Dentinal Crack Research Articles

Assessment of Debris Apical Extrusion, Unprepared Surface Areas, and Dentinal Crack Formation after Root Canal Preparation Using ProTaper Next, ProTaper Ultimate, and R-Motion File Systems

This study evaluated and compared the amount of apically extruded debris, unprepared wall surface areas, and dentinal crack formation resulting from root canal preparation using ProTaper Next (PTN), ProTaper Ultimate (PTU), and R-Motion (RM) file systems. Forty-five palatal roots of maxillary first molars were shortened to a uniform length of 12mm. The samples were divided randomly into three groups (n = 15/group) to be prepared using either PTN, PTU, and RM file systems. The investigator adopted modified Myers and Montgomery's approach to replicate the temperature of the human body. Debris was collected in vials and weighed before and after instrumentation with a sensitive balance. Every specimen was irrigated using distilled water during preparation, utilizing a side-vented needle. Weight before instrumentation was subtracted from weight after instrumentation to identify the weight of the collected debris. CBCT scans were taken before and after canal preparation using a Planmeca ProMax CBCT machine. The unprepared canal surface area was calculated by superimposing preoperative and postoperative CBCT images using the Mimics Medical program. After preparation, a low-speed diamond disc horizontally sectioned the roots at three, six, and nine millimeters from the apex. The specimens were examined under a digital microscope to detect crack formation. Statistical analysis was carried out using one-way (ANOVA) and Tukey (HSD) tests, with a significance level of p<0.05. There was no statistically significant difference in the quantity of debris extruded apically and dentinal crack numbers between the three shaping files (p > 0.05). Only the apical third of root canals prepared by PTU displayed a significantly lower unprepared surface area compared to PTN and RM. Instrumentation with PTN, PTU, and RM yielded similar amounts of apically extruded debris and dentinal cracks. The PTU files demonstrated higher effectiveness in preparing the apical third by reducing the unprepared surface area in the prepared root canal.

Comparative Evaluation of Microcrack Formation by K Files Using Mechanical Technique with Help of Reciprocating Contra-Angle Handpiece and Manual Technique: An Invitro Study

Introduction Effective root canal preparation is essential for successful treatment, focusing on thorough cleaning and shaping to prevent complications like vertical root fractures. Different tools, such as stainless steel and nickel-titanium files, offer advantages and drawbacks, impacting the risk of dentinal microcracks. This study examines the incidence of these cracks using both manual and reciprocating techniques with K files.  Material and Method This study involved 150 mandibular premolars, divided into five groups to evaluate dentinal crack formation with different file systems. Groups included manual and mechanical instrumentation with stainless steel (S.S.) and nickel-titanium (NiTi) files, with one control group. After standard root canal preparation and irrigation, each root was sectioned and examined under a stereomicroscope to document crack formation. Data was analysed using Chi-square test, and Fisher's Exact test.  Result There is no statistical significant difference among groups.  Conclusion Maintaining root integrity in root canal treatment is vital, with similar crack formation seen in both manual and reciprocating techniques. Reciprocating handpieces offer a cost-effective, efficient option, beneficial for student training in modern endodontics.

Dentinal Crack Formation Induced by Ultrasonic Tips and Laser as Compared to Conventional Burs During Root-end Preparation: A Systematic Review and Meta-analysis

Aim: The objective was to evaluate and compare the crack formation induced by ultrasonic tips and lasers with conventional burs during root-end preparation. Materials and Methods: The PROSPERO registration code for this study is CRD42023470898. Both manual and electronic database searches were performed up to 2023, August in three databases, namely, the Cochrane Library, PubMed and Google Scholar. In vitro or laboratory studies that employed the use of ultrasonic tips, LASER and conventional burs for root-end preparation on extracted teeth were collected. The data were extracted by two independent reviewers using a predesigned template. Information about the study design, year, full-text publications, inclusion and exclusion criteria were gathered. The PRISMA guidelines 2020 were followed in the reporting and execution of the systematic review and meta-analysis. To evaluate statistical heterogeneity, χ² values and I² values were employed in conjunction with a random-effects model for the meta-analysis. Results: A total of 689 articles were identified. After removing the duplicates in total 567 articles were screened. Finally, six articles were included in the meta-analysis. QUIN Risk of Bias tool showed an overall moderate risk of bias in the included studies. The pooled odds ratio for crack formation was 1.77 (0.82, 3.82) for ultrasonic tips and conventional burs suggesting higher odds of crack formation for ultrasonic tips. Conclusion: None of the included studies provided information on sample size calculation, sampling technique, randomization or blinding. The meta-analysis suggests higher chances of crack formation from ultrasonic followed by laser and conventional burs preparation. Therefore, efforts to standardize an acceptable procedure for root-end cavity preparation should be made in future study, along with encouragement of the clinical application of the same, taking into account issues like economic feasibility and convenience of usage.

