REVIEW ARTICLE 195

Hany Mohamed Aly Ahmed, Norhayati Luddin Accessory mesial roots and root canals in mandibular teeth: Case reports, SEM analysis and literature review

Hany Mohamed Aly Ahmed Department of Restora- tive , School of Dental Sciences, Universiti Sains Malaysia, Kelantan, Key words accessory root, accessory root canal, mandibular molar, middle mesial canal, root, Malaysia root canal Norhayati Luddin Department of Restora- Adequate knowledge on the root and root canal morphological variations is essential for successful tive Dentistry, School of Dental Sciences, Universiti endodontic treatment. Mandibular molar teeth show considerable variability and complexity in their Sains Malaysia, Kelantan, external and internal radicular morphology that require special attention from dental practitioners to Malaysia provide the best clinical outcomes for the patients. This report aims to describe two clinical cases of Correspondence to: Dr Hany Mohamed Aly mandibular molar teeth with accessory mesial roots/root canals. The first case demonstrates a suc- Ahmed cessful identification and endodontic management of a three-rooted mandibular second molar with Department of Restorative Dentistry, an accessory mesial root, and the second case presents a mandibular first molar with five root canals, School of Dental Sciences, in which three separate mesial root canals were identified. With the aid of SEM and radiographic Universiti Sains Malaysia, Kubang Kerian, 16150, examination, both external and internal radicular morphological analysis were also performed on Kelantan, Malaysia an extracted mandibular second molar having an apical mesial root bifurcation. In addition, Tel: 00-601-29857937 Email: hany_endodontist@ a review on the literature was undertaken to identify the available in vitro and in vivo studies that hotmail.com demonstrated these anatomical aberrations in the mesial root of mandibular molar teeth.

Introduction molar tooth with an accessory mesial root can be rather common4,12-18. In addition, some studies and Thorough knowledge on root and root canal morph- reported cases demonstrated the occurrence of four- ology is a fundamental prerequisite for successful rooted mandibular molar teeth having double mesial root canal treatment1. Accessory roots in mandibular roots4,5,16,18-22. permanent molar teeth have been comprehensively Apart from this external anatomical aberration, investigated in previous studies2-7, and it can be mandibular molar teeth show an increased likelihood concluded that the occasion of this anatomical ab- for internal morphological variations including root erration varies according to ethnicity, gender and canals with unusual configurations, lateral and furca- association with some diseases4, 8-10. While the oc- tion canals and inter-canal communications1,23-25. currence of radix entomolaris (accessory distolingual Within this complex anatomy of the root canal sys- roots) and radix paramolaris (accessory buccal roots) tem, the increased prevalence of additional root is usually mentioned as the typical clinical finding canals, which is significantly influenced by ethnicity for three-rooted mandibular permanent molar and age1,26, is considered at the forefront of chal- teeth6,11, the occasion of three-rooted mandibular lenges facing clinicians while performing endodontic

ENDO (Lond Engl) 2012;6(3):195–205 196 Ahmed/Luddin Accessory mesial roots and root canals in mandibular molar teeth

