INTERNAL ANATOMY OF PERMANENT TOOTH - Endodontic approaches.

INTERNAL ANATOMY OF PERMANENT TOOTH concepts, review, techniques for missed canals. Advancements.

1. 1 GOOD MORNING

2. 2 GUIDED BY Dr. P.V. KARTEEK VARMA READER PRESENTED BY V.SINDHU 1 st MDS INTERNAL ANATOMY OF PERMANENT TEETH

3. 3 MIND MAP INTRODUCTION ROOT CANAL SYSYTEM ROOT CANAL SYSYTEM CLASSIFICATIONS -APICAL CONSTRICTION -APICAL FORAMEN -ACCESSSORY FORAMEN -ROOT CANAL RAMIFICATIONS -CANAL CURVATURES -ISTHMUS -APICAL DELTA INDIVIDUAL TOOTH ANATOMY CONCLUSION REFERENCES -TOOTH MORPHOLOGY - ACCESS OPENING -VARIATIONS & MANAGMENT -CASE REPORTS METHODS FOR DETERMINING EXTRA CANALS -WEINS -VERTUCCI -NEWER SYSTEM

4. CONTENTS Introduction Root canal anatomy Classifications of root canal Individual tooth anatomy & Variations Tooth morphology and access opening Case reports Methods to determine extra canals Conclusions References 4

5. INTRODUCTION “Of all the phases of anatomic study in the human system, one of the most complex is the pulp cavity morphology” – M.T.BARRETT The knowledge of root canal architecture will help us in Effective debridement To know the apical termination of instrumentation 3d obturation of canal 5

6. ROOT CANAL ANATOMY Root canal system : It is the space within the tooth that contains pulp tissue. It is divided into 2: Coronal – Pulp chamber Radicular – Root canal 6 The pulp chamber in the coronal part of the tooth consists of a single cavity with projections (pulp horns) into the cusps of the tooth.

7. 7 Occupies the coronal portion of pulp cavity. PULP CHAMBER: Roof of pulp chamber - Dentin covering the pulp chamber occlusally or incisally. Pulp horn -Accentuation of the roof of the pulp chamber directly under a cusp or developmental lobe. Floor of pulp chamber- Runs parallel to the roof and consists of dentin bounding the pulp chamber near the cervical area of the tooth. Canal orifices- Openings in the floor of pulp chamber leading in to root canals.

8. 8   Law of Centrality : the floor of the pulp chamber is always located in the center of the tooth at the level of the CEJ (cemento-enamel junction). Law of the CEJ : The CEJ is the most consistent, repeatable landmark for locating the position of the pulp-chamber. Based on relationship of pulp chamber to the clinical crown: KRAUSNER AND RANKOW LAWS

9. 9 Law of symmetry 1 : except for maxillary molars, the orifices of the canals are equidistant from a line drawn in a mesial-distal direction through the pulp chamber floor. Law of symmetry 2 : except for the maxillary molars, the orifices of the canals lie on a line perpendicular to a line drawn in a mesial-distal direction across the center of the floor of the pulp chamber. Law of Color Change : the color of the pulp chamber floor is always darker than the walls. Based on relationship of pulp chamber floor to root canal orifices

10. 10   Law of orifice location 1 : the orifices of the root canals are always located at the junction of the walls and the floor. Law of orifice location 2 : the orifices of the root canals are located at the angles in the floor wall junction. Law of orifice location 3 : the orifices of the root canals are located at the terminus of the root developmental fusion lines.

11. 11 DENTINAL MAP Dark developmental lines may be identified linking canal entrances. T he location of an undetected canal entrance may be indicated by tracking along the developmental line.