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

Background and objectives: Root canal preparation following obturation with rotary instruments and different obturation techniques may lead to formation of microcracks in the root canal wall, void and gaps between the canal wall and obturation material. Aim: This study aimed to evaluate dentinal microcracks and voids formation after using two different files TruNatomy (TRN) and Genius (GN) and two obturation techniques Single Cone (SC) and GuttaCore (GC) using Microcomputed tomography scan (micro-CT). Methods: 40 extracted mandibular premolars were decoronated, leaving 13mm roots. The roots were randomly divided into two main groups TRN and GN ((n=20)) according to instrumentation, afterwards each group subdivided into two subgroups ((n=10)) according to obturation techniques. The root canals instrumented with TRN and GN file and obturated with Single Cone (SC) and GuttaCore (GC) obturation techniques. AH Plus sealer was used in all groups. The specimens were scanned with Micro-CT before and after root canal preparation and after obturation. subsequently, all pre-and postoperative cross-sectional images of the roots were screened to identify the presence of dentinal defects. Furthermore, the percentage of voids volume calculated. Data were analyzed statistically to determine difference between groups, the level of statistical significance was at p &lt; 0.05. Results: GN revealed the least number of microcracks. There were no significant differences between groups in the incidence of dentinal microcracks. The highest percentage of filling material was observed in GC groups. There were significant differences between the obturation groups in the number of voids present after obturation (P &lt; 0.001). Conclusion: The instrumentation of root canals induces dentinal microcracks. Obturation have no effect on the formation of cracks. None of the root canal filling procedures yield fillings that are void-free. Keywords: Dentinal crack, Voids, Micro CT, Guttacore, Singlecone, TruNatomy, Genius.

Comparative evaluation of the effects of different torque settings on dentinal crack formation using single- and multi-file system: An in vitro study.

To improve efficiency, biomechanical preparation in root canal treatment is shifting from manual SS to nickel-titanium (NiTi) rotary devices. While multi-file NiTi systems entail crack and fracture issues, modern single-file systems address these concerns. The aim of this study was to evaluate and compare the effects of different torque settings on dentinal crack formation using single-file systems (SFS) (One Curve [OC]) and multi-file systems (ProTaper Next [PTN]) at different levels of the tooth. The study was conducted on 45 freshly extracted human mandibular premolars divided into groups: OC at minimal and maximal torque, PTN at minimal and maximal torque, and a control group. After canal preparation, teeth were horizontally sectioned at 3, 6, and 9 mm from the apex, and then examined for cracks using a stereomicroscope. This was analyzed using Chi-square test. PTN group: Highest crack rates at the middle (55.6%) and apical (77.8%) thirds with maximum torque; OC group: Highest rates at the middle (22.2%) with minimal torque and apical (11.1%) with maximum torque. Maximal torque settings had more incidence of cracks compared to minimal torque settings. It can be stated that SFS (OC) produced less cracks compared to multi-file system (PTN) at both minimal and maximal torque settings.

Evaluation of Canal-centering Ability and Apical Transportation of Hyflex-EDM, OneShape, WaveOne Gold, and Reciproc Files: An Ex Vivo Study.

