Debris extrusion and foraminal deformation produced by reciprocating instruments made of thermally treated NiTi wires.

To evaluate the amount of apically extruded debris, percentage of foraminal enlargement and apical foramen (AF) deformation that occurred during root canal preparation with different reciprocation systems: Reciproc, WaveOne (M-Wire), and ProDesign R (Shape Memory Technology Wire) at two different working lengths (WLs): 0.0 and 1.0 mm beyond the AF. The AF of 120 root canals in 60 mesial roots of mandibular molars were photographed with stereomicroscope and randomly assigned into four groups: manual, Reciproc (REC), WaveOne (WO), and ProDesign R (PDR); subsequently, they were further subdivided according to the WL (n=15). Teeth were instrumented, coupled to a dual collecting chamber, and then another photograph of each AF was captured. Extrusion was analysed by determining the weight of extruded debris. Each AF diameter was measured in pre- and post-instrumentation images to determine deformation, which was analysed, and afterwards the final format of AFs was classified (circular/oval/deformed). We found no significant differences when analysing each system at different WLs. When considering each WL, REC and WO showed highest extrusion values (P<.05); for AF enlargement, differences were observed only for WO, when it was used beyond the AF; differences were observed among M-Wire groups beyond the AF (P<.05). AF deformation was observed in all groups; PDR showed the lowest AF deformation values at both WLs; M-Wire groups showed 50% strain beyond the AF. Authors concluded that beyond the apical limit, the alloy and taper are important aspects when considering extrusion and deformation.

Effect of Reciprocating Systems and Working Lengths on Apical Microcrack Development: a micro-CT Study.

The objective of this study was to evaluate the effect of root canal preparation with single-file reciprocating systems at different working lengths on the development of apical microcracks using micro-computed tomographic (micro-CT) imaging. Forty extracted human mandibular incisors were randomly assigned to 4 groups (n=10) according to the systems and working length used to prepare the root canals: Group A - WaveOne Gold at apical foramen (AF), Group B - WaveOne Gold 1 mm short of the AF (AF-1 mm), Group C - Unicone (AF) and Group D - Unicone (AF-1 mm). Micro-CT scanning was performed before and after root canal preparation at an isotropic resolution of 14 µm. Then, three examiners assessed the cross-sectional images generated to detect microcracks in the apical portion of the roots. Apical microcracks were visualized in 3, 1, 1, and 3 specimens in groups A, B, C, and D, respectively. All these microcracks observed after root canal preparation already existed prior to instrumentation, and no new apical microcrack was detected. For all groups, the number of slices presenting microcracks after root canal preparation was the same as before canal preparation. Root canal preparation with WaveOne Gold and Unicone, regardless of the working length, was not associated with apical microcrack formation.

Effect of Reciprocating Systems and Working Lengths on Apical Microcrack Development: a micro-CT Study

Abstract The objective of this study was to evaluate the effect of root canal preparation with single-file reciprocating systems at different working lengths on the development of apical microcracks using micro-computed tomographic (micro-CT) imaging. Forty extracted human mandibular incisors were randomly assigned to 4 groups (n=10) according to the systems and working length used to prepare the root canals: Group A - WaveOne Gold at apical foramen (AF), Group B - WaveOne Gold 1 mm short of the AF (AF-1 mm), Group C - Unicone (AF) and Group D - Unicone (AF-1 mm). Micro-CT scanning was performed before and after root canal preparation at an isotropic resolution of 14 µm. Then, three examiners assessed the cross-sectional images generated to detect microcracks in the apical portion of the roots. Apical microcracks were visualized in 3, 1, 1, and 3 specimens in groups A, B, C, and D, respectively. All these microcracks observed after root canal preparation already existed prior to instrumentation, and no new apical microcrack was detected. For all groups, the number of slices presenting microcracks after root canal preparation was the same as before canal preparation. Root canal preparation with WaveOne Gold and Unicone, regardless of the working length, was not associated with apical microcrack formation.

