Removing fractured endodontic instruments with a modified tube technique using a light-curing composite.
BACKGROUND
The aim of this in vitro study was to assess an alternative method using light-curing composite for removing fractured endodontic instruments with a tube technique.


METHODS
Two different stainless steel endodontic instruments (ISO 20: Hedstrom files, K-files; VDW, Munich, Germany) were cut at the diameter of 0.4 mm. These fragments were fixed in a vise leaving a free end of 1 or 2 mm. Cyanoacrylate (Instant Fix; Henry Schein Dental, Melville, NY), dual-curing Rebilda DC (VOCO, Cuxhaven, Germany), and light-curing SureFil SDR (Dentsply, York, PA) were placed into microtubes (N'Durance Syringe Tips; Septodont, Saint-Maur, France) and shifted over the instruments (n = 20 in each group). After polymerization, pull-out tests were performed with a constant speed of 2 mm/min; failure load was measured digitally. Data were analyzed using the Kruskal-Wallis test followed by the Dunn test for pairwise comparison.


RESULTS
The median failure load was up to 62.5 N for SDR, 35.8 N for Rebilda, and 14.7 N for cyanoacrylate, respectively. Both tested composites yielded significantly higher values in pull-out tests than cyanoacrylate. The disconnecting force was highest when light-cured composite SDR was used for fixation. Removing Hedstrom files resulted in higher values than removing K-files. The median force when using SDR was 79.7 N (interquartile range, 66.0-86.8 N) in Hedstrom files and 53.3 N (interquartile range, 47.1-58.5 N) in K-files.


CONCLUSIONS
Within the limitations of this study, the use of light-curing composite inside of the microtube was superior compared with the use of cyanoacrylate or chemically cured composite, which are being used presently.
Department of Operative Dentistry, Universitätsklinikum Münster, Münster, Germany. Electronic address: mwefel@uni-muenster.de.
Michael
M
Wefelmeier
Institute of Biostatistics and Clinical Research, Münster, Germany.
Maria
M
Eveslage
Institute of Biostatistics and Clinical Research, Münster, Germany; Central Interdisciplinary Ambulance in the School of Dentistry, Universitätsklinikum Münster, Münster, Germany.
Sebastian
S
Bürklein
Department of Operative Dentistry, Universitätsklinikum Münster, Münster, Germany.
Klaus
K
Ott
Department of Operative Dentistry, Universitätsklinikum Münster, Münster, Germany.
Markus
M
Kaup
D003786:Dental Pulp Cavity; D004868:Equipment Failure; D005547:Foreign Bodies / Q000628:therapy*; D006801:Humans; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D008422:Materials Testing; D018915:Root Canal Preparation / Q000295:instrumentation*
Endodontic instrument; fractured; removal; tube technique