therapy. Even though mandibular molar teeth are shaped using sizes 2 and 3 Gates-Glidden drills (Mani, usually presented with double mesial root canals, as Tochigi, Japan ). The working length was determined many as four canals have been reported in the mesial using electronic apex locator (Element Diagnostic root of mandibular molar teeth27-30. Unit, SybronEndo, Orange, California, USA), and the Because of these external and internal anatom- canals were initially instrumented using hand K-Flex- ical discrepancies, it is of prime importance for the ofiles (Dentsply Maillefer, Ballaigues, Switzerland) up clinicians to clearly identify their morphological land- to sizes 25 and 30 for the mesial and distal canals, marks. Hence, this article aims to present two clin- respectively. Subsequently, with the aid of a NaviTip ical cases and one extracted mandibular molar tooth needle gauge 29 (Ultradent, South Jordan, Utah, having these anatomical aberrations in the mesial USA), the canals were injected with an aqueous root. In addition, a literature search for the available radiopaque calcium hydroxide paste (UltraCal XS, and relevant articles, cited in PubMed and Google Ultradent, South Jordan, Utah, USA), and the access Scholar from 1971 to 2011, was undertaken to iden- cavity was then temporized using a fast set highly tify the available in vitro and in vivo studies that viscous conventional glass ionomer cement (Ionofil demonstrated this aberrant anatomy. Molar AC Quick, Voco, Cuxhaven, Germany). In the following visit, the hand mechanical instrumentation was continued up to sizes 35 and 45 for the mesial Case 1 and distal root canals, respectively. Finally, the canals A 30-year-old male patient was referred with the were obturated using the lateral compaction tech- chief complaint of a dull pain while chewing on nique (Figs 1c and d). the mandibular right side. The medical history was noncontributory. The clinical examination revealed Case 2 a large and deep carious cavity related to the man- dibular right second molar with slight pain on per- A 40-year-old male patient presented with the main cussion. There was no evidence of current swelling or complaint of severe pain while chewing on man- tooth mobility. Radiographically, the tooth showed dibular left side of the jaw. Clinical and radiographic widening of the periodontal ligament spaces around examinations revealed a large proximal carious le- the mesial and distal roots (Fig 1a). A second mesial sion related to his mandibular left first molar with root was identified (Fig 1a). The pulp of the tooth severe pain on percussion and loss of periapical was provisionally diagnosed as necrotic with asym- periodontal ligament space (Fig 2a). Following tomatic apical periodontitis. Following caries excava- local anaesthesia, the caries was excavated, and tion, the pulp was confirmed to be necrotic and a was initiated after the pulp root canal treatment was scheduled. exposure was confirmed. All endodontic procedures were performed with Similar to the previous case, all treatment steps the aid of magnification using 4× prismatic dental were employed with the aid of assisted magnifi- loupes (Heine, Herrsching, Germany), accessory cation and accessory illumination. The tooth was light emitting diode illumination (LED) (3S, Heine, isolated and the access cavity was prepared, after Herrsching, Germany) and rhodium plated front restoring the distal wall using a fast set highly vis- surface mirror (Hahnenkratt, Königsbach-Stein, Ger- cous conventional glass ionomer cement (Ionofil many). After the administration of local anaesthesia Molar AC Quick, Voco). The working lengths were and rubber dam isolation, the access cavity prep- determined for the four root canals (MB – mesio- aration was completed. During exploration of the buccal; ML – mesiolingual; DB – distobuccal; DL – pulp chamber, a wide buccolingual dimension of the distolingual) using electronic apex locator (Element mesial access cavity wall was noted, indicating the Diagnostic Unit, SybronEndo). The DB and DL root complete division of the mesial root into two well- canals were connected at the apical third of the root separated mesial root components (Fig 1b). by one apical foramen. The canals were coronally Following this, the mesiobuccal (MB), mesio- shaped using Gates-Glidden drills (Mani) (sizes 2 lingual (ML) and distal (D) root canals were coronally and 3) and apically instrumented to a flexible file

ENDO (Lond Engl) 2012;6(3):195–205 Ahmed/Luddin Accessory mesial roots and root canals in mandibular molar teeth 197

Fig 1 (a) Periapical radiograph showing the external outlines of the two mesial roots (white arrows). (b) An intraoral photograph showing the wide buccolingual dimension of the me- sial orifices. (c and d) Postoperative periapical radiograph.

a b

c d

size 25 (Mani). Then, an aqueous radiopaque cal- arate apical foramen (Fig 2c). The orifice and about cium hydroxide paste (UltraCal, Ultradent) was in- 2 mm of the coronal third of the MM canal were troduced into the canals as intracanal medicament flared using a Gates-Glidden drill (Mani) (size 2), and using NaviTip needles gauge 29 (Ultradent), and the mechanical instrumentation was continued using the access cavity was then temporized using glass stainless steel flexible hand files (Mani) until only size ionomer cement (Ionofil Molar AC Quick, Voco). 30 to reduce the risk of perforation, while the MB In the subsequent visit, a thorough exploration and ML canals were prepared at size 35. The distal of the mesial groove between the MB and ML canal root canal was instrumented up to size 50. Finally, orifices was performed using an endodontic explorer the canals were obturated using the lateral compac- under magnification and a middle mesial (MM) root tion technique (Fig 2d). canal was located (Fig 2b). The canal showed a sep-

ENDO (Lond Engl) 2012;6(3):195–205 198 Ahmed/Luddin Accessory mesial roots and root canals in mandibular molar teeth

Fig 2 (a) Preoperative radiograph showing large proximal cavitation and loss of periapical periodontal ligament space. (b) Intraoral photograph showing the orifices of the three mesial canals. (c) The three master cones in place after mechanical instrumentation. (d) Postoperative periapical radiograph.

a b

c d

Scanning electron microscope (SEM) under a desktop SEM (FEI Phenom, Eindhoven, The and radiographic evaluation of a Netherlands). The SEM analysis revealed the pres- mandibular molar with unusual ence of furcation, lateral canals and multiple for- anatomy of the mesial root amina at both apices (Figs 3b to 3i). The radiographic The external and internal morphological features of examination showed three mesial canals, in which a badly decayed mandibular second molar extracted the mesiobuccal and middle mesial root canals were from an 18-year-old male patient with an apically connected at the middle third of the root (Fig 3j). bifurcated mesial root were evaluated (Fig 3a). After resection of the bifurcated mesial root using a hard tissue microtome (Exakt, Norderstedt, Germany), it Discussion was applied to a small piece of plasticine attached onto a metal stub for SEM. The stub was then fit- The incidence of missed roots and root canals in ted into a charge reduction sample holder for non- root canal treated teeth has been reported as high conductive samples, and the sample was examined as 42%31. This high percentage indicates that the

