Root Canal Anatomy & Complexity

Root Canal Anatomy is often believed be to either one or two canals per root.  The cartoon below demonstrates the traditional thinking.

While this cartoon is useful for patient education, it highly underestimates the complexity of the root canal anatomy. 

Other features in addition to the main canals are lateral canals, fins, and isthmuses which join multiple canals.

Elaborate dye studies have been done to better illustrate the complexity of the root canal system.  More accurate root canal morphology is represented by the images below. 

 

These studies demonstrate communication from the main canals laterally as well channels between the canals.

These spaces within the root canal anatomy contain pulpal tissue, and can harbor bacteria in an endodontically involved tooth.

 

 

 

 

 

 

 

 

 

 

 

 

These spaces (lateral canals, isthmuses, and fins), must be treated in addition to the main canals.  Failure to do will result in persistent pathology and non-healing osseous lesions.  The additional lateral spaces are highly prevalent in the terminal 3mm of the root canal system.

CASE REPORT

32 year old female presented with pain in the lower left quadrant.  Dental history revealed root canal treatment were performed on #18 & #19, 8 months prior. 

 Diagnostic Testing revealed:

#18: Sensitive to percussion and palpation. Periodontal probings are within normal limits.  Radiograph reveals periradicular radiolucency.

#19:  No sensitivity to percussion and palpation.

While the current root canal obturation “looks” adequate, clearly bacteria are present within adjacent spaces of the root canal system.  After discussion with the patient, endodontic retreatment was decided as the appropriate treatment plan.

After adequate anesthesia, endodontic retreatment was initiated.  Previous obturation material (thermafill carriers) were removed with chloroform & hand files.  2 main canals were present.  The mesial and distal canals were cleaned and shaped to apical terminus of 40 with a .06 flare.  Copious Irrigation with NaOCl, EDTA was performed.

At this point, the tertiary features (lateral canals, fins, and isthmus) must be treated and disinfected.  This achieved by two methods:

1.)  Mechanical debridement

2.) Chemical debridement

Chemo-mechanical debridement is required to remove the smear layer, which binds to the walls of the main canals.  This debris must be removed to allow chemical antimicrobials to access the entire root canal system.

A size 15 file with a 45 degree bend is gently maneuvered along the walls of the main canals in 360 degrees.  This is done with the entire chamber filled with EDTA.  Tactile sensation is achieved as the instrument engages the lateral spaces.  After engaged, those spaces can be further enlarged with larger hand files.  In addition, chelating agents (EDTA) help dissolve and remove the smear layer.  With most cases, we employ positive/negative irrigation system to allow the irrigation to flow to the apical portion of the root canal system.  The check film shows gutta percha and sealer sealing the entire root canal system via warm vertical condensation.

Final film shows a much more adequate obturation of the tooth canal system.  The access was sealed with composite resin.