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Internal anatomy of tooth


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descriptive presentation on internal anatomy of teeth

Published in: Health & Medicine

Internal anatomy of tooth

  2. 2.  Introduction  Pulp chamber anatomy  Root canal and classification of root canal systems  Apical foramen  Accessory foramen  Apical constriction  Isthmus  C shaped canals  Anatomy of individual teeth  Developmental disturbances  Conclusion  References
  3. 3. What we cannot see, we cannot negotiateand what we cannot negotiate we fail to prepare!
  4. 4.  Beyond the simple perception is often the intricate internal tooth anatomy and a complex root canal system.  Root canal treatment has transformed remarkably since the hollow tube theory was postulated in 1930.  Research into the morphology of the pulp has revealed that the dental pulp takes many intricate shapes and configurations before reaching the tooth apex.  As a professional, one should be aware of all the probable nooks and crannies of the complex root canal, its protean permutations and combinations, to render the finest possible treatment.
  5. 5. Apical foramen Lateral canals Furcation canals Pulp chamber Pulp horn Floor Roof
  6. 6. Krasner and Rankow studied the pulp chamber of 500 extracted teeth and their consistent observation regarding the pulp chamber anatomy in all teeth led to the formulation of new laws, forming guidelines for locating the pulp chamber and root canal orifice. The anatomic laws/patterns observed are categorized into two groups: 1) Relationships of the pulp-chamber to the clinical crown. 2) Relationships of the root canal orifice on the pulp chamber floor.
  7. 7. • 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.
  8. 8.  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.
  9. 9. • 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.
  10. 10. DENTINAL MAP
  11. 11. Type I Mature straight roots (having closed apex with apical constriction) Slightly Curved Severely Curved Dilacerated Bayonet Type II Mature but not straight root canals, which may be:
  12. 12. A. Tubular root apex B. Blunderbus apex Type III Immature (open apex) canals (Straight or curved)
  13. 13. Type I: Single canal with single orifice and single apical foramen Type II: A canal with a single orifice that divided into two canals and exit with a single apical foramen According to Weine Classification of the root canal system
  14. 14. Type IV : Single canal with two orifices and two apical foramen Type III : Two canals with two orifices and single apical foramen
  15. 15. Type V –a root canal configuration having more than two canals that branched off from the main canal more than 3mm from the apex defined as another main canal.
  17. 17. Vertuccis’s Classification
  18. 18. Sert and Bayirli in 2001 reported fourteen new root canal configurations, which were not included in the classification by Vertucci or other classification systems
  19. 19. According to Gulabivala & co - workers
  20. 20.  Root canal curvatures were classified by different authors as follows:  By Ingle and Taintor (1980) and Pucci and Reig (1986).  Apical curve.  Gradual curve.  Sickle-shape curve.  Dilacerations.  Bayonet.  Zidell’s (1987) classification of root canal systems.  Severe curve.  Dilacerated curve.  Bayonet curve.  Apical bifurcation.  Apical curve.  Additional canals.  Lateral and accessory canals.
  21. 21.  Schneider’s (1986) classification on the basis of degree of curvature in the main root canals. It is measured using protractor.  Easy: straight and curved <5º  Average: curved >10º and <25º  Difficult: curved >25º D) According to Weine curved canals are also grouped based on their degree of curvature. i) Curvatures of 30º to 45º ii) Curvatures of 45º to 60º iii) Curvatures of 60º to 90º iv ) Curvatures of greater than 90º v) Bayonet curved canals.
  22. 22.  E) Backman et al (1976) and Southard et al (1990) classified root canals on the basis of “Radius Quotient” which was obtained by dividing a given angle by its radius measurements.  F) Dobo Nagy et al (1971) devised a classification based on Schneider’s angle and the radius of the circle that could be superimposed on the curved part of the root canal.  G) Mathematical classification of root canal form, by Csaba Dobo Nagy et al in 1995 is as follows.  Straight or ‘I’ form.  Apical curve or ‘J’ form.  Curved canal along its entire length or ‘C’ form.  Muticurved or ‘S’ form.
  23. 23. 1. Tooth apex (radiographic apex) 2. Apical foramen (major foramen) 3. Apical constriction (minor foramen) 1 2 3 Anatomy of the Root Apex (Kutler’s studies)
  24. 24. According to Ingle the anatomy of the root apex is partially determined number location apical blood vessel (during development of the apex)  young and erupting tooth the foramen is funnel shaped The mouth of funnel shaped is filled with the periapical tissue, which is later replaced by dentin and cementum. As the root develops, the apical foramen becomes narrower.
  25. 25.  The apical foramen is the main apical opening of the root canal.  It is frequently eccentrically located away from the anatomic or radiographic apex.  An accessory foramen is an orifice on the surface of the root communicating with a lateral or accessory canal.  They may exist as a single foramen or as multiple foramina
  26. 26.  The location and shape of the apical foramen may undergo changes as a result of functional influences on the teeth.  A tooth may be tipped from horizontal pressure, or it may migrate mesially, causing the apex to tilt in the opposite direction.  Under these conditions the tissues entering the pulp through the apical foramen may exert pressure on one wall of the foramen, causing resorption.  At the same time cementum is laid down on the opposite side of the apical root canal.  Thus, the principal apical foramen might be in the center of the root originally, the foramen gradually shifts with aging , mesial and occlusal drift, and continuous cementum deposition.
  27. 27.  With increasing age, minor diameter of apical foramen becomes narrower while their major diameter becomes wider from the deposition of dentin and cementum.  Sometimes the apical opening is found on the lateral side of the apex, although the root itself is not curved.  All root canals deviate from the long axis of their roots.
  28. 28.  Green’s detailed studies (1955, 1956, and 1960) of the anatomy of the root apices of teeth demonstrated the major apical foramens are situated directly at the apex more frequently in the Maxillary First Premolar and Mandibular Second Premolar Maxillary central and Lateral incisors, In the Maxillary molars and all the mandibular teeth with the exception of the second premolar the main apical foramina coincide with the apices less frequently.
