NiTi Rotary Systems Research Articles

Shaping ability of ProTaper Gold and ProTaper Universal files by using cone-beam computed tomography.

This study evaluated and compared the shaping ability of ProTaper Gold (PG) (PG; Dentsply, Tulsa Dental Specialties, Tulsa, OK, USA) system with ProTaper Universal (PU) (PU; Dentsply Maillefer, Ballaigues, Switzerland) using cone-beam computed tomography (CBCT) imaging. Forty mesiobuccal canals of mandibular first molars with curvatures of 25-30° were divided into two experimental groups (n = 20) according to the rotary nickel-titanium (NiTi) file system used in canal instrumentation as follows: Group PG and group PU. Canals were scanned before and after instrumentation using CBCT scanner to evaluate root canal transportation and centering ratio at 3, 5, and 7 mm from the apex and volumetric changes. Data were statistically analyzed using independent t-tests and the significance level was set at P < 0.05. There was no significant difference between PG and PU systems in the mean volume of removed dentine, canal transportation, and centering ratio (P > 0.05). The PG and PU NiTi rotary systems showed similar root canal shaping abilities in the preparation of mesial canals of mandibular first molars.

Scanning Electron Microscopic Evaluation of Root Canal Walls after shaping with Different Single-use Rotary Systems

ABSTRACT The aim of the present study was to investigate the cleaning efficacy of four new single-use rotary nickel–titanium (NiTi) systems. A total of 48 single-rooted freshly extracted teeth were divided into four groups. Root canals were shaped with the single-use NiTi systems (ProTaper Next, F360, OneShape and F6 SkyTaper) using 5.25% NaOCl and 17% ethylenediaminetetraacetic acid (EDTA) solutions. Specimens were fractured longitudinally and prepared for scanning electron microscopic (SEM) analysis at standard magnification of 2,500?. The presence/absence of debris smear layer and smear layer at coronal, middle, and apical third of each canal were evaluated using a five-step scale for scores. Numeric data were analyzed using Kruskal–Wallis and Mann–Whitney U statistical tests and significance was predetermined at p&lt; 0.05. Analysis of variance test showed no significant differences among the NiTi systems (p &gt; 0.05). The same results were assessed considering the smear layer scores. Analysis of variance confirmed that the apical third of the canal maintained a higher quantity of debris and smear layer after preparation of all the samples. All the single-use rotary NiTi systems left dentinal walls generally free of debris, even if a small amount of smear layer is visible, especially in the apical third of the root canal. All tested single-use systems seem to be effective in removing smear layer from root canals, if irrigating protocols are respected. How to cite this article Dagna A, Gastaldo G, Beltrami R, Bianchi S, Poggio C. Scanning Electron Microscopic Evaluation of Root Canal Walls after shaping with Different Single-use Rotary Systems. Int J Experiment Dent Sci 2016;5(2):93-98.

Shaping ability of single versus multi file rotary Ni-Ti systems in curved root canals

Objectives The aim of this study is to compare the shaping ability (straightening of curved root canals, apical transportation, preparation time) of single and multi-file rotary systems during the preparation of curved root canals in extracted human molar teeth. Methods Sixty mandibular molars were divided according to the instrument used into three groups of 20 teeth each: group PTU (ProTaper Uneiversal), group PTN (ProTaper Next) and group OS (One Shape). Using standardized pre- and post-instrumentation radiographs, straightening of canal curvature was determined using image analysis software. A double-digital standardized radiographic technique was used to determine apical transportation. Preparation time was also recorded. Data were analysed using one-way analysis of variance (ANOVA) and post hoc Tukey's test, and significance was set at P Results During root canal preparation, no instruments fractured. The use of PTN resulted in significantly less canal straightening followed by OS then PT. There were no significant differences between the three groups with respect to apical transportation. PTN were significantly faster than PTU and OS. Conclusion Under the conditions of this study, ProTaper Next Protaper Universal and One Shape instruments respected original canal curvature and were safe to use. Protaper Next was the fastest among them.

