The Operating Microscope Enhances Detection and Negotiation of Accessory Mesial Canals in Mandibular Molars

By Karapinar-Kazandag M, Basrani B, Friedman S

Date: 08/2010
Journal: JOE


•Purpose: assess the ability to locate and negotiate mesial canals in 1st and 2nd molars using magnifying loupes and microscopes.

•N= 96 (48 – 1st molars / 48 – 2nd molars)

Exclusion criteria: Previous RCT, C shaped, calcified canals, deficient coronal structure,  abnormal anatomy, fused or single roots, C-shaped canals.


  • Follows previous study on maxillary molars
  • Periapical radiograph taken from B-L direction.
  • Teeth were mounted in mannequins to simulate clinical situation.
  • Standard access was made in all teeth using loups (4.5X)
  • Teeth were divided into 3 groups each assigned to one endodontist to assess the mesial canals.
  1. 1st stage: only loupes were used, troughing with ultrasonic tips. Size 6 k files. canal was negotiated until it was risky to continue further apically, mesial canal was no longer detectable, or perforation occurred.
  2. 2nd stage: microscope was used instead of loups.
  3. 3rd  stage: RG was taken with k file in the mesial canal.
  4. 4th stage : chamber photographed with the aid of a stereomicroscope. # of canals and location was assessed.
  5. 5th stage: RG taken from M aspect after resecting D root depth of dentin removal was measured.
  6. 6th stage: All molars were sectioned at :1 mm, 4 mm, and 8 mm from the apex.  To assess for mesial canal

Most highlighted Results:

•use of microscope improves increased the allocation of middle mesial canal in 1st and 2nd molars (16% to 18%).

•Incidence of middle mesial canal in 1st molar was (18%), 2nd molar (22%) •45% accessory mesial canals were close to ML canal.

•30% of accessory mesial canals were in the middle.

•All accessory mesial canals joined a main canal. 1st molar : 42% joined MB, 2nd :55% joined ML.

•None of accessory canals were observed 4 mm from the apex.

•Depth of dentin removed to negotiate or rule out was 1 mm in 1st mandibular molar, 0.7 in 2nd  molar.

Clinical significance:

Impact of visual aids on detection of the canal, understanding the anatomy of accessory mesial canal could help in  detecting, instrumenting extra canals.