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• Basic steps in root canal treatment

  1. Pulp extirpation

  2. Working length determination

  3. Root canal preparation

  4. Canal irrigation or Disinfection
• Know the average length of teeth
• Tooth lengths


  • Maxillary central: 23mm
  • Maxillary lateral: 22mm
  • Maxillary canine: 26.5mm
  • Maxillary first premolar: 20.5mm
  • Maxillary second premolar: 21.5mm
  • Maxillary first molar: 20.5mm
  • Maxillary second molar: 20mm
  • Mandibular central: 20.5mm
  • Mandibular lateral: 21mm
  • Mandibular canine: 25.5mm
  • Mandibular first premolar: 20.5mm
  • Mandibular second premolar: 22mm
  • Mandibular first molar: 21mm
  • Mandibular second molar: 20mm

  
• Pulp extirpation


  1. Removal of pulp tissue

  2. Materials used: Endodontic spoon excavator, Barbed broach, Irrigate with sodium hypochlorite
• Endodontic spoon excavator


  For removal of coronal pulp
• Barbed broach


  To remove radicular pulp tissue
• Removing radicular pulp with barbed broach

  1. At apical third or working length: 360 degrees clockwise and pull out the whole tissue, with copious irrigation with NaOCl

  2. When inserting, there needs to be a looseness of the instrument in order to turn it in clockwise rotation 360 degrees

  3. When inserting, there must be enough space for the barbed broach to turn; if it is too tight, the spikes will bind around the wall of the pulp canal and will cause instrument breakage — make sure it is loose
• In cases where barbed broach cannot reach estimated working length

  1. Irrigate with sodium hypochlorite (NaOCl) to dissolve pulp tissue

  2. Use small files at estimate correct working length

  3. File #10 or #8 or #6 if it's too narrow in the canal
• In necrotic teeth


  1. Irrigate canal with NaOCl

  2. Careful at the apical third: may have viable C-fibers, since the apical area is rich in blood supply; may feel sensitivity

  3. Anesthesize partially dead teeth
• Summary of pulp extirpation


  • Used to remove coronal pulp?
  • Used to remove radicular pulp?
  • Proper way to use answer in #2?
  • Irrigate with?
• Working length


  • Incisal edge (anterior) or highest cusp tip (molars) up to apical apex
  • Length between a coronal reference point and the apical limit of preparation
  • Important in determining prognosis of RCT treatment
  • Distance from a coronal reference point to the point at which canal preparation and obturation should terminate
• Coronal reference point


  • Anterior teeth — incisal edges
  • Posteriors - highest cusp tip
• Apical constriction


  • Narrowest point of apical foramen
  • Do not go beyond apical constriction — serve as apical matrix
• Guidelines for reference point

  1. Do not use weakened enamel or diagonal lines of fracture as reference point

  2. Reduce weakened cusps/incisal edge to a well-supported structure or build-up badly broken areas of the crown
• Apical constriction located 0.5 to 1mm from the radiographic root apex where the cementodentinal junction (CDJ) is located
• Working length determination


  1. Done upon completion of access preparation

  2. Full pulp extirpation is usually at the radicular pulp
• Radiographic tooth length


  Distance measured from a reference point up to the radiographic root apex

  
• Steps in measuring the working length based on radiographic method

  1. Determine the reference point

  2. Measure (mm) distance from reference point to the radiographic tooth apex

  3. Compute the working length: radiographic tooth length minus 1 mm

  4. Prepare #10 or #15 file to estimated working length with rubber stopper or instrument stop

  5. Verify the WL: take a radiograph with file at predetermined WL

  6. Adjust WL computation if file is: beyond, short, or flush
• Electronic apex locator


  Determines electronically, whether you are at the apex of the root
• Summary of working length determination

  • Distance of WL from radiograph apex?
  • How to verify final WL?
  • Why small k-files should be used during WL determination?
  • Armamentarium to prepare for WL determination?
• Root canal preparation