To evaluate and compare canal-centering ability (CCA), canal transportation (CT), and dentinal crack formation by using Hyflex-electrical discharge machining (EDM), OneShape, WaveOne Gold, and Reciproc single file system in the mesiobuccal root of maxillary first molar at coronal, middle, and apical third using cone-beam computed tomography (CBCT) and scanning electron microscopy (SEM). Mesiobuccal roots of 120 freshly extracted maxillary molar teeth were divided into four experimental groups; Hyflex-EDM, OneShape, WaveOne Gold, and Reciproc (n = 30/group). Preinstrumentation scanning was done using CBCT for all samples at coronal one-third (4 mm), middle one-third (8 mm), and apical one-third (12 mm). After cleaning and shaping with standard irrigation protocol, the specimens were again scanned. Canal-centering ability and CT were calculated using pre- and postinstrumentation CBCT values. A scanning electron microscope was used to identify dentinal crack formation. No significant difference was found for CCA by any of the systems at coronal, middle, and apical third, respectively. However, OneShape was found to have better CCA at the coronal third and WaveOne Gold at the middle and apical third. There was a significant difference in canal transportation at the apical third (p = 0.004) with WaveOne Gold having the least CT followed by Reciproc at the apical third. OneShape resulted in more dentinal cracks in the coronal and middle thirds. Also, Hyflex-EDM was better in the apical third. No difference in CCA was observed between the groups. The lowest values for CT were obtained for WaveOne Gold (similar to Reciproc) whereas both rotary files showed higher values for CT. Also, OneShape showed the most dentinal at all levels. Furthermore, Hyflex-EDM and WaveOne Gold produced the least dentinal cracks at all levels. Given that the Reciprocating file system had the least CT and least dentinal cracks, the clinical success rate of root canal treatment (RCT) with the Reciprocating file system can be a better choice to improve the longevity of root canal-treated teeth.

Dentinal Microcracks after Root Canal Preparation in Primary Root: An In Vitro Evaluation of ProTaper Gold and Kedo-S Rotary File Systems.

There is a possibility of dentinal crack formation in primary teeth after root canal preparation using rotary files. To evaluate and compare the effect of ProTaper-Gold and Kedo-S rotary files on crack formation after root canal preparation in primary molars. A total of 120 freshly extracted mandibular primary molars (6-9 years) were randomly divided into three groups of 40 each: ProTaper-Gold, Kedo-S, and Hand H-files, respectively. The roots were covered with a snuggly fitting surgical glove and stabilized in the teeth slot of a silicone mold of mandibular mixed dentition. Dental casts were obtained in a mixture of plaster of paris and sawdust. A screw system was incorporated in the cast for stabilization of the cast into the phantom head. All the root canals were instrumented in a standard operating position till 1 mm short of the radiographic apex. All roots were then stained and sectioned perpendicular to the long axis at the furcation level and 2 mm below the furcation to obtain one section per tooth. Sections were examined under a stereomicroscope at 25× magnification for any crack formations and recorded. Data were analyzed using Wilcoxon signed-rank and Kruskal-Wallis tests (p = 0.05). The total number of cracks in terms of percentage following the use of ProTaper Gold, Kedo-S, and H-files were 35, 10, and 0%, respectively, on the upper surface and 15, 5, and 0% on the lower surface. Within the group, there was a statistically significant difference in ProTaper-Gold (p = 0.001). The use of ProTaper-Gold resulted in a greater number of dentinal cracks compared to Kedo-S and H-files. Patil MB, Mandroli PS, Jalannavar P, et al. Dentinal Microcracks after Root Canal Preparation in Primary Root: An In Vitro Evaluation of ProTaper Gold and Kedo-S Rotary File Systems. Int J Clin Pediatr Dent 2023;16(5):692-697.

Comparison of Root Dentinal Crack Formation after Coronal Pre-Flaring using Different Rotary Instruments: An In vitro Study.

