutta-percha master cones (Figures 1C, D), the root canals were dried with paper points and obturated with laterally compacted gutta-percha (Meta Biomed Co., Ltd., Cheongju City, Chungbuk, Korea) and AH26 sealer (Dentsply, DeTrey, Konstanz, Germany) (Figures 1E, F). Coronal access was restored with a temporary filling material (Zonalin, Kemdent, UK) and the patient referred to another dentist for a coronal restoration and completion of the treatment. At the 3-months follow up examination, tooth #30 was functional and asymptomatic, with no clinical  signs. There was radiographic evidence   140  Aminsobhani et al. IEJ -Volume 5, Number 3, Summer 2010 Figure 2. Three-month follow up radiograph  of periapical osseous healing (Figure 2). Further follow up examinations were recommended for evaluation of treatment outcome.  Discussion Thorough understanding about root canal morphology plays an important role in the success of root canal therapy. Anatomical variations in root canal system should be considered when exploring the floor of the pulp chamber.  Multiple canals in the mesial root of mandibular molars have been reported in several cases (4-9); however only two reports have described four canals in the mesial root of mandibular first molars (11,13). Reeh described an interesting retreatment case of a seven-canalled mandibular first molar with four canals in the mesial root and three canals in the distal root (11). Kontakiotis and Tzanetakis described four independent root canal orifices in the mesial root of a mandibular first molar with the aid of a dental operating microscope (13).  Exploration of the pulp floor groove under magnification and illumination revealed two further independent root canal openings between the already treated two mesial orifices. The two buccal canals merged into one foramen; the same was true for the two lingual canals (i.e. a total of 2 foramina in the mesial root). Meticulous radiographic evaluation of the root and periodontal ligament outlines can help to predict unusual anatomy. Moreover, the use of a sharp explorer, as well as the additional methods such as troughing of the grooves with ultrasonic tips, magnification and illumination can assist to locate extra root canal orifices (14-16).  Conclusion  In conclusion, although detecting extra canals in teeth with atypical internal anatomy is challenging, repeated attempts should be made to find all root canals.  References  1. Skidmore AE, Bjorndal AM. Root canal morphology of the human mandibular first molar. Oral Surg Oral Med Oral Pathol 1971;32:778-84. 2. Pineda F, Kuttler Y. Mesiodistal and buccolingual roentgenographic investigation of 7,275 root canals. Oral Surg Oral Med Oral Pathol 1972;33:101-10. 3. Vertucci FJ.Root canal anatomy of the human permanent teeth. Oral Surg Oral Med Oral Pathol 1984;58:589-99. 4. Baugh D, Wallace J. Middle mesial canal of the mandibular first molar: a case report and literature review. J Endod 2004;30:185-6. 5. Ricucci D. Three independent canals in the mesial root of a mandibular first molar. Endod Dent Traumatol 1997;13:47-9. 6. DeGrood ME, Cunningham CJ. Mandibular molar with 5 canals: report of a case. J Endod 1997;23:60-2. 7. Beatty RG, Krell K. Mandibular molars with five canals: report of two cases. J Am Dent Assoc 1987;114:802-4. 8. Martinez-Berna A, Badanelli P. Mandibular first molars with six root canals. J Endod 1985;11:348-52. 9. Fabra-Campos H. Unusual root anatomy of mandibular first molars. J Endod 1985;11:568-72. 10. Pomeranz HH, Eidelman DL, Goldberg MG. Treatment considerations of the middle mesial canal of mandibular first and second molars. J Endod 1981;7:565-8. 11. Reeh ES. Seven canals in a lower first molar. J Endod 1998;24:497-9. 12. Goel NK, Gill KS, Taneja JR. Study of root canals configuration in mandibular first permanent molar. J Indian Soc Pedod Prev Dent 1991;8:12-4. 13. Kontakiotis EG, Tzanetakis GN. Four canals in the mesial root of a mandibular first molar. A case report under the operating microscope. Aust Endod J 2007;33:84-8. 14. Weller RN, Hartwell GR. The impact of improved access and searching techniques on detection of the mesiolingual canal in maxillary molars. J Endod 1989;15:82-3. 15. Stropko JJ. Canal morphology of maxillary molars: clinical observations of canal configurations. J Endod 1999;25:446-50. 16. Yoshioka T, Kobayashi C, Suda H. Detection rate of root canal orifices with a microscope. J Endod 2002;28:452-3. 

Retreatment of a 6-Canalled Mandibular First Molar with Four Mesial Canals: A Case Report

Journals Portal, Shahid Beheshti University of Medical Sciences

Canal morphology of maxillary molars: clinical observations of canal configurations.

Detection rate of root canal orifices with a microscope.

Four canals in the mesial root of a mandibular first molar. A case report under the operating microscope.

Mandibular first molars with six root canals.

Mandibular molar with 5 canals: report of a case.

Mandibular molars with five canals: report of two cases.

Mesiodistal and buccolingual roentgenographic investigation of 7,275 root canals. Oral Surg Oral Med Oral Pathol

Middle mesial canal of the mandibular first molar: a case report and literature review.

Root canal morphology of the human mandibular first molar. Oral Surg Oral Med Oral Pathol

Seven canals in a lower first molar.

Study of root canals configuration in mandibular first permanent molar. J Indian Soc Pedod Prev

The impact of improved access and searching techniques on detection of the mesiolingual canal in maxillary molars.

Three independent canals in the mesial root of a mandibular first molar. Endod Dent Traumatol

Treatment considerations of the middle mesial canal of mandibular first and second molars.

Unusual root anatomy of mandibular first molars.

Vertucci FJ.Root canal anatomy of the human permanent teeth. Oral Surg Oral Med Oral Pathol

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Retreatment of a 6-Canalled Mandibular First Molar with Four Mesial Canals: A Case Report

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