Comparison of the Relative Risk of Molar Root Perforations Using Various Endodontic Instrumentation Techniques

By Kessler JR, Peters DD, Lorton L

Date: 01/1983
Journal: JOE


Purpose: To determine the relative risk of accidental perforation of the mesial canal of mandibular molars

  • N = 60 mandibular 1st and 2nd molars

Exclusion criteria: unusual morphology, gross caries, damage from extraction.


  • Sample divided to 3 groups (20 teeth each / 40 canals)
  • Group 1: 1A no instrumentation
    1B standard instrumentation to size 35
  • Group 2: 2A: apical preparation to size 35 then step-back to #60(circumferential filling )
    2B: same as 2A but anti-curvature filing
  • Group 3: 3A apical preparation like group 2, coronal flaring with gates glidden size 2,3

  3B like 3A but coronal flaring using round bur size 2,4 with lateral force toward safety zone

  • Teeth mounted in resin block then sectioned (Figure 1). In each canal, shortest distance from the canal toward mesial and distal surfaces, and the diameter between 2 areas was measured using measuring microscope

Most highlighted Results:

  • From all techniques, the standard removed the least dentin and from flare technique: the anti-curvature (Table 1)
  • Gates glidden left least average thickness at all levels except 1st level
  • GG had highest number of specimens with less than 0.5 mm remaining thickness
  • On mesial walls, round bur significantly removed more dentin than other flare techniques.
  • Area 4-6 mm from orifice had significantly more thin sections

Clinical Significance:

Understanding the root canal morphology is important in avoiding procedural mishaps, care should be taken to instrument canals properly and create proper pathway for endodontic instruments