Mtwo Rotary Files Research Articles

An In Vitro Comparative Assessment of Shaping Capacity of a Single-File System Over Multiple-File System in Root Canals.

The study's objective was to contrast the two distinct rotary file techniques used to shape mandibular first molars. The investigation involved twenty recently removed mandibular molars. A digital single-lens reflex (DSLR) camera was placed in a fixed position, a muffle block was built, and images of each tooth's three cross sections were obtained. The specimens were split into the following two groups at random: Rotary files from WaveOne were used to prepare group A and Mtwo rotary files were used to prepare group B. At the coronal, middle, and apical thirds of the root canals, WaveOne file system demonstrated improved centering ability compared with the Mtwo file system (P 0.05). When compared to the Mtwo file system, WaveOne file system demonstrated improved centering capabilities and needed significantly less time to build the curved canals.

Evaluation of postoperative pain using warm versus room temperature sodium hypochlorite as an irrigant in mandibular molars with irreversible pulpitis: A randomized controlled trial.

The study evaluates and compare the effect of 3% warm NaOCl with NaOCl at room temperature in root canal irrigation on postoperative pain. In this randomized controlled trial, mandibular molars with symptomatic irreversible pulpitis in healthy 18-year-old patients and above were included. The sample consisted of 56 patients evaluating the postoperative pain, allocated randomly into 2 groups of 3% NaOCl at two different temperatures, i.e. at room temperature and at 60°C. Endodontic treatment was initiated for each group and instrumentation was done using MTwo rotary files. The final irrigation was performed according to the groups assigned. For each included tooth, preoperative and postoperative pain scores at 6, 12, 24, 48, and 72 h were collected through the Heft Parker Visual Analog Scale. Statistical analysis was performed using independent t-test, Chi-square test, Mann-Whitney U-test, and Friedman test followed by Wilcoxon test. The mean percentage reduction in pain scores was significantly higher among the warm NaOCl group as compared to the control group at different time intervals (P < 0.001). The mean number of analgesics taken was significantly lower among the warm NaOCl group as compared to the control group (P < 0.001). The warm NaOCl group recorded less postoperative pain than the control group during the first 72 h following single-visit endodontic therapy.

Comparison of Coronal Discoloration Induced by White MTA and CEM Cement

Coronal discoloration of endodontically treated teeth is a challenge in clinical dentistry. This study aimed to compare coronal discoloration induced by White Mineral Trioxide Aggregate and Calcium-enriched mixture cement. Fifty single-rooted, unrestored premolar teeth extracted for orthodontic reasons were selected. After access cavity preparation, all the root canals were instrumented with MTWO rotary files up to #40.6%. The specimens were randomly assigned to two experimental groups, White Mineral Trioxide Aggregate and Calcium-enriched mixture cement groups (n = 20), and two control groups (n = 5). In the White Mineral Trioxide Aggregate and Calcium-enriched mixture cement groups, the material was condensed via the access cavity 3 mm below the cementoenamel junction to a thickness of 3 mm. Tooth color was assessed using computer analysis of digital images. Tooth color measurements were recorded at eight time intervals: before material placement (but after tooth preparation), at 24 h, 48 h, one week, two weeks, four weeks, eight weeks, and sixteen weeks after material placement. Data were analyzed using t-test, ANOVA, repeated measure ANOVA, and Tukey HSD tests. The significance level was set at 5% for all the tests. Cervical discoloration of teeth in both experimental groups significantly increased over time (p &lt; 0.05). However, samples in the White Mineral Trioxide Aggregate group showed more discoloration in cervical regions than Calcium-enriched mixture cement specimens after two, four, eight, and sixteen weeks (p &lt; 0.05). Applying both White Mineral Trioxide Aggregate and Calcium-enriched mixture cement induced coronal discoloration; however, White Mineral Trioxide Aggregate samples exhibited greater cervical discoloration than Calcium-enriched mixture cement specimens after two, four, eight, and sixteen weeks.

