• Irfan ullah Khan
  • Muhammad Baksh Sobhi


Bckground: Achieving and maintaining correct working length is critical to success in endodontic therapy. This involves placing the file in to the canal to feel the apical constriction, preparing the canal upto that extent and then filling the entire canal upto the apical constriction with gutta percha points. Detection of the apical constriction is affected if the coronal part of the canal is narrow or obstructed due to dentine deposition. This usually happens in curved canals and gives the operator a false feeling of the apical constriction. The aim of this study was to compare the effect on tactile detection of apical constriction in mandibular molars with curved roots, between the preflared and non-flared root canals. Methods: This study was carried out at Armed Forces Institute of Dentistry, Rawalpindi, Pakistan, from February to April 2002. Seventy patients coming for the endodontic treatment of their mandibular first molars were selected. The study included only mandibular molars with curved mesial canals. The total no of patients were divided equally into the preflared and non-flared groups. In both groups a No. 15 K file was used to detect or feel the apical constriction but in the preflared group the coronal portion of the canal was flared/prepared using Hedstrom files   (No. 25–55) and Gates Glidden Drills No. 02 to No. 05 before inserting the No. 15 file. The tooth was radiographed at this moment and the distance between the tip of the file and the radiographic apex was measured. The location of the tip was classified as: a) Within 1 mm of the radiographic apex, b) Under extended, more than 1 mm of radiographic apex, and c) Over extended, beyond the radiographic apex. Results: In the non-flared group 31.4% belonged to group ‘a’, 40% to group ‘b’, and 28.57% to group ‘c’. In the flared group 80% belonged to group ‘a’, 5.7 % to group ‘b’, and 14.28% to group ‘c’. Conclusions: Results of this study suggest that preflaring greatly improves the tactile sense to feel the apical constriction in curved canals.Key words: Preflaring; Apical constriction; Curved canals; Mandibular molars; and Working length.


Ingle JI. In: Endodontics. 4th ed. Philadelphia; Lea & Febiger, 1994: 191-208.

Cohen S, Burns RC. In: Pathways of the Pulp. 5th ed. St Louis, CV Mosby, 1991:174-88.

Certosimo FJ, Milos MF, Walker T. Endodontic working length determination where does it end? Gen Dent 1999; 47(3):281-6.

Sobhi MB, Manzoor MA. An In vitro study of change in working length following instrumentation of first molar teeth. J Coll Physicians Surg Pak 2002;2(2):71-3.

Zahn Z. Determination of working length in endodontics 1. Radiographic Method. ZWR 1991;100(1):30-5.

Kutler Y. Microscopic investigation of root Apexes. J Am Dent Assoc 1955;50:544-52.

Grove CJ. The Value of Dentino Cemental Junction in Pulp Canal Surgery. J Dent Res 1931;11:466-8.

Seidberg BH. Clinical investigation of measuring working length of root canals with an electronic device and with digital tactile sense. J A Dent Assoc 1975;90:379.

Ibarrola JL, Chapman BL, Howard JH. Effect of Preflaring on Root ZX Apex Locators. JOE 1999;25(9):625-6.

Stabholz A, Rotstein I, Torabinejad M. Effect of Preflaring on tactile detection of apical constriction. JOE 1995;21(2):92-4.

NJD Smith. Dental radiography. St Louis, Blackwell Science, 1980:51.

Leslie F, Morgan and Montgomery S. An evaluation of crown down pressure less technique. JOE 1984;10(10):491-8.

Ruddle C, Barbara S. Endodontic canal preparation: Breakthrough cleaning and shaping strategies. Dent Today 1994;13(2):44,46,48-9.

Al-Omari MA, Dummer PM. Canal blockage and debris extrusion with eight preparation techniques. JOE 1995;21(3):154-8.