ENDO (Lond Engl) 2012;6(3):195–205 Ahmed/Luddin Accessory mesial roots and root canals in mandibular molar teeth 199

a b c d

e f h h

MB MM ML

Fig 3 (a) Mandibular second molar with an apically bifurcated mesial root. (b and c) Identification of a furcation canal. (d and e) Detection of a lateral canal at the buccal surface of the mesiolingual root component. (f to i) Multiple foramina in the mesiobuccal and mesiolingual roots. (j) The middle mesial canal was identified, and was connected to the mesiobuccal canal. i j variability in intra- and extra-radicular anatomy is roots (usually not possible to define which one is the rule rather than the exception. Due to these mor- the accessory), or by folding of the HERS to form an phological complexities, it is of prime importance for independent root35. The splitting or folding of the the clinician to ignore the absolute confidence of the HERS results in the formation of a bifurcation area, pre-estimated number of roots and root canals. This which may have furcation canals. The specimen for broad anticipation, accompanied with clinical thor- SEM analysis used in the present study exhibited this oughness by utilising well exposed and processed anatomical variation at the furcation area, located periapical radiographs with different angulations, apically, between the mesial roots (Figs 3b and 3c). assisted magnification and accessory illumination, This apical location of the furcation area, encasing front surface mirrors, proper access cavity prepar- the furcation canals, together with the increased ation and accurate intra- and inter-canal exploration, prevalence for lateral canals, apical ramifications would facilitate the detection of these anatomical and accessory foramina in this apical part of the root aberrations6,32,33. (Figs 3d to 3i), would serve as a well-protected en- An accessory root, also known as an extra root, vironment for micro-organisms that may complicate supernumerary root, supplementary root or addi- the optimisation of root canal preparation. tional root, refers to the development of an increased Interestingly, some controversial opinions do exist number of roots in teeth compared with that clas- with regard to the application of the term accessory sically described in dental anatomy34. Its forma- roots. In 1971, De Souza-Freitas et al12 studied the tion usually occurs either by splitting the Hertwig’s anatomical variations of mandibular first molar roots epithelial root sheath (HERS) to form two similar in two ethnic groups, and commented that disto-

ENDO (Lond Engl) 2012;6(3):195–205 200 Ahmed/Luddin Accessory mesial roots and root canals in mandibular molar teeth

Table 1 Summary for the occurrence of accessory mesial roots in mandibular molar teeth. (CBCT: cone beam computed tomography, M: Molar, *: unpublished data).

Author/s Year Type of study Percentage % (number of teeth/total) de Souza-Freitas 1971 In vivo (clinical survey) – 4.5% (38/844) of children with European descent (1st M) et al12 (radiographic) – 2.8% (13/466) of children with Japanese descent (1st M) Barker13 1973 In vitro (extracted teeth) % not listed (2nd M). Specimens from Department of Anatomy, University of Sydney, Australia Barker et al38 1974 In vitro (radiographic) % not listed (2nd M). Specimens from Department of Anatomy, University of Sydney, Australia Manning14 1990 In vitro 2% (3/149) (2nd M) (clearing technique)

Younes et al4 1990 Phase I: In vitro – 0.51% (2/385) of Saudi Arabian (1st M) (extracted teeth) – 0.21% (1/457) of Egyptian (1st M)

Midtbø and 1994 In vivo (clinical survey) – 6.1% (2/33 patients) Turner syndrome (1st M) Halse8 (radiographic) – 9.1% (3/33 patients) Turner syndrome (2nd M) Huang et al16 2007 In vivo (radiographic) – 6.3% (21/332) (3-rooted 1st M) Taiwanese Han Chinese – 4.5% (15/332) (4-rooted 1st M) patients

Huang et al18 2010 In vivo (clinical survey) – 22.5% (117/521) (3-rooted 1st M) (CBCT) – 18% (94/521) (4-rooted 1st M) Taiwanese Han Chinese patients

Zhang et al39 2011 In vivo (clinical survey) – 0.4% (1/232) (4-rooted 1st M) (CBCT) Ahmed* 2011 In vivo (clinical survey) – 4.44% (2/45) of Saudi Arabian (1st and 2nd M) – 1.81% (1/55) of Egyptian (1st and 2nd M)

