Factors associated with the removal of fractured NiTi instruments from root canal systems.

OBJECTIVE To evaluate the influence of various factors on the success or failure of attempts to remove fragments of separated NiTi instruments from root canals. STUDY DESIGN Instrument removal attempts were undertaken on 72 teeth with a separated NiTi instrument using a variety of techniques and armamentarium. Factors including type of tooth, degree of root canal curvature, location of fragment in relation to the root canal curvature, and radiographic length of fragment were analyzed. A success of treatment was defined as removal or complete bypassing of the fragments. RESULTS The overall success rate was 53%. The success rate for ProFile fragments was 41% and for the NiTi K-file 60%. The success rate in maxillary teeth was higher than that in mandibular teeth. Of 52 instruments in molars, 28 were successfully removed or bypassed. Of the 12 fragments in premolars, only 2 were removed. All 8 cases in anterior teeth were retrieved completely. When the fragment was localized before the curvature, complete removal was achieved. When the fragments were located at and beyond the curvature, the success rates were 60% and 31%, respectively. In canals with a slight, moderate, and severe curvature, the success rates were 100%, 83%, and 43%, respectively. In general, the longer the fragment, the greater the chance for successful removal or bypass. CONCLUSIONS Favorable factors for removal of separated NiTi fragments are straight root canals, anterior teeth, localization before the curvature, fragments longer than 5 mm, and hand NiTi K-file.

[1]  H. Gerstein,et al.  An initial investigation of the bending and torsional properties of Nitinol root canal files. , 1988, Journal of endodontics.

[2]  W. Johnson.  Color atlas of endodontics , 2002 .

[3]  J. Powers,et al.  Differential scanning calorimetric studies of nickel titanium rotary endodontic instruments. , 2002, Journal of endodontics.

[4]  R. T. Rice,et al.  Re-treatment in endodontics. , 1987, Oral surgery, oral medicine, and oral pathology.

[5]  M Hülsmann,et al.  Methods for removing metal obstructions from the root canal. , 1993, Endodontics & dental traumatology.

[6]  I. Bonetti,et al.  A comparison of molar root canal preparation using stainless-steel and nickel-titanium instruments. , 1999, Journal of endodontics.

[7]  C. D'Arcangelo,et al.  Broken instrument removal--two cases. , 2000, Journal of endodontics.

[8]  Stephen Cohen,et al.  Pathways of the Pulp , 1976 .

[9]  S. W. Schneider,et al.  A comparison of canal preparations in straight and curved root canals. , 1971, Oral surgery, oral medicine, and oral pathology.

[10]  C. Phillips,et al.  Endodontic complications of root canal therapy performed by dental students with stainless-steel K-files and nickel-titanium hand files. , 1999, Journal of endodontics.

[11]  B. Sattapan,et al.  Defects in rotary nickel-titanium files after clinical use. , 2000, Journal of endodontics.

[12]  M Hülsmann,et al.  Influence of several factors on the success or failure of removal of fractured instruments from the root canal. , 1999, Endodontics & dental traumatology.

[13]  O Nagai,et al.  Ultrasonic removal of broken instruments in root canals. , 1986, International endodontic journal.

[14]  P. Dummer,et al.  Shaping ability of .04 and .06 taper ProFile rotary nickel-titanium instruments in simulated root canals. , 1999, International endodontic journal.

[15]  Jeff R Ward,et al.  Evaluation of an ultrasonic technique to remove fractured rotary nickel-titanium endodontic instruments from root canals: clinical cases. , 2003, Journal of endodontics.