Comparison of apical transportation and centering ability of Mtwo and Reciproc R25 in severely curved canals using cone-beam computed tomography

Surface roughness and cyclic fatigue resistance of a novel shaping system: An in-vitro study

Recently developed Nickel-Titanium (NiTi) instruments with practical changes have resulted in safer instrumentation. In addition, topographical features on the file surface are a contributing factor to clinical durability. Therefore, this study aimed to investigate both the cyclic fatigue resistance and the roughness change of MTwo and Rotate instruments (VDW, Munich, Germany). Each instrument (n = 6/each group) was scanned with an atomic force microscopy prior to and after instrumentation. In addition, cyclic fatigue testing was conducted for each instrument (n = 11/each group) with stainless-steel blocks, including 45°-60°-90° degrees of curvature milled to the instruments' size. The roughness parameters increased for both systems after instrumentation (p<0.05). Both systems presented an increased roughness following instrumentation (p<0.05). The cyclic fatigue resistance was lowest at 90° for both systems (p<0.05), whereas the Rotate files presented a higher resistance than that of the Mtwo files (p<0.05). Compared to the Mtwo files, Rotate files presented better resistance, while the resistance decreased as the curvature increased.

Cone-Beam Computed Tomography Assessment of Canal-Centering Ability for Traditionally Used Nickel Titanium and Nickel Titanium Files with Reciprocating Hand Piece and Wave-One Files

Aim of the Study:

Need for our study was to evaluate a comparison between canal preparation ability of nickel–titanium (NiTi) hand files with step-back manual technique, of NiTi files installed on a reciprocating hand piece and of Wave-One files utilizing noninvasive cone-beam computed tomography (CBCT) technique.

Materials and Methods:

Thirty extracted intact single-rooted human mandibular premolars were used in the study, segregated in three sets of 10 specimens each, where canal instrumentation was done by different methods using NiTi in step-back technique, using reciprocating hand piece with NiTi files and using primary file with the use of Wave-One reciprocating system. Later, evaluation of centering ability was conducted using the references through CBCT images.

Results:

Hand NiTi files showed even less canal centering ability as compared to other two sets. Mesiodistal diameter at 9 mm length of the prepared canal was 1.06 and later was 0.98, which shows excessive preparation in case of Set I versus Set II. In case of comparison between Set III and Set I, mesiodistal diameter at 9 mm length of the prepared canal was 0.99, and later was 1.06, depicting better canal shaping ability with Wave-One file.

Conclusion:

The use of hand NiTi files installed on a reciprocating hand piece would be economically beneficial producing the similar results as that of wave one without any deviation from the original canal anatomy.