lingual roots are the real supplementary roots, and classified according to their level of bifurcation (apical, they did not consider the mesial root bifurcation as middle or cervical) and whether they are separated a third root, even though many authors defined this or fused. As such, the extracted tooth sample in this mesial root bifurcation as extra roots4,8,15,16,18,22,36. study would be classified as three-rooted mandibular Besides this disagreement, it is not clear whether molar tooth with well separated, double mesial roots the level of root bifurcation and degree of separation in which the level of bifurcation is at the apical third. should also be considered or not before defining any These criteria have almost been followed with other root component as an accessory root. Onda et al20 ex- teeth such as three-rooted maxillary with amined the shape and number of roots in mandibular double buccal roots37. molar teeth extracted from Indian skulls. Interestingly, A review on the literature indicates that the oc- the authors defined and correlated the increase in casion of accessory mesial roots in mandibular molar root number with the presence of distolingual root, teeth, commonly in the 1st molar, ranges from about accessory lingual root and bifurcation of the mesial 0.2% to over 20%4,8,12-14,16,18,38,39 (Table 1). This root. Those samples were then divided according to was found more frequently in some populations the level of mesial root bifurcation, either more or less such as Taiwanese Han Chinese16,18, that can reach than one third of the root length. Accordingly, it seems 22.5%18, and to a lesser extent in the Middle East sensible that all root bifurcations that have their own (Saudi Arabians and Egyptians)4, Chinese39, and some root canals defined as extra roots which can then be populations with European and Japanese descents12.

ENDO (Lond Engl) 2012;6(3):195–205 Ahmed/Luddin Accessory mesial roots and root canals in mandibular molar teeth 201

In addition, this anatomical variant has been reported in patients with Turner syndrome8. MB MM ML It can be noted from the first case that the me- MB sial access cavity wall was wide in a buccolingual di- mension (Fig 1b). The alteration in the access cavity MM configuration is usually a common landmark for teeth having accessory roots6, especially when they are well separated with a coronal bifurcation (Figs 1a and 1b, ML and Fig 5b). During the mechanical preparation of three-rooted mandibular molar teeth, it is important a b c to evaluate the dentine wall thickness and curvature of accessory roots6,17. This is because when these Fig 4 (a) A mesial root in mandibular molar with a middle mesial (MM) canal orifice close to the mesiobuccal canal (MB). (b) Despite this, the MM canal communicates with roots are relatively thin, the root canal instrumenta- mesiolingual canal (ML). (c) The MM was shaped to size 35. tion should be performed with caution to avoid strip perforation caused by over-enlargement of the en- cased root canals. Additionally, accessory mesial roots b) A confluent – when the prepared canal origin- can also be presented with severe curvatures17. These ated as a separate orifice but apically joined the curved roots should be treated carefully, using flexible mesiobuccal or mesiolingual canal (Figs 3 and 4). files and suitable sized irrigation needles with lubrica- c) The least frequent variant is the independent – tion40, to preserve the normal root canal geometry, when the prepared canal originated as a sep- and prevent the incidence of unexpected complica- arate orifice and terminated as a separate for- tions such as instrument separation6. amen (Fig 2). Even when the middle mesial Similar to accessory roots, accessory root canals in- canal is confluent or independent, its orifice lo- dicate an increased number of root canals compared cation shows considerable variations. It can be with that classically described41,42. The occurrence of located near the mesiolingual orifice45,63, equi- an accessory mesial root canal in mandibular molar distant between the mesiobuccal and mesiolin- teeth (commonly the 1st molar) shows a wide preva- gual canals 46,63 (Fig 2), or near the mesiobuc- lence from 0.4 to over 18%25,38,42-62 (Table 2). This is cal orifi ce64 (Figs 3 and 4). The close proximity commonly observed in patients of a young age43,46,48. of the orifice to either the mesiobuccal or me- Many studies demonstrated this anatomical variation siolingual orifice does not necessarily indicate its in some population groups such as Chinese47,61,62, Tai- commun ication to that nearby canal. Sometimes wan Chinese59, Turkish49,55, South Asian Pakistanis51, it is connected to the one with the far orifice64 Burmese52, Thai53, Japanese54,58, Sudanese56, Sri (Fig 4), or even remains separate65. Lankan58 and Jordanian60. However, many of these studies did not consider the patient’s age with regard In order to locate these canals, the clinicians should to their findings49,51-53,55,60. As such, the comparison be aware of the clinical landmarks and diagnostic between these population groups might not be entirely aids that would help in identifying the anatomy of relevant as the age factor might have greater contribu- the root canal space to prevent the undesirable con- tion, or more closely associated, with the presence of sequences when they are left untreated66. These are accessory root canal rather than ethnicity. summarised in the following points: Owing to the morphological variations of the t The wide buccolingual dimension of the access middle mesial canal, also named as intermediate cavity may indicate the presence of more than canal46, Pomeranz et al43 classified it into three two mesial canals29 (Fig 5). classes: t In some instances, a bleeding point or bubbling a) A fin – when at any stage during debridement, on the middle mesial canal orifice resulting the instrument could pass freely between the from the interaction between sodium hypo- mesiobuccal or mesiolingual canal and the mid- chlorite and the remaining soft tissues can be dle mesial canal. observed48.