12. 12 Tooth apex (radiographic apex) 2. Apical foramen (major foramen) 3. Apical constriction (minor foramen) ANATOMY OF THE ROOT APEX ( KUTLER’S STUDIES) COHEN PATHWAYS OF PULP 10 TH EDITION

13. 13 A pical foramen: Apical foramen is the "circumference or rounded edge, main opening of the root canal that differentiates the termination of the cemental canal from the exterior surface of the root “ It does not normally exit at the anatomic apex but rather is offset 0.5 to 3 mm. It may undergo changes due to functional influences on the teeth like tipping forces . Foramen gradually shifts its position with aging, mesial drift, cementum deposition COHEN PATHWAYS OF PULP 10 TH EDITION Diameter is 502um in younger (18to25) Diameter is 681um in old (above 55 )

14. Apical constriction/ minor apical foramen : Apical part of the root canal with the narrowest diameter. 0.5–1 mm from the major apical foramen (Vertucci 2005). The distance is greater in older individuals because of the buildup of cementum. Often used as the reference point of apical termination of canal instrumentation and filling procedures 14 COHEN PATHWAYS OF PULP 10 TH EDITION

15. With increase in age minor diameter becomes narrower and major diameter becomes wider with deposition of dentine and cementum Sometimes apical opening is found on the lateral side of the apex, although root is not curved itself. 15 COHEN PATHWAYS OF PULP 10 TH EDITION

16. 16 Various types of the apical constriction “Current Challenges and Concepts in the Preparation of Root Canal Systems: A Review” Ove A. Peters ,JOE -2004 ,30 , 559 -67

17. Space between major and minor apical diameter – FUNNEL SHAPED, HYPERBOLIC or having the shape of a MORNING GLORY Distance between major and minor diameter is : 0.5mm in younger individuals 0.67 mm in older individuals so it is advisable to restrict the working length 1 to 2 mm short of apex in older individuals 17

18. THE CEMENTODENTINAL JUNCTION : The region where the dentin and cementum are united. CDJ does not always coincide with the apical constriction. The location of the CDJ ranges from 0.5 to 3.0 mm short of the anatomic apex 18

19. 19 Weine recommends the following termination points for therapy 1 mm from the apex when there is no bone or root resorption 1.5 mm from the apex when there is only bone resorption 2 mm from the apex when there is bone and root resorption .

20. ROOT CANAL RAMIFICATIONS : 20 The ramifications found in the region of the dental root , according to PUCCI & REIG , are: 1.Main canal 2.Collateral canal 3.Lateral canal 4.Secondary canal 5.Accessory canal 6.Intercanal 7.Recurring canal

21. LATERAL AND ACCESSORY CANALS 21   -A  channel leading from the root pulp  laterally through the dentin to the  periodontal tissue; may be found anywhere in the tooth root but is more common in the apical third of the root . - Incidence is more in posteriors than anteriors teeth - Mean diameter is 6 to 60 Um ( Hess et al 1983) COHEN PATHWAYS OF PULP 10 TH EDITION

22. 22 COHEN PATHWAYS OF PULP 10 TH EDITION

23. APICAL DELTA: The presence of dichotomy or branching of the root canal near the apex, giving a Y shaped structure forming a delta at the apex Following endodontic therapy , the pulp tissue in the uninstrumented delta may inflammed leading to re infection 23

24. ISTHMUS An isthmus is a narrow, ribbon-shaped communication between two root canals that contains pulp or pulpally derived tissue. 24 Classification by KIM et al

25. CANAL CURVATURES: 25 According to the Schneiders method, considering both the angle of curvature together with the radius of the curve is supposedly the exact method of describing the canal curvature. Mild curvature – 5 degree or less Moderate curvatures – 10- 20 degree Severe curvature - 25-70 degree Sharp curves with a short radius and S-shaped curvatures are always very demanding and easily result in transportation, ledges and even perforations

26. CLASSIFICATIONS OF ROOT CANAL SYSTEMS 26

27. WEINE’S CLASSIFICATION 27

28. Vertucci’s classification 28

29. 29 Int Endod J. 2017 Aug;50(8):761-770 A new system for classifying root and root canal morphology.

30. 30 Int Endod J. 2017 Aug;50(8):761-770 A new system for classifying root and root canal morphology.

