anatomy of pulp cavity and access opening.pptx

tooth pulp cavity, incisor, molar, canine

1. Anatomy of Pulp Cavity and Its Access Opening Presented By - Aditya Bhagat PG IIIrd Year

2. Pulp Cavity - the central cavity entirely enclosed by dentin except at the apical foramen D ivided into the following: A coronal portion - pulp chamber A radicular portion - root canal Pulp chamber In anterior teeth - pulp chamber gradually - merges into the root canal In multirooted teeth, pulp - cavity consists of a single pulp chamber and usually three root canals, can vary from 1 to 4 or more.     Anatomy of Pulp Cavity and Its Access Opening 2

3. Roof of the pulp chamber consists of dentin covering the pulp chamber occlusally or incisally Pulp horn is an accentuation of the roof of the pulp chamber directly under a cusp or developmental lobe. The term refers more commonly to the prolongation of the pulp itself directly under a cusp. Floor of the pulp chamber runs parallel to the roof and consists of dentin bounding the pulp chamber near the cervical area of the tooth, particularly dentin forming the furcation area The canal orifices- openings in the floor of the pulp chamber leading into the root canals. Anatomy of Pulp Cavity and Its Access Opening 3

4. Root Canals - The root canal is the portion of the pulp cavity from the canal orifice to the apical foramen. for convenience it may be divided into three sections, namely: coronal, middle, and apical thirds.   Accessory canals , or lateral canals , are lateral branching of the main root canal generally occurring in the apical third or furcation area of a root Lateral canal is an accessory canal that branches to the lateral surface of the root and may be visible on a radiograph. Apical foramen is an aperture at or near the apex of a root through which the blood vessels and nerves of the pulp enter or leave the pulp cavity. Accessory foramina are the openings of the accessory and lateral canals in the root surface Anatomy of Pulp Cavity and Its Access Opening 4

5. Goals of Access Cavity Preparation According to Vertucci , the following are the objectives of access cavity preparation: Removal of all carious tooth structure Conservation of sound tooth structure Complete de-roofing of the pulp chamber Removal of coronal pulp tissue (vital and necrotic) Location of all root canal orifices Straight line access to the root canal Anatomy of Pulp Cavity and Its Access Opening 5

6. Clinical Guidelines for Access Cavity Preparation I. Preoperative Considerations A. Armamentarium for Access Cavity Preparation Front surface mouth mirrors Airotor and slow-speed rotary handpieces Burs: These include the following: –– Round carbide burs (No. 2, No. 4, and No. 6) for caries removal and defining the external outline shape –– Diamond burs with round cutting ends for axial wall extensions –– Fissure carbide burs and diamond burs with safety tips. Anatomy of Pulp Cavity and Its Access Opening 6

7. Round diamond burs for entry into teeth with porcelain or ceramometal restorations and trans metal burs for teeth with metal restorations –– For calcified teeth, extended long shank burs such as Mueller burs ( Brasseler , USA) and LN burs (Dentsply Maillefer , USA) Endodontic spoon excavator Endodontic explorers, e.g DG-16 Additional aids –– Magnification and illumination aids –– Ultrasonic tips –– Microopeners and microdebriders   (a) Endodontic excavator. (b) DG–16 endodontic explorer. ( Courtesy: Hu- Friedy Mfg Co., USA. ) Start X ultrasonic tips 1, 2, 3, and 5 for access refinement. ( Courtesy: Dentsply Maillefer . ) Anatomy of Pulp Cavity and Its Access Opening 7

8. B. Assessment of Occlusal Tooth Anatomy The following clinical observations are indicative of an unusual root canal anatomy: Abnormality in the size and shape of the tooth prominent cingulum of a mandibular incisor - an extra canal may be found lingually. Prominent lingual cusp of a mandibular bicuspid - extra canal may be found lingually. (c) Prominent buccal cusp and wide crown mesiodistally - a mesiobuccal canal or root may be found in the maxillary first premolar. (d) Prominent buccal cusp and wide crown buccolingually on the mesial half in the maxillary molar – a second mesiobuccal canal may frequently be found. (e) Where unusually small canals are seen, an extra canal may be found, as in the distal root of a mandibular molar. Anatomy of Pulp Cavity and Its Access Opening 8

