Authors: Dr.Padmanabh Jha, Dr. Vineeta Nikhil, Dr. Ambuj Arora.
Subharti Dental college, Meerut.

ABSTRACT:
Abnormalities in the root canal anatomy are a commonly occurring phenomenon. A thorough knowledge of the root canal anatomy and its variations is necessary for successful completion of the endodontic treatment. Mandibular second premolars usually have a single root and a single root canal. Mandibular second molars generally ahve two roots and 3 root canals. The incidence of extra roots itself in these teeth is quite rare. Often considered an enigma to the endodontist, the mandibular first premolar with dual canals dividing at various levels of the root can generate complex mechanical problems. Reports about the incidence of extra roots in these teeth are quite rare. This paper attempts at explaining a rare case of successful endodontic management of a two-rooted mandibular second premolar and three rooted mandibular second molar with awareness of data pertaining to the number of canals, knowledge of canal morphology, correct radiographic interpretation, and tactile examination of canal walls which are important in detecting the presence of multiple canals.

Introduction:
Root anatomy is highly complex and unpredictable. An awareness and understanding of presence of additional root and unusual root canal morphology is essential as it determines the successful outcome of endodontic treatment. In spite of all procedural protocol if clinician misses an additional root or canals it could pose great challenge to the clinician and thus can lead to failure of endodontic treatment.¹
Evidence indicates that root morphology is almost limitless in its variability. The relative simplicity and uniformity of the external surfaces of roots often masks their internal complexity. From the consistency of certain anatomical features in tooth type, as well as from different races, it is apparent that such features are genetically determined. Apart from the surprising variations revealed in such anatomical studies, there are important anthropological implications in the findings as well as important inferences for the endodontist.^2,3.
Human molars show considerable anatomic variation and abnormalities with respect to number of roots and root canals. Unusual tooth anatomy associated with the mandibular molars has been investigated in several studies.^4-9.
Manning has studied the root canal anatomy of 149 extracted mandibular second molars using clearing technique. He found that 22%had single roots, 76% had two roots, and 2% had three roots.¹⁰ Costa Rocha et al. studied the external and internal anatomy of 628 extracted mandibular first and second molars. Analysis of mandibular second molars root showed that 84.1% presented two separate roots, 15.9% fused roots and 1.5% three roots.¹¹ The anatomy of mandibular second molar has racial variations; using periapical radiographs of 328 patients (105, Mongoloid origin; 106, Negro; 117, Caucasian), Ferraz and Pécora reported an incidence of three-rooted mandibular second molar in 2.8% of patients of Mongoloid origin, 1.8% of Negro origin, and 1.7% Caucasian.¹²
The anatomies of mandibular premolars have been examined extensively (Pineda & Kuttler 1972, ElDeeb 1982, Shapira & Delivanis 1982, Vertucci 1984, Bram & Fleisher 1991, Wong 1991, Kartal & Yanıkoglu 1992, Calıskan et al. 1995). Vertucci (1984) determined the incidence of a second canal in mandibular first premolars to be 26% and 3% for second premolars. Studies by Trope et al andSabala et al reported their in vivo results on root number and internal canal morphology by number of patients rather than by the total number of teeth. Two or more canals were found in the mandibular second premolar tooth in 5.2% and 4.4%.of the patients, respectively.
Presented here is a report of a case displaying morphological variations in the permanent mandibular second molar and second premolar, which is very rarely reported in the literature.