31. 31 Int Endod J. 2017 Aug;50(8):761-770 A new system for classifying root and root canal morphology.

32. 32 Int Endod J. 2017 Aug;50(8):761-770 A new system for classifying root and root canal morphology.

33. INDIVIDUAL TOOTH ROOT CANAL ANATOMY 33

34. MAXILLARY CENTRAL INCISOR Average Length 22.5 mm No. of Roots 01 No. of Canals 01 (99.4%) 02 (0.6%) 34 COHEN PATHWAYS OF PULP 10 TH EDITION Variations and anomalies: Fusion-2.6% Gemination-0.94% Radicular grooves-0.9%

35. MAXILLARY LATERAL INCISOR Average Length 22.0 mm No. of Roots 01 No. of Canals 01 (93.4%) 02 (6.6%) 35 COHEN PATHWAYS OF PULP 10 TH EDITION Variations and anomalies Radicular grooves – 3% Dens invaginatus Fusion, Gemination Peg shaped lateral incisor

36. 36 DENS INVAGINATUS/DENS IN DENTE/TOOTH WITHIN TOOTH has been classified into three types based on severity, from simple to more complex. Type 1 is an invagination that is confined to the crown. Type 2 is an invagination that extends past the cementoenamel junction but does not involve the periradicular tissues. Type 3 is an invagination that extends beyond the cementoenamel junction and can have a second apical foramen. Often surgical and orthograde root canal therapy is necessary to treat this condition.* COHEN PATHWAYS OF PULP 10 TH EDITION

37. DENS INVAGINATUS 37 An update on the diagnosis and treatment of dens invaginatus J Zhu ,  X Wang ,  Y Fang ,  JW Von den Hoff ,  L Meng , Australian Dental Journal   https://doi.org/10.1111/adj.12513

38. Treatment for Type I dens invaginatus includes minimally invasive procedures and sealing of the defect with restorative materials. Bishop (2008) indicated that minor debridement with ultrasonic instruments and use of sealants may be successful in Type I and Type II cases In cases where pulpal involvement is foreseen, the treatment could range from conservative pulpotomy to a full-fledged root canal treatment. Use of aqueous intracanal medicaments and thermoplasticizing techniques have been seen to provide successful results. Surgical treatments may be indicated in cases of dens invaginatus with extensive infection in the periapical region as well as in cases of Type III with complex root canal anatomy and incomplete root canal development. Methods that have been utilised include : intentional reimplantation and removal of invaginated portion . A tooth with dens invaginatus having severe mobility, pulpal and periapical infection may need to be extracted. 38 Kallianpur , Shreenivas & Sudheendra , Us & Kasetty , Sowmya & Joshi, Prathamesh . (2012). Dens invaginatus (Type III B). Journal of oral and maxillofacial pathology : JOMFP. 16. 262-5. 10.4103/0973-029X.99084.

39. PALATO GINGIVAL GROOVE 39 Attam K, Tiwary R, Talwar S, Lamba AK. Palatogingival groove: endodontic-periodontal management—case report. Journal of endodontics . 2010 Oct 1;36(10):1717-20. Palato-radicular Groove Disto -lingual Groove Radicular Lingual Groove Corono-radicular Groove Cingulo-radicular Groove Vertical developmental Radicular Groove and Interruption Groove

40. 40

41. MAXILLARY CANINE 41 Average Length 26.5 mm No. of Roots 01 No. of Canals 01 (96.5%) 02 (3.5%) COHEN PATHWAYS OF PULP 10 TH EDITION

42. MAXILLARY FIRST PREMOLAR Average Length 20.6 mm No. of Roots 2-3 No. of Canals 1 – 06% 2 – 95% 3 – 01% 42 COHEN PATHWAYS OF PULP 10 TH EDITION

43. 43 Examples of upper premolars with three roots. The roots of upper first premolars are very delicate and may curve quite sharply buccally,palatally, mesially or distally, so instrumentation needs to be carried out with great care. Cross-sections taken at different levels in a maxillary first premolar showing the division of the buccal canal.