  29. 29. The physiological foramen or apical constriction is considered the narrowest diameter of the root canal and was thought to be located at the cemento-dentinal junction. Langeland histologically demonstrated that the cemento- dentinal junction being highly irregular (e.g. 3mm higher on one wall than on the opposite wall) did not at all coincide with the apical constriction. Physiological foramen is considered as the apical limit of the root canal preparation. It is also known as histological foramen, because it is located at the junction between the pulpal connective tissue and interstitial loose connective tissue of the periodontal ligament.
  30. 30.  The apical constriction of the canal usually occurs within the dentin, just prior to the initial layers of cementum.  Kuttler referred to this site as the minor diameter of the canal.  Site to terminate canal preparation and build up the apical dentin matrix.  Major diameter was found to be approximately twice as wide as the minor diameter.  This means that the longitudinal view of the canal seen as tapering funnel till the tip at exit and then widens again.  When viewed in longitudinal section the configuration between the minor and major diameters resembles that of a morning glory flower.
  31. 31.  Apical constriction have been classified by Dummer et al  Type A: The traditional single constriction.  Type B: A tapering constriction with the narrowest portion of the canal very near to the actual apex.  Type C: A number of constrictions were present.  Type D: Where the constriction was followed by a narrow, parallel portion of canal  A fifth type was also seen where the canal had been completely blocked with secondary dentin or cementum
  32. 32.  Kuttler reported that the distance between the center of the foramen and the narrowest part of the apical canal was 524μm (18 to 25 yrs) to 659μm (above 55 yrs).  Mizutani et al reported the distance to be 0.825 to 1.010 mm.  The apical constriction tends to occur about 0.5 to 1mm from the apical foramen (Chapman 1969)
  33. 33.  Chapman (1969) noted vast majority of constrictions were found between 0.7 to 3mm from the apex.  Mizutani et al (1992) reported the vertical distance between the apex and apical constriction for maxillary anterior teeth were 0.8 to 1.0mm.
  34. 34.  The apical constriction is commonly advocated as the ideal termination for root canal treatment, being a natural narrowing of the root canal and almost at the termination of the pulp.  This is supposedly where an apical stop is formed against which the obturation materials are packed.  As this constriction is usually not present, the apical foramen may be a more useful landmark.  The distance between the apical constriction (when present) and the apical foramen ranges from 0.5 to 1.0mm for the teeth of different ages.  When the apical foramen is located, the position, of the apical constriction (if it exists) can be estimated, if the apical constriction is not present, the preparation and obturation will usually be within confines of the root.
  35. 35.  In fact, it is difficult to locate either the apical constriction or the apical foramen clinically or radiographically.  Although 0.5 to 1mm short of the radiographic apex is commonly used as the termination point.  It is an attempt to debride and obturate close to the apical foremen but hopefully, not beyond.
  36. 36.  no apical injury  no injury to the periodontal ligament  maintenance of accessory lateral canals  no extrusion of root canal fi lling material  no apical transport of infected pulpal tissues  adequate compaction of the root canal filling against the canal walls  no infected tissue remnants within the canal
  37. 37.  It has been demonstrated that when periradicular lesion is present root resorption not visible radiographically is likely.  When the periapical tissue exhibited normal structures ,the corrected working length should be established 1mm from radiographic apex.  When bone resorption is evident the corrected working length is established 1.5mm short of apex.  When bone and apex exhibit resorption the length should be 2mm from apex.
  38. 38.  Lateral canals and accessory foramina are integral parts of a normal pulp cavity rather than exceptions. Location: A lateral canal can be found anywhere along the length of a root and tends to be at right angle to the main root canal.  Accessory canals usually branch off the main root canal somewhere in the apical region.  Lateral canals are found in profusion in the roots of posterior teeth and occasionally in the roots of anterior.  The presence of lateral canals in the furcation areas of molar teeth is well documented and their incidence is high.
  39. 39. Content:  Lateral and accessory canals contain fibrous tissue.  The connective tissue , same as that found in the pulp but more closely resembles the connective tissue of the periodontal ligament. Incidence:  The incidence of lateral and apical canals reportedly increases in posterior teeth, toward the apical third of the root.  In younger teeth and multirooted teeth it has been found to vary from 2-3% to over 72%  Gross methods of detection, such as vulcanite corrosion specimens of the root canals have indicated that there is an incidence of 16.9% of such canals, in all teeth (Hess 1925).  In anterior teeth, accessory and / or lateral canals were observed in an incidence of 34%.
  40. 40. Size:  According to Hess et al (1983) accessory canal foramina have a mean diameter of 6 to 60μm.  The size of accessory and lateral canal structures varies with diameter ranging from 1mm to size of blood vessels.
  41. 41.  In molars, a multitude of accessory canals are present within the cementum “web” fusing the roots.  The presence of a dichotomy or branching of the pulp canal near the apex of the tooth, giving a Y-shaped branching of the root canal near the apex of the tooth are evident.  Such apical deltas were also found to be frequent by Hess et al (1983).  In the distal roots of lower molars and in the palatal roots of upper molars, many anomalies in size and shape of the root canals are found.  Frequently, in these teeth the canals fan out toward the apex of the tooth in a ‘canoe shaped’ arrangement.  Following endodontic treatment, the pulp tissue in the uninstrumented branches may become inflamed, but usually retains its vitality with the passage of time, continuous deposition of dentin or cementum tends to narrow the lumen of these canals.
  42. 42. An isthmus is defined as a ribbon shaped intercanal connection or transverse anastomosis or a corridor between two root canals encompassing dental pulp and pulp related tissue. Observed between any two root canals within the same root. As the isthmus houses the dental pulp, it might serve as a potential site for bacterial growth and thus, making complete debridement of this area indispensible. Whenever two or more root canals are present, an isthmus should be suspected and all attempts should be made in detecting and debriding it.