9. Major principle of the endodontic cavity outline form: The internal anatomy of the tooth (pulp) dictates the external outline form. - accomplished by extending preparation from the inside cavity to the outside surface, that is, working from inside to outside. Size and shape of endodontic coronal preparations relates to the size and shape of the pulp and chamber. C. Complicating Factors Access cavity preparation would be challenging and has to be prepared carefully in the following conditions: Rotated teeth/ malpositioned teeth Tipping/mesial tilting of the tooth Grossly decayed teeth Teeth with full-coverage restorations Abutment teeth of fixed prostheses Teeth with extensive calcifications Anatomy of Pulp Cavity and Its Access Opening 9

10. D. Radiographic Assessment Visualization of the internal anatomy of the tooth can be done using preoperative periapical radiographs. Box 12.1 presents some of the features that can be visualized using periapical radiographs.   Mesiodistal tilt of the tooth Size and shape of the pulp chamber Thickness of the roof of the pulp chamber Presence of pulp stones Variations in the number of canals and/or roots Extent of root and canal curvature Radiographic changes in the furcation and/or periradicular region II. Clinical Considerations A. Complete Removal of Carious Tooth Structure and Other Restorative Material B. Complete De-Roofing and Removal of Dentinal Shoulders The overhanging roof of the pulp chamber misdirects the instrument causing mishaps Anatomy of Pulp Cavity and Its Access Opening 10

11. Removal of the dentinal shoulders provides straight line access to the root canals. The following dentinal shoulders are to be taken into consideration: - Mandibular anteriors  Lingual shoulder - Maxillary anteriors  Palatal shoulder - Premolars  Mesial and distal shoulders - Maxillary molars  Buccal and mesial shoulders - Mandibular molars  Mesial and distal shoulders Anatomy of Pulp Cavity and Its Access Opening 11

12. Krasner and Rankow’s Laws of Access Opening Law of centrality: The floor of the pulp chamber is always located in the center of the tooth at the level of the CEJ. Law of concentricity: The walls of the pulp chamber are always concentric to the external surface of the tooth at the level of the CEJ. Law of the CEJ: The distance from the external surface of the clinical crown to the wall of the pulp chamber is the same throughout the circumference of the tooth at the level of the CEJ. The CEJ is the most consistent, repeatable landmark for locating the position of the pulp chamber. Anatomy of Pulp Cavity and Its Access Opening 12

13. Law of symmetry 1: Except for maxillary molars, the orifices of the canals are equidistant from a line drawn in a mesiodistal direction through the pulp chamber floor. Law of symmetry 2: Except for maxillary molars, the orifices of the canals lie on a line perpendicular to a line drawn in a mesiodistal direction across the center of the floor of the pulp chamber. Anatomy of Pulp Cavity and Its Access Opening 13

14. Anatomy of Pulp Cavity and Its Access Opening 14 Law of color change: The color of the pulp chamber floor is always darker than the walls. Law of orifices location 1: The orifices of the root canals are always located at the junction of the walls and the floor. Law of orifices location 2: The orifices of the root canals are located at angles in the floor–wall junction. Law of orifices location 3: The orifices of the root canals are located at the terminus of the root developmental fusion lines.

15. Individual Tooth Anatomy Maxillary Central Incisor Single root with single canal. Pulp Chamber ‰. Located in the center of the crown and equidistant from the dentinal walls ‰. Mesiodistally broad ‰. In young patient, it shows three pulp horns correspond to enamel mamelons on the incisal edge   Root Canal ‰ . Usually one root with one straight root canal Anatomy of Pulp Cavity and Its Access Opening 15

16. Commonly Found Anomalies ‰ . Palatogingival groove ‰ . Talon’s cusp ‰ . Fusion ‰ . Gemination Clinical Considerations ‰ . Pulp horn can be exposed following a relatively small fracture of an incisal corner in the young patient ‰ .I Placing the access cavity too far palatally makes straight line access difficult ‰ . . Labial perforation is most commonly seen during access cavity preparation Anatomy of Pulp Cavity and Its Access Opening 16

17. Access Opening:   Access Shape is slightly triangular, with the base of the triangle toward the incisal edge (Fig. g and h). The enamel is penetrated in the center of the palatal surface at an angle perpendicular to it with a No. 4 round bur (Fig b). After penetration of the enamel, the bur is directed along the long axis of the tooth until A “drop” of the bur into the chamber may be felt if the chamber is large enough. (Fig. c). The roof of the pulp chamber are remove by working from the inside to the outside following the internal anatomy ( Fig.d ). Anatomy of Pulp Cavity and Its Access Opening 17

18. This makes the access cavity walls confluent with the lateral and incisal walls of the pulp chamber and provides the access cavity with a “straight line” penetration to the apical root canal. A Gates-Glidden drill (usually No. 4) / orifice enlarger is used to remove the palatal shoulder by working from inside to outside   Anatomy of Pulp Cavity and Its Access Opening 18