44. Because of the mesial concavity of the root , the clinician must take care not to overextend the preparation in that direction, as this could result in perforation. Possibility of isthmus is 16% at 1mm from the apex They have the 48% of multiple foraminas at the apex largest accessory foramina of diameter 53um mean value , and most complicated root morphology, so possible reason for failure 44 COHEN PATHWAYS OF PULP 10 TH EDITION

45. MAXILLARY SECOND PREMOLAR Average Length 21.5 mm No. of Roots 1 – 3 No. of Canals 1 – 75% 2 – 24% 3 – 01% 45 COHEN PATHWAYS OF PULP 10 TH EDITION

46. MAXILLARY FIRST MOLAR Average Length 20.8 mm No. of Roots 03 No. of Canals 04 – 93% 03 – 07% 46 The maxillary first molar is the largest tooth in volume and one of the most complex in root and canal anatomy . The three individual roots of the maxillary first molar (i.e., mesiobuccal root, distobuccal root, and palatal root) form a tripod A line drawn to connect the three main canal orifices—the mesiobuccal (MB) orifice, distobuccal (DB) orifice, and palatal (P) orifice—forms a triangle, known as the molar triangle.

47. 47 The clinician must always keep in mind that the location of the MB-2 canal varies greatly ; Usually 54.3% increased to 62%) this canal generally is located mesial to or directly on a line between the MB-1 and palatal orifices, within 3.5 mm palatally and 2 mm mesially of the MB-1 orifice These authors found that not all MB-2 orifices lead to a true canal. A true MB-2 orifice was present in only 84% of molars in which a second orifice was identified. COHEN PATHWAYS OF PULP 10 TH EDITION

48. 48 Troughing or countersinking with ultrasonic tips mesially and apically along the mesiobuccal pulpal groove . This procedure causes the canal, when present, to shift mesially , meaning that the access wall must be moved farther mesially . Troughing may need to be 0.5 to 3 mm deep. Care must be taken to avoid furcal wall perforation of this root. COHEN PATHWAYS OF PULP 10 TH EDITION

49. 49

50. 50 The average distance between MB1 and P was 6.91 ± 1.47 mm, between MB1 and MB2 2.61 ± 0.64 mm and MB2-T 1.26 ± 0.36 mm. There were no statistically significant differences in the presence and/or absence of the MB2 canal in terms of age or gender CBCT technique for location of the MB2 canal of maxillary first molar. Pablo Betancourt* , Pablo Navarro, Ramon Fuentes Biomedical Research 2017; 28 (16): 6937-6941

51. 51 Kottoor J, Velmurugan N, Surendran S. Endodontic management of a maxillary first molar with eight root canal systems evaluated using cone-beam computed tomography scanning: a case report. Journal of endodontics . 2011 May 1;37(5):715-9. The MB2 is notoriously challenging to locate and negotiate, but with the correct magnification, light, equipment, knowledge and experience it can be treated predictably.

52. MAXILLARY SECOND MOLAR Average Length 20.0 mm No. of Roots 03 No. of Canals 04 – 37% 03 – 63% 52 Coronally , the maxillary second molar closely resembles the maxillary first molar. The root and canal anatomy are similar to those of the first molar, although differences occur. The distinguishing morphologic feature of the maxillary second molar is that its three roots are grouped closer together and are sometimes fused. Also, they generally are shorter than the roots of the first molar and not as curved.