  43. 43.  Type I - Is two or three canals with no notable communication.  Type II - Is two canals that possess a definite connection between the two main canals.  Type III- Is three canals that possess a definite connection between them.  Type IV- Is when the canals extend into the isthmus area.  Type V- Is the true connection or corridor throughout the section.
  44. 44.  Cooks and Cox first discovered the C-shaped anomaly in mandibular second and third molars in 1979.  There are two common possible outcomes for the C-shaped mandibular molar those that exhibit. A single, ribbon like, C-shaped canal from orifice to apex . Three distinct canals below the C-shaped orifice, the more common form .  C-shaped canal prevents effective cleaning, shaping and obturation during a root canal therapy.  The C-shaped canal has been observed in mandibular first premolars, mandibular first, second and third molars, maxillary first molars and maxillary second molars.  The occurrence of a C-shaped canal and its improper negotiation can lead to failure in endodontic therapy and hence should be gingerly examined.
  45. 45.  The size and shape of the pulp are influenced by age. In the young person, pulp horns are long, pulp chambers are large, root canals are wide, apical foramen are broad ,and dentin tubules are wide , regular, and are filed with protoplasmic fluid.  With increasing age pulp horn recede, pulp chambers becomes smaller in height rather than in width, and root canals become narrower from deposition of secondary and reparative dentin.  Moreover, apical foramen deviates from the exact anatomic apex, and their minor diameter becomes narrower while their major diameter becomes wider from the deposition of dentin and cementum.  Dentinal tubules become narrower and even obliterated by the deposition of peritubular dentin forming sclerotic dentin, and they lose their regularity and become tortuous.  Reparative dentin may be devoid of dentinal tubules, and the moisture content of the dentin is reduced.
  46. 46. MAXILLARY CENTRAL INCISORS Length of tooth (mm) Canal Lateral canals Apical ramification s Root curvature (%) Average length 23.5 One canal 99.4% 23% 13% Straight 75 Maximum length 25.6 Two canals 0.6% Distal curve 8 Minimum length 21.0 Mesial curve 4 Range 4.6 Labial curve 9 Lingual curve 4
  47. 47. Pulp chamber follows the contour of the crown 3 pulpal horns located in the center equidistant from the dentinal walls. It is broad mesiodistally, The chamber is ovoid mesiodistally.
  48. 48.  Maxillary central incisor usually has one canal. There are many case reports of two root canals in maxillary central incisor.  Follows the direction of the curved root.  Broader labiopalatally,  Large and simple in outline, conical in shape,  Centrally located.  The apical foramen is centrally located in the anatomic apex in only 12% of cases.
  49. 49. Cross section at three level.  Cervical level: canal is ovoid mesiodistally.  Middle root level: canal is ovoid to round.  Apical third level: canal is generally round in shape. An unusual large apical third have canal which is more ovoid  The mean distance of the apical foramen to the root apex ranges from 0.30 to 0.49mm  Lateral canals may be present 23%, usually 49.1% in the apical third area.  Apical delta is present in 1% of cases.
  50. 50. Gemination: Its attempt at division of a single tooth germ by an invagination with resultant incomplete termination of two teeth. Incidence 0.5-2.5% in primary teeth. Incidence 0.00.8% in permanent teeth. Dental fusion and gemination are used to define two different morphological dental anomalies, characterized by the formation of a clinically wide tooth.
  51. 51. Fusion : Union of two normally separated tooth germs. Depending upon the stage of development of the teeth at the time of union, fusion may be either complete or incomplete. The dentin however is always confluent in cases of true fusion. 1. Complete: Fusion begins before calcification. The crown incorporates features of both participating teeth with regard to their enamel, dentin, cementum and pulp. 2. Incomplete: Fusion occurs at a later stage. The tooth might exhibit separate crowns and fusion may be limited to the roots alone with pulp canals fused or separate.
  52. 52. MAXILLARY LATERAL INCISORS Length of tooth (mm) Canal Lateral canals Apical ramifications Root curvature (%) Average length 22.8 One canal 93.4% 10% 12% Straight 30 Maximum length 25.1 Two canals 6.6% Distal curve 53 Minimum length 20.5 Mesial curve 3 Range 4.6 Labial curve 4 Bayonet and gradual curve 6
  53. 53. Pulp chamber: Shape is similar to that of the maxillary central incisor.  two pulp horns,  It is broad mesiodistally  The division between pulp chamber and root canal is indistinct.
  54. 54.  Slender shaped , wider labiolingually than mesiodistally.  The root apex is sharper than that of the central incisor, displaying a common deflection to distal and palatal side.  The maxillary lateral incisors usually have one root.  Variations in number of roots have been reported but are rare
  55. 55.  Follows the direction of the curved root.  Maxillary lateral incisor usually has one canal.  Survey of De Deus (1992) reported that 3% of maxillary lateral incisors may have 2 canals.  Walvekar et al in 1997 reported a case of 3 root canals.  These cases are thought to be the result of abnormal development of the tooth and the root.  They often manifest clinically as gemination, fusion and concrescence.
  56. 56. Cross section at three levels. Cervical level: Canal is wider in labiopalatal dimension. Midroot level: canal is ovoid. Apical third level: canal is generally round and gradually curved
  57. 57.  Developmental alterations which are most commonly associated with maxillary lateral incisors are  microdontia  hypodontia  Dens invaginatus  Dens evaginatus (talon cusp).  Microdontia teeth are smaller than the normal size,  Microdontia of maxillary lateral incisor is called as “peg lateral”  Crown - cone shaped with converging mesial and distal surfaces.  Root - usually shorter than crown
  58. 58.  Peg shaped lateral incisors incidence – approx 2% to 5% of the general population  Women show a slightly higher frequency than men.  Usually they are found equally on the right and left, unilaterally or bilaterally, Peg lateral is usually associated with other dental anomalies like  tooth agenesis,  maxillary canine first premolar transposition,  palatal displacement of one or both maxillary canine teeth,  buccally displaced canine,  mandibular lateral incisor-canine transposition
  59. 59.  Hypodontia developmentally missing one or more teeth.  Congenitally missing maxillary lateral incisors are the second most common dental abnormality  Absence may be either unilateral or bilateral.  Associated complications of missing maxillary lateral incisors are compromised aesthetics and occlusal imbalance in the maxillary and mandibular dental arch, leading to psychological distress in some patients.
