Abstract
BackgroundThe purpose of this study was to investigate the consistency of working length control between hand instrumentation in comparison to engine driven Mtwo nickel-titanium rotary files.Material and MethodsForty extracted maxillary molars were selected and divided onto two parallel groups. The working lengths of the mesiobuccal root canals were estimated. The teeth were fixed in a phantom head. The root canal preparation was carried out group 1 (n=20) with hand K-files, (VDW, Munich, Germany) and group 2 (n=20) with Mtwo instruments (VDW, Munich, Germany). Vestibulo-oral and mesio-distal directional x-ray images were taken before the preparation with #10 K-file, inserted into the mesiobuccal root canal to the working length, and after preparation with #25, #30 and #40 files. Working lenght changes were detected with measurements between the radiological apex and the instrument tips.ResultsIn the Mtwo group a difference in the working competency (p<0.05) could be noticed only in the vestibulo-oral direction from #10 to #40 file. The hand instrument group showed a significant difference in working length competency for each larger file size (p<0.05) (ANOVA). Regression analysis in the hand instrumentation group indicated a working length decrease with a mean of 0,2 mm after each consecutive file size (p<0.01).ConclusionsThe outcome of our trial indicated a high consistency in working length control for root canal preparation under simulated clinical condition using Mtwo rotary files. Mtwo NiTi rotary file did therefore proved to be more accurate in comparison to the conventional hand instrumentation. Key words:Working length, Mtwo, nickel-titanium, hand preparation, engine driven preparation.
Highlights
The biomechanical objectives of root canal preparation are to eliminate pulp tissue and infection from the root canal system and to develop a continuously tapering conical form while the apical foramen is maintained in its original shape and position [1]
To simulate clinical conditions during root canal instrumentation, teeth were integrated into a maxillary arch model at the corresponding anatomical position together with an antagonist mandibular arch model in a dummy head fixed to a phantom torso (Frasaco Phantom Head 6/3, Frasaco, Tettnang, Germany)
The Regression analysis in the hand instrumentation group indicated a tendency toward a shortening of the real Working length with a mean of 0,2 mm by the insertion of each files
Summary
The biomechanical objectives of root canal preparation are to eliminate pulp tissue and infection from the root canal system and to develop a continuously tapering conical form while the apical foramen is maintained in its original shape and position [1]. Under-instrumentation of the canals means that the tip of the file does not reach to the working length resulting in remnants of the pulp tissue to be left near the apex of the roots. The principal purpose of this trial was to explore and evaluate the consistency of working length control by a comparison between hand instrumentation with K-files and with Mtwo engine driven NiTi rotary files. The purpose of this study was to investigate the consistency of working length control between hand instrumentation in comparison to engine driven Mtwo nickel-titanium rotary files. Conclusions: The outcome of our trial indicated a high consistency in working length control for root canal preparation under simulated clinical condition using Mtwo rotary files. Mtwo NiTi rotary file did proved to be more accurate in comparison to the conventional hand instrumentation
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