53. 53 When four canals are present, the access cavity preparation of the maxillary second molar has a rhomboid shape and is a smaller version of the access cavity for the maxillary first molar . If only three canals MB, DB, and P) usually form a flat triangle and sometimes almost a straight line . The mesiobuccal canal orifice is located more to the buccal and mesial than in the first molars present , the access cavity is a rounded triangle with the base to the buccal . COHEN PATHWAYS OF PULP 10 TH EDITION

54. MAXILLARY THIRD MOLAR Average Length 17.0 mm No. of Roots 1 - 3 No. of Canals - 54 CBCT images of maxillary 3 rd molar (18) with 5 root canals

55. MANDIBULAR CENTRAL INCISOR Average Length 20.7 mm No. of Roots 01 No. of Canals 01 – 58% 02 – 42% 55 Kashid V, Baonerkar H. Mandibular Incisors with Type II Anatomy in a Single Patient: Report of Two Cases. Indian J Oral Health Res 2015;1:74-8

56. MANDIBULAR LATERAL INCISOR Average Length 20.7 mm No. of Roots 1 – 2 No. of Canals 01 – 58% 02 – 42% 56

57. MANDIBULAR CANINE Average Length 25.6 mm No. of Roots 01 No. of Canals 01 – 94% 02 – 06% 57 Lower canines may Occasionally(14%) be found with two separate roots . Lateral canals are seen in 30% of cases Book ASABDJ. Endodontics: Part 4 Morphology of the root canal system. 2004;197(7):379–83.

58. MANDIBULAR FIRST PREMOLAR Average Length 21.6 mm No. of Roots 01 No. of Canals 01 – 73% 02 – 27% 58 mandibular premolars are difficult to treat. They have a high flare-up and failure rate. 44% of accessory canals are present A possible explanation may be the extreme variations in root canal morphology in these teeth. COHEN PATHWAYS OF PULP 10 TH EDITION

59. 59 Crowns of mandibular premolars are tilted lingually relative to their roots , and the starting location must be adjusted to compensate for this tilt . Crown is having 30’ lingual inclination with that of the root. In mandibular first premolars the starting location is halfway up the lingual incline of the buccal cusp on a line connecting the cusp tips. Mandibular second premolars require less of an adjustment because they have less lingual inclination COHEN PATHWAYS OF PULP 10 TH EDITION

60. MANDIBULAR SECOND PREMOLAR Average Length 22.3 mm No. of Roots 01 No. of Canals 01 – 85% 02 – 15% 60 A lower second premolar with a severe distal curve at the apex.

61. MANDIBULAR FIRST MOLAR Average Length 21.0 mm No. of Roots 2 – 3 No. of Canals 03 – 67% 04 – 33% 61 It often is extensively restored, and it is subjected to heavy occlusal stress. Therefore the pulp chamber frequently has receded or is calcified The tooth usually has two roots, but occasionally it has three, with two or three canals in the mesial root and one, two, or three canals in the distal root. The canals in the mesial root are the MB and ML canals; a middle mesial (MM) canal sometimes is present in the developmental groove between the MB and ML canals

62. RADIX ENTOMOLARIS , RADIX PARAMOLARIS The radix entomolaris (RE) is a supernumerary root located distolingually in mandibular molars prevalence is 3 to 9 % , whereas the radix paramolaris (RP) is an extra root located mesiobuccally prevalence is 1 to 5 %. Each root usually contains a single root canal. The orifice of the RE is located disto - to mesiolingually from the main canal or canals of the distal root; the orifice of the RP is located mesio - to distobuccally from the main mesial root canals . A dark line or groove from the main root canal on the pulp chamber floor leads to these orifices. 62 COHEN PATHWAYS OF PULP 10 TH EDITION

63. A - first molar with a radix entomolaris B - radix entomolaris on a third molar C - first molar with a separate radix paramolaris D - first molar with a fused radix paramolaris 63

64. 64 Radix entomolaris Radix paramolaris

65. TAURODONTISM 65

66. 66 Variable dimensions for establishing the taurodontism index: vertical height of the pulp chamber (V1), distance between the lowest point of the roof of the pulp chamber to the apex of the longest root (V2), and distance between the baseline connecting the two CEJ and the highest point in the floor of the pulp chamber (V3). Establishing a condition of taurodontism is made when V1 is divided by V2 and multiplied by 100 (V1/V2) * 100 . Taurodontic index (TI) =V1/V2 X100. Taurodontism is diagnosed in molars in which TI is above 20 and variable 3 exceeds 2.5 mm. Degrees of taurodontism hypo taurodontism : TI 20–30, meso taurodontism : TI 30–40, hyper taurodontism : TI 40–75.