Resumo O objetivo deste estudo foi avaliar o efeito da instrumentação de canais radiculares utilizando sistemas reciprocantes de lima única em diferentes comprimentos de trabalho sobre o desenvolvimento de microfissuras apicais utilizando imagens de microtomografia computadorizada (micro-CT). Quarenta incisivos inferiores humanos extraídos foram distribuídos aleatoriamente em 4 grupos (n=10) de acordo com os sistemas e comprimentos de trabalho utilizados para preparar os canais radiculares: Grupo A - WaveOne Gold no forame apical (FA), Grupo B - WaveOne Gold 1 mm aquém do FA (FA-1 mm), Grupo C - Unicone (FA) e grupo D - Unicone (FA-1 mm). Escaneamentos de micro-CT foram realizados antes e após o preparo dos canais a uma resolução isotrópica de 14 μm. Em seguida, três examinadores avaliaram as imagens de secção transversal geradas para detectar microfissuras na porção apical das raízes. Microfissuras apicais foram visualizadas em 3, 1, 1 e 3 espécimes nos grupos A, B, C e D, respectivamente. Todas essas microfissuras observadas após o preparo dos canais radiculares já existiam antes da instrumentação e não foi detectada nenhuma nova microfissura apical. Para todos os grupos, o número de cortes apresentando microfissuras após o preparo dos canais radiculares foi o mesmo verificado antes do preparo dos canais. A instrumentação de canais radiculares utilizando WaveOne Gold e Unicone, independentemente do comprimento de trabalho, não foi associada à formação de microfissuras apicais.

Enlargement of the apical foramen of mature teeth by instrumentation and apicoectomy. A study of effectiveness and the formation of dentinal cracks.

OBJECTIVE: In the last few years there have been attempts to revascularize mature necrotic teeth instead of performing a standard root canal treatment. Apical foramen enlargement (AFE) would be necessary for regenerative treatments of mature teeth. In the literature, AFE has been made through apicoectomy and instrumentation. However, no standardized methods have been described yet, which may affect the success of the therapy. Our aim was to describe the effectiveness and damage to dental structures of five methods for AFE. METHODS: Two hundred and ten human teeth were assigned to one control group (n = 10) and four treatment groups (n = 50 each): instrumentation was up to file #80 0.5 mm coronal to the apex (I), at apex level (II), 0.5 mm beyond the apex (III) and apicoectomy at 2 and 4 mm from the apex (IV). The apical foramen diameter was measured before and after treatment. The formation of clinically visible fractures (CVF) and microcracks was analysed clinically and with ESEM, respectively. Thirty-two in situ sheep's teeth were also instrumented, to compare damage in in situ and ex vivo teeth. RESULTS: The foramen diameter was augmented by 0.15, 0.47, 0.54 0.06 and 0.32 mm in human teeth of groups I, II, III, apicoectomy at 2 and 4 mm, respectively. CVF were more frequent as the working length was augmented. No statistical differences were found for microcrack formation. In situ teeth showed significantly less damage. CONCLUSIONS: Instrumentation at apex level seems to be the most effective and least harmful technique for AFE, while apicoectomy is not a useful method.

Modelo teórico de la endodoncia actual / Theoretical model of the current endodontics

Para comprender en profundidad cada una de las técnicas endodónticas de aplicación clínica, propuestas en la actualidad por los autores de diferentesescuelas de endodoncia, debemos previamente conocer el modelo teórico o paradigma preconizado por cada una de ellas. Ello nos permitirá discernir yseleccionar la más adecuada a las necesidades clínicas de nuestros pacientes, dirigiendo la investigacióny desarrollo de nuevas propuestas en el marco de determinado paradigma. La ciencia es multidisciplinaria y generadora de diferentes modelos teóricos aplicables en la endodoncia. Un modelo esencialmente técnico-quirúrgico busca el éxito apoyado enla limpieza, conformación y obturación tridimensional de los conductos radiculares. Eso es necesario pero no suficiente; por cuya razón, Maisto dio un salto cualitativo preconizando un nuevo paradigma endodóntico basado en la reparación apical. Este nuevo modelo teórico nos permite la formulación de nuevas conductas terapéuticas, desarrollar nuevosmateriales y proponer técnicas de instrumentación y obturación que engloben tanto al conducto radicular,como a su zona de influencia en el sistema de inserción dental y el hueso alveolar que lo rodea.

To understand in depth each of the endodontic techniques of clinical application, currently proposed by the authors of different schools of endodontics,we must first know the theoretical model orparadigm advocated by each of them.This will allow us to discern and select the mostappropriate of the clinical needs for our patients, directing research and developmentof new proposals within the framework of agiven paradigm. The science is multidisciplinary and generates different theoretical modelsapplicable to endodontics. An essentially technical-surgical model seekssuccess based on cleaning, shaping and three-dimensional obturation of the rootcanals. That is necessary but not enough, which leadMaisto to make a qualitative leap by advocating anew endodontic paradigm based on apical repair.This new theoretical model allows us to formulate new therapeutic behaviors, develop new materials and propose techniques of instrumentation and obturation that concerns both the root canal and its area of influence in the dental insertion system and the surrounding alveolar bone.