Efficacy of three Ni–Ti rotary systems for removal of filling materials from root canal system of extracted teeth

ObjectivesThe aim of the present laboratory study was to evaluate the efficacy of ProTaper Next (PTN) in removing root canal fillings and comparing it with ProTaper Universal (PTU) and ProTaper Retreatment (PTR). MethodsRoot canals in 60 single-rooted teeth were instrumented and obturated with gutta-percha and MTA Fillapex sealer then stored for one week. After that, the samples were divided randomly into three groups according to the instrument used in retreatment. Group 1, retreatment was done using ProTaper Retreatment (PTR), Group 2, retreatment was done using ProTaper Universal (PTU), and Group 3, retreatment was done using ProTaper Next (PTN). The total time required to achieve the end-point of root filling removal was recorded for each sample. Roots were split longitudinally, canals were observed using a stereomicroscope at 10×. The images were subjected to morphometric analysis to assess the amount of remaining root filling material. Statistical analysis was performed by ANOVA and Tukey's honest significance difference post hoc tests were run on the data to determine significant differences between the groups. ResultsPTN showed the shortest time for removal of the root canal filling material followed by PTR then PTU which had the longest time. PTN produced a statistically significantly lower remaining filling material in both middle and apical third when compared to the other two systems. However, both PTU and PTR produced statistically significantly less remaining debris in the coronal third. ConclusionProTaper Next was efficient in removal of gutta-percha and MTA Fillapex root canal sealer.

Cone-beam Computed Tomographic Analysis: Comparison of the Efficacy of Two Rotary Retreatment Systems for Removal of Filling Material from Primary Teeth Obturated with Contemporary Endodontic Sealers

ABSTRACT Introduction This study has used cone-beam computed tomography (CBCT) to evaluate the efficacy of two different nickel titanium (NiTi) rotary retreatment systems for removal of filling material from teeth obturated with contemporary endodontic sealers. The operative time required for removal of root filling materials was also evaluated. Methods Sixty root canals were randomly divided into three groups according to the sealer used for obturation: AH Plus Jet, mineral trioxide aggregate (MTA) Fillapex, and RoekoSeal Automix (RSA) (all, n = 20). After obturation, each group was subdivided into two subgroups according to the NiTi retreatment rotary system: Mtwo retreatment (Mtwo-R) file subgroup and ProTaper-UR subgroup—both instrumented with Mtwo-R files. Teeth were scanned with a microcomputed tomography before and after obturation. Results Residual filling material was observed in 100% of the specimens after retreatment. No difference was found between Mtwo-R and ProTaper-UR systems (p &gt; 0.05). The RSA was more effectively removed from dentin walls than AH Plus Jet (p &lt; 0.05), with no difference to MTA Fillapex (p &gt; 0.05). Thus, teeth obturated with RSA required less operative time to be retreated (both, p&lt;0.05). Conclusion ProTaper-UR and Mtwo-R systems were effective in removing the filling materials after instrumentation, but they could not eliminate them completely. Moreover, teeth obturated with silicone-based sealer RSA showed less residual filling material in dentin walls compared to the epoxy resin-based sealer (AH Plus Jet), which exhibited no difference compared to the salicylate resin-based sealer (MTA Fillapex). Teeth obturated with silicon-based sealer also required less operative time to be retreated despite the NiTi rotary retreatment system tested. How to cite this article Moreira CS, Martinho FC, Coelho MPB, Júnior LRMC, da Silva EG, Torres CRG, Gomes APM. Cone-beam Computed Tomographic Analysis: Comparison of the Efficacy of Two Rotary Retreatment Systems for Removal of Filling Material from Primary Teeth Obturated with Contemporary Endodontic Sealers. World J Dent 2015;6(3):129-137.

Efficacy of NiTi rotary systems cleaning process compared to manual instruments in narrow and flattened root canals

Efficacy of NiTi rotary systems cleaning process compared to manual instruments in narrow and flattened root canals

Single File Niti-Rotary Systems

The cleaning and shaping of root canals is a major step in root canal treatment procedure, which aims at removal of all the tissue debris from the root canal space while removing the inner layers of root canal dentin. With Nickel titanium (NiTi) rotary instruments this goal is easier to achieve, even in curved root canals. The recently introduced Single file NiTi-rotary systems such as WaveOne, Reciproc, OneShape&F360 claim to be able to completely prepare and clean root canals with only one instrument. Use of single file rotary systems, are cost effective, time saving, reduce instrument fatigue and possible crosscontamination. The purpose of this article is to review single file Niti-Rotary systems for canal preparation.