The aim of this study was to see the incidence of cracks in root dentin after coronal flaring using various rotary instruments such as Gates Glidden (GG) drills, ProTaper Universal SX, OneFlare, and HyFlex EDM. Seventy freshly extracted premolar teeth with single canal were collected. All the teeth were randomly divided into five groups of fourteen each (n = 14), of which one group served as the control and the rest of the four groups were instrumented with GG drills, ProTaper Universal SX, OneFlare, and HyFlex EDM, respectively. The GG drills resulted in a higher rate of crack formation in root dentin (P < 0.05) than the ProTaper Universal SX, OneFlare, and HyFlex EDM instruments (P > 0.05). The use of GG drills resulted in more crack formation. However, the results for the ProTaper Universal SX, OneFlare, and HyFlex EDM flaring instruments were less in terms of crack formation.

Effect of Different Nickel–Titanium Rotary Systems on Dentinal Crack Formation During Root Canal Preparation in Primary Molars: An in Vitro Study

Effect of Different Nickel–Titanium Rotary Systems on Dentinal Crack Formation During Root Canal Preparation in Primary Molars: An in Vitro Study

Influence of Optimum Torque Reverse Motion on Dentinal Cracks after Root Canal Preparation with Two Nickel-Titanium Rotary Systems.

Objectives:This study was aimed to evaluate the cause-effect relationship between canal preparation with ProTaper Next (PTN) and ProTaper Gold (PTG) using optimum torque reverse (OTR) motion or continuous rotation and dentinal crack formation.Materials and Methods:Fifty distobuccal roots of human maxillary first molars were divided into five groups; Group I: PTG Full rotation, Group II: PTG in OTR, Group III: PTN Full rotation, Group IV: PTN in OTR, Group V: unprepared (control group). After mechanical preparation, the distobuccal roots were sectioned horizontally at 3, 6, and 9 mm from the apex. Images were captured using a stereomicroscope at 25X to determine the presence or absence of dentinal cracks. Friedman test was used to compare between root sections followed by Wilcoxon signed-rank test for pairwise comparison. Kruskal–Wallis test was used to compare between tested rotary systems followed by pairwise comparison with Dunn Bonferroni correction (α = 0.05).Results:Crack development was significantly higher in PTG using OTR motion 36.7% followed by PTN using OTR 33.3%, while the control group showed no cracks. PTG and PTN with full rotation showed crack development with 23.3% and 13.3%, respectively.Conclusions:The type of motion kinematics used during mechanical preparation have an impact on dentinal crack formation. Nickel-titanium instruments with larger taper tend to induce more cracks.

Evaluation of dentinal crack propagation, amount of gutta percha remaining and time required during removal of gutta percha using two different rotary instruments and hand instruments - An In vitro study.

One of the most important goal of non surgical endodontic retreatment is the successful removal of gutta percha and sealers from the root canal system. A variety of techniques have been recommended for retreatment procedures for the removal of gutta-percha and sealers with or without the help of adjunctive chemical solvents, by using stainless steel hand files or nickel-titanium rotary files, gate glidden burs, heated instruments, ultrasonic instruments, and lasers 1,3. The current advancements in the design of NiTi instruments have proved efficacious in the removal of filling materials from the root canal wall and various studies have also confirmed their cleaning ability and efficacy 4,5. Nevertheless, the use of rotary instrumentation can lead to the formation of dentinal cracks in the root canal dentin. Many researchers have reported the incidence of crack formation and propagation after the procedure with manual, rotary and reciprocating instruments. The behavior of rotary instruments in the generation of defects have been the point of greatest interest during many years 6. These dentinal cracks can be defined as defects with a complete crack line extending from inner root canal space up to the outer surface of the root when the tensile stress in the root canal wall exceeds the tensile stress of dentin 7. This study was conducted to investigate and to compare the amount of dentinal microcracks formation with various new instrumentation methods and conventional hand filing method. It also looks into amount of gutta-percha removed after retreatment from the canal and the time required for all the instrumentation technique. Sixty extracted human maxillary first molars with curved roots were mounted on addition silicone impression material incorporated in an aluminium hollow block, then instrumented using step-back preparation with 35 size K files. Obturation was done using gutta-percha with AH plus sealer. These were stored for 14 days and divided into three groups Mani GPR, Endostar Re Endo and H file and were subjected to retreatment procedures. Retreatment was considered complete when no filling material was observed on the canal wall and the canal was smooth and free of visible debris. The samples were examined under scanning electron microscope and the number of cracks were calculated. The percentage of root canal filling material and time taken was recorded. The data obtained were analyzed by using descriptive statistics, ANOVA (Analysis of Variance), chi-square test and Scheffe's post hoc test through SPSS for window (version 22.0). All the techniques showed similar amount of crack propagation, with no statistical difference between the group. Retreatment done using H Files required more time and removed less material. The coronal third showed less amount of gutta-percha remnants than the apical third in all groups. All the groups showed a similar amount of crack propagation. Less number of cracks were observed in the coronal one third and more amount of cracks were found at the apical third. Endostar RE Endo rotary instrument proved to be most effective and least time-consuming. Hedstrom Files required more time and removed less material.