  60. 60.  Dens invaginatus is a developmental anomaly resulting in a deepening or invagination of the enamel organ into the dental papilla prior to calcification of the dental tissues.  Permanent maxillary lateral incisors are most commonly involved.  In ‘dens invaginatus’ the clinical appearance of the crown may vary, ranging from a normal form to more unusual forms such as greater labio-lingual or mesio-buccal diameter, peg-shaped, barrel- shaped and conical.  Concurrence of talon cusp and dens invaginatus within the same tooth is rare.  For this association, studies have revealed an incidence ranging from 0.89% to as high as 9.2%.
  61. 61.  Most commonly accepted classification belonging to Oehlers (1957) who described three types:  Type I = an enamel invagination in the crown only;  Type II = an enamel-lined invagination that invades the root but remains confined within it as a blind sac and may communicate with the dental pulp;  Type III = an invagination that extends from the crown to the apex and is penetrated by a second foramen laterally or apically on the root surface.  In this type, any infection within the invagination can lead to an inflammatory response within the periodontal tissues, giving rise to a peri-invagination periodontitis
  62. 62.  Dens evaginatus originates in the palatal cingulus, often being bilateral and is known as “talon cusp”.  So, the talon cusp is described as an anomalous hyperplasia of the cingulum of maxillary and mandibular incisors resulting in the formation of a supernumerary cusp resembling an eagle’s talon. Complications like Caries,  Periapical lesions,  Irritation of tongue during speech and  mastication  Occlusal interference accidental cusp fracture, displacement of the affected tooth, temporomandibular joint pain and periodontal problems because of excessive occlusal force
  63. 63. Classified on the basis of degree of formation and extent by Hattab F N et al (1996) into following three types –  (1) True talon (an additional cusp that prominently projects from the palatal surface of a primary or permanent anterior tooth and extends at least half the distance from the cemento-enamel junction to the incisal edge)  (2) Semitalon (an additional cusp of 1 mm or more but extending less than the distance from the cemento-enamel junction to the incisal edge)  (3) Trace talon (enlarged or prominent cingulum and variations, i.e., conical, bifid, or tubercle-like).
  64. 64.  Is a developmental anatomic aberration with an infolding of enamel organ and the epithelial sheath of Hertwig before the calcification phase.  Embryologically, it is related to a mild form of dens invaginatus.  The maxillary lateral incisor (LI) is most commonly (93.8%) affected.  Clinically, a V-shaped notch is seen with altered or interrupted cemento-enamel junction (CEJ).
  65. 65. MAXILLARY CANINES Length of tooth (mm) Canal Lateral canals Apical ramifications Root curvature (%) Average length 26.0 One canal 96.5% 24% 8% Straight 39 Maximum length 28.9 Two canals 3.5% Distal curve 32 Minimum length 23.1 Mesial curve 0 Range 5.8 Labial curve 13 Lingual curve 7 Bayonet and gradual curve 7
  66. 66. One Canal 96.5% Two or More Canals 3.5% One Canal at Apex 98.8% Two or More Canals at Apex 1.2% Maxillary Canine
  67. 67.  A specimen 33.5mm in length has been reported by Pucci FM and Reig R.  Pulp chamber:  are the largest of all single-rooted teeth.  Labiopalatally, the chamber is triangular  Mesiodistally, it is narrow, sometimes resembles a flame.  Only one pulp horn is present  In cross-section, the chamber is ovoid in shape, with the greater diameter labiopalatally.
  68. 68. Normally straight, single and symmetrical labio-lingually, tapers to sharp apex. However, the rare incidence of bifidity has been reported. The root is bent distally The apical part of the root is often abruptly curved distally, sometimes labio-distally.
  69. 69.  Wider labiopalatal than mesiodistally, in the middle third, it tapers gradually to an apical constriction.  In cross-section, the root canal is wider in the labio-palatal direction in cervical third, ovoid in middle third and round in the apical third.  The apical foramen is centrally located in the anatomic apex in 14% of cases.  The mean distance of apical foramen from the root apex ranges from 0.30 to 0.62mm.
  70. 70. Pulp chamber  narrow mesiodistally.  pulp horn under each cusp.  Buccal pulp horn is more prominent than the palatal.  The roof of the pulp chamber is coronal to the cervical line.  The floor of the pulp chamber is convex, usually with two canal orifices, one buccal and the other palatal and it lies deep in the coronal third of the root below the cervical line In cross-section, the pulp chamber is wide and ovoid in a buccopalatal dimension
  71. 71. has two roots in 54.6% of cases. In 21.9%, the roots are separated, whereas in 32.7% the roots are partially fused. 43% have one root and 2.4% have 3 roots. When two roots are present, they may diverge as much as 25% from each other. When three roots are present, one is palatal and two are buccal which closely resemble the configuration of a small maxillary second molar.
  72. 72.  In a tooth with a single canal through the length of the root, the canal is ovoid in shape, wider bucco-palatally than mesiodistally in the cervical and middle thirds and round in the apical third.  When two canals are present the palatal canal is generally the larger of the two canals, it is directly under the palatal cusp, and its orifice can be penetrated by following the palatal wall of the pulp chamber.  The buccal canal is directly under the buccal cusp, and its orifice can be penetrated by following the buccal wall of the pulp chamber.