19. Maxillary Lateral Incisor Single root with a Single canal system Pulp Chamber Similar to central incisor except that Incisal outline is more rounded Two pulp horns are present Root Canal Single root with smaller canal is seen when compared to central incisor Maxillary Lateral Incisor Anatomy of Pulp Cavity and Its Access Opening 19

20. Commonly Found Anomalies Palatogingival groove Peg laterals Fusion Gemination Dens invaginatus Anatomy of Pulp Cavity and Its Access Opening 20

21. Clinical Considerations ‰ . . Palatal curvature of apical third can cause ledge formation - complicate surgical procedures like root end cavity preparation and root resection ‰ . Lateral canals are more common than maxillary central incisors ‰ . Labial perforation is common error during access cavity   Access Opening : Similar to that for the maxillary central incisor, but it is smaller and usually more ovoid. No. 2 round bur may be used instead of a No. 4. Anatomy of Pulp Cavity and Its Access Opening 21

22. Maxillary Canine Single root with a single canal system - Type 1. Pulp Chamber Labiopalatally , pulp chamber is almost triangular in shape Mesiodistallys it is narrow, resembling a flame One pulp horn corresponding to one cusp is seen Root Canal A single root canal which is wider labiopalatally than mesiodistaly Anatomy of Pulp Cavity and Its Access Opening 22

23.   Commonly Found Anomalies Dens invaginatus Dilacerations Two roots with two canals   Clinical Considerations Surgical access sometimes becomes difficult because of the long length of the tooth 32% canals may show distal apical curvature Abscess of maxillary canine perforates the labial cortical plate below insertion of levator muscles of the upper lip and drains into the buccal vestibule If perforation occurs above the insertion of levator muscles of lip, drainage of abscess occurs into the canine space, resulting in cellulitis   Anatomy of Pulp Cavity and Its Access Opening 23

24. Access Opening : The access opening for the maxillary canine is similar to maxillary central and lateral incisors. Shape of the access opening - circular to ovoid. Anatomy of Pulp Cavity and Its Access Opening 24

25. Maxillary First Premolar It has two roots with two canals. Canal form is usually Type 1. Pulp Chamber It is wider buccopalatally with two pulp horns, corresponding to buccal and palatal cusps Palatal canal is usually larger than buccal canal Roof of pulp chamber is coronal to the cervical line Floor is convex with two canal orifices Root Canal Two roots with two canals are seen commonly. Buccal canal is directly under the buccal cusp and palatal canal is directly under the palatal cusp 25 Anatomy of Pulp Cavity and Its Access Opening

26. Commonly Found Anomalies Dens evaginatus Dilacerations Clinical Considerations Radiograph with different angulations - to avoid superimposition of canals Avoid overflaring of the coronal part of buccal root to avoid the perforation of mesial groove. The buccal canal is directly under the buccal cusp - orifice can be located by following the buccal wall of the pulp chamber. The palatal canal is larger- directly under the palatal cusp - orifice can be penetrated by following the palatal wall of the pulp chamber. Anatomy of Pulp Cavity and Its Access Opening 26

27. In teeth with single roots, straight roots - 38.4% and distal curve present in 36.8%. Whether maxillary first premolars have one or two roots, they have two root canals at the apex in 69% of cases.   Access Opening – No. 2 round bur used to penetrate the enamel in the center of the occlusal surface between the buccal and lingual cusps, along the long axis of the tooth. The operator frequently feels the bur “drop” into the pulp chamber when the chamber is large. To remove the roof of the pulp chamber, one should place the bur alongside the walls of the chamber and cut occlusally Anatomy of Pulp Cavity and Its Access Opening 27

28. A tapered cylinder, self-limiting diamond bur is used to remove the remaining roof of the pulp chamber   Clinical Note The border of the ovoid access cavity of a maxillary premolar should not extend beyond half the lingual incline of the facial cusp and half the facial incline of the palatal cusp Anatomy of Pulp Cavity and Its Access Opening 28

29. Maxillary Second Premolar Single root with single canal system Pulp Chamber ‰. Pulp chamber - wider buccopalatally and narrower mesiodistally ‰. Cross-section - narrow and ovoid shape Root Canal ‰. In more than 60% of cases, a single root with a single canal is found ‰. If two canals - they may be separated along the entire length of the root or merge to form a single canal apically Anatomy of Pulp Cavity and Its Access Opening 29