Micro-computed Tomographic Analysis of Apical Microcracks before and after Root Canal Preparation by Hand, Rotary, and Reciprocating Instruments at Different Working Lengths.

INTRODUCTION: This study aimed to compare apical microcrack formation after root canal shaping by hand, rotary, and reciprocating files at different working lengths using micro-computed tomographic analysis. METHODS: Sixty mandibular incisors were randomly divided into 6 experimental groups (n = 10) according to the systems and working lengths used for the root canal preparation: ProTaper Universal for Hand Use (Dentsply Maillefer, Ballaigues, Switzerland), HyFlex CM (Coltene-Whaledent, Allstetten, Switzerland), and Reciproc (VDW, Munich, Germany) files working at the apical foramen (AF) and 1 mm short of the AF (AF - 1 mm). The teeth were imaged with micro-computed tomographic scanning at an isotropic resolution of 14 µm before and after root canal preparation, and the cross-sectional images generated were assessed to detect microcracks in the apical portion of the roots. RESULTS: Overall, 17 (28.3%) specimens presented microcracks before instrumentation. Apical microcracks were present in 1 (ProTaper Universal for Hand Use), 3 (Hyflex CM), and 2 (Reciproc) specimens when the instrumentation terminated at the AF. When instrumentation was terminated at AF - 1 mm, apical microcracks were detected in 3 (ProTaper Universal for Hand Use) and 4 (Hyflex CM and Reciproc) specimens. All these microcracks detected after root canal preparation were already present before instrumentation, and no new apical microcrack was visualized. For all groups, the number of slices presenting microcracks after root canal preparation was the same as before canal preparation. CONCLUSIONS: Root canal shaping with ProTaper Universal for Hand Use, HyFlex CM, and Reciproc systems, regardless of the working length, did not produce apical microcracks.

Detection of Apical Root Cracks Using Spectral Domain and Swept-source Optical Coherence Tomography.

INTRODUCTION: This study aimed to evaluate the ability of 2 optical coherence tomographic (OCT) systems to detect apical dentinal microcracks. METHODS: Twenty extracted human single-rooted mandibular incisors were selected. After root canal preparation with an R40 Reciproc file (VDW, Munich, Germany), the specimens presenting apical microcracks were identified using micro-computed tomographic (micro-CT) scanning as the gold standard. Then, the apical portions of the roots were imaged with spectral domain OCT (SD-OCT) and swept-source OCT systems, and the resulting images were blindly evaluated by 3 independent examiners to detect microcracks. The diagnostic performance of each OCT device was calculated, and statistical analysis was performed. RESULTS: Based on the micro-CT images, 12 (60%) roots presented dentinal microcracks in the apical region. The images generated by the OCT systems were able to show microcrack lines at the same location as the corresponding micro-CT cross sections. Although the diagnostic performance of the SD-OCT device was superior, there were no statistically significant differences between the 2 OCT devices (P > .05). Interexaminer agreement was substantial to almost perfect for the SD-OCT system and moderate to almost perfect for the swept-source OCT system, whereas intraexaminer agreement was substantial to almost perfect for both OCT devices. CONCLUSIONS: The detection ability verified for both OCT systems renders them promising tools for the diagnosis of apical microcracks.

Comparison of fracture resistance of simulated immature teeth with an open apex using Biodentine and composite resin: An in vitro study.

AIM: To evaluate the fracture resistance in simulated immature teeth that had been backfilled using composite resin and Biodentine after using Biodentine as an apical plug material immediately and after 3 months of aging. MATERIALS AND METHODS: Sixty extracted human maxillary central incisors were simulated in an immature open apex. The roots of all the specimens were then standardized to a length of 10 mm and canals were instrumented to obtain the radicular dentin thickness around 1.5 mm. All the specimens were then randomly divided into three groups of twenty teeth each. Group I (control) - 4 mm apical plug of Biodentine backfilled with thermoplasticized gutta-percha. Group II - 4 mm apical plug of Biodentine and then backfilled with ParaCore. Group III - completely filled with Biodentine. Ten samples from each group were randomly divided into two subgroups. In subgroup A: Specimens were stored for 1 week. In subgroup B: Specimens were stored in phosphate-buffered saline solution for 3 months and were subjected to universal testing machine. Statistical analysis was done using one-way analysis. RESULTS: No significant difference in fracture resistance between the groups was observed when tested immediately. After 3 months of aging, only Biodentine group showed a significant reduction in fracture resistance without significant reduction with other two groups. CONCLUSION: Biodentine group has shown a drastic reduction in fracture resistance after 3 months of aging, and hence cannot be recommended as a reinforcement material in immature teeth with thin dentin walls.