Comparative evaluation of efficacy of different endodontic file systems for removal of gutta percha from root canals using CBCT

Aim- To evaluate the removal of gutta percha by hand file system, rotary file system and reciprocating file system from root canals by using CBCT. Materials and Method: Root canals of 42 extracted human mandibular premolars were prepared using the ProTaper Universal rotary system and then obturated. Root filling quality was confirmed on CBCT images. Specimens were divided into 3 groups (n = 14) according to the system used for filling removal, group 1: H File, group 2: MTwo rotary retreatment file, and group 3:WaveOne file. Each specimen was sent for CBCT Analysis. Statistical Analysis Used: Evaluation of data was done statistically using One-way Analysis of Variance and Tukey’s post hoc test. Results: There was statistical difference in all the groups (P&gt;0.05). All systems demonstrated presence of remnants of filling material. Mean reduction in the volume of GP after retreatment of Group I was 0.006mm3, Group II was 0.002mm3 Group III was 0.003mm3. Conclusion: The system responsible for a better removal of root canal filling material was the MTwo Retreatment file system, followed by the WaveOne system and H File.

Comparative evaluation of efficacy of different endodontic file systems for removal of gutta percha from root canals using CBCT

Aim- To evaluate the removal of gutta percha by hand file system, rotary file system and reciprocating file system from root canals by using CBCT. Materials and Method: Root canals of 42 extracted human mandibular premolars were prepared using the ProTaper Universal rotary system and then obturated. Root filling quality was confirmed on CBCT images. Specimens were divided into 3 groups (n = 14) according to the system used for filling removal, group 1: H File, group 2: MTwo rotary retreatment file, and group 3: WaveOne file. Each specimen was sent for CBCT Analysis. Statistical Analysis Used: Evaluation of data was done statistically using One-way Analysis of Variance and Tukey’s post hoc test. Results: There was statistical difference in all the groups (P&gt;0.05). All systems demonstrated presence of remnants of filling material. Mean reduction in the volume of GP after retreatment of Group I was 0.006mm3, Group II was 0.002mm3 Group III was 0.003mm3. Conclusion: The system responsible for a better removal of root canal filling material was the MTwo Retreatment file system, followed by the WaveOne system and H File.

Computed Tomographic Assessment of Remaining Dentin and Risk of Perforation after Kedo-S and Mtwo Rotary Instrumentation in Root Canals of Primary Teeth: An In Vitro Study.

BackgroundRoot canal cleaning is a key step in the endodontic treatment of the primary molars. An innovative generation of endodontic instruments has been devised with the aim of emerging better procedures. The objective of the study is to assess the preparation of time, the risk of lateral perforation, and the removal of dentin from Kedo-S and Mtwo rotary instruments on primary teeth.Study designThis is an in vitro experimental study comparing the two groups.Materials and methodsA total of 50 extracted mandibular primary first molars are collected, divided randomly into two groups of 25 teeth each. Group I: Kedo-S Pediatric rotary file, Group II: Mtwo rotary file. Distal canal is standardized for evaluation and teeth are sectioned at the CEJ. The teeth were instrumented according to manufacturer's guideline. Both the groups are scanned before and after instrumentation of the canal using cone-beam computed tomography (CBCT) and values are evaluated.ResultsCompared with Mtwo files, Kedo-S files need less instrumentation time and limited lateral perforation. No statistical differences were reported between the instrumentation of Kedo-S and Mtwo with regard to the amount of dentin removed.ConclusionIn pediatric endodontics, Kedo-S pediatric rotary file can be considered an effective alternative to traditional rotary files because it requires less instrumentation time and preserves dentin thickness.How to cite this articleSwaminathan K, Rakkesh KM, Haridoss S. Computed Tomographic Assessment of Remaining Dentin and Risk of Perforation after Kedo-S and Mtwo Rotary Instrumentation in Root Canals of Primary Teeth: An In Vitro Study. Int J Clin Pediatr Dent 2022;15(S-1):S87-S91.

Full counterclockwise rotary motion kinematics enhances the removal of gutta-percha and bioceramic sealer from root canals: A computed tomographic study.