ENDO (Lond Engl) 2012;6(3):195–205 202 Ahmed/Luddin Accessory mesial roots and root canals in mandibular molar teeth

Table 2 Summary for the occurrence of accessory mesial root canals in mandibular molar teeth. Root canal configurations (3-3, 3-2, 2-3, 3-1, 3-4, 3-2-1, 3-2-3) are included. (CT: computed tomography, microCT: micro-computed tomography; CBCT: cone beam computed tomography, M: molar, *: unpublished data).

Author/s Year Type of study Percentage (number of teeth/total) Barker et al38 1974 In vitro (radiographic and epoxy – % not listed (1st M) resin moulds) Pomeranz et al43 1981 In vivo (clinical survey) – 11.5% (7/61) (1st M) – 12.8% (5/39) (2nd M) Vertucci44 1984 In vitro (clearing technique) – 1% (1/100) (1st M) Martinez-Berna and 1985 In vivo (clinical survey) – 1.48% (21/1418) (1st M) Badanelli45 – 0.42% (4/944) (2nd M)

Fabra-Campos46 1985 In vivo (clinical survey) – 2.76% (4/145) (1st M) Walker47 1988 In vitro (radiographic) – 1% (1/100) (1st M) Fabra-Campos48 1989 In vivo (clinical survey) – 2.6% (20/760) (1st M) Çali4kan et al49 1995 In vitro (clearing technique) – 3.39% (1st M) – 1.96% (2nd M) de Carvalho and Zuolo50 2000 In vitro (operating microscope) – 17.2% (16/93) (1st M) – 4.5% (5/111) (2nd M) Wasti et al51 2001 In vitro (clearing technique) – 3.3% (1/30) (1st M) Gulabivala et al52 2001 In vitro (clearing technique) – 10.8% (15/139) (1st M) Gulabivala et al53 2002 In vitro (clearing technique) – 6.78% (8/118) (1st M) – 3.33% (2/60) (2nd M) Villegas et al54 2004 In vitro (clearing technique) – 4.76% (3/63) (1st M) Sert and Bayirli55 2004 In vitro (clearing technique) – 1.5% (3/200) (1st M)(Male) Ahmed et al56 2007 In vitro (clearing technique) – 4% (4/100) (1st M) Navarro et al57 2007 In vitro (CT) – 14.8% (4/27) (1st M) In vitro (SEM) – 12% (3/25) (1st M) Peiris58 2008 In vitro (clearing technique) – 1% (1st M) (Sri-Lankan) – 2.6% (1st M) (Japanese) Peiris et al25 2008 In vitro (clearing technique) – 1.13% (2/177) (1st M) Chen et al59 2009 In vitro (clearing technique) – 5.46% (10/183) (1st M) Al-Qudah and 2009 In vitro (clearing technique) – 4.55% (15/330) (1st M) Awawdeh60 – 1.41% (5/355) (2nd M) Gu et al61 2010 In vitro (microCT) – 2.2% (1/45) (3-rooted 1st M) Karapinar-Kazandag 2010 In vitro (loupes followed by – 14.58% (7/48) (1st M) et al42 operating microscope) (negoti- – 18.75% (9/48) (2nd M) ated canals) Wang et al62 2010 In vitro (CBCT) – 2.68% (11/410) (2-rooted 1st M) – 0.69% (1/144) (3-rooted 1st M) Ahmed* 2011 In vivo (clinical survey) – 1.81% (1/55) (Egyptian) (1st and 2nd M)

t Adequate magnification and illumination pro- t Cone beam computed tomography (CBCT) can vide a great precision while troughing the also provide a supportive diagnostic tool, which groove between the mesiobuccal and mesio- is recommended when conventional periapical lingual canals1. This can be performed using a radiographs provide limited information and fur- long shank small round bur or ultrasonic tips67. ther anatomical details are required to be iden- t After troughing, a sharp endodontic explorer tified68. This advanced technology can also be and/or small K-files (size 8 or 10) can be used. performed when the mesial root is scheduled Sometimes, the use of methylene blue staining for endodontic surgery. The identification of an is helpful1. undetected independent middle mesial canal by

ENDO (Lond Engl) 2012;6(3):195–205 Ahmed/Luddin Accessory mesial roots and root canals in mandibular molar teeth 203

Buccal

MD

Lingual a bcdef

Fig 5 Schematic illustration showing the orifices location in mandibular molar teeth with accessory mesial roots/root canals: (a) Normal location of the mesial orifices in a single mesial root. (b) The presence of a well-separated accessory mesial root can be corresponded by a wide buccolingual dimension (blue double arrow) of the mesial access cavity wall. (c) A third middle mesial root canal may be located at any position (black doted double arrow) between the normally positioned mesial canals enclosed in single mesial root. (d and e) The wide buccolingual dimension can also be observed in a single mesial root with more than two mesial canals. (d) Three mesial canals; (e) Four mesial canals.(f) Mesial and distal concavities can be observed at the middle third of the mesial root.

