Effect of Preflaring on Tactile Detection of the Apical Constriction

By Stabholz A, Rotstein I, Torabinejad M

Date: 01/1995
Journal: JOE


Purpose: To compare the efficacy of “feeling” the apical constriction in flared and nonflared root canals by tactile sensation.

  • N= 120 root canals.

Exclusion criteria: complicated anatomy, external root resorption, severe curvature,


  • Access cavity in all teeth.
    • Group 1: (n=68) no pre-flaring – Apical constriction detected using #15 or 20 K-files
    • Group 2: (n=52) canal orifice enlarged and coronally pre-flared with GG #2-4, H-files, Ultrasonic files. Size 15 and 20 K-file inserted in the canal until apical constriction was felt.
  • Radiograph taken then the distance between tip of the file and the radiographic apex was measured.
  • Results classified: (a) within 1 mm of the radiographic apex. (b) underextended 1 mm or more. (c) overextended.

Most highlighted Results:

  • 75% of preflared group and 32% of non-flared were within 1 mm from RG apex.
  • Files inserted in preflared root canals had a significantly lower incidence of overextension (21%) than the non flared (41%).

Clinical Significance:

  • Pre-flaring increased accurate tactile detection of the apical constriction and reduced occurrence of overextension


(a)Within 1 mm of the radiographic apex (b)Underextended l mm or more short of the radiographic apex

(c)Overextended beyond the radiographic apex.