67. 67 Tsesis I, Shifman A, Kaufman AY. Taurodontism : an endodontic challenge. Report of a case. Journal of endodontics . 2003 May 1;29(5):353-5. In this case, TI equaled 56 and variable 3 equaled 10 mm, clearly indicating hypertaurodontism .

68. MANDIBULAR SECOND MOLAR Average Length 19.8 mm No. of Roots 02 No. of Canals 02 – 13% 03 – 79% 04 – 08% 68

69. C- SHAPED CANALS C-shaped canals ( 8-30%) The main cause for C-shaped roots and canals is the failure of Hertwig’s epithelial root sheath to fuse on either the buccal or lingual root surface. The C-shaped canal system can assume many variations in its morphology 69

70. 70 C shaped canal configuration in mandibular 2 nd molar Jafarzadeh H, Wu Y. The C-shaped Root Canal Configuration : A Review. 2007;33(5):517–23.

71. 71 Mrinalini , Dr & Sodvadia , Urvashi B. & Hegde , Mithra . (2023). Endodontic management of a C-shaped root canal using thermoplasticised obturation with a modified gutta-percha cartridge design. Case report. The New Zealand dental journal. 119. 91-94.

72. MANDIBULAR THIRD MOLAR Average Length 18.5 mm No. of Roots 1 - 2 No. of Canals - 72 The developmental anatomy of lower third molars may be quite bizarre.

73. METHODS FOR DETERMINING EXTRA CANALS 73

74. Over the period of years, certain techniques have been devised to identify aberrant anatomy and locating extra canals. These can be summed up as: 1. Multiple radiographs : Well angulated radiographs should be taken. ( Mesio -angular, disto -angular, straight) when evaluating an endodontic failure. 2. Digital radiography : This offers a variety of software features, significantly enhancing radiographic diagnostics in identifying hidden, calcified or untreated canals. 74 Batra , Dr. (2023). The Six In Six: Management Of A Mandibular First Molar With 4 Distal And 2 Mesial Canals. Journal of Pharmaceutical Negative Results. 167-172. 10.47750/pnr.2023.14.03.23.

75. Visual enhancers : Magnifying loupes, head-lamps, transilluminating devices, dental operating microscopes are used to improve visualization. 75

76. Micro-Openers (DENTSPLY Maillefer , Tulsa, OK) are excellent instruments for locating canal orifices when a dental dam has not been placed. -These flexible, stainless steel hand instruments have #.04 and #.06 tapered tips. They also have offset handles that provide enhanced visualization of the pulp chamber. 76

77. 5. Piezoelectric ultrasonic . Troughing of grooves with-ultrasonic tips (CPR tips) 77

78. 6. White line test : Shelf of dentin meets the pulpal floor and forms a groove. Necrotic tissue and debris forms a white line adjacent to the MB1 canal which can be used to trace MB2 78

79. 7. Red line test : In vital cases, blood flows into the orifices, fins and isthmus areas, this appears red adjacent to the MB1 thus serving as a road map for identification of MB2 canal orifice. 79

80. 8. Dyes : 1% methylene blue dye is irrigated into the pulp chamber and subsequently rinsed thoroughly with water, dried and visualized to see where the dye has been absorbed. Frequently the dyes will be absorbed into the orifices, fins and isthmus areas 80

81. 9.Champagne bubble test using Sodium Hypochlorite : After cleaning and shaping procedures, the access cavity is flooded with NaOCl and the solution is observed to see if bubbles are emanating toward the occlusal table from canal orifice. A positive bubble reaction signifies that NaOCl is -reacting with residual tissue within the instrumented or the missed canal or with the residual chelator present within the prepared canal. 81

