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. 2024 Feb 8;17(4):827.
doi: 10.3390/ma17040827.

Cyclic Fatigue of Different Reciprocating Endodontic Instruments Using Matching Artificial Root Canals at Body Temperature In Vitro

Sebastian Bürklein  1 , Paul Maßmann  1 , Edgar Schäfer  1 , David Donnermeyer  2
Affiliations

Cyclic Fatigue of Different Reciprocating Endodontic Instruments Using Matching Artificial Root Canals at Body Temperature In Vitro

Sebastian Bürklein et al. Materials (Basel). .

Abstract

Reciprocating motion expands the lifetime of endodontic instruments during the preparation of severely curved root canals. This study aimed to investigate the time to fracture (TTF) and number of cycles to failure (NCF) of different reciprocating instruments (n = 20 in each group) at body temperature using a dynamic testing model (amplitude = 3 mm). Reciproc Blue (RPB), size 25/.08, WaveOne Gold (WOG) 25/.07, Procodile (Proc) 25/.06, R-Motion (RM_06) 25/.06 and R-Motion (RM_04) 30/.04 instruments were tested in their specific reciprocating motion in artificial matching root canals (size of the instrument ± 0.02 mm; angle of curvature 60°, radius 5.0 mm, and centre of curvature 5.0 mm from apical endpoint). The number of fractured instruments, TTF, NCF, the and lengths of the fractured instruments were recorded and statistically analysed using the Chi-Square or Kruskal-Wallis test. Both TTF (median 720, 643, 562, 406, 254 s) and the NCF (3600, 3215, 2810, 2032, 1482 cycles) decreased in the following order RM_06 > RPB > RM_04 > Proc > WOG with partially significant differences. During testing, only six RM_06 instruments fractured, whereas 16/20 (RPB), 18/20 (Proc), and 20/20 (RM_04, WOG) fractures were recorded (p < 0.05). Within the limitations of the present study, blue-coloured RPB and RM instruments exhibited a significantly superior cyclic fatigue resistance compared to SE-NiTi and Gold-wire instruments. Heat treatment, cross-sectional design and core mass significantly influenced the longevity of reciprocating instruments in cyclic dynamic testing.

Keywords: NiTi; amplitude; cycles to failure; dynamic testing; lifetime; reciprocating motion.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Reciprocating instruments included in the study; Reciproc Blue (RPB), Procodile (Proc), R-Motion 25/.06 (RM_06), WaveOne Gold (WOG), R-Motion 30/.04 (RM_04).
Figure 2
Figure 2
Time to fracture of the different groups with mean, median, 95% confidence interval and outliers. Bars/groups with the same alphabet letter did not differ significantly (significance level p < 0.05).
Figure 3
Figure 3
Number of cycles to failure of the different groups with mean, median, 95% confidence interval and outliers. Bars/groups with the same alphabet letter did not differ significantly (significance level p < 0.05).
Figure 4
Figure 4
Cross-sectional characteristics of the tested instruments exactly at 6 mm from the tip. Note: different core mass (dotted line) and outer diameter (full circle) were obvious.
See this image and copyright information in PMC

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