Complete removal of gutta-percha and sealer is an important step during retreatment. The aim of this study was to assess the efficacy and time taken by full counterclockwise rotary motion of a reciprocating file in the removal of gutta-percha and BioRoot™ RCS bioceramic sealer. Thirty-six extracted human mandibular premolars were instrumented with Mtwo rotary files and obturated using lateral condensation technique with gutta-percha and BioRoot™ RCS bioceramic sealer. The teeth were divided into three retreatment groups (n = 12) based on the kinematics used: Group I, Mtwo retreatment (Mtwo-R) files; Group II, Reciproc files used in reciprocation mode (Reciproc-R); and Group III, Reciproc files used in full counterclockwise motion (Reciproc-CCW). The efficacy of gutta-percha and bioceramic sealer removal was assessed by volume of gutta-percha removed using cone-beam computed tomography and area of remaining gutta-percha and bioceramic sealer using ImageJ software after longitudinal sectioning. Statistical analysis was done by one-way analysis of variance test and Tukey's multiple post hoc tests. Reciproc-CCW motion was significantly efficient in the removal of gutta-percha and bioceramic sealer in comparison to Mtwo-R files and Reciproc-R. The time taken for gutta-percha and sealer removal was least for Reciproc-R (325.5 ± 101.68 seconds) and was statistically significant in comparison to the other groups. Within the limitations of the study, Reciproc-CCW was an effective method of removal of gutta-percha and bioceramic sealer during retreatment.

Effect of two different volumes of sodium hypochlorite on endodontic treatment outcome following single-visit root canal treatment: A split-mouth, double-blind, randomized controlled trial

Aim: This split-mouth (SM), randomized controlled trial was planned to assess the influence of two different volumes (15 ml and 25 ml) of 2.5% of sodium hypochlorite (NaOCl) on the endodontic treatment outcome of teeth with apical periodontitis (AP) by radiographic and clinical evaluation.Materials and Methods: The study protocol was approved by the ethics committee (25/XX/IEC/2017/11). Using block randomization, permanent lower molars with pulp necrosis and chronic AP (periapical index [PAI] of 3 or above) were allotted to two treatment groups as Group I (low volume [LV]) and Group II (high volume (HV)) wherein 3 ml and 5 ml of NaOCl irrigant were used after each Mtwo rotary file, respectively. This NaOCl was activated by a sonic handpiece. With power at 0.80, P < 0.05, and minimum clinically significant mean intergroup difference set at 0.40 units (standard deviation – 0.88 unit) while using the change in PAI score as the primary outcome, a total of 46 subjects per group were recruited to adequately show a difference in success at the 12-month follow-up. Clinical (at 24 h, 3, 6, 9, and 12 months) and radiographic (6 and 12 months) assessment of all cases was done.Results: Due to SM design of the study, there was no difference in the demographics of subjects between both the groups. Pain scores between both groups were statistically nonsignificant preoperatively (P = 0.857) and at 24 h (P = 0.852). However, there was statistically significant difference in preoperative and 24 h pain scores in Group I (P = 0.000) and Group II (0.000). Comparison of intergroup preoperative and 12-month follow-up PAI scores revealed no statistically significant difference (P = 0.667). However, there was statistically significant difference in preoperative and 12-month follow-up PAI scores in Group I (P = 0.000) and Group II (P = 0.000). Intergroup comparison of PAI scores at baseline (P = 0.894) and follow-up (P = 0.526) revealed no significant difference.Conclusion: Based on the results of the present study, it can be suggested that there is no significant advantage of using HV of NaOCl over LV as far as periapical healing and postendodontic pain are concerned.

Comparison of Cutting Efficiency and Safety of 10/0.04 RaCe and Mtwo Rotary File Systems in Reaching the Full Root Canal Working Length: An In Vitro Study

Introduction: Both RaCe and Mtwo rotary systems introduced the 10/0.04 file as the first file used in the root canal (Glide path). This study aims to compare different factors of both the rotary systems, including cutting efficacy, file fracture, topography changes of files, and changes of the root canal. Materials and Methods: In this laboratory study, 12 RaCe and 12 Mtwo files were prepared and tested on 24 resin blocks with 30° curvature. The time to reach the working length was recorded. Topographical changes of the files have been observed with a stereomicroscope if needed. Changes in resin blocks were measured by photographing and using Photoshop software. Data were analyzed through an independent two-sample t test and likelihood-ratio chi-squared test. Results: Time to reach the working length was significantly lower in the RaCe group than in the Mtwo group (3.57 ± 0.56 s vs. 10.33 ± 2.25 s, P < 0.001). File fracture did not occur in any of the two rotary systems. Topographical changes of the files in RaCe group were also less than the Mtwo group (P = 0.032). Conclusion: The RaCe file is faster in reaching the working length. Both files are safe and do not cause drastic changes in the root canal.

