Comparison of newly formed microcracks after instrumentation using Protaper Next, Reciproc and Self-Adjusting File systems

Abstract

Purpose: The purpose of the present study is to assess the rate of newly formed microcracks comparatively during root canal instrumentation by using ProTaper Next, Reciproc, and Self-Adjusting File systems using micro-computed tomography. Subjects and methods: Thirty mesial roots of mandibular molars were randomly assigned to 3 experimental groups (n = 10) as follows, ProTaper Next, Reciproc and Self-Adjusting File system. Preoperative and postoperative scans were obtained at the isotropic resolution of 13.68 µm. Cross-section images were examined to identify the presence of newly formed dentinal microcracks. Results: The Self-Adjusting File and Reciproc systems caused a higher rate of new microcrack formation than the ProTaper Next group (p<0.001). There were also significant differences in the new microcrack formation between Reciproc and Self-Adjusting File groups (p<0.001). Conclusion: Reciproc and Self-Adjusting File systems caused a higher rate of newly formed microcraks compared to ProTaper Next system.

A critical analysis of research methods and experimental models to study dentinal microcracks

“…In a recent study, the apical occurrence of dentinal defects was investigated at three working lengths: short canal preparation (apical foramen −1 mm), at the apical foramen and over preparation (apical foramen +1 mm), and no new microcracks were created (Belladonna et al, 2021). Notwithstanding the similar findings of most publications, some micro‐CT studies reported the development of new microcracks after root canal preparation (Aggarwal et al, 2021; Alkahtany & Al‐Madi, 2020; Çakici et al, 2019; Ceyhanli et al, 2016; Jain et al, 2018; Jamleh et al, 2015, 2021; Mandava et al, 2018; Tsenova‐Ilieva et al, 2019; Table 2). The explanation for these dissimilar findings is addressed later on in this review.…”

“…Currently, our digital search revealed 27 confirmatory studies using micro‐CT imaging technology to evaluate the frequency of dentinal microcracks after root canal preparation in extracted/stored teeth published in peer‐reviewed journals from research groups worldwide (Table 2). Eighteen of them found no new dentinal microcracks (Arumugam & Yew, 2021; Bayram et al, 2017a, 2017b; Belladonna et al, 2021; Cassimiro et al, 2017; De‐Deus et al, 2014, 2015, 2016, 2017c; Martins et al, 2021; Miguéns‐Vila et al, 2021; de Oliveira et al, 2017a, 2017b; Rödig et al, 2019; Stringheta et al, 2019; Ugur Aydin et al, 2019; Vieira et al, 2020; Zuolo et al, 2017), whilst nine studies reported the development of new defects after canal preparation (Aggarwal et al, 2021; Aksoy et al, 2019; Alkahtany & Al‐Madi, 2020; Çakici et al, 2019; Ceyhanli et al, 2016; Jain et al, 2018; Jamleh et al, 2021; Mandava et al, 2018; Tsenova‐Ilieva et al, 2019).…”

“…These contradictory results seem puzzling, but a critical appraisal of the methods and outcome reports can provide interesting insights. For instance, authors evaluated several micro‐CT cross‐sectional images and explained the incidence of new cracks after canal preparation on the basis of the design features of instruments such as tip design, cross‐sectional geometry, taper type, flute form, pitch, and metallurgy (Aggarwal et al, 2021; Mandava et al, 2018), the use of Gates‐Glidden drills for coronal root canal flaring (Alkahtany & Al‐Madi, 2020; Mandava et al, 2018), the greater contact between larger instruments and the canal walls (Çakici et al, 2019; Ceyhanli et al, 2016; Jamleh et al, 2021), the rotational forces and constant torque (Alkahtany & Al‐Madi, 2020; Ceyhanli et al, 2016; Jain et al, 2018), the instrument stiffness (Aggarwal et al, 2021; Jain et al, 2018), the instrument kinematics (Aggarwal et al, 2021; Alkahtany & Al‐Madi, 2020), and the type of sample (Aggarwal et al, 2021). These are indeed confounding factors considering that other studies using similar samples, materials and protocols found no new crack after canal preparation.…”

“…Since 2014, new findings from in vitro , ex vivo and in situ studies using micro‐computed tomographic (micro‐CT) imaging technology reshaped the overall panorama and understanding on the development of dentinal defects produced by root canal preparation and filling procedures (Aggarwal et al, 2021; Aksoy et al, 2019; Alkahtany & Al‐Madi, 2020; Arashiro et al, 2020; Arumugam & Yew, 2021; Aydin et al, 2014; Bayram et al, 2017a, 2017b; Belladonna et al, 2021; Çakici et al, 2019; Cassimiro et al, 2017; Cavalcante et al, 2020; Ceyhanli et al, 2016; De‐Deus et al, 2014, 2015, 2016, 2017b, 2017c, 2020; Jain et al, 2018; Jamleh et al, 2015, 2021; Mandava et al, 2018; Martins et al, 2021; Miguéns‐Vila et al, 2017; de Oliveira et al, 2017a, 2017b; Rödig et al, 2019; Shemesh et al, 2018; Stringheta et al, 2019; Vieira et al, 2020; Zuolo et al, 2017). The achievements from these studies identified that: (i) root dentinal microcracks observed in cross‐sectional images of extracted teeth are not caused by canal shaping procedures; (ii) dehydration often causes cracking of the dentinal tissue, regardless of canal instrumentation; (iii) dentinal microcracks do not predispose the root to fracture in a laboratory setting using extracted teeth; (iv) microcracks observed in root sections of extracted teeth ( in vitro ) cannot be confirmed in a fresh cadaver model ( in situ ); (v) dentinal microcracks caused by endodontic procedures and observed in cross‐sectional images of extracted roots are a phenomenon that has never been reported in clinical practice.…”

Dentinal Microcracks after Root Canal Instrumentation Using Instruments Manufactured with Different NiTi Alloys and the SAF System: A Systematic Review

“…The main aim of endodontic therapy is to clean and fill the RCS in order to preserve or regain the integrity of the periapical tissues [45]. Despite continuous developments in instruments to improve RCS cleaning [46], dentin microcracks continue to be a source of concern for clinicians and researchers [47,48] as they often contribute to the instrumented tooth fracturing and extraction [49][50][51]. Although, there are multiple factors that contribute to dentinal crack formation like the design of the file, flexibility of file, and stress on the tooth surface used during instrumentation.…”