Root surface strain during canal shaping and its influence on apical microcrack development: a preliminary investigation

To determine the root surface strain (RSS) generated during root canal shaping and its effects on apical microcrack development. Twenty-five extracted human mandibular premolars were selected and decoronated. The teeth were instrumented with either the ProTaper (PT) or WaveOne (WO) (Dentsply Maillefer) NiTi rotary systems (n=10 per group) or used as controls (n=5). Instrumented root canals were enlarged to ProTaper F4 (size 40, 0.06 taper) or using WaveOne LARGE (size 40, 0.08 taper) instruments according to the manufacturer's instructions. An electrical strain gage (KFG02-120-C1-16, Kyowa Dengyo, Tokyo, Japan) was fixed on the proximal root surface and connected to a strain amplifier via a bridge box in order to measure RSS. During canal shaping, the strain output of the amplifier was recorded. The instantaneous RSS induced by each instrument and the maximum RSSs were determined. All teeth were then stained with contrast media and imaged with micro-computed tomography (micro-CT) at an isotropic resolution of 10μm to detect microcracks. The mean maximum RSS values (microstrain) and mean number of microcracks recorded for both groups were tested for statistical significance using Mann-Whitney U-test. Presence/absence of microcracks in both groups was compared by chi-square tests. Increased baseline RSS from strain accumulation during canal shaping was observed, with similar maximum RSS (mean±SD) for PT (416.6±185.1 μstrain) and WO (398.2±163.8 μstrain) (P=0.94). The interevaluator reliability for microcrack detection using micro-CT had a kappa value of 0.998. Compared to the PT group, there was a trend for fewer samples with microcracks in the WO group (P=0.051). On the micro-CT images, apical microcracks were detected in 20 PT and 11 WO samples (P=0.10). The microcracks were observed in the buccolingual direction in all WO and 81% of PT samples. No vertical root fractures were found. The maximum RSS obtained during canal shaping was poorly correlated with the number of microcracks found (R(2) =0.093). Based on these preliminary data, canal shaping appears to cause apical microcracks regardless of the type of rotary instrument motion. Contrast-enhanced micro-CT was able to identify microcracks in roots.

Conservation of dentin thickness in the root canals orifice following two preparation techniques

Objective: The aim of this study was to evaluate the amount of dentine removed after canal preparation using ProTaper (PT) and Greater Taper (GT) rotary instruments. Materials and Methods: Twenty extracted human teeth with single roots were selected and sectioned at the level of CEJ. The roots were distributed in two groups (n= 20) using stratified randomization, and prepared under simulated clinical conditions with ProTaper (PT) and Greater Taper (GT) rotary NiTi system. The pre- and post-preparation photographs were traced and superimposed, dentin thickness was measured at the levels of canal periphery, canal area, tooth area, mesial dentin thickness, distal dentin thickness, buccal dentin thickness and lingual dentin thickness both before and after preparation. Results: The thickness of removed dentin was significantly different between the two preparation techniques (p&lt;0.01) at the level of both tooth and canal area with more conservation for GT system while ProTaper system more conservative at buccolingual width than mesiodistal width, and GT system was more conservative at mesiodistal dimension than buccolingual dimension. Conclusion: GT rotary instrumentation prepares root canals has greater conservation of dentine structure on the overall dimensions of the root, while the ProTaper system is more conservative at buccolingual dimension.

Sword of Endodontist: A Review

AbstractThe last decade has been witness to phenomenal growth in endodontic technology. The introduction of these new technologies has resulted in endodontics becoming easier, faster and most importantly, better. NiTi alloys overall are softer than stainless steel, are not heat treatable, have a low modulus of elasticity (about one fourth to one fifth that ofstainless steel) but a greater strength, are tougher and more resilient, andshow shape memory and superelasticity. The latter two properties arethe main reasons why NiTi alloys have succeeded in endodontics. Thepurpose of this article is to review the design features of different rotary instruments used for pulp space preparation. Important mechanical features include thevariability of taper, rake angle, cross-sectional geometry, tip configuration, design of blades, helical angle and pitch. These design features influence flexibility, cutting efficiency and safety. In this review, design features of commonlyused NiTi rotary systems are summarized.

Antibiofilm activity of three irrigation protocols activated by ultrasonic, diode laser or Er:YAG laser in vitro.