EVALUATION OF DENTINAL CRACKS AFTER ROOT CANAL INSTRUMENTATION WITH FOUR DIFFERENT ROTARY NITI FILE SYSTEMS: PROTAPER UNIVERSAL, PROTAPER NEXT, HYFLEX-CM AND WAVE-ONE

Introduction: Aim of the study was to observe and compare the dentinal cracks caused by instrumentation of root canal with rotary Protaper Universal, Protaper Next, Hyex CM and WaveOne systems. Methods: One hundred ten mandibular premolars with mature apex and straight single canals (&lt;10°) were selected and stored in distilled water. Root canals were divided into control (uninstrumented) group (n=10), 4 experimental groups (n=25) instrumented with Protaper Universal, Protaper Next, Hyex CM, and WaveOne. Root canals were stained with 1% methylene blue dye and horizontal sectioning was done at 3mm, 6mm and 9mm from apex and viewed under 30-fold magnication of stereomicroscope and digital images were captured using camera attached to it to determine presence of dentinal cracks. Data was analysed using chi-square test. Results: The control group showed no cracks. All experimental groups showed presence of dentinal cracks. There were signicant difference between Protaper Universal group and Control, Hyex CM and WaveOne group (p&lt;0.05) with Protaper universal group showing maximum cracks and Hyex CM and Wave One showing least number of cracks. No signicant difference was found between Protaper Next, Hyex CM and WaveOne group (p&gt;0.05). Conclusion: Within limitations of the study, it can be concluded that Protaper Universal, Protaper Next, Hyex CM and WaveOne systems results in dentinal crack formation after instrumentation in roots canals

Farklı Taperlı Koronal Genişletme Enstrümanlarının Rotasyonel ve Resiprokal Tek Eğe Sistemlerindeki Dentin Çatlağı Oluşumuna Etkisinin İncelenmesi: İn Vitro Çalışma

Objective: The purpose of this study was to evaluate the effect of using single-file with different tapered coronal flaring files on dentinal crack. Material and Methods: Human extracted mandibular premolars (n=128) were selected and divided into four groups (n=32) based on the coronal flaring instruments; Group 1, One Flare; Group 2, Endoflare; Group 3, Gates Glidden Drills; Group 4, Control Group. Specimens divided into four subgroups based on the single file system (n=8): Subgroup A, HyFlex EDM: Subgroup B, Reciproc Blue: Subgroup C, One Shape: Subgroup D, WaveOne Gold. All roots were then sectioned at 3, 6, and 9 mm from the apex. The sections were inspected under a stereo-microscope at 2.5X and 5X to determine the presence of microcracks. The data were analyzed using the chi-square test (p=0.05). Results: There was no statistically significant difference between the distributions of dentinal cracks caused by the use of single-file systems with different coronal flaring files (p>0.05). There was no statistically significant difference between the distributions of dentinal cracks according to single file systems (p>0.05). There was also no statistically significant difference between the distributions of dentinal cracks according to coronal flaring files (p>0.05). Conclusion: The use of coronal flaring instruments combinations with single file systems reduced the observation of dentin cracks. One Flare files caused less dentinal cracks than the other instruments test.

Dentinal microcracks induced by endodontic procedures: A scientometric and bibliometric analysis.