82. 10.Ruddle‘s solution : This irrigant is a "cocktail" containing 5% sodium hypochlorite ( NaOCl ), Hypaque and 17% EDTA. Hypaque is a water-soluble, radiopaque , contrast solution which can be utilized to visualize root canal system anatomy, monitor the remaining wall thickness during preparation procedures, detect pathological defects and manage iatrogenic mishaps. The composition of the Ruddle Solution simultaneously provides the "solvent action" of fullstrength NaOCl , "visualization" as its radiopacity closely matches that of gutta-percha . 82 Batra , Dr. (2023). The Six In Six: Management Of A Mandibular First Molar With 4 Distal And 2 Mesial Canals. Journal of Pharmaceutical Negative Results. 167-172. 10.47750/pnr.2023.14.03.23.

83. CONCLUSION Root canal system is extraordinarily complex with numerous intricacies , including accessory canals and isthami . A clinician should open his/her mind to the various possible canal morphologies and should not stick only to a limited and standard number of canal patterns. These undetected extra roots or root canals are a major reason for the failure . To avoid this, the endodontist must consider the judicious use of high-end diagnostic imaging techniques for successful management of complicated cases. “ The eyes can only see what the mind knows ”; therefore, the endodontist should be well-versed with the anatomic variations before and during performing the root canal therapy. 83

84. REFERENCES GROSSMAN -13 th EDITION COHEN- pathways of pulp 10 th EDITION INGLE’S – 6 th EDITION MORPHOLOGY OF ROOT CANAL SYSTEM BRITISH DENTAL JOURANL VOLUME 197. Int Endod J. 2017 Aug;50(8):761-770 A new system for classifying root and root canal morphology. http://intranet.tdmu.edu.ua . Jafarzadeh H, Wu Y. The C-shaped Root Canal Configuration : A Review. 2007;33(5):517–23. Calberson FL, Moor RJ De, Deroose CA. The Radix Entomolaris and Paramolaris : Clinical Approach in Endodontics. 2007;33(1):58–63 Book ASABDJ. Endodontics: Part 4 Morphology of the root canal system. 2004;197(7):379–83. 84

85. Batra , Dr. (2023). The Six In Six: Management Of A Mandibular First Molar With 4 Distal And 2 Mesial Canals. Journal of Pharmaceutical Negative Results. 167-172. 10.47750/pnr.2023.14.03.23. Tsesis I, Shifman A, Kaufman AY. Taurodontism : an endodontic challenge. Report of a case. Journal of endodontics . 2003 May 1;29(5):353-5. Kottoor J, Velmurugan N, Surendran S. Endodontic management of a maxillary first molar with eight root canal systems evaluated using cone-beam computed tomography scanning: a case report. Journal of endodontics . 2011 May 1;37(5):715-9. Valerian Albuquerque D, Kottoor J, Velmurugan N. A new anatomically based nomenclature for the roots and root canals-part 2: mandibular molars.  Int J Dent . 2012;2012:814789. doi:10.1155/2012/814789 Attam K, Tiwary R, Talwar S, Lamba AK. Palatogingival groove: endodontic-periodontal management—case report. Journal of endodontics . 2010 Oct 1;36(10):1717-20. 85

86. Kallianpur , Shreenivas & Sudheendra , Us & Kasetty , Sowmya & Joshi, Prathamesh . (2012). Dens invaginatus (Type III B). Journal of oral and maxillofacial pathology : JOMFP. 16. 262-5. 10.4103/0973-029X.99084 An update on the diagnosis and treatment of dens invaginatus J Zhu ,  X Wang ,  Y Fang ,  JW Von den Hoff ,  L Meng , Australian Dental Journal Mrinalini , Dr & Sodvadia , Urvashi B. & Hegde , Mithra . (2023). Endodontic management of a C-shaped root canal using thermoplasticised obturation with a modified gutta-percha cartridge design. Case report. The New Zealand dental journal. 119. 91-94 . 86

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