30. Commonly Found Anomalies Dens invaginatus Taurodontism Two roots with two or three canals Clinical Considerations Narrow ribbon-like canal is difficult to clean and obturate If one canal is present, orifice is indistinct, but if two canals are present, two orifices are seen   The access opening for the maxillary second premolar is basically the same as that for the maxillary first premolar. It is varied only as dictated by the anatomic structure of the pulp chamber. Anatomy of Pulp Cavity and Its Access Opening 30

31. Maxillary First Molar It has three roots with three to four canals. Pulp Chamber Largest pulp chamber Bulk of pulp chamber lies mesial to the oblique ridge  Roof converges and lingual wall disappears, forming triangular form Orifices of root canals are located in the three angles of the floor; palatal orifice is the largest and easiest to locate and appears funnel-like in the floor of pulp chamber Distobuccal canal orifice is located more palatally than mesiobuccal canal orifice More than 80% of teeth show presence of two canals in mesiobuccal root. MB2 is located 3 mm palatally and 2 mm mesially to the MB1 orifice Anatomy of Pulp Cavity and Its Access Opening 31

32. Access opening :   Bur is placed in central fossa and directed towards the palatal canal, where the pulp chamber of this tooth is largest. A “drop” of the bur into the pulp chamber may be felt if the chamber is large. In partially calcified chambers, the drop of the bur is not felt, and the operator has to rely on the measurements made from the radiograph to avoid Perforation. Anatomy of Pulp Cavity and Its Access Opening 32

33. The shape and size of the internal anatomy of the pulp chamber guide the cutting. A tapered-cylinder, self-limiting diamond bur is used to deroof the pulp chamber. The access opening is triangular, with round corners extending toward, but not including, the mesiobuccal cusp tip, marginal ridge, and oblique ridge. This triangular preparation permits direct access to the root canal orifices. Anatomy of Pulp Cavity and Its Access Opening 33

34. Clinical Note ŠŠThe triangular access preparation in a maxillary molar is modified into a rhomboidal shape whenever the MB-2 canal is suspected or traced. MB2 should be searched 2–3 mm palatal to the MB-1 canal, in the direction of an imaginary line connecting the MB-1 and palatal canal. Modify the mesial wall of the access cavity and trough or countersink with the help of ultrasonic tips mesially and apically along the mesiobuccal pulpal groove. ŠŠTwo separate and distinct mesiobuccal canals occur in 84% of teeth in which two separate orifices are traced. According to Nallapati , the following are the possible locations of the MB-2 canal in the maxillary first molar: Present on the developmental line that connects MB-1 and palatal canal Present mesial to the developmental line that connects MB-1 and palatal canal Anatomy of Pulp Cavity and Its Access Opening 34

35. Appears as a groove on the palatal wall of the MB-1 canal Splits off the MB-1 canal in the middle third of the canal Splits off the MB-1 canal in apical third of the canal ŠŠThe clinician should always suspect the presence of the MB-2 canal and modify the access cavity accordingly. Anatomy of Pulp Cavity and Its Access Opening 35

36. Maxillary Second Molar It has three roots with three to four canals almost similar to first molar. Pulp Chamber Similar to first molar except that it is narrower mesiodistally ‰Roof is more rhomboidal in cross-section and floor is an obtuse triangle Mesiobuccal and distobuccal canal orifices lie very close to each other. S ometimes all the three canal orifices lie in a straight line Root Canal Similar to first molar except that roots tend to be less divergent and may be fused. Anomalies present Two palatal canals and two palatal roots Fusion of roots Taurodontism Clinical Considerations ‰ Similar to maxillary first molar Anatomy of Pulp Cavity and Its Access Opening 36

37. Maxillary second molar lies closer to the maxillary sinus than first molar   Access Opening: Similar to maxillary first molar, with the variations in anatomic structure. Anomalies: The most frequent anomalies in the maxillary second molar are the presence of only one root and one canal. Anatomy of Pulp Cavity and Its Access Opening 37

38. Maxillary Third Molar Pulp Chamber It is similar to second molar but displays great variations in shape, size and form of pulp chamber with presence of one, two, three or more canals at times. Clinical Considerations Maxillary third molar is closely related to maxillary sinus and maxillary tuberosity.   Access Opening: The access opening is similar to that for the maxillary second molar, with modifications for variations in anatomic structure.   Anatomy of Pulp Cavity and Its Access Opening 38