Comparison of the cleaning efficacy of XP-endo shaper and Mtwo rotary files in oval-shaped canals

Cleaning and shaping of root canals are essential steps for the success of endodontic therapy. This study compared two types of rotary files in oval-shaped root canals: XP-endo shaper (FKG, La Chaux-de- Fonds, Switzerland) and Mtwo (VDW, Germany, Munich) with regard to cleaning ability and canal preparation. Mtwo is a system of nickel-titanium files with S-shaped cross-sectional design and XP-endo shaper can change its shape according to the temperature. This in vitro study was performed on 16 pairs of freshly extracted contralateral mandibular premolars with a single oval-shaped canal that were selected and divided into two groups according to the root canal instrumentation technique: XP-endo shaper and Mtwo. Then, each root cut into three coronal, middle and apical sections and processed for histologic evaluation of canal wall planning and the presence of debris. Sections were evaluated by using AutoCAD 2017 software. Statistical analysis was used to compare between both the groups using repeated measures multivariate analysis of variance with Bonferroni correction for post hoc comparison and independent sample t-tests. The level of statistical significance was set at P < 0.05. With a statistically significant difference in the middle third, untouched area and area with debris in XP-endo shaper group were smaller (respectively P = 0.013 and P = 0.011). Despite the percentage difference between groups, there was not a statistically significant difference in other sections. Statistically in the middle section of the oval-shaped canals, the XP-endo shaper performs better than the Mtwo rotary files.

Influence of Rotation Speed of Mtwo Files on Root Canal Instrumentation Time with Different Canal Curvatures.

The aim of this study was to analyze the effect of rotation speed on the instrumentation time of root canals with different curvatures using Mtwo NiTi rotary instruments. Forty root canals were selected and divided into 2 groups, according to the angle of curvature (group A>30°, group B<30°). Both groups were divided into 2 subgroups (n=10), according to the rotational speed used for root canal instrumentation (150 rpm: group A1 and B1; 250 rpm: group A2 and B2). The total instrumentation time and the total number of instrumentation cycles (NCI) required to complete root canal preparation were registered for each canal. The mean and standard deviation were then calculated. Data were then statistically analyzed using two-way ANOVA and interaction effect P-values (P<0.05). During root canal instrumentation, there were no file fractures. Total instrumentation time of the low speed groups A1 (150 rpm) and B1 (150 rpm) were significantly higher (P<0.05) than that of the high speed groups, A2 (250 rpm) and B2 (250 rpm); however, there was no statistically significant difference in terms of NCI between the different groups (P>0.05). Statistical difference was not found between the different angles of curvature, group A1 vs B1 and A2 vs B2 in terms of total instrumentation time (P>0.05) and NCI (P>0.05). This ex-vivo study showed that canal preparation with Mtwo rotary files could be completed safely with an increase of the instrumentation time at low rotational speed independently of the root canal curvature.

Comparison of push-out bond strength of bioceramic sealer with bioceramic coated and non-bioceramic coated Gutta-percha: an in vitrostudy