Reasons for Apical Surgery Treatment in an Underserved New York City Population.

Endodontic retreatment often involves remaking restorations. The total cost may steer the treatment towards surgery. The aim of this study was to retrospectively record the reasons for performing apical surgery in an economically deprived patient population. The clinical reasons (59%) for apical surgery were most common, but the nonclinical (financial) reasons (41%) emerged as a major cause. The finding that 41% of the apicoectomies were performed because of nonclinical constraints is a high figure and may not reflect the situation generally. Still, economic factors potentially play a major role in the selection of surgical versus nonsurgical endodontic retreatment.

Effect of glide path and apical preparation size on the incidence of apical crack during the canal preparation using Reciproc, WaveOne, and ProTaper Next systems in curved root canals: A stereomicroscope study.

This study evaluated the effect of creating a glide path and apical preparation size on the incidence of apical cracks during canal preparation in mandibular molar teeth with curved canals. One hundred and forty extracted teeth were used. The teeth were randomly assigned to one control group or six experimental groups (n = 20 per group) for canal preparation. No preparation was performed on teeth in the control group. In three of the six experimental groups, a glide path was not created; a glide path was created on the curved mesial canals of all teeth in the remaining three experimental groups. All teeth in experimental groups were then instrumented with the following systems: Reciproc, WaveOne (WO), and ProTaper Next (PTN). Digital images of the apical root surfaces of these teeth were recorded before preparation, after instrumentation with size 25 files, and after instrumentation with size 40 files. The images were then inspected for the presence of any new apical cracks and propagation. There was no significant difference between the experimental groups during canal preparation using size 25 files (p > 0.05). Reciproc and WO caused more new apical cracks than did PTN during canal preparation using size 40 files (p < 0.05). However, canal preparation using size 40 files did not cause propagation of existing cracks (p > 0.05). Performing a glide path prior to canal preparation did not change the incidence of apical crack during preparation. Additionally, increasing apical preparation size may increase the incidence of apical crack during canal preparation. SCANNING 38:585-590, 2016. © 2016 Wiley Periodicals, Inc.

Comparison of dentinal and apical crack formation caused by four different nickel-titanium rotary and reciprocating systems in large and small canals.

This study compared dentinal and apical crack formation after instrumentation with different nickel-titanium systems at two different working lengths (WL) in large and small canals. Two hundred and eighty human teeth were randomly distributed into two control and 12 experimental groups (n=20 each). Large and small canals were instrumented by the WaveOne, Protaper Universal System (PTU), Twisted File (TF), or Twisted File Adaptive (TFA) at 1 mm shorter than canal length (CL-1 mm) or 1 mm beyond apical foreman (CL+1 mm). Horizontal sections were microscopically observed to evaluate the dentinal cracks (only large canals). Scanning electron microscopy images were taken before and after instrumentation to assess apical cracks. All file types caused more apical cracks in small canals than in large canals regardless of the WL. During over-instrumentation (WL=CL+1 mm), the WaveOne and PTU groups developed significantly more dentinal cracks at the 6 and 9 mm sections than the TF and TFA groups.

An Evaluation of Apical Cracks in Teeth Undergoing Orthograde Root Canal Instrumentation.