39. Mandibular Central Incisor It is the smallest tooth in the arch. Pulp Chamber It is wider labiolingually than mesiodistally Cross-section - ovoid Root Canal There can be Single canal with one foramen in 65% cases Two canals with one foramen in 28% cases Two canals with separate foramen in 7% cases Commonly Found Anomalies Dens invaginatus ‰Germination Fusion Anatomy of Pulp Cavity and Its Access Opening 39

40. Clinical Considerations ‰. Because of groove along the length of root and narrow canals, weakening of the tooth structure or chances of strip perforations are increased ‰. It is common to miss the presence of two canals on preoperative radiograph if they are superimposed ‰. Second canal is usually found lingual to the main canal Access Opening : Similar to maxillary anterior teeth, with the variations due to smaller size demands. Shape - long and oval. Proper access enables to explore the cervical third of the root to determine whether a second root canal is present. Anatomy of Pulp Cavity and Its Access Opening 40

41. Mandibular Lateral Incisor Pulp Chamber Similar to central incisor except that it has larger dimensions. Root Canal ‰. Similar to central incisor ‰. Root is straight or distally curved Clinical Considerations These are similar to central incisor.   Access Opening: The access opening is made in the same manner as for the mandibular central incisor. Anatomy of Pulp Cavity and Its Access Opening 41

42. Mandibular Canine It has single root with single canal system. Pulp Chamber ‰. Ovoid in cross-section - broader labiolingually and narrower mesiodistally Root Canal ‰ It has one root and one canal in 94% cases but two roots with separate foramen are present in 6% cases Anatomy of Pulp Cavity and Its Access Opening 42

43. Commonly Found Anomalies Dilaceration Dens invaginatus Two roots with two canals Two canals in single root   Access Opening: Similar as for the maxillary canine, with the variations dictated by a smaller anatomic dimension. Anatomy of Pulp Cavity and Its Access Opening 43

44. Mandibular First Premolar It has single root with single canal but occasionally division of root is present in apical third. Pulp Chamber Buccolingually, wider and ovoid in cross-section Mesiodistally narrow Two pulp horns present, buccal horn being more prominent Anatomy of Pulp Cavity and Its Access Opening 44

45. Commonly Found Anomalies Dens evaginatus Dens invaginatus Two roots with two canals ‰Single root splits into two, of which buccal is straight and lingual splits at right angle, giving letter “h” appearance. Clinical Considerations Perforation at distogingival margin is caused by failure to recognize the distal tilt of premolar Anatomy of Pulp Cavity and Its Access Opening 45

46. Access opening- The mandibular first premolar has 30° lingual tilt of the crown to the long axis of the root. To compensate for the tilt and prevent perforations, the enamel is penetrated at the upper third of the lingual incline of the facial cusp with a bur centered mesiodistally and directed along the long axis of the root. The access cavity is ovoid, extending buccolingually. This ovoid access preparation permits exploration for bifurcations or trifurcations in the middle and apical thirds. Anatomy of Pulp Cavity and Its Access Opening 46

47. Mandibular Second Premolar Root Canal Usually only one root and one canal is seen. Clinical Consideration They are similar to mandibular first premolar. ‰Pulp Chamber ‰. It is similar to first premolar except that lingual pulp horn is more prominent ‰. Cross-section shows an oval shape with greater dimensions buccolingually Anatomy of Pulp Cavity and Its Access Opening 47

48. Access Opening: Same as for the mandibular first premolar, except that: the enamel penetration is initiated in the central fossa, the ovoid access opening is wider mesiodistally, as dictated by the wider pulp chamber.   Anatomy of Pulp Cavity and Its Access Opening 48

49. Mandibular First Molar Pulp Chamber It is quadrilateral in cross-section at the level of the pulp floor being wider mesially than distally Roof is rectangular in shape with straight mesial and rounded distal wall. Four or five pulp horns are present Mesiobuccal orifice is present under the mesiobuccal cusp Mesiolingual orifice is located in a depression formed by the mesial and lingual walls ‰Distal orifice is the widest of all three canals. It is oval in shape with greater diameter in buccolingual direction   Anatomy of Pulp Cavity and Its Access Opening 49

50. Anomalies present Taurodontism Radix entomolaris —supernumerary roots C shaped canals Clinical Considerations Over enlargement of mesial canals should be avoided to prevent procedural errors To avoid superimposition of the mesial canals, radiograph should be taken at an angle   Access Opening: The access opening for the mandibular first molar follows the anatomic features of the pulp chamber. The enamel and dentin are penetrated in the central fossa with the bur angled towards the distal root, where the pulp chamber is largest. Anatomy of Pulp Cavity and Its Access Opening 50