  73. 73.  In rare cases have shown three root canals.  When two root canals are present, the cervical thirds are ovoid in shape, at midroot they are almost round, and in the apical third they are round and small.  Maxillary 1 PM have 2 root canals at apex in 69% of cases and 26% of cases have single root canal at apex.  The apical foramina are centrally located in 12% of cases, and being a mean distance of 0.55mm from the anatomic apex.  Transverse channels between the canals are common
  74. 74. MAXILLARY FIRST PREMOLARS Length of tooth (mm) Canals (%) Direction Curvature of roots Single root Double roots Buccal Palatal Average length 21.8 One canal One foramen 9 Straight 38 28 45 Maximum length 23.8 Two canals One foramen 13 Distal curve 37 14 14 Minimum length 18.8 Two canals Two foramina 72 Mesial curve 0 0 0 Range 5 Three canals Three foramina 6 Labial curve 15 14 28 Lingual curve 3 36 9 Bayonet curve 0 8 0
  75. 75.  Pulp chamber :  Narrow mesiodistally.  Wider buccopalatally than the maxillary first premolar  Two pulp horns, buccal and palatal.  The roof of pulp chamber is coronal to the cervical line.  The pulp floor is deeper if two canals are present.  If one root canal is present, the root canal orifices will be indistinct, but if two canals are present, two distinct orifices will be visible.  In cross-section, the pulp chamber has a narrow, ovoid shape.
  76. 76. Root:  Maxillary second premolars have single root in 90.3% of patients.  7.7% have 2 roots that are partially fused;  2% have 2 well-developed roots.  Approximately 15% of the time, 2 separate roots are present, each with a single canal. An extremely rare variant has 3 separate roots (Weine). Root canals:  One canal at apex is present in 75% of the cases.  If two canals are present they may be separate or converge at apex.  Majority of canals are curved and only 9.5% are straight.
  77. 77. In cross-section at three levels. Cervical third: Canals are ovoid and narrow.  Middle third: When one canal is present it is ovoid, and when two canals are present they are round.  Apical third: Canal is round regardless of whether one or two canals are present.  The apical foramen is centrally located in 12% of cases.  Gutmann reported that the apical foramen has been demonstrated to be on the lateral root surface 78% of the time with a mean distance of 0.62 mm from the anatomical apex.
  78. 78. MAXILLARY SECOND PREMOLARS Length of tooth (mm) Canals (%) Root curvature (%) Average length 21 One canal One foramen 75 Straight 9.5 Maximum length 23 Two canals Two foramina 24 Distal curve 27 Minimum length 19 Three canals 1 Mesial curve 1.6 Range 4 Buccal curve 12.7 Lingual curve 4.0 Bayonet curve 20.6
  79. 79. Pulp chamber:  Largest  Four pulp horns: Mesiobuccal, distobuccal, mesiopalatal and distopalatal.  The arrangement of four pulp horns gives the pulpal roof a rhomboidal shape in cross section.  The four walls forming the roof converge toward the floor where the lingual wall almost disappears; the floor of the pulp chamber thus has a triangular form in cross section.
  80. 80.  The Palatal orifice is the largest, round or oval in shape and easily accessible for exploration.  The Mesiobuccal orifice is under the mesiobuccal cusp is long buccopalatally, and may have a depression at the palatal end in which the orifice of a fourth canal may be present.  The mesiobuccal orifice is located by insinuating the tip of a long shank explorer, in a mesiobuccal - apical inclination into the point angle created at the juncture of the buccal wall, mesial wall, and sub pulpal floor of the pulp chamber.  The Distobuccal orifice is located slightly distal and palatal to the mesiobuccal orifice and is accessible from the mesial for exploration.  The floor of the pulp chamber is in the cervical third of the root, and the roof is in the cervical third of the crown.
  81. 81. The maxillary first molar has three roots. Mesiobuccal root:  It is broad in the buccopalatal direction.  The majority of the roots have a distal curve (78%), but some are straight (21%) and some are “S” or bayonet shaped (1%). Distobuccal root:  It is small and is more or less round in shape.  It is straight in 54% of cases, has a distal curve in 17% has a mesial curve in 19% and has an “S” or bayonet shape in 10% of cases.
  82. 82. Palatal root:  largest diameter and is the longest root of the maxillary first molar.  It is straight in only 40% of cases.  It may curve buccally (55%), mesially (4%) or distally (1%).  The root may curve in the apical third toward the buccal.  Such a curvature is not apparent radiographically, which may lead to perforation of the root if the instruments are not precurved during cleaning and shaping procedures.  Oswald in 1979 stated that this curvature is so common that it should be assumed that the curve is present until proved otherwise.  One may see a divergence of as much as 45º between the palatal and buccal roots.
  83. 83.  The maxillary first molar usually has three root canals.  Mesiobuccal.  Distobuccal.  Palatal. Mesiobuccal root canal:  It is the narrowest of the three canals.  Jou Yi-Tai (2004) reported that the cross sections of 90% of mesiobuccal canals were oval or flat in mesiodistal direction, but round in apical third.  The canal anatomy of mesiobuccal root has been described by a number of investigators and the incidence of the mesiobuccal-2/mesiopalatal- 2 canals ranges widely. This variation may be because of the different criteria used for evaluating the presence of this canal.  From in vitro studies, the presence of mesiobuccal-2 canal ranges from 51.5% to 95.2% whereas, in vivo studies, the presence of mesiobuccal-2 canal ranges from 18.6% to 77.2%..
  84. 84.  On average, Mesiobuccal-2 canal is located 1.8 mm away from the mesiobuccal canal in a palatomesial direction.  More recently, some authors have found a higher percentage of mesiobuccal canals than these previous studies revealed.  This could be due to their strict attention to the internal anatomy of the tooth, the change in the access opening (creating a more heart shape form or rhomboidal shape) and the use of a surgical microscope.  Another suitable explanation could be the low age of patients treated. It is well known that in normal development or in response to carious or restorative insult, the mesiobuccal canal orifice becomes hidden by an overhanging mesial dentinal shelf.
  85. 85.  Hess in 1925 reported the prevalence of four root canals in maxillary permanent molar to be 53%.  Gutmann has shown 4 canals anywhere from 46 to 72% of the time.  However, the actual continuation of these canals into 2 separate foramina only ranges from 14 to 42%.  Ingle (2002) reported the presence of 3 canals in 41.1%, 4 canals in 56.5% and 5 canals in 2.4% of cases.