To investigate the impact of three irrigation protocols, activated by three different methods, on mature biofilms of Enterococcus faecalis in vitro. Root canals in 280 single-rooted teeth were instrumented using a rotary Ni-Ti system. Biofilms of E. faecalis were generated based on a previously established protocol. Samples were randomly divided into three experimental (n = 80) and one control (n = 40) group based on the irrigation protocol employed: group 1 (NaOCl + Etidronic acid), 1 : 1 mixture of 6% NaOCl and 18% etidronic acid; group 2 (NaOCl-EDTA), 3% NaOCl followed by 17% EDTA; group 3 (NaOCl-EDTA-NaOCl), 3% NaOCl followed by 17% EDTA and a final flush of 3% NaOCl. Saline served as the control. Samples were further divided into four subgroups (n = 20) based on the activation method: subgroup A, no activation; subgroup B, ultrasonic activation; group C, diode laser; group D, Er:YAG laser. Confocal laser scanning microscopy was used to assess bacterial viability in situ. Root dentine powder was obtained for determining the colony-forming units (CFU mL(-1) ). Data were analysed by appropriate statistical analyses with P = 0.05. All experimental irrigation protocols caused complete destruction of the biofilm in the root canal lumen. Within the dentinal tubules, all groups had a significantly higher percentage of dead bacteria than the saline control (P < 0.05). There was no significant difference between NaOCl + etidronic acid and NaOCl-EDTA-NaOCl (P > 0.05), whereas both groups brought about more bacterial reduction than NaOCl-EDTA (P < 0.05). There was no significant difference between diode laser and Er:YAG laser in any of the groups (P > 0.05). Both diode and Er:YAG laser were more effective than ultrasonic activation and conventional syringe irrigation in reducing E. fecalis biofilms (P < 0.05). The use of NaOCl after or in combination with a chelator caused the greatest reduction of E. faecalis. Diode laser and Er:YAG laser activation were superior to ultrasonics in dentinal tubule disinfection.

Cleaning efficacy of different root canal preparation systems and irrigation regimens

PurposeTo compare the cleaning efficacy of root canal walls after using two Nickel–Titanium (Ni–Ti) rotary files (Flexmaster and Mtwo) and one hand Ni–Ti file (Ni–Ti flex-K) when associated with different final irrigation regimens (SmearClear, 17% ethylene diamine tetra acetic acid (EDTA) and sodium hypochlorite). Materials and methodsNinety extracted human premolars with similar range of canal curvature (21–39°) were selected. After crown removal and working length determination, roots were divided into three equal groups according to root canal instrumentation: Group I and Group II were prepared using Flexmaster, Mtwo Ni–Ti rotary systems respectively where Group III was prepared using hand NiTi flex-K files. Each group was further subdivided into three equal subgroups according to root canal final irrigation; subgroup A: SmearClear, subgroup B: 17% EDTA and subgroup C: NaOCl. Roots were then splitted longitudinally and processed for scanning electron microscopic (SEM) examination to evaluate and score the root canal cleanliness. ResultsFinal root canal irrigation using either SmearClear or 17% EDTA had significantly better cleaning efficiency than that of NaOCl in all tested groups. Ni–Ti hand files had significantly less cleaning efficacy than that of rotary systems except in subgroup C using NaOCl.

Comparing the Fracture Rate of Hero 642, FlexMaster and Mtwo in the Simulated Canals.

File fracture is one of the main procedural mishaps in endodontic treatment. The aim of this in vitro study was to compare the fracture rate of three NiTi rotary systems; Hero 642, Mtwo and FlexMaster in artificial canals. In this study, bovine long bone was used. After primary preparation of bones, longitudinal sections with 4-cm diameter were cut and encoded. Subsequently, semicircular sections were prepared. A total number of 500 canals were created in the same way; the upper 3 mm of the canals were initially prepared with orifice shapers and then canals were filed with FlexMaster files sizes 25/0.02 and 25/0.04 to 13 mm of canal length. The prepared canals were assigned into 3 groups of the following systems: Hero 642, Mtwo and FlexMaster. Six selected instruments were used from each system; the files were applied 13 mm along the canals for 10 sec with manufacturer's suggested speed and torque. The number of the canals prepared by each file before its separation was recorded; finally the data was analyzed with ANOVA test. Mean number of prepared canals in Mtwo, FlexMaster and Hero groups before file separation was 15, 25 and 32, respectively. RESULTS of this study showed that the number of prepared canals by Hero 642 was more than FlexMaster and Mtwo systems.