51. The access opening is usually trapezoidal with round corners or rectangular if a second distal canal is present. The access opening extends toward the mesiobuccal cusp to uncover the mesiobuccal canal, lingually slightly beyond the central groove and distally slightly beyond the buccal groove. Anatomy of Pulp Cavity and Its Access Opening 51

52. Mandibular Second Molar It has two roots with three canals.   Pulp Chamber It is similar to the first molar but smaller in size Root canal orifices are smaller and lie closer Root Canal Two roots with two or three canals seen. If two canals are seen, both orifices are in mesiodistal midline If two orifices are not on mesiodistal midline, one should search for another canal on opposite side Anatomy of Pulp Cavity and Its Access Opening 52

53. Anomalies present C-shaped canals, that is, mesial and distal canals become fused into a fin Taurodontism Fused roots Single canal Radix entomolaris Clinical Considerations Perforation can occur at mesiocervical region if one fails to recognize the mesially tipped molar Anatomy of Pulp Cavity and Its Access Opening 53

54. Clinical Note apex of the root and the mandibular canal may be closer than that of the mandibular first molar. There is a significant incidence of this tooth having two canals only: one mesial and one distal Access Opening: Similar to mandibular first molar. Because of the buccoaxial inclination, it is sometimes necessary to reduce a large portion of the mesiobuccal cusp to clean and shape the mesiobuccal canal. Anatomy of Pulp Cavity and Its Access Opening 54

55. Mandibular Third Molar Pulp Chamber and Root Canals Pulp cavity resembles the first and second molar but with enormous variations, that is, presence of one, two, or three canals and “C-shaped” root canal orifices Clinical Considerations Root apex is closely related to the mandibular canal Alveolar socket may project onto the lingual plate of the Mandible   Access Opening: The access opening for the mandibular third molar is created as for the mandibular first and second molars, with the variations that anatomic structure dictates. Anatomy of Pulp Cavity and Its Access Opening 55

56. A Paradigm Shift in Designs of Access Cavity Preparations   Newer advances in access designs • Conservative Endodontic Access Cavity • Ninja Endodontic Access Cavity • Orifice-Directed Dentin Conservation Access Cavity • Incisal Access • Calla Lilly Enamel Preparation • Image guided endodontic access preparations.     Anatomy of Pulp Cavity and Its Access Opening 56

57. Conservative endodontic access cavity ( cecs ) Given by - David Clark and Khademi D eveloped Conservative or constricted access cavities Tooth penetrated centrally at the fossa and then as per need extended in order to find out canal orifices Care should be taken while instrumentation and using the right type of armamentarium during preparation. Fracture strengths in mandibular molar prepared according to the traditional endodontic as well as conservative endodontic methods of preparing the cavities A representation of traditional cavity (green dots) and conservative cavity (brown line) in mandibular molar 57 Anatomy of Pulp Cavity and Its Access Opening

58. Ninja endodontic access cavity ( necs ) The Ninja access cavity is also called as “PEAC” (point endodontic access cavity) as well as “UEC” (ultraconservative endodontic cavity .   1-4 sketches showing, occlusal view (1-3) and sagittal view (4) of designs of access cavity of lower molars (first). Traditional access cavity (1-4) (blue-dashed line), conservative access cavity (1,3 and 4)(green), and the “ninja” ultraconservative cavity (2-4)(pink). Comparing the 3 kinds of access cavity designs; in no.4 (sagittal view) and in no.3 (occlusal view) respectively. 58 Anatomy of Pulp Cavity and Its Access Opening

59. It is seen to be in line same as enamel cut which is 90⁰ or greater, to occlusal area, leaving the root canal orifices tracing from the various visual angulations a lot easier. Gianluca Plotino et al in a in vitro study, compared fracture strength of the restored teeth and root with the conservative cavity, the traditional cavity, or the ninja endodontic access cavity. The results showed reduction in the fracture probability of the teeth treated endodontically with Conservative Endodontic Access Cavity and NEC Increased fracture strength were seen with CEC and NEC, which was greater than teeth with traditional endodontic access cavity. Therefore, we can say that Ninja endodontic access cavity was found to have a better resistance of fracture when compared to conventional access prepared cavity. 59 Anatomy of Pulp Cavity and Its Access Opening

