Incidence of microcracks after preparation of straight and curved root canals with three different NiTi instrumentation techniques assessed by micro‐CT

Abstract

All authors have contributed significantly and are in agreement with the manuscript. AbstractThis study evaluated the effect of three different NiTi instrumentation techniques on the incidence of microcracks after the preparation of straight and curved root canals using micro-CT. Roots from mandibular premolars and maxillary molars (n = 66) with the same mean canal curvatures were assigned to three groups of straight and three groups of curved roots (n = 11). After preoperative micro-CT scans, root canals were prepared with Reciproc, OneShape and ProTaper Next to size 25. Specimens were scanned again, and pre-and post-operative cross-sectional images (n = 75 263) were screened to identify the presence of dentinal microcracks. Overall, microcracks were detected in 2.97% (n = 2236) of the cross-sectional images. No new dentinal microcracks were observed after root canal instrumentation of straight and curved canals with the tested NiTi systems. Instrumentation with Reciproc, OneShape and ProTaper Next did not induce the formation of dentinal microcracks irrespective of canal curvature.

Micro‐computed tomographic assessment of dentinal microcrack formation in straight and curved root canals in extracted teeth prepared with hand, rotary and reciprocating instruments

“…2019, Rödig et al . 2019) that also showed a lack of relationship between microcrack formation and biomechanical preparation with hand, rotary or reciprocating instruments by using micro‐CT analysis.…”

“…2017, Rödig et al . 2019). Thus, micro‐CT investigations in which straight and curved root canals are instrumented by different techniques and analysed under similar experimental conditions are necessary to provide a better understanding of the factors related to the development of dentinal microcracks.…”

Root dentinal microcracks: a post‐extraction experimental phenomenon?

“…Our group have published several studies both on stored extracted teeth and on teeth from cadavers using nondestructive micro-CT evaluation, and all of them convey the same conclusion: no new microcracks were induced by root canal Letter to the Editor International Endodontic Journal, 53,[137][138][139][140][141][142]2020 instrumentation or canal filling (De-Deus et al 2014, 2015,b, Zuolo et al 2017. Moreover, there are other studies using micro-CT confirming that root dentinal microcracks are not related to mechanical shaping of the canal (Bayram et al 2017a,b, Oliveira et al 2017, R€ odig et al 2019, U gur Aydın et al 2019. Taken together, these reproducible micro-CT outcomes largely contrast with the results of previous cross-sectioning studies and therefore provide strong evidence to support the rationale of our conclusion.…”

INCIDENCE OF DENTINAL DEFECTS AFTER ROOT CANAL PREPARATION USING HYFLEX EDM and MPRO FILES

“…In the current study, a stereomicroscopic analysis was performed to examine dentinal defects because this technique was accepted by many previous studies to be simple and allow direct examination of dentinal defects as supported by Abou Elnasr and Abd El Kader (2014) (26) and Algarni et al, (2019) (25). On the other hand, it has the following limitations; it permits examination of usually three or four specific levels with the chance of missing defects that might be related to other levels as described by Ustun et al,(2015) (29) and Rödig et al, (2019) (16). Also, this technique does not allow comparing pre and post-operative images of the same root, thus pre-operative micro-cracks might not be observed (23).…”

“…Three files were used sequentially; one orifice opener file M18 (18/0.04) used in an in and out pecking motion with brushing outstrokes to preflare the canal and two shaping and finishing files M20 (20/0.04), M25 (25/0.06) used to prepare the remaining part only in an in and out pecking motion. MPro files were used at 450 rpm rotational speed and recommended torque (3N.cm for M18; 1.5N.cm for both M20 and M25) (13,16). After completion of instrumentation, prepared specimens were irrigated with 3ml of 17% EDTA solution for 1min followed by a final flush of 3ml 2.5% Sodium hypochlorite and dried with paper points.…”