CBCT helps the operator to optimise the retro- good anticipation of these anatomical variations, grade cavity preparation, or may even change as well as clinical thoroughness during every root the treatment plan to an attempt for orthograde canal treatment procedure, are essential for the op- endodontic approach. Despite these benefits and timisation of root canal therapy, thus maintaining a due to the possibility of some misleading findings high rate of clinical success. in CBCT views, it should adjunctly be correlated with the clinical picture69. Acknowledgement Once found, great consideration should be given to the external anatomy of the mesial root while The SEM images were taken with the kind assistance performing mechanical instrumentation. Berutti of Mr Chairul Sopian and Ms Nora Aziz, technolo- and Fedon70 demonstrated that the distal surface gists at the Craniofacial Science Laboratory, School of the mesial root is concave, and that the dentine/ of Dental Sciences, Universiti Sains Malaysia. cementum thickness at this area is one fifth less than its usual appearance in the radiograph. In addition to this distal concavity, the mesial root can also be References presented with a mesial depression (Fig 5f). As a 1. Vertucci FJ. Root canal morphology and its relationship to result of this anatomical landmark, the middle mesial endodontic procedures. Endodontic Topic. 2005;10:3–29. 2. Turner CG, 2nd. Three-rooted mandibular first permanent canal, which sometimes has a lesser diameter than molars and the question of American Indian origins. Am J the other two canals46, should not be over-enlarged Phys Anthropol 1971;34:229–241. to prevent the danger of perforation. Gates-Glidden 3. Carlsen O, Alexandersen V. Radix entomolaris: identifica- tion and morphology. Scand J Dent Res 1990;98:363–373. drills should be avoided or used with great caution 4. Younes SA, al-Shammery AR, el-Angbawi MF. Three-rooted when required. The use of enlarging files to size 30 permanent mandibular first molars of Asian and black groups in the Middle East. Oral Surg Oral Med Oral Pathol or 35 is considered safe and adequate45,64,71 (Fig 4). 1990;69:102–105. 5. Carlsen O, Alexandersen V. Radix paramolaris in permanent mandibular molars: identification and morphology. Scand J Dent Res 1991;99:189–195. 6. Calberson FL, De Moor RJ, Deroose CA. The radix ento- Conclusion molaris and paramolaris: clinical approach in endodontics. J Endod 2007;33:58–63. The mesial root in mandibular molar teeth shows 7. Song JS, Choi HJ, Jung IY, Jung HS, Kim SO. The preva- lence and morphologic classification of distolingual roots an increased prevalence for external and internal in the mandibular molars in a Korean population. J Endod radicular aberrations. Adequate knowledge and 2010;36:653–657.

ENDO (Lond Engl) 2012;6(3):195–205 204 Ahmed/Luddin Accessory mesial roots and root canals in mandibular molar teeth

