Root canal anatomy and access cavities


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Brief Explanation on Root canal anatomy and Access Cavity shapes.

Root canal anatomy and access cavities

  1. 1.  Definition : Endodontics is the branch of dentistry dealing with diseases of the dental pulp.
  2. 2.  The number of canals in a tooth correlates to the number of roots in a tooth.  The space inside the root canals is filled with a highly vascularized and highly innervated loose connective tissue, called the dental pulp.  The pulp tissue is in communication with the periodontium and the rest of the body through the apical foramen.
  3. 3.  Central region contains nerves and blood vessels.  Innermost layer, - contains fibroblasts and undifferentiated mesenchymal cells.  Zone of Weil – This is a cell free zone, rich in capillaries and nerve fibres.  Odontoblastic layer – outermost layer, contains odontoblasts and is next to the predetin and mature dentin.
  4. 4.  Primary Function is to form Dentin  Nutritive – provides nutrients to the organic surroundings  Sensory – sensitive to temperature, pressure or trauma  Protective – forms secondary dentin, when under attack from bacteria.
  5. 5.  Accessory canals are branches of the main canal that form a communication between the pulp and periodontum.  They also contain vessels and nerves, and can be located anywhere between the level of furcation to the apex.  30% of lower incisors have lingual and labial canals.  85% of mesiobuccal roots contain two canals (MB1 and MB2), in upper molar teeth.
  6. 6. The shape of the preparation is dictated by :  The shape of the pulp chamber  The morphology of the canals. It is important that straight line access to the apical foramen is created.
  7. 7.  The access cavity is initiated in the middle of the palatal side of the tooth.  Initial preparation should be at 90° to the palatal aspect of the tooth.  Once dentine has been reached the angulation of the bur is changed to follow a long axis of the tooth using a slow handpiece.
  8. 8.  Initial preparation is made in the middle of the fissure. The cavity is then extended buccally and palatally.  NB : Marginal ridges must not be involved in this presentation, as this would compromise the integrity of the tooth.
  9. 9.  Initial Preparation is done in the mesial pit.  The cavity is then extended in the mesial half of the tooth to include all canals.  The mesial marginal ridge must not be damaged in upper molars as the cavity should lay mesially to it.  However lower molar teeth, have a distal canal, which is located just past the middle of the tooth.
  10. 10. Irrigation in Endodontic treatment serves the following purposes:   Lubricate canal  Dissolve the pulp remnants  Washing out debris created by canal instrumentation  Kill/remove the bacteria/micro- organisms in root canal  Clean the smear layer
  11. 11.  Sodium Hypochlorite :Dissolves necrotic tissue and kills bacteria quite effectively.  Kills bacteria quite effectively.   Chelators: Such as EDTA, remove the smear layer.  Hydrogen Peroxide: Used to be used a lot, however studies have shown it to be ineffective.  Chlorhexidine: Has been shown to remove significant number of bacteria.
  12. 12.  ENDOVAC TECHNOLOGY – the use of apical negative pressure irrigation, significantly improves cleaning and disinfection more closely to the apex.  ENDOACTIVATOR – Sonically driven system, enables the irrigant to travel deep into the pulpal system, enabling better cleaning.
  13. 13.  Tooth Anatomy – Revision  Root canal anatomy  Accessory canals  Access cavities  Irrigants  Recent Developments in Endodontics.
  14. 14.  tics/1043  v=QrUgCNQs038  Endodontics Lecture from Blackboard. By Dr Qualtrough.  rrigation-endo  2399(07)00095-7/abstract