INTRODUCTION: Dentinal damage and cracks induced by orthograde preparation methods have been reported in studies using extracted teeth. The purpose of this in situ investigation was to evaluate dentinal cracks in nonextracted teeth after final instrumentation. The null hypothesis is that orthograde root canal instrumentation will have no effect on crack initiation in teeth retained in the natural periodontium. METHODS: Mandibular first and second premolars of pig jaws were selected. Forty single-rooted canals were divided into 5 groups (n = 8): (1) WaveOne (Dentsply Tulsa Dental Specialties, Tulsa, OK) 25/08; (2) ProTaper rotary S1, S2, F2 (25/08) (Dentsply Tulsa Dental Specialties); (3) crown-down GT hand files 20/12, 20/10, 20/08 (Dentsply Tulsa Dental Specialties); (4) positive control (purposefully cracked); and (5) negative control (uninstrumented teeth). After instrumentation, superficial soft tissue was removed, and bone was carefully peeled away with surgical burs to the level of the root apices. Roots were resected 1 mm coronal to the working length, stained with caries indicator dye, and transilluminated; images were captured and viewed at 30× magnification to determine the presence or absence of dentinal cracks. RESULTS: WaveOne, ProTaper rotary, and GT hand files produced no cracks. All positive controls had cracks; all negative controls had no cracks. CONCLUSIONS: Within the limits of this investigation, the presence of natural periodontal structures may prevent cracking or dentinal damage in teeth receiving orthograde root canal instrumentation.

Hemisection: A Treatment Option for an Endodontically treated Molar with Vertical Root Fracture.

Vertical root fractures (VRF) in endodontically treated teeth have long been reported and pose diagnostic difficulties. A hemisection/root resection procedures removes the fractured fragments completely, and retains a portion of the compromized tooth offers a predictable treatment option. The key to this rests in ideal case selection involving balancing all indications and contraindications. The success of the treatment depends on careful case selection based on a firm set of guidelines. This article presents a case with VRF in an endodontic treated molar. This article describes the case of a 65-year-old man with a VRF on the mesial root and a healthy periodontium supporting the distal root making it ideal for retention as well as restoration and support of the final prosthesis. Also, the patient was motivated to try and save as much of the tooth as possible. Postoperatively no untoward complication was reported making it an alternative treatment option in patients with VRF in a molar, willing to retain the remaining tooth portion. With all other factors balanced, it allows for retaining the remaining intact portion of the tooth structure.

Management of the sodium hypochlorite accident: a rare but significant complication of root canal treatment.

A 66-year-old female patient presented to the accident and emergency department, 3 h following a dental appointment. Significant right-sided facial swelling, bruising and pain were present. The patient had been sent by her general dental practitioner with a covering letter explaining that a hypochlorite accident had occurred during root canal treatment of the upper right first premolar tooth. An iatrogenic perforation was suspected. The patient was admitted under the care of the maxillofacial team and intravenous antibiotics, analgesia and steroids were administered. The patient was prepared for the possibility of requiring surgical intervention under a general anaesthetic. No nerve injury was encountered and the periorbital tissues were spared. A full recovery was made by the patient with no surgical intervention required but significant bruising and swelling were present up to 4 weeks following the incident.

Accuracy of electronic apex locators to detect root canal perforations with inserted metallic posts: an ex vivo study.

INTRODUCTION: The detection of possible root canal perforations caused during a metal post placement is frequently difficult to diagnose. The aim of this study was to investigate the accuracy of apex locators to diagnose such perforations. MATERIALS AND METHODS: Thirty mesiolingual root canals of extracted mandibular molars were instrumented (30/.04) and a post space was prepared. A root canal perforation was intentionally made at the bi-furcation (n = 15). Metal posts were cemented in 15 perforated and 15 non-perforated root canals. The teeth roots were embedded in an agar-agar solution. The resulting measurements ("short" or "beyond" the apex) disclosed if a perforation could be identified with five different apex locators (ProPex II, Elements Apex Locator, Apex NRG, Raypex 5 and Raypex 6). The sensitivity and specificity (95% interval confidence) were calculated. RESULTS: All devices excluded the absence of perforations (100% with 95% confidence interval [78%; 100%] specificity). The Apex NRG and Raypex 6 detected all perforations (100% with 95% confidence interval [78%; 100%] sensitivity). The ProPex II, Elements Apex Locator, and Raypex 5 detected 14 out of 15 perforations (93% with 95% confidence interval [68%; 100%] sensitivity). CONCLUSIONS: All devices determined root canal perforations, due to metallic posts, within clinical acceptable ranges.

Morphological analysis of apical foramen over-instrumented by three rotary NiTi systems.