Background:Due to the large number of publications relating the occurrence of dental microcracks to endodontic procedures, this bibliometric study evaluated the scientific pattern and trends in literature and provided an overview of scientific production in this context.Aim:To analyze, quantify, and characterize the scientific production and trends of published articles evaluating dentinal microcracks formation after endodontic treatment procedures between 2010 and 2020 using bibliometric indicators.Materials and Methods:Published articles were found by the search in the Medline (PubMed) and Scopus database using the combination of the following keywords: Dentinal crack OR Dentinal Microcrack OR Crack formation OR Dentin Defect AND Endodontic treatment OR Root canal preparation OR Canal Preparation OR Root canal treatment OR endodontic procedures. The search was also conducted in the Journal of Endodontics and International Endodontic Journal. After inclusion and exclusion criteria application, data from all studies included were collected.Results:Among the 556 results after the search, 45 studies were included and analyzed in this bibliometry. No trend was observed in terms of the increasing number of articles over time. Most of them used an in vitro design, compared the effect of different endodontic techniques/systems for root canal instrumentation on dentinal microcracks formation, and were conducted in Turkey, Brazil, and India. Journal of Endodontics and International Endodontic Journal were the main journals with a higher number of articles published. Interestingly, studies conducted with some funding did not lead to higher citation numbers. Moreover, a relevant proportion of studies did not consider the inclusion of control groups, baseline evaluation, or statistical analysis. Micro-CT was the main technique used to evaluate microcrack presence.Conclusion:Microcrack formation after the use of different endodontic techniques/systems has been constantly evaluated in the literature. There is a pattern of methodologies used, which may explain the concentration of these studies in specific journals and countries.

An in vitro comparative evaluation of dentinal crack formation caused by three different nickel-titanium rotary file systems in primary anterior teeth.

Cleaning and shaping of the canals damages the root dentin which becomes a gateway to dentinal cracks and thereby causes failure of the treatment. The aim of this study was to assess and compare dentinal crack formation caused by three different nickel-titanium (NiTi) rotary file systems in primary anterior teeth. The present in vitro study is an experimental, comparative study. One hundred fifty extracted primary anterior teeth were included in this study. The teeth were randomly divided into five groups. Group 1: Pedoflex rotary file system, Group 2: Prime Pedo™ rotary file system, Group 3: Kedo-S2 rotary file system, Group 4: K-files, and Group 5: no instrumentation. Roots were sectioned and viewed under a stereomicroscope for the presence of any cracks. The data were analyzed using the Chi-square test and Kruskal-Wallis test. In the coronal, middle, and apical thirds, Group 2 showed a maximum number of crack formations in the middle third (57%), followed by Group 3 (43.3%) and Group 1 (36.7%). Groups 4 and 5 showed no crack formation in all the root sections. The middle third showed a maximum number of crack formations compared to the coronal and apical thirds. Rotary systems render various benefits with an acceptable success in comparison to conventional hand instrumentation. Within the limitation of this study, it was found that Pedoflex rotary file system was the best with the least number of crack formations.

Effect of RaCe, ProTaper, and V-Taper rotary systems on dentinal crack formation during endodontic treatment: An in vitro study.

Background. Prevention of dentinal crack formation is of utmost importance in endodontic treatment. This study aimed to evaluate the effect of RaCe, ProTaper, and V-Taper rotary systems on dentinal crack formation in three root regions during endodontic treatment. Methods. Seventy human mandibular first molars were selected randomly, and their distal roots were used. Ten samples were assigned to the control group, and sixty samples were assigned to three groups (n=20). Each group was prepared with RaCe, ProTaper, or V-Taper rotary files according to the manufacturers’ instructions. A stereomicroscope was used to view cracks at ×40 magnification. Friedman’s, chi-squared, and Kruskal-Wallis tests were used for statistical analysis of data (P < 0.05). Results. A comparison of the three rotary systems did not reveal any significant differences in the number of cracks between the three root thirds evaluated (P > 0.05). A comparison of the number of cracks in the coronal, middle, and apical thirds in each rotary system showed that the number of cracks in the middle third was fewer than that in the two other thirds only in the V-Taper group (P < 0.05), with no significant differences in the ProTaper and RaCe groups between the different root regions (P > 0.05). Conclusion. The application of RaCe, ProTaper, and V-Taper rotary files resulted in a similar rate of crack formation in endodontic treatment. V-Taper files created the minimum number of cracks in the middle third.