A comparative study of the debridement efficacy and apical extrusion of dynamic and passive root canal irrigation systems

BackgroundRoot canal irrigation carries a risk of extrusion of irrigant into the periapical tissues which can be associated with pain, swelling, and tissue damage. Studies have shown less extrusion with sonic or apical negative pressure devices compared with syringe and side-port needle or passive ultrasonic irrigation with continuous irrigant flow. This study aimed to evaluate the effectiveness of the EndoVac irrigation system, regarding 1) debris removal and 2) the control of apically extruded irrigating solution.MethodsFifty extracted human single-rooted teeth were used in this study. The teeth were then randomly divided into three experimental groups according to the type of irrigation used and one control group. In group 1, irrigation was performed using the EndoVac irrigation system. In group 2, irrigation was performed using a 30-gauge, tip-vented irrigation needle. In group 3, irrigation was performed using a 30-gauge, side-vented irrigation needle. The control group received instrumentation with no irrigation to serve as a control for cleaning efficiency. Root canal instrumentation was performed using the Profile NiTi rotary system with a crown-down technique. All of the experimental teeth were irrigated with the same amount of 5.25% sodium hypochlorite. The amount of extruded irrigating solution was then measured by subtracting the post-instrumentation weight from the pre-instrumentation weight using an electronic balance. The cleanliness of debris removal was evaluated using scanning electron microscopy.ResultsEndoVac irrigation had the least amount of extrusion followed by the side-vented and tip-vented method. The difference between the groups was statistically significant (P <0.01). As for the cleaning results, the debris collection in the EndoVac and tip-vented groups was the least in the apical third. In the control and the side-vented groups, the debris was the greatest in the apical third, but this difference was not significant among the three experimental groups.ConclusionsThe EndoVac irrigation system extruded significantly less irrigant solution than either needle irrigation system. Debris collection was the least in the apical third for the EndoVac irrigation system. No significant difference was found in the cleaning efficiency among the three irrigation systems.

SEM analysis of defects and wear on Ni–Ti rotary instruments

SEM analysis of endodontic instruments from a Ni-Ti rotary system was assessed, before and after using them, considering their defects and deformations. Twenty Twisted File®, BioRąCe®, Mtwo®, and EndoWave® instruments were micrographed at 190× magnification. The files were washed and micrographed again to view alterations as to the presence or absence of irregular edges, grooves, microcavities, and scraping. Simulated root canal preparations were performed using these instruments. The instruments were cleaned and received a microscopic analysis after being used five times. After analysis tests were tested using Fisher's exact test and Kappa to evaluate the concordance among examiners. There was a statistically significant difference with respect to deformations between Twisted File® and other instruments (p < 0.05). There was no statistically significant difference in strains between the other groups (p > 0.05). All Twisted File® instruments showed the same defects; however damage were lower than those found in BioRace® and Mtwo®. The Endowave® did not show the same defects. In accordance with the data we conclude that the presence of defects was higher in Twisted File® instruments as the instruments and BioRace® Mtwo® brand, the defect rate was smaller and Endowave® instruments had no defects. Regarding the presence of wear after five uses among the groups all instruments showed changes in their cutting blades.

Comparison of the shaping ability of GT® Series X, Twisted Files and AlphaKite rotary nickel-titanium systems in simulated canals

BackgroundEfforts to improve the performance of rotary NiTi instruments by enhancing the properties of NiTi alloy, or their manufacturing processes rather than changes in instrument geometries have been reported. The aim of this study was to compare in-vitro the shaping ability of three different rotary nickel-titanium instruments produced by different manufacturing methods.MethodsThirty simulated root canals with a curvature of 35˚ in resin blocks were prepared with three different rotary NiTi systems: AK- AlphaKite (Gebr. Brasseler, Germany), GTX- GT® Series X (Dentsply, Germany) and TF- Twisted Files (SybronEndo, USA).The canals were prepared according to the manufacturers’ instructions. Pre- and post-instrumentation images were recorded and assessment of canal curvature modifications was carried out with an image analysis program (GSA, Germany).The preparation time and incidence of procedural errors were recorded. Instruments were evaluated under a microscope with 15 × magnifications (Carl Zeiss OPMI Pro Ergo, Germany) for signs of deformation. The Data were statistically analyzed using SPSS (Wilcoxon and Mann–Whitney U-tests, at a confidence interval of 95%).ResultsLess canal transportation was produced by TF apically, although the difference among the groups was not statistically significant. GTX removed the greatest amount of resin from the middle and coronal parts of the canal and the difference among the groups was statistically significant (p < 0.05). The shortest preparation time was registered with TF (444 s) and the longest with GTX (714 s), the difference among the groups was statistically significant (p < 0.05). During the preparation of the canals no instrument fractured. Eleven instruments of TF and one of AK were deformed.ConclusionUnder the conditions of this study, all rotary NiTi instruments maintained the working length and prepared a well-shaped root canal. The least canal transportation was produced by AK. GTX displayed the greatest cutting efficiency. TF prepared the canals faster than the other two systems.

