ROOT CANAL MORPHOLOGY

• Root Canal Morphology and its Significance

  1. Diagnosis to know indication and case selection for root canal

  2. Treatment to guide us in all treatment procedures

  3. Prognosis to predict the outcome of the treatment
• Root Canal System


  • The entire space in the dentin where the pulp is located
  • 2 Parts: Pulp chamber (Pulp horns), Root canals (Canal orifice, Apical foramen)
• Accessory Canals


  • Minute canals that extend in a horizontal, vertical, or lateral direction from the pulp to the periodontium
  • Avenues for the passage of irritants
• Root Canal System


  • Miniature version of the external anatomy of the tooth
  • The problem in the root canal system is its vast variability and the presence of irregularities
  • A straight access on the root canal is needed for good cleaning, shaping, and obturation
• Determination of the Root Canal Configuration

  1. If only one canal is present, it usually is located in the center of the access preparation

  2. If only one orifice is found and it is not in the center of the root, another orifice probably exists, and must be searched for on the opposite side

  3. The closer two orifices are, the greater the chance the two canals join at some point in the body of the root

  4. As the distance between orifices in a root increases, the greater is the chance the canals will remain separate

  5. If the first file inserted into the distal canal of a mandibular molar points either in a buccal or lingual direction, a second canal is present

  6. Whenever a root contains two canals that join to form one, the lingual/palatal canal generally is the one with direct access to the apex

  7. When one canal separates into two, the division is buccal and palatal/lingual, and the lingual canal generally splits from the main canal at a sharp angle, sometimes nearly a right angle

  8. Apical constriction is the portion of the root canal with the smallest diameter, found 0.5 to 1.5mm coronal to the apical foramen

  9. CDJ is the point in the canal where cementum meets dentin, the point where pulp tissue ends and periodontal tissues begin

  10. Apical Foramen is the rounded edge that differentiates the termination of the cemental canal from the exterior surface of the root
• • The space between the minor apical diameter and major apical diameter is funnel-shaped or hyperbolic
  • The mean distance between them is 0.5 mm in a young person and 0.67 mm in an older individual
  • The apical foramen is larger than the cross-sectional diameter of #50 and #60 root canal files
  • The apical foramen does not normally exit at the anatomic apex, but rather is offset 0.5 to 3 mm
• Vertucci’s classification of root canal morphology

  • Type I: A single canal extends from the pulp chamber to the apex (1)
  • Type II: Two separate canals leave the pulp chamber and join short of the apex to form one canal (2-1)
  • Type III: One canal leaves the pulp chamber and divides into two in the root; the two then merge to exit as one canal (1-2-1)
  • Type IV: Two separate, distinct canals extend from the pulp chamber to the apex (2)
  • Type V: One canal leaves the pulp chamber and divides short of the apex into two separate, distinct canals with separate apical foramina (1-2)
  • Type VI: Two separate canals leave the pulp chamber, merge in the body of the root, and separate short of the apex to exit as two distinct canals (2-1-2)
  • Type VII: One canal leaves the pulp chamber, divides and then rejoins in the body of the root, and finally separates into two distinct canals
• Root canal types


  • Type VI: Two separate canals leave the pulp chamber, merge in the body of the root, and separate short of the apex (2-1-2)
  • Type VII: One canal leaves the pulp chamber, divides and then rejoins in the body of the root, and finally separates into two distinct canals short of the apex (1-2-1-2)
  • Type VIII: Three separate, distinct canals extend from the pulp chamber to the apex (3)
• Methods of studying the pulp

  • Grinding
  • Histological methods
  • Radiography
  • Clearing technique
  • Acrylic cast/Silicone injection
  • Computed Tomography
• Ground Section


  1. Cutting the tooth structure longitudinally or cross-sectionally using a carborundum stone

  2. Disadvantages: it might destroy the real features of the anatomy, anti-curvature filling
• Histologic Section


  1. Tooth is decalcified using hydrochloric acid and thinned down using microtome, stain is used then the slide is viewed under the microscope

  2. Disadvantages: risk of shrinkage of tooth anatomy
• Radiograph


  1. Shows a two-dimensional picture of a three-dimensional object

  2. Disadvantages: only the mesio-distal dimension is seen but not the depth, tube-shift technique, SLOB
• Clearing Technique


  1. Tooth is decalcified in 10% hydrochloric acid solution then injected with Methylene Blue and cleared with Methyl Methacrylate

  2. Gives a good idea of the canal irregularities

  3. Disadvantages: a little bit of shrinkage and the natural anatomy is not restored well
• Acrylic Cast/Silicone Injection Technique


  Flowable resin is injected into the cavity and the tooth is dissolved away to expose the hardened internal anatomy
• Computed Tomography


  1. Provides information of the root canal anatomy in three dimensions with high-resolution digital images

  2. Advantages: less exposure to radiation, lack of distortion and magnification, good tool for patient education

  3. Disadvantages: Expensive
• Factors affecting root canal morphology
• Age affects root canal morphology by physiologic deposition of secondary dentin causing the pulp to become smaller as one ages, faster deposition along the roof and floor of the pulp chamber
• Irritants affect root canal morphology by tertiary dentin deposition
• Irritants affect root canal morphology by internal resorption, an indicator of pulpal pathosis, results if clastic cells within the pulp are active, if it continues, forms a perforation necessitating tooth removal
• Calcifications affect root canal morphology by being radiopaque structures in the pulp chamber, removal is necessary for better cleaning, shaping, filing, and obturation
• Factors affecting root canal morphology include trauma, open apex, developmental anomalies like Dens evaginatus, Dilaceration, Taurodontism, Radix Entomolaris, Radix Paramolaris
• Number of canals in maxillary teeth

  • 11/21 - 100% have 1 canal
  • 12/22 (curved distally or distopalatally) - 100% have 1 canal
  • 13/23 - 100% have 1 canal
  • 14/24 - 90% have 2 canals (buccal and palatal), 10% have 1 canal
  • 15/25 - 53% have 1 canal, 47% have 2 canals
  • 16/26 - 60% have 4 canals (DB, MB1, MB2, P), 40% have 3 canals (DB, MB, P)
  • 17/27 - 62% have 3 canals, 38% have 4 canals
• Number of canals in mandibular teeth

  • 31/41 - 70% have 1 canal, 30% have 2 canals (facial and lingual)
  • 32/42 - 55% have 1 canal, 45% have 2 canals (lateral has a higher chance of having 2 canals than central, the 2nd canal is usually lingual to the main canal)
  • 33/43 - 70% have 1 canal, 30% have 2 canals
  • 34/44 - 70% have 1 canal, 30% have 2 canals
  • 35/45 - 85% have 1 canal, 15% have 2 canals (the first premolar has a higher chance of having 2 canals)
  • 36/46 - 70% have 3 canals (MB, ML, D), 30% have 4 canals (MB, ML, DB, DL)
  • 37/47 - 75% have 3 canals (MB, ML, D), 25% have 2 canals (M, D)