Incidence of dentinal crack formation after root canal preparation using different rotary files

Incidence of dentinal crack formation after root canal preparation using different rotary files

Effect of rotary systems and root canal preparation and dentin crack formation

Evidence indicates that root canal preparation is a critical step upon which the prognosis of the endodontic treatment depends. Vertical root fractures can furtherly develop as propagations from the previously formed dentin cracks. Therefore, root canal preparation should be carefully approached with the minimal crack formation and careful dentin removal. Different modalities have been proposed in the literature and rotary systems are most commonly used nowadays. Although the reported efficacy of these modalities is high, evidence shows that they are usually associated with a considerable risk of crack formation. In the present literature review, we have discussed the effects of rotary instrumentation and root canal preparation on dentinal crack formation based on evidence from the different studies in the literature. Our evidence showed that all of the investigated approaches to prepare root canals adequately can result in crack formation. The different rotary instrumentations also showed variable frequencies of developing dentinal cracks, and evidence from some comparative investigations shows that ProTaper modalities are associated with the least frequencies of the events. However, to make a solid conclusion for clinical practice, further research is still needed to validate our current evidence.

Stereomicroscopic Evaluation of Microcrack Formation in Dentin by ProTaper Next, Revo S, and WaveOne Gold File System.

Background:During the biomechanical preparation of the root canal by rotary file systems, stress is generated within the canal, which leads to dentinal microcrack formation. Such defects are evaluated only under the microscope.Aim:The present study aimed to evaluate dentinal microcrack formation after instrumentation with ProTaper Next (M-wire), Revo S (conventional NiTi), and WaveOne Gold (Gold-wire) file systems under the stereomicroscope.Materials and Methods:Forty single-rooted teeth free from any defect were selected and divided into four groups (Control, PTN, RS, and WOG). Experimental groups were instrumented with file system used in the study, and the control group were left unprepared. Samples were further decoronated and sectioned at 3 mm, 6 mm, and 9 mm from the apex perpendicular to the long axis and examined under a stereomicroscope at ×25 for different types of microcracks (no fracture, complete fracture, partial fracture, and other fracture).Statistical Analysis Used:Data analysis was done by the Chi-square test using the SPSS version 17.0 software. A two-sided (α = 2) P < 0.05 (P < 0.05) was considered statistically significant.Results:The null hypothesis was rejected. There was a statistically significant difference between the groups. All file systems created microcracks in the root dentin. WOG group showed an incidence of 66.7% for no fracture, PTN group had 40% for other fracture, and RS group had 60% for complete fracture.Conclusion:Single file system WOG with gold wire technology proves to be the best choice for canal preparation among the tested groups in terms of least dentinal crack formation.

English

BACKGROUND Advances in root canal instruments have led to lesser frequency of dentinal crack formation. Not many studies have been reported in literature that compare crack formation using instruments based on control memory (CM) and M wire technology. The study intended to evaluate and compare the prevalence of dentinal cracks formed by ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland), HyFlex CM (Coltene, Whaldent) and Wave One (Dentsply, Maillefer) reciprocating file systems at the apical and middle third of the mesiobuccal root canal of mandibular molars under scanning electron microscope (SEM). METHODS Forty-five extracted sound human mandibular molars were decoronated and mesial roots were retained followed by root canal instrumentation using ProTaper Next, HyFlex CM and WaveOne reciprocating files. Roots were then sectioned perpendicular to the long axis of teeth and viewed under scanning electron microscope to detect the presence of cracks. RESULTS ProTaper Next system produced more cracks compared with HyFlex and Wave One (P &lt; 0.05) but there was no statistically significant difference between all the three groups. All the file systems showed more incidences of cracks in the apical third compared to middle third. CONCLUSIONS All the NiTi instruments produced cracks and the highest incidence of cracks was seen in the apical third compared to middle third region. KEY WORDS Dentinal Cracks, HyFlex CM, ProTaper Next, Root Canal, Wave One