OBJECTIVE: To evaluate morphological changes of the apical surface after root canal preparation with 1 mm beyond the apical foramen using ProTaper Universal (PTU) files, K3 files and Twisted files (TF), respectively. METHODS: Seventy teeth with a centered apical foramen and 70 teeth with a deviated apical foramen were included as group A and group B respectively. In each group, 20 teeth were randomly assigned for root canal preparation with PTU, K3 and TF files, respectively; the remaining 10 teeth were used as the control group without any preparation. The apical foramens were examined with scanning electronic microscopy. The foramen integrity damage (FID) and dentin defects (DDs) were noted and compared between different groups. RESULTS: FID and DD were significantly less in Group A. DDs was not found in the control group. Preparation with PTU, K3, and TF files caused FID in 6.67%, 10%, and 3.33% of teeth in the group A, and in 20%, 26.67%, and 10% in Group B, respectively. Preparation with PTU, K3, and TF files caused DD in 6.67%, 6.67%, and 3.33% of teeth in Group A, and in 23.33%, 26.67%, and 6.67% in Group B, respectively. PTU and K3 files produced more DDS than TF files. However, no significant difference was found between groups using PTU and K3 files. CONCLUSION: Rotary instrumentation caused less damage on the apical surface in foramencentered root canals than foramen-deviated root canals when working beyond the canal length. TF files had a tendency to produce less DDS compared with PTU or K3 files during over-instrumented root canals.

Repair of apical root resorption associated with periodontitis using a new intracanal medicament protocol.

Endodontic therapy is indicated for cases of traumatic tooth dislocation associated with pulp necrosis and/or inflammatory resorption. Here we describe the management of a maxillary left lateral permanent incisor that suffered lateral luxation, leading to pulp necrosis and root resorption, in a 13-year-old boy. The traumatized tooth was treated successfully by intracanal medication with calcium hydroxide, 2% chlorhexidine gel and zinc oxide for 12 months without any need to change the dressing, followed by conventional root canal filling. The postoperative course was uneventful and a stable clinical outcome was obtained with evidence of periapical lesion repair and stabilization of the resorption process.

Histologic evaluation of the effects of Emdogain gel on injured root apex in rats.

INTRODUCTION: This study investigated the effects of Emdogain gel (EMD) on the injured open apex within periapical lesions. METHODS: Periapical lesions were induced in rats by opening the pulp chambers of the mandibular first molars and filing the apical foramen through the distal root canal with #25 K-files to make an open apex. The teeth were exposed to the oral environment for 7 days. Then we irrigated the distal root canals and divided them into EMD-treated and propylene glycol alginate-treated groups. The rats were killed 7, 14, and 28 days after treatment and examined histochemically. RESULTS: In the EMD-treated rats, more cells expressed transforming growth factor-ß1 or bone morphogenetic protein-2 at 7 days after treatment, and the regeneration of cementum and bone was observed around the root apex at 14 days after treatment. Conversely, in the propylene glycol alginate-treated group, few cells expressed transforming growth factor-ß1 or bone morphogenetic protein-2, and apical periodontal tissue recovery was rarely seen within the periapical lesions throughout the experiment. CONCLUSIONS: These results suggest that EMD does not irritate injured periapical tissue and may create a favorable environment that promotes the healing of destroyed periapical tissues.

Lack of causal relationship between dentinal microcracks and root canal preparation with reciprocation systems.

INTRODUCTION: This study aimed to evaluate the frequency of dentinal microcracks observed after root canal preparation with 2 reciprocating and a conventional full-sequence rotary system using micro-computed tomographic analysis. METHODS: Thirty mesial roots of mandibular molars presenting a type II Vertucci canal configuration were scanned at an isotropic resolution of 14.16 µm. The sample was randomly assigned to 3 experimental groups (n = 10) according to the system used for the root canal preparation: group A-Reciproc (VDW, Munich, Germany), group B-WaveOne (Dentsply Maillefer, Baillagues, Switzerland), and group C-BioRaCe (FKG Dentaire, La-Chaux-de-Fonds, Switzerland). Second and third scans were taken after the root canals were prepared with instruments sizes 25 and 40, respectively. Then, pre- and postoperative cross-section images of the roots (N = 65,340) were screened to identify the presence of dentinal defects. RESULTS: Dentinal microcracks were observed in 8.72% (n = 5697), 11.01% (n = 7197), and 7.91% (n = 5169) of the cross-sections from groups A (Reciproc), B (WaveOne), and C (BioRaCe), respectively. All dentinal defects identified in the postoperative cross-sections were also observed in the corresponding preoperative images. CONCLUSIONS: No causal relationship between dentinal microcrack formation and canal preparation procedures with Reciproc, WaveOne, and BioRaCe systems was observed.