8. Midtbø M, Halse A. Root length, crown height, and root 31. Hoen MM, Pink FE. Contemporary endodontic retreat- morphology in Turner syndrome. Acta Odontol Scand ments: an analysis based on clinical treatment findings. 1994;52:303–314. J Endod 2002;28:834–836. 9. De Moor RJ, Deroose CA, Calberson FL. The radix entomo- 32. Buhrley LJ, Barrows MJ, BeGole EA, Wenckus CS. Effect laris in mandibular first molars: an endodontic challenge. Int of magnification on locating the MB2 canal in maxillary Endod J 2004;37:789–799. molars. J Endod 2002;28:324–327. 10. Song JS, Kim SO, Choi BJ, Choi HJ, Son HK, Lee JH. 33. England MC, Jr, Hartwell GR, Lance JR. Detection and Incidence and relationship of an additional root in the treatment of multiple canals in mandibular premolars. mandibular first permanent molar and primary molars. J Endod 1991;17:174–178. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 34. Neville BW, Damm DD, Allen CM, Bouquot JE. Abnor- 107:e56–60. malities of teeth. In: Neville BW, Damm DD, Allen CM, 11. Tu MG, Huang HL, Hsue SS, et al. Detection of perman- Bouquot JE (eds). Oral & Maxillofacial Pathology, ed 2. ent three-rooted mandibular first molars by cone-beam Philadelphia, PA, USA: WB Saunders, 2002:88. computed tomography imaging in Taiwanese individuals. 35. Türp JC, Alt KW. Anatomy and morphology of human J Endod 2009;35:503–507. teeth. In: Alt KW, Rösing FW, Teschler-Nicola M (eds). 12. de Souza-Freitas JA, Lopes ES, Casati-Alvares L. Anatomic Dental Anthropology. Fundamentals, Limits and Prospects. variations of lower first permanent molar roots in two ethnic Austria: Springer, 1998:71–94. groups. Oral Surg Oral Med Oral Pathol 1971;31:274–278. 36. Plotino G. A mandibular third molar with three mesial roots: 13. Barker BC. Dental anthropology: some variations and anom- a case report. J Endod 2008;34:224–226. alies in form. Aust Dent J 1973;18:132–140. 37. Bellizzi R, Hartwell G. Evaluating the maxillary pre- 14. Manning SA. Root canal anatomy of mandibular second molar with three canals for endodontic therapy. J Endod molars. Part I. Int Endod J 1990;23:34–39. 1981;7:521–527. 15. Kannan SK, Suganya, Santharam H. Supernumerary roots. 38. Barker BC, Parsons KC, Mills PR, Williams GL. Anatomy of Indian J Dent Res 2002;13:116–119. root canals. III. Permanent mandibular molars. Aust Dent J 16. Huang RY, Lin CD, Lee MS, et al. Mandibular disto-lingual 1974;19:408–413. root: a consideration in periodontal therapy. J Periodontol 39. Zhang R, Wang H, Tian YY, Yu X, Hu T, Dummer PM. Use 2007;78:1485–1490. of cone-beam computed tomography to evaluate root and 17. Ravanshad S, Nabavizade MR. Endodontic treatment of a canal morphology of mandibular molars in Chinese indi- mandibular second molar with two mesial roots: report of a viduals. Int Endod J 2011;44:990–999. case. Iran Endod J 2008;3:137–140. 40. Ahmed HMA, Luddin N. Endodontic management of a 18. Huang RY, Cheng WC, Chen CJ, et al. Three-dimensional maxillary molar using a modified incremental instrumenta- analysis of the root morphology of mandibular first molars tion technique. Inter J Dent Clin 2011;3:78–79. with distolingual roots. Int Endod J 2010;43:478–484. 41. Cleghorn BM, Christie WH, Dong CC. The root and root 19. Friedman S, Moshonov J, Stabholz A. Five root canals in canal morphology of the human mandibular first : a mandibular first molar. Endod Dent Traumatol 1986;2: a literature review. J Endod 2007;33:509–516. 226–228. 42. Karapinar-Kazandag M, Basrani BR, Friedman S. The op- 20. Onda S, Minemura R, Masaki T, Funatsu S. Shape and erating microscope enhances detection and negotiation number of the roots of the permanent molar teeth. Bull of accessory mesial canals in mandibular molars. J Endod Tokyo Dent Coll 1989;30:221–231. 2010;36:1289–1294. 21. Sidow SJ, West LA, Liewehr FR, Loushine RJ. Root canal 43. Pomeranz HH, Eidelman DL, Goldberg MG. Treatment morphology of human maxillary and mandibular third considerations of the middle mesial canal of mandibular molars. J Endod 2000;26:675–678. first and second molars. J Endod 1981;7:565–568. 22. Peiris R, Pitakotuwage N, Takahashi M, et al. Mandibular 44. Vertucci FJ. Root canal anatomy of the human permanent permanent second molar with four roots and root canals: a teeth. Oral Surg Oral Med Oral Pathol 1984;58:589–599. case report. Odontology 2009;97:51–53. 45. Martinez-Berna A, Badanelli P. Mandibular first molars with 23. Weine FS. The C-shaped mandibular second molar: inci- six root canals. J Endod 1985;11:348–352. dence and other considerations. Members of the Arizona 46. Fabra-Campos H. Unusual root anatomy of mandibular first Endodontic Association. J Endod 1998;24:372–375. molars. J Endod 1985;11:568–572. 24. Mannocci F, Peru M, Sherriff M, Cook R, Pitt Ford TR. The 47. Walker RT. Root form and canal anatomy of mandibular isthmuses of the mesial root of mandibular molars: a micro- first molars in a southern Chinese population. Endod Dent computed tomographic study. Int Endod J 2005;38:558–563. Traumatol 1988;4:19–22. 25. Peiris HR, Pitakotuwage TN, Takahashi M, Sasaki K, Kanaz- 48. Fabra-Campos H. Three canals in the mesial root of man- awa E. Root canal morphology of mandibular permanent dibular first permanent molars: a clinical study. Int Endod J molars at different ages. Int Endod J 2008;41:828–835. 1989;22:39–43. 26. Neaverth EJ, Kotler LM, Kaltenbach RF. Clinical investi- 49. Çali4kan MK, Pehlivan Y, Sepetçio1lu F, Türkün M, gation (in vivo) of endodontically treated maxillary first Tuncer SS. Root canal morphology of human permanent molars. J Endod 1987;13:506–512. teeth in a Turkish population. J Endod 1995;21:200–204. 27. Goel NK, Gill KS, Taneja JR. Study of root canals con- 50. de Carvalho MC, Zuolo ML. Orifice locating with a micro- figuration in mandibular first permanent molar. J Indian Soc scope. J Endod 2000;26:532–534. Pedod Prev Dent 1991;8:12–14. 51. Wasti F, Shearer AC, Wilson NH. Root canal systems of the 28. Reeh ES. Seven canals in a lower first molar. J Endod mandibular and maxillary first permanent molar teeth of 1998;24:497–499. south Asian Pakistanis. Int Endod J 2001;34:263–266. 29. Kontakiotis EG, Tzanetakis GN. Four canals in the mesial 52. Gulabivala K, Aung TH, Alavi A, Ng YL. Root and canal root of a mandibular first molar. A case report under the morphology of Burmese mandibular molars. Int Endod J operating microscope. Aust Endod J 2007;33:84–88. 2001;34:359–370. 30. Aminsobhani M, Shokouhinejad N, Ghabraei S, Bolhari B, 53. Gulabivala K, Opasanon A, Ng YL, Alavi A. Root and Ghorbanzadeh A. Retreatment of a 6-canalled mandibular canal morphology of Thai mandibular molars. Int Endod J first molar with four mesial canals: a case report. Iran Endod 2002;35:56–62. J 2010;5:138–140.