  86. 86.  The distobuccal root usually has a single root canal, which is narrow, tapering canal sometimes flattened in a mesiodistal direction but generally cone shaped, ending in a small, round canal in the apical third.  The percentage of two root canals in the distobuccal root in an investigation done by Pineda and Kuttler teeth proved to be 3.6%  The apical foramen is centrally located in only 19% of these cases.  The mean distance of the foramen ranging from 0.45 to 0.58mm from the root apex.  The canal exits to a lateral surface 81% of the times.  The possibility of fusion of distobuccal root canal with the palatal root and canal exists with the formation of a C-shaped canal. Radiographic determination of this variation is very difficult.
  87. 87.  The palatal canal is ovoid mesiodistally and taper toward the apex, where it becomes a small, round canal.  Frequency of curvature of palatal root canal.  Type 1 (<10º) – 10%  Type 2 (>10º & <20º) – 54%  Type 3 (>20º) – 36% This is based on Miller’s classification 1975  Nature of curvature of palatal root canals  Curve to the buccal – 85%.  Curve to the buccal and to the palatal – 13%.  Curve to the palatal only – 2%.
  88. 88.  The average location of the apical foramen is 0.50 - 0.64mm from the root apex. The canal exits to a lateral surface 88.5% of the time.  The apical foramen is centrally located in only 18% of the cases.  Peter and Laib in 2000 investigated the thickness of the apical foramen of maxillary molar canals which ranges in 78 to 540μm.  Large apical canal diameter, 1mm from the root apex, was demonstrated histo- morphologically.
  89. 89.  Taurodontism is a morpho-anatomical change in the shape of the tooth in which the body of the tooth is enlarged and the roots are reduced in size  Characterized - enlargement of the pulp chamber with the body of the tooth enlarged at the expense of the roots and apically displaced furcation areas .  The bifurcation or trifurcation may be only a few millimeters above the apices of the roots.
  90. 90. Classification In 1928 , Shaw classified this condition as  hypotaurodontism  mesotaurodontism  hypertaurodontism
  91. 91. MAXILLARY FIRST MOLAR Length of tooth Mesi obuc cal (mm) Distobuc cal (mm) Palat al (mm) Canal (%) Curvature of roots Directi on Pala tal (%) Mesi al (%) Dist al (%) Canals in mesiobuccal root Average length 19.9 19.4 20.6 Three 41.1 Straigh t 40 21 54 One canal One foramen 41. 1 Maximu m length 21.6 21.2 22.5 Four 56.5 Distal 1 78 17 Two canals One foramen 40 Minimum length 18.2 17.6 17.6 Five 2.4 Mesial 4 0 19 Two canals Two foramina 18. 9 Range 3.4 3.6 3.8 Buccal 55 0 0 Lingua l 0 0 0 Bayone t 0 1 10
  92. 92.  The pulp chamber is similar to that of the maxillary first molar except it is narrower mesiodistally.  The roof of the pulp chamber is more rhomboidal in cross section.  The floor of the pulp chamber is an obtuse triangle in cross section, and the mesiobuccal and distobuccal canals are closer together and may appear to have a common opening, but they are readily distinguishable from each other. Sometimes, all three canal orifice may in a straight line. Occasionally canal curve into the chamber at a more horizontal angle, making it necessary to remove a “lip” of dentin so that the canal can be entered more in a direct line with the canal axis.
  93. 93.  The palatal root is usually straight, but in 37% of cases it has a buccal curve.  The mesiobuccal root usually curves distally; only 22% of these roots are straight.  The distal root is usually straight, but in 17% of cases it has mesial curve.  Peikoff in 1996 reported that the ‘standard’ 3-rooted tooth is only one anatomical variation encountered during root-canal treatment of maxillary second molar tooth. Variations in the root anatomy of the maxillary second molar, which include fewer or greater number of roots than the normally described 3-root forms.
  94. 94. The variation of the morphology of the root canal systems which were found are:  Variant 1 (56.9%) – 3 separate roots, mesiobuccal, distobuccal and palatal, with one canal in each root.  Variant 2 (22.7%) – 3 separate roots, with one canal in the distobuccal and palatal and 2 canals in the mesiobuccal root.  Variant 3 (9%) – Similar to variant 1 except that the mesiobuccal and distobuccal roots join in the apical region resulting in one common apex, join to form one common apical foramen. The palatal root is separate and has one canal.  Variant 4 (6.9%) – 2 separate roots, a buccal and a palatal with one canal in each root.
  95. 95.  Variant 5 (3.1%) – one conically shaped root with a confluence of all canals into one main canal system.  Variant 6 (1.4%) – 4 separate roots mesiobuccal, distobuccal and the unusual occurrence of two separate palatal roots, a mesiopalatal and a distopalatal. Each root has a single canal with the possible exception of the mesiobuccal which could have 2 canals as in variant 2.  According to Gutmann the pulp cavity spaces and radicular anatomy of this tooth are very similar to those of the first molar with the exceptions that there is a greater incidence of root fusion in this tooth, as well as the presence of ‘C’ – shaped canals and canal orifices.
  96. 96. Length of tooth Mesiobuc cal (mm) Distobuc cal (mm) Palata l (mm) Number of roots Curvature of roots Directio n Palata l Mesia l Dist al Canals in mesiobuccal root Average length 20.2 19.4 20.8 Thre e 54 Straight 63 22 54 One canal One foramen 63 Maximum length 22.2 21.3 22.6 Fuse d 46 Distal 0 54 ? Two canals One foramen 13 Minimum length 18.2 17.5 19.0 Mesial 0 0 17 Two canals Two foramina 24 Range 4.0 3.8 3.6 Buccal 37 Lingual 0 MAXILLARY SECOND MOLARS
  97. 97.  The pulp chamber of the maxillary third molar similar second molar with 3 canal orifices.  But it may also have an odd shaped chamber with four or five root canal orifices or a conical chamber with only one root canal.  Root and root canals  The maxillary third molar has 3 well developed roots that are closely grouped.  It may also have fused roots, one conical root, or 4 or more independent roots.  The roots may be straight, curved or dilacerated and they may be fully or partially developed.  Maxillary third molars with root presented an extremely unpredictable internal anatomy ranging from one to six canals. (Sidow 2000).