60. Dentin conservation and orifice-directed access cavity (truss access cavity)   The main motive of the “truss” access cavity design is to leave some amount of dentin between two prepared cavities for preserving the dentin. Different cavities are made in order to approach the canals. Here, we reach the pulp chamber through the crown discontinuities in either caries or a previously done restoration. Hence, it is an approach which is decided by the lesion.   It minimizes the restorative necessity of the teeth by taking benefit of the absent hard tissue structures for access.   Two separate cavities made preserving the dentin in between the two cavities.   A representation of traditional cavity (green dots) and truss cavity (orange dots) in mandibular molar. 60 Anatomy of Pulp Cavity and Its Access Opening

61. The limiting factors of this design of cavity : inclination of the tooth, complexity of the anatomy, For example, in the mandibular molars, we make two different cavities to reach the mesial as well as the distal canals but in the maxillary molars, the “ mesio -buccal” and the “ disto -buccal” canals are reached in a cavity only as well as a complete different cavity for the palatal canal is made.   Experts conducted an in vitro study of strength of teeth treated endodontically with NECs, TECs or CEC and found that both CECs and NECs presented a higher fracture strength than TECs in maxillary as well as mandibular molars and premolars Traditional cavities leads to a good conservation of the canal’s original anatomy, present while shaping when compared to Conservative Cavity , specifically at apical portion. Rate of finding out MB2 of traditional (60%), conservative (53.3%) are higher than Ninja (31.6%) cavities statistically.   61 Anatomy of Pulp Cavity and Its Access Opening

62. Fracture types are seen to be less serious in case of CEC preparation when compared to traditional cavity The conservation of dentin resulted in an increased fracture resistance in conservative category which is double the resistance of fracture the traditional category.   It is clearly seen that in both traditional as well as conservative cavities there are both good and poor results because focusing on too much of conservative cavities can result in improper cleaning and shaping as well as the incapability to get more than the expected number of canals which leads to bad prognosis of the ongoing treatment.   Hence, we should strike a balance between both the types of cavities and use a particular design which would result in less failure. 62 Anatomy of Pulp Cavity and Its Access Opening

63. Calla lily enamel preparation Enamel is cut at 45º in order to engage enamel rods and to provide a favorable C factor. The shape of the preparation resembles a Calla Lily with almost complete involvement of the occlusal surface that aid in resisting the compressive forces. Traditional access cavity was compared with Calla Lily enamel preparation and it was seen that unfavourable C factor as well as poor engagement of rods of enamel are present when the old amalgam or composite is removed or in case of the traditional access, which makes 90 degree with the occlusal table.   At 45 degree, the enamel then is cut in shape of Calla Lily. Traditional access cavity (parallel-sided) 90° to the occlusal table (A), compared with the Calla Lily access preparation where enamel is cut at 45° (B). 63 Anatomy of Pulp Cavity and Its Access Opening

64. Calla Lily enamel preparation is based on the principle of ICE: “I”-Infinity edge “C”-Compression based “E”-Enamel driven (engage 70% enamel and 30% dentin)   64 Anatomy of Pulp Cavity and Its Access Opening

65. Image-guided endodontic access preparations It utilizes those images easily accessible to clinicians. Rather than “one common size fitting all”, it ascertains specific location as well as size of access cavity. The purpose is to judiciously preserve dentin and prepare as small an access cavity possible [8]. To customize the kind of access depending on a particular tooth is the ideal action of this system. Image guided endodontic access preparations are of two types mainly; • CT Dynamic access • CT/ CBCT guided static 3D templates Dynamic access: known very commonly as X entry access. Popularized by Charles M Buchanan. The technique was traditionally used in implantology. The procedure utilizes CBCT volume plan to prepare access by 3D assessment of jaw position and bur position with overhead cameras and software.   65 Anatomy of Pulp Cavity and Its Access Opening

66. Static 3D template: This utilises CBCT images and 3D surface scanners to create virtual images of burs and guide sleeves.   A virtual template is designed and printed using 3D printers. Templates are attached to models and access is prepared with specially designed burs. 66 Anatomy of Pulp Cavity and Its Access Opening

67. Yiseul Choi BSDH et al in 2021 conducted a study in which Access opening guide was produced using a 3D printer (AOG-3DP).   The purpose of this study was to determine the effectiveness of using an AOG-3DP during access opening for shortening the preparation time and preventing overpreparation of teeth during endodontic access.     Two groups were made. The AOG-3DP was produced and applied in the test group, while no aid was used in the control group. Production of the access opening guide   Images of each sample were obtained using 100- μ m-resolution CBCT   Mimics software (Materialize, Leuven, Belgium) was used to convert the CBCT images into Stereo Lithography (STL) files of 3D reconstructions, which were used to design a three-unit AOG-3DP with the aid of Exocad software.   67 Anatomy of Pulp Cavity and Its Access Opening