Background: The goal of the endodontic treatment is to achieve a fluid-tight impervious seal to prevent the ingress of bacteria and the occurrence of any pathology in future. The endodontic sealer plays a crucial role in obtaining the hermetic seal by filling all the spaces and by binding to the root dentin and to the core obturating material, which is usually gutta-percha. Aim: This study aimed to compare the push-out bond strength of Endosequence BC sealer with bioceramic coated gutta-percha and non-bioceramic coated gutta-percha. Materials and methods: A total of 36 extracted human maxillary central incisors were decoronated to standardize the root length of 15mm. Working length was determined and Biomechanical preparation for all the samples was done with a Mtwo (VDW Company) rotary file till 40/.06. Samples were randomly divided into three groups containing 12 teeth in each group based on the obturation procedure, namely Group 1: Endosequence BC sealer along with Endosequence bioceramic coated gutta-percha (n=12), Group 2: Endosequence BC sealer along with normal gutta-percha (n=12), Group 3: AH Plus sealer along with normal gutta-percha. All the samples were obturated using single cone technique. The specimens were sectioned orthogonally at middle third to obtain three sections of 1mm thick. All the samples were subjected to the push-out bond strength test with the universal testing machine. The data were subjected to one-way Analysis of Variance (ANOVA) followed by post hoc analysis. Results: Samples obturated with Endosequence BC sealer with Endosequence bioceramic coated gutta-percha showed the maximum push-out bond strength followed by Group 3 and Group 2. One-way Anova showed significant differences (p=0.021) among the groups. In posthoc analysis, the specimens from group 1 exhibited significant differences (p=0.016) with the group 2 specimens. Conclusion: The push-out bond strength of Endosequence Bioceramic sealer with Endosequence Bioceramic coated gutta-percha was significantly higher than that of Endosequence Bioceramic sealer with normal gutta-percha and AH Plus sealer with normal gutta-percha.

Smear Layer Removal from Root Canal Dentin and Antimicrobial Effect of Citric Acid-modified Chlorhexidine.

Objective:To study the effectiveness of various concentrations of citric acid (CA) added to 2% chlorhexidine (CHX) on smear layer removal from the root canal wall and antimicrobial efficacy against Enterococcus faecalis (E. faecalis) and Candida albicans (C. albicans).Methods:Fifty-three single-rooted mandibular premolars were decoronate and the root canals underwent mechanical instrumentation using MTwo rotary files to size 40/0.06. The samples were then randomly divided into 5 groups according to the root canal irrigants to be used: 17% ethylenediaminetetraacetic acid (EDTA), 2% CHX, 1%, 6%, and 10% citric acid-modified 2% chlorhexidine (CAmCHX). Three teeth irrigated with phosphate-buffered saline (PBS) were used as a negative control. The smear layer removal effectiveness was evaluated under scanning electron microscopy (SEM). Images were randomly taken at the apical, middle, and coronal third level. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U tests. Disc diffusion and direct exposure tests were performed along with three additional control groups consisting of 1%, 6%, and 10% CA groups to assess and compare the antimicrobial efficacy of irrigants against E. faecalis and C. albicans. Statistical analysis was conducted using one-way ANOVA and Dunnett’s T3 tests.Results:Smear layer removal effectiveness in 17% EDTA group and 6% and 10% CAmCHX groups were not significantly different in the coronal and apical third of the root canal (P>0.05), however at the middle third of the root canal, the 10% CAmCHX group had significantly less remaining smear layer than all of the other experimental groups (P<0.05). There was significantly more smear layer remnant in the CHX group (P<0.01). For antimicrobial efficacy, the largest growth inhibition zone against E. faecalis was recorded in the 10% CAmCHX group (P<0.05). For planktonic E. faecalis, 1%, 6%, and 10% CAmCHX demonstrated an insignificant difference in antimicrobial efficacy compared to CHX (P>0.05). CA demonstrated no antifungal effect against C. albicans. Whereas, 6% and 10% CAmCHX resulted in the largest growth inhibition zone. Also, adding CA to CHX resulted in an insignificant difference in antifungal effect against planktonic C. albicans compared to CHX (P>0.05).Conclusion:When CA was added into CHX, the mixed irrigant demonstrated smear layer removal ability. Additionally, its antimicrobial effect remained the same.

Apical Debris Extrusion by Novel Endostar E5 Compared to Other Commercial Rotary Files: An in Vitro Study

Objective: To compare the amount of apical debris extrusion in samples instrumented by EndoStar E5, ProTaper Universal, and M-two rotary files. Material and Methods: Forty-five freshly extracted non-carious mandibular premolar teeth with single roots and single canals were acquired, and randomly divided into 3 groups (n=15). Samples in Groups 1, 2, and 3 were instrumented using EndoStar E5 (EE5), ProTaper Universal (PTU), and M-two (MTO) rotary file, respectively. Following instrumentation, the debris extruded was collected in pre-weighed Eppendorf tubes and stored in an incubator at 70°C for 5 days. Tubes containing the dry extruded debris were then weighed. One-way analysis of variance was applied to the weights obtained followed by Tukey’s post hoc test for multiple comparison. Results: The mean debris extruded (mg) for the 3 groups were 1.23 (±0.72), 2.16 (±0.66), and 1.39 (±0.86) for EE5, PTU, and MTO respectively. Samples instrumented with PTU were associated with significantly higher debris extrusion (p 0.05). Conclusion: The novel EE5 and M-two rotary files result in less debris extrusion compared to PTU in mandibular premolars.