  98. 98.  Pulp chamber:  smallest tooth in the arch.  The pulp chamber is small and flat mesiodistally.  three distinct pulp horns present in a recently erupted tooth  Labiolingually, the pulp chamber is wide and ovoid in cross section in the cervical third of the crown and tapers incisally.  Roots:  The mandibular central incisor has 1 root, which is flat and narrow mesiodistally but wide labiolingually.
  99. 99. Root canals:  Rankine – Wilson & Henry reported a correlation between crown shape and canal configuration, short squatty crowns had blunted roots usually with a divided or split canal when two canals are present, the labial canal was the straighter. The point of division for divided canals was in the cervical 3rd of the root.  In cross section,  Cervical level: the canal is ovoid in labiolingual direction.  Middle level : canal is ribbon shaped due to the flatness of the root in this region.  Apical level: canal is round in shape.
  100. 100.  The apical foramen is situated centrally in the root in 25% of cases..  The distribution of the smallest root thickness at the 1mm level from the apical foramen was similar regardless of the root canal thickness.  The majority of the teeth had a thickness between 1 and 1.5 mm at the smallest part of the root and 21.8% had a thickness of less than 1mm at the smallest part of the root.
  101. 101.  Pulp chamber:  The configuration of the mandibular lateral incisor is similar to that of the mandibular central incisor, but the lateral tooth has larger dimensions.  Root:  the root of the mandibular lateral incisor is larger than that of the mandibular central incisor.  The majority of the roots are straight or distally or labially curved, but the distal curve of the lateral incisor is sharper.  It can have more than one root.
  102. 102. Root canals:  The incidence of double canals and their anatomy in cross section is same as that of central incisor (Vertucci 1985)  Gutmann reported that in cross section, in the middle and apical third, the root may be ovoid to figure of ‘8’ or dumbbell shaped.  Apical foramen in the center of the radiographic apex in 20% of cases.  The major foramen exiting a mean distance of 0.20-0.46mm from the apex.  Presence of isthmus in mandibular (central and lateral) incisors, was present in 20% of the teeth at the 1mm level, 30% at the 2mm level and 55% at 3mm level, as reported by Mauger and Schindler in 1998
  103. 103. Length of tooth Central incisors (mm) Lateral incisors (mm) Canal Central incisors (%) Lateral incisors (%) Root curvature Average length 21.5 22.4 One canal one foramen 73 56.9 Straight 60% Maximum length 23.4 24.6 Two canals one foramen 26 14.7 Distal curve 23% Minimum length 19.6 20.2 Two canals two foramens 6.5 29.4 Mesial curve 0% Range 3.8 4.4 Lateral canals 5.2 13.9 Labial curve 13% Lingual curve 0% MANDIBULAR CENTRAL AND LATERAL INCISORS
  104. 104.  Pulp chamber:  The mandibular cuspid resembles the maxillary cuspid, but it is smaller in all dimensions.  The pulp chamber is narrow mesiodistally. When viewed labiolingually, the chamber tapers to a point in the incisal third of the crown, but it is wide in the cervical third.  No distinct demarcation exists between the pulp chamber and the root canal. Root:  This tooth usually has a slight labial axial inclination of the crown.  Although the tooth usually has a single root, it may have 2 in 2.3% of cases.  Gutmann reported that in extreme cases of fusion during root formation, 2 separate roots, labially and lingually placed, can form in the mandibular canine.
  105. 105. Root canals:  When one root canal is present, a labiolingual view of the root shows a canal that is broad in the middle third and tapers to a constriction in the apical third. It is ovoid in cross section in the cervical and middle thirds of the root and round in the apical third
  106. 106. Length of tooth (mm) Canals Lateral canals Root curvature (%) Average length 25.2 One canal Two canals Two foramina 94% 6% 9.5% Straight 68 Maximum length 27.5 Distal curve 20 Minimum length 22.9 Mesial curve 1 Range 4.6 Labial curve 7 Lingual curve 0 Bayonet curve 2
  107. 107.  Pulp chamber:  Transitional tooth between anterior and posterior teeth,  Anatomic structure it resembles both types of teeth.  The mesiodistal width of the pulp chamber is narrow.  Buccolingually, the pulp chamber is wide, prominent buccal pulp horn.  In the young tooth, one sees a small lingual pulp horn that may disappear with age and may give the pulp chamber an appearance similar to that of a mandibular cuspid.  The prominent buccal cusp and the smaller lingual cusp give the crown of the mandibular first premolar about a 30º lingual tilt.  In cross-section, the chamber is ovoid, with the greater diameter buccolingually. If only one canal is present, no distinct division will be seen between the pulp chamber and the root canal.