68. On the occlusal side of the AOG-3DP, a hole with a diameter of at least 2 mm was drawn that connected all of the orifices of the root canals. The height of the AOG-3DP was designed to be 10 mm, Finally, the occlusal surface was designed to be perpendicular to the pulp chamber. The final design was then 3D printed using a stereolithography type 3D from tough resin. Designing the AOG-3DP. A simulated AOG-3DP (A) and a produced AOG-3DP (B) 68 Anatomy of Pulp Cavity and Its Access Opening

69. Access opening   Access preparations in both the control and test groups were performed T he AOG-3DP was placed on the crowns of the samples in the test group, while no aid was used in the control group. The preparation procedure for achieving each access opening was timed from the start of the access preparation until all canals were identified. All prepared samples were imaged using CBCT for the 3D visualization and measurement of the preparation. This measurement was quantified as the volume difference between an ideal cavity and the prepared cavity. A 10-mm deep ideal cavity that had the same occlusal shape as that of the hole of the designed AOG-3DP was simulated, and its volume was measured using Mimics software. 69 Anatomy of Pulp Cavity and Its Access Opening

70. The actual prepared cavity volume for both the group was measured with Mimics software by converting the post preparation CBCT images into STL files (Figure 2). 3D visualization and measurement of overpreparation. Original prepared cavity (A), a 10-mm deep ideal cavity (B), and comparison of the ideal and prepared cavities on the coronal side (yellow shading, prepared cavity; red lines, ideal cavity) (C) 70 Anatomy of Pulp Cavity and Its Access Opening

71. The volume difference between the ideal and prepared cavities was calculated by subtracting the actual volume from the ideal volume.  The mean times required for achieving access opening in the two groups are presented in the figure below. Comparison of the control and AOG-3DP groups. (A) Comparison of access opening times. The times for achieving access opening in the control and AOG-3DP groups were 327.2 ± 135.5 and 97.4 ± 106.6 s (mean ± SD), respectively, in the premolar group, and 547.43 ± 269.6 and 104.57 ± 55.5 s in the molar group. (B) Volume differences between the ideal and prepared cavities, which were 38.1 ± 32.2 and 72.2 ± 60.6 mm 3 for the premolars and molars, respectively, in the control group, and − 2.0 ± 14.4 and − 8.7 ± 16.8 mm 3 in the test group. 71 Anatomy of Pulp Cavity and Its Access Opening

72. Using the AOG- 3DP significantly reduced the preparation time by 75.9% for premolars and by 81% for molars. Compared with the control group, samples in the test group generally demonstrated minimal preparation while still achieving straight-line access into all canals. Periapical-view images of the test group showed straight line access into all canals, while the control groups displayed errors such as over flaring from the orifice, a remaining pulp chamber roof, and excessive tooth removal that almost resulted in perforation.  The average volume differences between the ideal and prepared cavities were 38.1 and 72.2mm3 for the premolars and molars, respectively, in the control group. In contrast, the prepared cavities were much closer to the ideal cavities when using theAOG-3DP, with a mean difference of − 2.0mm3 for premolars and −8.7mm3 for molars.   72 Anatomy of Pulp Cavity and Its Access Opening

73. D ifficulties encountered during the design and manufacture processes. Difficult to produce AOG-3DPs for use with the anterior teeth. When preparing anterior teeth with an AOG-3DP, the head of the handpiece was caught by the guide on the incisal edge and so a special long bur was needed. When using a diamond bur, it will be necessary to consider the angle between the AOG-3DP and the head of the handpiece in order to achieve a suitable angle for the preparation. Second, accuracy errors could occur depending on the insertion direction of the bur used with the AOG-3DP. If the bur is not positioned exactly perpendicular to the occlusal side of the guide, the produced area might be distorted and overprepared Several methods were investigated for reducing this error with the implant guide, drill guide sleeve, placing a metal tube in the hole, and designing a special bur for the hole. 73

74.   Third: S trength and stability of 3D printed guides. Since 3D-printed guides wereprinted using light-curable resin, there was a possibility of destroying the AOG-3DP as well as the teeth during access opening, making the end result different from the original design.   Biggest problem of the AOG-3DP based on CBCT is of exposing patients to radiation and the additional cost According to the American Association of Endodontist and American Academy of Oral and Maxillofacial R adiology, CBCT should be performed when the level of difficulty of RCT is high or when it is difficult to perform the required evaluations using existing panoramic and periapical views. 74 Anatomy of Pulp Cavity and Its Access Opening

75. THANK YOU