ENDO (Lond Engl) 2012;6(3):195–205 Ahmed/Luddin Accessory mesial roots and root canals in mandibular molar teeth 205

54. Villegas JC, Yoshioka T, Kobayashi C, Suda H. Frequency 62. Wang Y, Zheng QH, Zhou XD, et al. Evaluation of the of transverse anastomoses with and without apical com- root and canal morphology of mandibular first permanent munication in Japanese population teeth. Aust Endod J molars in a western Chinese population by cone-beam 2004;30:50–52. computed tomography. J Endod 2010;36:1786–1789. 55. Sert S, Bayirli GS. Evaluation of the root canal configur- 63. Bond JL, Hartwell GR, Donnelly JC, Portell FR. Clinical man- ations of the mandibular and maxillary permanent teeth agement of middle mesial root canals in mandibular molars. by gender in the Turkish population. J Endod 2004;30: J Endod 1988;14:312–314. 391–398. 64. DeGrood ME, Cunningham CJ. Mandibular molar with 5 56. Ahmed HA, Abu-bakr NH, Yahia NA, Ibrahim YE. Root and canals: report of a case. J Endod 1997;23:60–62. canal morphology of permanent mandibular molars in a 65. La SH, Jung DH, Kim EC, Min KS. Identification of in- Sudanese population. Int Endod J 2007;40:766–771. dependent middle mesial canal in mandibular first molar 57. Navarro LF, Luzi A, Garcia AA, Garcia AH. Third canal in the using cone-beam computed tomography imaging. J Endod mesial root of permanent mandibular first molars: review 2010;36:542–545. of the literature and presentation of 3 clinical reports and 66. Yesilsoy C, Porras O, Gordon W. Importance of third mesial 2 in vitro studies. Med Oral Patol Oral Cir Bucal 2007;12: canals in mandibular molars: report of 2 cases. Oral Surg Oral E605–609. Med Oral Pathol Oral Radiol Endod 2009;108:e55–58. 58. Peiris R. Root and canal morphology of human permanent 67. Aminsobhani M, Bolhari B, Shokouhinejad N, Ghorban- teeth in a Sri Lankan and Japanese population. Anthropol zadeh A, Ghabraei S, Rahmani MB. Mandibular first and Sci 2008;116:123–133. second molars with three mesial canals: a case series. Iran 59. Chen G, Yao H, Tong C. Investigation of the root canal con- Endod J 2010;5:36–39. figuration of mandibular first molars in a Taiwan Chinese 68. Patel S. New dimensions in endodontic imaging: Part 2. Cone population. Int Endod J 2009;42:1044–1049. beam computed tomography. Int Endod J 2009;42:463–475. 60. Al-Qudah AA, Awawdeh LA. Root and canal morphology 69. Krithikadatta J, Kottoor J, Karumaran CS, Rajan G. Mandibu- of mandibular first and second molar teeth in a Jordanian lar first molar having an unusual mesial root canal morph- population. Int Endod J 2009;42:775–784. ology with contradictory cone-beam computed tomography 61. Gu Y, Lu Q, Wang H, Ding Y, Wang P, Ni L. Root canal findings: a case report. J Endod 2010;36:1712–1716. morphology of permanent three-rooted mandibular first 70. Berutti E, Fedon G. Thickness of cementum/dentin in mesial molars--part I: pulp floor and root canal system. J Endod roots of mandibular first molars. J Endod 1992;18:545–548. 2010;36:990–994. 71. Ryan JL, Bowles WR, Baisden MK, McClanahan SB. Mandibular first molar with six separate canals. J Endod 2011;37:878–880.

ENDO (Lond Engl) 2012;6(3):195–205