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  • Author: Zoi-Despoina Tzima x
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Background/Aim: To investigate the incidence of procedural errors with the use of a novel nickel-titanium rotary system (Hyflex CM, Coltene/Whaledent, Altstätten Switzerland), evaluate the technical quality of root canal treatments and assess a questionnaire completed by the participants themselves in an undergraduate dental clinic between 2014 and 2017 (Department of Endodontology, School of Dentistry, Aristotle University of Thessaloniki).

Material and Methods: 118 undergraduate students in their first year of clinical practice performed a root canal treatment on a patient’s molar (maxillary/mandibular). None of the participants had previous experience in rotary instrumentation. The periapical radiographs were taken with the use of the paralleling technique for standardization and were collected and evaluated by the investigator. After the root canal treatment was performed the students completed a questionnaire in order to evaluate their training on rotary instrumentation.

Results: The overall incidence of instrument separation, apical perforation, root perforation, straightening and ledges was 0.8%, 4.4%, 2.3%, 5.5% and 29% respectively on root canal level. Ledges were detected more often in mandibular mesiobuccal canals. The frequency of root canals with an ‘acceptable’ filling was 68.4%, while overfilled and underfilled canals were found to be 8.6% and 16.2% respectively. The response rate was high (94.9%), 35% of the participants encountered no difficulty in the use of rotary instrumentation and 98.2% would use it again.

Conclusions: The incidence of procedural errors was considerably low and the technical quality of the filled root canals was superior to that of similar studies. The responses of the questionnaire demonstrated a positive attitude toward rotary instrumentation.


Background/Aim: The present study examined the resistance to cyclic fatigue of three different rotary Ni-Ti instruments: K3XF (Kerr, Orange, CA), HyFlex CM (Coltene/Whaledent, Altstätten, Switzerland) and X7 EdgeFile (EdgeEndo, Albuquerque, New Mexico).

Material and Methods: Thirty instruments (n=30) of each type were used with tip size 25 and 0.04 taper. All instruments were constrained to 600 of curvature with a radius of 5 mm by the use of two grooved stainless steel rods and rotated at a speed of 300 rpm and 3.0 Ncm of torque. The time until separation was recorded for each of the instruments and the number of cycles to fracture (NCF) was calculated. Statistical analysis was performed using R Programming language.

Results: The X7 EdgeFile instrument showed significantly greater resistance to cyclic fatigue when compared to the HyFlex CM and the K3XF with mean NCF for each instrument 1046 ± 311, 707 ± 219 and 360 ± 96 respectively. HyFlex CM performed significantly better than K3XF.

Conclusions: The X7 EdgeFile Ni-Ti file appears to be significantly more resistant to fracture, due to flexural fatigue, than the HyFlex CM and the K3XF.