  Systematic procedure of removing pulp tissue, debris, and microorganism with the use of files, irrigants, and chemical while shaping to facilitate filling of the root canal system
• Mechanical objectives of root canal preparation

  • Create a continuously tapering canal preparation while preserving the natural or original configuration of the canal
  • Prevent perforating apical foramen (do not go past the apical foramen)
  • Keep apical foramen as small as practical; only within the apical constriction (the narrowest part)
  • Make terminus the narrowest (apical constriction) cross-section of the preparation
  • Prepare the canal in multiple planes all around the walls
• Importance of canal shaping

  • Facilitates cleaning of root canal by removing restrictive dentin and allowing greater volume of irrigant to work deeper
  • Eliminate the pulp, bacteria and their endotoxins due to the NaOCl that dissolves tissues and kills bacteria
  • Forms a preparation for proper obturation
• Biologic objective of root canal preparation

  • To remove all the pulp tissue, bacterial by-products, caries, organic substrates, and microflora from the root canal system
• Anatomic considerations before starting root canal preparation
• Effect of packing dentinal debris apically
• Methods used for root canal preparation


  • Stepback procedure using hand-held files
  • Crown-Down Procedure using hand-held files or rotary instrument
• Serial filling


  The sequential use of successively larger sizes of instruments at the working length
• Canal patency or straight-line access


  The ability to insert a #10 or #15 file up to the working length passively (no resistance)
• Scouting


  Process of checking the presence of a straight-line access through the position of the file (whether straight or bended)
• Apical gauging


  Procedure which involves the selection of the file that gives a snug fit at the working length
• Apical patency or straight–line access


  The ability to insert a #10 or #15 file up to the working length passively (no resistance)
• Scouting


  Process of checking the presence of a straight–line access through the position of the file (whether straight or bended)
• When inserting the #10 or #15 file

  Check if the file is inclined/bended, which could be due to dentinal overhangs in the walls
• Apical gauging


  • Insert file into the canal, then feel with your tactile senses whether there is a snug fit upon removal of file
  • Once you pull out the file, you will feel a tug-back or resistance when removing (means that you are at the narrowest part of the apical foramen; you have reached the apical matrix — correct file)
  • Feels like a small tug-back (slight frictional resistance of a master point to withdrawal, which indicates a relative degree of adaptation at least in 2 dimension)
• Tuning or 'Stepback'


  • Part of RC preparation that involves using files from the WL at 0.5 or 1 mm increment (1 mm is used in CDU)
  • Go backwards 1mm
• Motions of instrumentation


  • Reaming — inserting the file at its working length and turning it to a ¼ or ½ clockwise rotation
  • Circumferential filing — push and pull motion of files along canal walls
  • Turn and pull — ¼ clockwise rotation and pull
  • Watch–winding — approx 30° to 60° clockwise then counterclockwise movement of instrument
  • Balanced force — 90° clockwise rotation followed with a 180–270° counterclockwise rotation with slight apical pressure
• Guidelines during instrumentation


  • Work with wet canals - If canal is dry, it could cause breakage of the instrument, or breakage of the root if working with a large file
  • Always use smaller file size to explore/scout canals - File #10 or #15s are usually used
  • Use increment sequentially - Do not jump from one small size to a bigger size
  • Do circumferential filing motion during enlarging and stepback
  • Never force instruments into the canal length - Otherwise it could cause binding and breakage of instruments
  • Clean files, especially the flutes, after each use in the canals (after each increments)
  • Pre–curve stainless steel files when working on curved canals
  • Always check for canal patency
  • Move to next file size when canal walls feel smooth and when current file is loose in the canal
• Stepback technique


  1. This technique starts from apex to crown

  2. The sequential use of successively smaller to larger sizes of instruments to prepare from the apical to the coronal portion of the root canal
• Initial apical file (IAF)

  First file with an apical resistance or snug fit/tug-back at the WL (apical gauging)