Comparison of postoperative pain intensity after using reciprocating and continuous rotary glide path systems: a randomized clinical trial.

ObjectivesThe aim of this study was to compare postoperative pain intensity after root canal treatment with One G (OG) vs. R-Pilot (RP) files used for glide path preparation.Materials and MethodsNinety-three single-canaled mandibular premolar teeth with asymptomatic non-vital pulp were randomly assigned into 3 groups (n = 31): OG, RP, or without glide path (WGP). After creating the glide path, the root canals were prepared using sequential Mtwo rotary files to size 30/0.05. One endodontic specialist carried out single-visit endodontic treatment. The patients were asked to rate the severity of postoperative pain on a visual analogue scale at 24, 48, and 72 hours after the visit. They were also asked to record their intake of prescribed analgesics taken. The data were analyzed using the χ2, Friedman, Kruskal-Wallis, and Mann-Whitney U tests.ResultsIn all 3 groups, postoperative pain decreased significantly at each time interval (p < 0.05). At 24 hours, the OG group had less postoperative pain than the WGP group (p < 0.05). However, no significant difference was found between the RP group and the others. No statistically significant difference was found among the WGP, OG, and RP groups in postoperative pain intensity at 48 or 72 hours or in analgesic tablet intake at the 3 assessed time intervals.ConclusionsThe OG group had less postoperative pain than the WGP group in the first 24 hours. The OG and RP systems were similar regarding postoperative pain intensity and analgesic intake.

Evaluation of Dentin Adaptability of Fluoride Varnish as a Root Canal Sealer Using Scanning Electron Microscopy.

Objectives:This study aimed to assess the dentin adaptability of a certain type of fluoride varnish, as a novel root canal sealer, in comparison with AH-Plus sealer.Materials and Methods:Twenty-four extracted single-rooted, single-canal human permanent teeth with straight and fully formed roots and no internal calcification, resorption or cracks, were selected and decoronated such that the remaining root length was 14 mm in all teeth. Root canals were prepared using the Mtwo rotary file system according to the manufacturer’s instructions and filled with gutta-percha and either AH-Plus (n=12) or fluoride varnish (n=12) via the lateral compaction technique. Each root was then sectioned at 4 and 8 mm distances from the apex for evaluation under a scanning electron microscope (SEM). The gap size between the sealer and dentin was measured. Statistical analysis was performed using the Kolmogorov-Smirnov test and t-test with the significance level set at 0.05.Results:The mean gap size was 14.407±1.402 μm and 8.342±0.694 μm in the roots obturated with AH-Plus and fluoride varnish sealers, respectively. The t-test revealed a statistically significant difference (P<0.001) in this regard between the two groups.Conclusion:Fluoride varnish, as a root canal sealer, has a superior adaptation to dentinal canal walls compared to the AH-Plus sealer.

Computed microtomography study of untreated, shaped and filled mesiobuccal canals of maxillary first molars.

This study assessed the effectiveness of modern endodontic shaping and filling procedures on mesiobuccal roots of maxillary molars with two canals. The canals of 20 mesiobuccal roots were treated with Mtwo rotary files, passive ultrasonic irrigation and Guttafusion obturators. X-ray computed microtomography analysis was carried out prior to treatment, after canal shaping and after canal filling to determine the alterations of the canal volume before and after the instrumentation, the volume of the hard tissue debris, and percentage of the volume occupied by filling materials. The shaping instruments and filling materials reached only partially the endodontic space of the second mesiobuccal canal and the accessory endodontic structures. Canal irregularities, ramifications, and interconnections were accumulation sites of hard tissue debris. This study demonstrated that rotary files, passive ultrasonic irrigation and carrier-based filling systems could be partially effective for the treatment of the mesiobuccal canals and their accessory endodontic structures.

