Design, metallurgical features, mechanical performance and canal preparation of six reciprocating instruments

Abstract

Aim To compare six reciprocating instruments regarding their geometric design, metallurgical characteristics, mechanical behaviour and ability to prepare root canals. Methodology A total of 246 new 25‐mm NiTi instruments (41 per group) from six reciprocating systems (Reciproc, Reciproc Blue, One Files, One Files Blue, Reverso Silver, and WaveOne Gold) were evaluated throughout a multimethod approach regarding their design using stereomicroscopy (number of blades and helix angle) and scanning electron microscopy (blades symmetry, cross section and surface finishing), nickel‐titanium composition, phase transformation temperatures, mechanical performance (cyclic fatigue, torsional and bending resistance) and unprepared canal surface area on anatomically matched mandibular molars assessed by micro‐CT. One‐way ANOVA and post hoc Tukey’s or Mood's median tests were selected depending on sample distribution with significance level set at 5%. Results The instruments had similarities regarding their metal composition and unprepared canal area, whilst differences in phase transformation temperatures and geometric design (number of blades, surface finishing and tip geometry) were observed. Overall, no difference was observed regarding the maximum torque values (P > 0.05), whilst One Files (72 s) and One Files Blue (414 s) had the shortest and longest times to fracture, respectively (P < 0.05). Similar angles of rotation were observed in Reciproc (310°), One Files (285°) and Reverso Silver (318°) instruments (P > 0.05), which were significantly lower than Reciproc Blue (492°), One Files Blue (456°) and WaveOne Gold (492°; P < 0.05). Maximum bending load demonstrated that Reciproc Blue (201.3 gf) was significantly more flexible that the other instruments (P < 0.05). Conclusion Although there were similarities in metal composition and percentage of unprepared canal surface, the instruments had differences in the overall geometric design, phase transformation temperatures and in the four mechanical resistance parameters (time to fracture, maximum torque, angle of rotation and maximum bending load).

Can Type of Instrumentation and Activation of the Final Irrigant Improve the Obturation Quality in Oval Root Canals? A Push-Out Bond Strength Study

“…Two recent investigations revealed the inability of PTN and WO to adhere to the surfaces of canal walls of mandibular molars. The uninstrumented area associated with these files were almost 41% for PTN and almost 29% for WO [ 1 , 19 ]. This could explain the results obtained in the current investigation with the samples instrumented with PTN and WO exhibiting lower values of dislocation resistance of the root canal fillings.…”

“…Clinical endodontics is flooded with an abundance of innovations in terms of instrument design, metallurgy, and kinematics [ 1 ]. Most file systems can productively clean canals with a round cross section.…”

Physical Properties of Modern Reciprocal Endodontic Systems and Fatigue Failure Testing in Simulated Clinical Conditions

“…In addition, the transformation temperatures and phase composition of the used NiTi alloys are important parameters. It is known that the durability of Reciproc Blue compared to WaveOne Gold is mainly attributed to different thermomechanical treatment, despite having a lower transformation temperature [46]. This is mainly explained by the presence of more stable martensite [13].…”

Role of the Crystallographic Phase of NiTi Rotary Instruments in Determining Their Torsional Resistance during Different Bending Conditions

“…The crystallographic phase of the NiTi alloy, the transition temperature range, and the effect of heat-treatments can be conveniently studied using the differential scanning calorimetry (DSC), in which the difference in thermal power supplied to a test specimen and an inert control specimen heated at the same rate is measured [ 15 ].…”