Micro-computed tomography assessment of dentinal microcracks after the preparation of curved root canals with rotary and reciprocal systems

Abstract

Background. Root canal preparation with nickel-titanium (NiTi) instruments may lead to the formation of microcracks in the root canal wall. Vertical root fractures may initiate from dentinal cracks, and eventually necessitate tooth extraction.Objectives. This study aimed to assess the effect of the instrumentation of curved root canals of mandibular molars with the 2Shape (2S) sequential rotary, EdgeFile ® X1 (EFX1) reciprocating and NeoNiTi (NN) rotational single-file systems on the formation of dentinal microcracks with the use of micro-computed tomography (micro-CT). Material and methods.Thirty curved mandibular molar root canals were instrumented with the 2S, EFX1 and NN systems (10 in each group). The teeth underwent micro-CT before and after instrumentation. Next, the pre-instrumentation and post-instrumentation cross-sectional images were evaluated and compared for the detection of dentinal microcracks. The number of microcracks in each group was calculated and reported as percentage. The data was analyzed using the McNemar's test with the IBM SPSS Statistics for Windows software, v. 25.0 (α = 0.05).Results. Out of the 29,280 cross-sectional images evaluated in this study, 11.5% showed dentinal microcracks (n = 3,362). On the post-instrumentation images, the frequency percentage of microcracks was 12.0% (n = 585) in the 2S group, 8.8% (n = 402) in the EFX1 group and 13.3% (n = 694) in the NN group. All of the microcracks detected on the post-instrumentation images were also present on the preinstrumentation images and no new microcracks were formed after root canal instrumentation with the aforementioned systems.Conclusions. Root canal instrumentation with the 2S, EFX1 and NN systems did not result in the formation of new dentinal microcracks.

Dentinal Crack Formation and Quality of Obturation Using Two Single File Systems and Two Obturation Techniques: A micro-CT Study.

“…29 Furthermore, no statistically significant difference was seen between crack formation at apical, middle, and coronal third (Table 1). However, the Genius file system had significantly fewer microcracks when compared with the TruNatomy, these findings are in accordance with previous reports (Govindaraju et al,2017, Oliveira et al, 2020, Shantiaee et al, 2021. This could be due to the low torsional and bending forces generated by the reciprocal movement compared to the continuous rotational movement.…”

Quantitative Evaluation of Apically Extruded Debris of Root Canal Dentin Layer with WaveOne, ProTaper Next, ProTaper Gold Rotary File Systems

“…In the present study, only three file systems were used for quantitative evaluation of apically extruded debris. However, use of minimally invasive file systems (TruNatomy, Dentsply, Tulsa Dental Specialties, Johnson City, TN, USA) designed to respect the true natural anatomy of the root canal system can minimize root dentin microcracks, which could have resulted in different study findings [38]. Therefore, further studies comparing different contemporary rotary canal preparation systems for residue formation are recommended.…”