  108. 108.  Root:  Mandibular first premolar usually has a short conical root. Bifurcation and trifurcation of the roots are most common anomalies in mandibular first premolar (Saler & Gunda, 1998). Bifurcation of roots among lower premolar, usually occurs buccolingually, but rarely bifurcation may occur mesiodistally also, (Goswami & Chandra, 1997).  Root canals:  If one canal is present, it will be cone shaped and simple in outline. Mesiodistally, such a root canal is narrow; buccolingually, it is broad and tapers toward the apical third.  In cross section, the cervical and middle thirds are ovoid, and the apical thirds is round
  109. 109. MANDIBULAR FIRST PREMOLAR Length of tooth (mm) Canals (%) Root curvature (%) Average length 22.1 One canal One foramen 73.5 Straight 48 Maximum length 24.1 Two canals One foramen 6.5 Distal curve 35 Minimum length 20.1 Two canals two foramina 19.5 Mesial curve 0 Range 4.0 Three canals 0.5 Buccal curve 2 Lingual curve 7 Bayonet curve 7
  110. 110.  Pulp chamber:  The pulp chamber of the mandibular second premolar is similar to that of the mandibular first premolar, except the lingual horn is more prominent under a well-developed lingual cusp.  Roots:  The mandibular second premolar usually has a single root, but on rare occasions 2 to 3 roots are present.  The root has a greater girth and is wider buccolingually than that of the mandibular first premolar.  Roots canals:  Scott Bram reported a case of mandibular second premolar with 4 root canals. There is no significant correlation of canal morphology with the occlusal anatomy of the mandibular second premolar
  111. 111. MANDIBULAR SECOND PREMOLARS Length of tooth (mm) Canals (%) Root curvature (%) Average length 21.4 One canal One foramen 85.5 Straight 39 Maximum length 23.7 Two canals One foramen 1.5 Distal curve 40 Minimum length 19.1 Two canals two foramina 11.5 Mesial curve 0 Range 4.6 Three canals 0.5 Buccal curve 10 Lingual curve 3 Bayonet curve Trifurcation curve 7 1
  112. 112.  Pulp chamber:  The roof of the pulp chamber of the mandibular first molar is often rectangular in shape.  The mesial wall is straight, the distal wall round, and the buccal and lingual walls coverage to meet the mesial and distal walls and to form a rhomboidal floor.  The roof of a pulp chamber has four pulp horns: mesiobuccal, mesiolingual, distobuccal and distolingual.  These four pulp horns recede with age, with a resulting decrease in the size of the pulp chamber.  The roof of the pulp chamber is located in the cervical third of the crown just above the cervical of the tooth, and the floor is located in the cervical third of the root.
  113. 113.  Three distinct orifices are present in the pulpal floor; mesiobuccal, mesiolingual and distal.  The mesiobuccal orifice is under the mesiobuccal cusp.  The mesiolingual orifice is located in a depression formed by the mesial and lingual walls.  The mesiobuccal and mesiolingual orifice may be close together under the mesiobuccal cusp.  The distal orifice is oval in shape.  The multiple orifices in the distal root are usually found in the buccal and lingual portion of the ovoid coronal root canal.
  114. 114.  Usually, 2 well-differentiated roots are present in the mandibular first molar, 1 mesial and 1 distal.  Both roots are wide and flat buccolingually, with a depression in the middle of the root buccolingually.  This anatomic characteristic may be accentuated in the mesial root.  A third root or “Radix Entomolaris” (RE) is found either distally or mesially in Eurasian and Indian populations in the less than 5% of cases
  115. 115. Length of tooth Mesial (mm) Distal (mm) Roots (%) Canals Curvature of roots Direction Distal Direction Mesial Distal Average length 20.9 20.9 Two 97.8 Two 6.7 Two canals One foramen 40.5 One canal 71.1 Straight 16 74 Maximum length 22.7 22.6 Three 2.2 Three 64.4 Two canals Two foramina 59.5 Two canals 28.9 Distal 84 21 Minimum length 19.1 19.2 Four 28.9 Two canal One foramen 61.5 Mesial 0 5 Range 3.6 3.4 Two canals 38.5 Buccal 0 0 Two foramina Lingual 0 0 MANDIBULAR FIRST MOLARS
  116. 116.  Pulp chamber:  The pulp chamber of the mandibular second molar is smaller than that of the mandibular first molar, and root canal orifices are smaller and closer together  Roots:  The majority of the mandibular second molar has 2 roots 71%,  but teeth with one root 27% and  3 roots 2% are also seen.  Root canals:  3 root canals are usually present; the most frequent variation is the presence of only 2 canals.  All 3 canals are small and ovoid in the cervical and middle 3rd and round in the apical 3rd.
  117. 117. Length of tooth Mesial (mm) Distal (mm) Canals (%) Curvature of roots (%) Mesial Distal Direction Single root Double root Mesial Distal Average length 20.9 20.8 One canal one foramen 13 92 Straight Distal 53 26 27 61 58 18 Maximum length 22.6 22.6 Two canals one foramen 49 5 Mesial Buccal 0 0 0 4 10 4 Minimum length 19.2 19.0 Two canals two foramina 38 3 Lingual Bayonet 2 19 0 7 0 6 Range 3.4 3.6 MANDIBULAR SECOND MOLARS
  118. 118.  Pulp chamber:  The pulp chamber of the mandibular third molar anatomically resembles the pulp chamber of the mandibular first and second molars.  It is large and possesses many anomalous configuration such as “C- shaped” root canal orifices.
  119. 119. Roots and Root canals:  The mandibular third molar usually has two roots and two canals, but occasionally one root and one canal or 3 roots and 3 canals can also be seen. The root canals are generally large and short.  Sidow and West in 2000 reported that the mandibular third molar 17% had one root,  77% had two roots,  5% had three roots.  The number of canals ranged from 1 to 3 with one root, 2 to 6 with 2 roots, 3 to 5 with 3 roots.4 to 5 in teeth with 4 roots,.C-shaped were identified with one or 2 roots.  The anatomy of a mandibular third molar cannot be predicted on the basis of the number of roots.
  120. 120.  Radiographic examination,  Placing files in the canals to determine the canal configuration  Root sectioning  Making polyester resin cast replicas of the pulp space  Staining and clearing techniques,  Direct observation with microscope,  Sectioning and macroscopic observation,  Stereo microscope,  Spiral computed tomography,  Cone beam computed tomography
  121. 121.  Vertucci used the clearing technique to study the root canal morphology of extracted mandibular anterior teeth. It has been reported that fine details of the root canal system can be visualized by staining and clearing.  This technique also makes canal negotiation with instruments unnecessary, thereby maintaining the original form and relation of canals, and provides a three-dimensional view of root canal.  The process of changing the tooth into a transparent object involves many physical and chemical changes.  The inorganic constituents of the tooth are first dissolved by decalcification, and further water, air, and lipid components are removed by dehydration and by subsequent immersion in the clearing agents