Effect of gutta-percha solvents on the bond strength of two resin-based sealers to root canal dentin

Objective. To evaluate the effect of two gutta percha solvents on the bond strength of two resin-based sealers to root canal dentin. Materials and methods. Root canals of extracted single rooted human mandibular premolars (n = 60) were decoronated and instrumented with a rotary NiTi system to an apical size of 40 and randomly divided into three groups (n = 20) based on the chemical treatment: Group I, saline (control); group II, Xylene and group III, Endosolv E. All groups were divided into two sub-groups (n = 10) based on the root filling material: sub-group A, epoxy resin sealer (AH Plus); sub-group B, methacrylate resin sealer (Epiphany). Roots were then sectioned and push-out tests were performed. The data was analysed using two-way analysis of variance (ANOVA) and a multiple comparison test (p = 0.05). Results. There was a significant difference in bond strength of both sealers between the control and test groups (p < 0.05). The bond strength of the epoxy resin sealer (sub-group A) in group II was significantly lower than in group III (p < 0.05). However, there was no significant difference between groups II and III for the methacrylate resin sealer (sub-group b) (p > 0.05). Conclusions. Gutta Percha solvents had an adverse effect on bond strengths of resin sealers to root canal dentin. This was dependent on the chemistry of the solvent and the sealer.

Methods and models to study nickel–titanium instruments

Over the past two decades, nickel–titanium (NiTi) instruments have become an important part of the armamentarium for root canal treatment. They are increasingly used by generalists and specialists to facilitate the cleaning and shaping of root canals. Despite the advertising claims of superiority of design for some NiTi rotary systems, few have been supported by objective well‐designed studies in the literature. A variety of experiments with different models and methods have been developed for studying the properties of NiTi instruments and how they fulfil these mechanical goals. One of the main issues is how to make a rational choice for the best study model that is relevant. This article aims to present an overview of those methods and devices that have been used in endodontic literature for studying NiTi files.

Computed Tomographic Evaluation of Canal Shape Instrumented by Different Kinematics Rotary Nickel-Titanium Systems

IntroductionThis study evaluated the effects of 2 different kinematics rotary nickel-titanium (NiTi) systems, Twisted File (TF), a continuous rotation full-sequence system, and WaveOne (WO), a reciprocating single-file system, on transportation, curvature, and volumetric changes of curved root canals by using cone-beam computed tomography. MethodsForty mesiobuccal canals of mandibular molars with angle of curvature ranging from 25°–35° were divided according to the NiTi rotary system used in canal preparation into 2 groups of 20 samples each, TF group and WO group. Canals were scanned by using an i-CAT cone-beam computed tomography scanner before and after instrumentation to evaluate canal transportation at coronal, middle, and apical thirds, canal curvature, and volumetric changes. The significance level was set at P ≤ .05. ResultsTF system recorded significantly lower mean of canal transportation than WO group at all canal thirds (apical P = .034, middle P = .003, and coronal P = .012). In both groups the apical third recorded the significantly least amount of transportation (P < .05). There was no significant difference between the 2 groups in canal curvature and volumetric changes after instrumentation (P > .05). ConclusionsBoth TF and WO NiTi systems can be safely used to the full working length, resulting in satisfactory preservation of the original canal shape.

Evaluation of two different root-end cavity preparation techniques: A scanning electron microscope study.

Objective:In this study, we aimed to evaluate and compare the dentinal walls of root-end cavities for the presence of cracks after cavity preparation using US retrotips and Er: YAG laser.Materials and Methods:Fifty single-rooted teeth were prepared by Protaper NiTi rotary system and obturated by lateral condensation. Three milimeters of root-end was resected. Twenty teeth were prepared with US retrotip (Group 1), 20 teeth with Er: YAG laser (Group 2), and 10 teeth without retropreparation (control group). The root-end surfaces were examined under a scanning electron microscope (SEM). Then the cracks of the resected root surfaces were evaluated on microphotographs.Results:No statistically significant difference was detected between US Group and Laser Group for complete, incomplete, intradentinal, and total number of cracks (P = 0.47, P = 0.80, P = 0.69, P = 0.869, respectively).Conclusion:Statistical analysis revealed no significant effect of retropreparation technique on the development of apical cracks (P > 0.05).