Case report:
A 31 year old female patient came to the department of conservative dentistry and endodontics with chief complaint of caries in lower left posterior teeth & food lodgement for few months. There was no complaint of pain but, she gave a history of moderate to severe pain about 6 months back which subsided after a course of antibiotics & analgesics.
Clinical examination showed carious mandibular left second molar & deep carious mandibular second premolar which gave no response to electric pulp test.
Radiographic examination revealed radiolucency in the crown of mandibular left second molar approximating the pulp & widening of PDL space in relation to the roots. It also revealed an additional root on the mesial side of mandibular left second molar and additional root of the second premolar. An additional radiograph with a 40-degree mesial angulation of the x-ray beam was recorded to confirm the presence of additional roots.Based on the subjective and objective findings, a diagnosis of pulp necrosis with chronic apical periodontitis was made.
After adequate isolation, access was gained to the pulp chamber. The coronal necrotic pulp tissue was removed and the chamber irrigated with 5.25% sodium hypochlorite solution.
Cleaning and shaping was completed and all the canals were obturated with gutta-percha and zincoxide eugenol based sealer. Subsequently, amalgam was used to retore the teeth post endodontically and the patient was recalled for fabrication of fixed partial denture.

Preoperative radiographs.
Working length determination radiographs.
Post-obturation radiographs.

Discussion:
The development of various areas of dentistry requires precise study of morphology of human teeth so that better oral health can be provided. Studies of the internal and external anatomy of teeth have shown that anatomical variations can occur in all group types, in individuals and in various racial groups. Anatomical variations should be expected as a frequent possibility. The clinician must therefore be fully aware of dental morphology in order to provide better care.¹¹
Researchers have shown that the anatomy of mandibular molars requires much attention since the number of roots and canals are quite variable. Maggiore et al. also noted that the roots of the mandibular second molar can vary from one to three roots.¹³ Manning reported three out of 149 mandibular second molars had three roots.¹⁰ Costa Rocha et al. in analysis of mandibular second molars root showed six teeth out of a total of 396 with three roots.¹¹
The anatomy of human teeth present racial variations; according to Ferraz and Pécora's report, three-rooted mandibular second molars were found in 3 teeth of Mongoloid origin, 2 teeth of Negro origin, and 2 of Caucasian origin patients.¹²
Radix entomolaris/paramolaris can be found on the first, second and third mandibular molar, occurring least frequently on the second molar, Bilateral occurrence of the RE ranges from 50 to 67%.¹⁴ Bolk reported the occurrence of a buccally located additional root: the RP. This macrostructure is very rare and occurs less frequently than the RE. The prevalence of RP, as observed by Visser10, was found to be 0% for the first mandibular molar, 0.5% for the second and 2% for the third molar.¹⁵
The etiology behind the formation of third root is still unclear. In dysmorphic, supernumerary roots, its formation could be related to external factors during odontogenesis, or to penetrance of an atavistic gene or polygenetic system (atavism is the reappearance of a trait after several generations of absence).¹
Vertucci, Seelig, and Gillis showed that the second premolar had only one root canal at the apex in 97.5% of the teeth studied and two canals in only 2.5%, three root canals were scarce. The frequency of three root canals in mandibular second premolars according to other authors appeared to range from 0 to 0.4%, which confirms these findings as being scarce. ¹⁶Zillich R, and Dowson J reported that "a second or third canal exists in at least 23% of first mandibular bicuspids." The canals may divide almost anywhere down the root”. Because of the absence of direct access, cleaning, shaping, and filling of these teeth can be extremely difficult.¹⁷

Knowledge of anatomic aberrations, such as root position, root shape and relative root outline will also help to decrease the failure rate of root canal therapy. From a clinical standpoint, when the initial radiograph shows the image of an unusual anatomic form it is recommended to take a second radiograph for additional information particularly with a mesial or distal projection.¹⁸
The following clues from diagnostic information and techniques might help clinicians detect additional root(s) and canal(s). A second radiograph from 15–20 degrees from either mesial or distal from the horizontal long axis of the root is necessary to accurately diagnose the number of roots and canals in premolar teeth. Yoshioka et al have indicated that sudden narrowing of the canal system on a parallel radiograph suggests canal system multiplicity. Martinez-Lozano et al have suggested a 40-degree mesial angulation of the x-ray beam to identify additional canals. A general guide line is that if the mid-root image diameter appears equal to or greater than the crown image diameter, then the tooth most likely has a variation in root canal configuration (Miyoshi et al,1977). The presence of additional canal should be suspected whenever an instrument demonstrates an eccentric direction on deeper penetration into the canal, termed directional control, as reported by Green(1973), or if the working length file appears off center in the radiograph. The use of magnification has been demonstrated to improve the clinician’s ability to visualize and access canals.
The use of 3-dimensional imaging methods in future large anatomic studies would be of value in assessing the occurrence and the frequency of anomalous canal morphology.