In Vitro Comparative Study of the Influence of Instrument Taper on the Fracture Resistance of Endodontically Treated Teeth: An Integrative Approach–based Analysis

IntroductionThe objective of this study was to examine the influence of instrument taper on the fracture resistance of endodontically treated roots under in vitro experimental conditions. MethodsIn total, 58 maxillary canines complying with the inclusion criteria were sectioned at approximately 13 mm from the apex. The roots were standardized with respect to the buccolingual-mesiodistal diameter and weight before being randomly distributed into 3 experimental groups (n = 14) and 1 control group (n = 16). The roots in group 1 were instrumented with hand files up to file 40/.02 and groups 2 and 3 with Mtwo (VDW, Munich, Germany) rotary files up to files 40/.04 and 40/.06, respectively. After mechanical preparation, the roots were obturated with gutta-percha and sealer. Roots in group 4 acted as uninstrumented controls. A vertical load was applied to each specimen using a universal testing machine until the roots fractured. Data were statistically analyzed by introducing an innovative approach integrating 1-way analysis of variance, confirmatory factor analysis, and regression analysis. ResultsThe mean fracture load was 357.47 ± 110.54 N for the control group, 338.86 ± 105.23 N for group 1, 297.74 ± 77.31 N for group 2, and 280.10 ± 68.51 N for group 3. However, only the difference between group 3 and the control group was statistically significant (P < .05). ConclusionsAfter instrumentation using hand files up to file 40/.02 and rotary files up to files 40/.04 and 40/.06, only the last appeared to change the fracture resistance of endodontically treated roots.

Dentinal Microcrack Formation During Root Canal Treatment with Mtwo Instruments and MicroSeal Filling Technique

Objective: The purpose of this study was to evaluate dentinal microcrack formation during root canal treatment using Mtwo NiTi rotary instruments and MicroSeal filling technique. Materials and Methods: Forty-five single-rooted teeth were selected for the present study and divided into 3 different groups ( n = 15): Group 1, in which root canals were instrumented with Mtwo rotary files; Group 2, in which root canals were instrumented with Mtwo rotary files and filled using the MicroSeal technique; and Group 3, that acts as a control group in which no instrumentation nor obturation were performed. Then, roots were sectioned 3 mm, 6 mm, and 9 mm from the apex and the cut surface has been observed under a stereomicroscope to check for the presence or absence of dentinal microcracks. Number of dentinal microcracks was registered for each group at different levels and data were statistically analyzed using the Chi-square test with a level of significance set at P &lt; .05. Results: No statistically significant differences were registered among groups ( P &lt; .05). No microcracks were detected in Groups 1 and 3, while two dentinal microcracks were registered in Group 2. Conclusions: Mtwo rotary instruments and the MicroSeal root canal filling technique did not significantly induce dentinal microcrack formation.

Antibacterial efficacy of newly suggested root canal irrigants in differently prepared root canals

Aim To evaluate the efficacy of trisodium phosphate (Na3PO4) and sodium bicarbonate (NaHCO3) irrigations against Enterococcus faecalis in differently prepared root canals. Materials and methods Ninety laboratory-infected root canals were endodontically prepared using K-file (group 1), Mtwo rotary (group 2) and OneShape rotary (group 3) file systems. Canals in each group were irrigated with the minimum bactericidal concentrations of sodium hypochlorite (subgroup 1), Na3PO4(subgroup 2) and NaHCO3(subgroup 3) solutions. Another 10 infected unprepared canals served as control group. Samples obtained from lumens and dentin linings of root canals were used to count the residual bacteria in each subgroup. Both two-way analysis of variance and Mann–Whitney comparisons at P value less than or equal to 0.05 were used to statistically analyze the results. Results All tested subgroups showed lower no of colony-forming units than the control (P 0.05). Conclusion Although none of the tested irrigation solutions are capable of completely eradicating E. faecalis, both Na3PO4 and NaHCO3 seem effective when used together with the nominated file systems.