CONCLUSION:
Endodontists must be aware of normal and abnormal root morphologies of tooth. An
accurate diagnosis of these supernumerary roots and canals can avoid endodontic failures. Magnification aids like loupes and dental operating microscopes along with radiographs taken from different angulations help to identify these abnormal root anomalies and increases the endodontic success.

REFERENCES:

1. N. Vimala,Nilesh Firake. “KNOW YOUR MANDIBULAR FIRST MOLAR” - A CASE REPORT. Scientific Journal Vol. III – 2009;
2. Grossman Endodontic Practice Edition-11th edition -Anatomy of the pulp cavity, 145-178.
3. John I. Ingle fifth edition Endodontics Endodontic Cavity Preparation ; 405 to 510.
4. Carlsen O. Root complex and root canal system: a correlation analysis using one-rooted mandibular second molars. Scand J Dent Res 1990;98:273-85.
5. Weine FS, Pasiewicz RA, Rice RT. Canal configuration of the mandibular second molar using a clinically oriented in vitro method. J Endod 1988;14:207-13.
6. Bond JL, Hartwell GR, Donnelly JC, Portell FR. Clinical management of middle mesial root canals in mandibular molars. J Endod 1988;14:312- 4.
7. Melton DC, Krell KV, Fuller MW. Anatomical and histological features of C-shaped canals in mandibular second molars. J Endod 1991;17:384-8.
8. Wells DW, Bernier WE. A single mesial canal and two distal canals in a mandibular second molar. J Endod 1984;10:400-3.
9. Rabie G. Mandibular molar with merging mesiobuccal and distal root canals. Endod Dent Traumatol 1985;1:191-4.
10. Manning SA. Root canal anatomy of mandibular second molars. Part I. Int Endod J 1990;23:34-9.
11. Rocha LF, Sousa Neto MD, Fidel SR, da Costa WF, Pécora JD. External and internal anatomy of mandibular molars. Braz Dent J 1996;7:33-40.
12. Ferraz JA, Pécora JD. Three-rooted mandibular molars in patients of Mongolian,Caucasian and Negro origin. Braz Dent J 1993;3:113-7.
13. Maggiore C, Gallottini L, Resi JP. Mandibular first and second molar. The variability of roots and root canal system. Minerva Stomatol 1998;47:409- 16.
14. Sujatha Irodi, Aamina Zoya Farook. Three Rooted Mandibular Molar; Radix Entomolaris and Paramolaris. INTERNATIONAL JOURNAL OF DENTAL CLINICS 2011:3(1):102-104
15. Shailendra Gupta Deepak Raisingani Rishidev Yadav. The Radix Entomolaris and Paramolaris: A Case Report. J. Int Oral Health 2011.
16. De Moor RJ, Calberson FL. Root canal treatment in a mandibular second premolar with three root canals. J Endod 2005;31:310 –3.
17. Kishore Raju Kothapalli. TWO-ROOTED MANDIBULAR FIRST PREMOLAR : CASE REPORT. Annals and Essences of Dentistry Vol. - II Issue 3 July – Sept. 2010; 93-95.
18. Fava LR, Dummer PM. Periapical radiographic techniques during endodontic diagnosis and treatment. Int Endod J 1997;30:250- 61.
19. Rödig T, Hülsmann M. Diagnosis and root canal treatment of a mandibular second premolar with three root canals. Int Endod J 2003;36:912–9.