Mesiobuccal Canals Of Mandibular Molars Research Articles

A cone-beam computed tomographic analysis of total dentin removed, canal transportation, and canal-centering ability following instrumentation with three different file systems: An in vitro study.

The aim of this study was to evaluate the shaping ability following instrumentation with XP-endo Shaper (XPS), TruNatomy (TRN), and HyFlex CM (HCM) file system. Fifty-four mesiobuccal canals of mandibular molars were selected and allocated into three groups randomly: XPS, TRN system, and HCM file system. Pre- and postinstrumentation scans were taken using a cone-beam computed tomography scanner to determine the amount of root dentin removed, mesiodistal and buccolingual transportation, and canal-centering ratio at 2, 5, and 8 mm from the root end. Data were statistically analyzed using Kruskal-Wallis test and the significance level was set at P = 0.05. TRN file system removed the least amount of root dentin. XPS showed statistically higher M-D canal transportation at 5 mm level from the apex. TRN file system showed better dentin preservation as compared to XPS and HCM. XPS showed the highest canal transportation at 5 mm. All three file systems performed similarly in terms of canal-centering ability.

Comparative Evaluation of Canal Transportation and Centering Ratio in Curved Canals: A Study of Cone-beam Computed Tomography and Micro-computed Tomography.

This study aimed to compare the accuracy and agreement between cone-beam computed tomography (CBCT) and micro-computed tomography (micro-CT) in the assessment of canal transportation and centering ratio following root canal instrumentation with rotary files. Twenty mesiobuccal canals of mandibular molars were prepared using the 2Shape sequential rotary system. CBCT and micro-CT scans were performed before and after instrumentation, and the magnitude of transportation and centering ratio were measured. The acceptable transportation was set at ≤0.15 mm. The accuracy and agreement between CBCT and micro-CT were calculated, and the intra-class correlation coefficient (ICC) and kappa coefficient were determined to assess the agreement between the two modalities. Statistical analyses were performed using repeated measures ANOVA. Transportation was detected by both modalities at all distances from the apex after instrumentation. The agreement between CBCT and micro-CT in assessing canal transportation was observed in 80%, 85%, 75%, and 75% of specimens at 1-, 3-, 5-, and 7-mm from the apex, respectively. The ICC for transportation and centering ratio was much lower than 0.75, indicating poor agreement between the modalities. The kappa coefficient did not show acceptable agreement between the methods. CBCT and micro-CT demonstrated poor agreement in assessing canal transportation and centering ratio. Micro-CT remains the preferred modality for in vitro investigations, while CBCT should be limited to clinical settings.

Reduction in Enteroccocus faecalis counts produced by three file systems in severely curved canals

Aim: This study evaluated the effectiveness of the mechanical reduction of intracanal bacteria produced by the endodontic systems Reciproc Blue (VDW GmbH), XP-Endo Shaper (FKG Dentaire) and ProTaper Next (Dentsply Sirona Endodontics) in severely curved canals by culture analysis. Methodology: Fifty severely curved mesiobuccal canals of mandibular molars were selected and instrumented. Following this, six specimens were selected as control, while 44 canals were contaminated with Enterococcus faecalis strains (ATCC 29212). Specimens were incubated for 21 days at 37 ºC. Then, contaminated specimens were randomly divided into 3 groups (n=14): ProTaper Next (G1), XP-Endo Shaper (G2) and Reciproc Blue (G3). Control Group: Six non-contaminated canals were prepared with one of the 3 file systems (n=2). Microbial samples were obtained before (S1) and after root canal preparation (S2). Two roots were observed using scanning electron microscopy to verify biofilm formation. Quantitative culture analyses of intracanal E. faecalis reduction was performed using CFUs, and the Wilcoxon test was used for intragroup analysis, and intergroup analysis was performed using Kruskal-Wallis test. The level of significance for all analyses was set at P < .05. Results: All systems presented effective bacterial reduction (p<0.05), but still had bacterial growth. ProTaper Next displayed the highest E. faecalis reduction (P<0.05), while XP-Endo Shaper and Reciproc Blue systems presented similar results (P>0.05). ProTaper Next showed the greatest antibacterial action when compared to the XP-Endo Shaper and Reciproc Blue systems. Conclusion: No instrumentation system rendered root canals completely free from bacteria.

Irrigant Agitation Techniques versus Passive Ultrasonic Irrigation for Removing Debris from Curved Root Canals: An Environmental Scanning Electron Microscopic Study.

The aim of this study was to compare the efficacy of passive ultrasonic irrigation (PUI) versus mechanical agitation of the irrigant promoted by the EasyClean (EC) and XP-Endo Finisher (XP-F) systems in removing debris from root canal walls, using environmental scanning electron microscopy (ESEM). Twelve curved mesiobuccal canals of mandibular molars were prepared with the ProTaper Next system up to file X2 (25/0.06). The specimens were embedded in flasks containing silicone putty, sectioned lengthwise, and a 4-mm long groove was made on the canal wall of the buccal half of the specimen, extending from 2 mm up to 6 mm short of the apex. Five cross-sectional markings were made along this groove to establish standardized locations for imaging. The same specimens were used to prepare a negative control group (without debris), a positive control group (completely covered by debris), and 3 experimental groups according to the final irrigation protocol employed: PUI, EC or XP-F. ESEM images were obtained and evaluated by 3 examiners. The amount of debris observed on the images was classified according to a 4-category scoring system. The kappa test was used to assess inter-examiner agreement, and the Kruskal-Wallis and Dunn tests were used to compare the scores (P<0.05). The scores attributed to the PUI, EC, and XP-F groups were statistically similar to those attributed to the negative control group (P>0.05). Based on this in-vitro study, the mechanical agitation of the irrigant promoted by EC and XP-F was as effective as using PUI to remove debris from the root canal walls.

Comparison of full rotation and reciprocating movements in regaining apical patency during endodontic retreatment

This study aimed to compare the continuous rotation and reciprocating movements of rotary files in achieving apical patency in root canal retreatment. This in vitro, experimental study evaluated 64 extracted mandibular molars. The teeth were prepared up to F3 with ProTaper Universal and obturated using lateral compaction technique. The teeth were divided into four groups (n = 16) based on the mesiobuccal canal curvature (Schneider's method) and type of rotational movement. Groups 1 and 2 included straight canal teeth retreated with WaveOne Gold and ProTaper Universal Retreatment system, respectively. Groups 3 and 4 included teeth with moderately curved root canals retreated with WaveOne Gold and ProTaper Universal, respectively. Apical patency was ensured by observing the tip of a hand K-file at the apical foramen. Data were analyzed using the Fisher's exact test. P < 0.05 was considered statistically significant. Apical patency was successfully achieved in all 16 teeth in group 1 (100%) and 15 teeth in group 2 (93.75%). No significant difference was noted between continuous rotation and reciprocating movements in straight canals (P = 1.00). Apical patency was successfully achieved in 15 teeth in group 3 (93.75%) and 12 teeth in group 4 (75%). No significant difference was noted between continuous rotation and reciprocating movements in moderately curved canals either (P = 0.333). Both continuous rotation and reciprocating movements are equally effective in achieving apical patency in straight or moderately curved mesiobuccal canal of mandibular molars.

Diagnostic accuracy of two cone-beam computed tomography systems for detection of strip perforation in the mesial root of mandibular molars

Aim: This study aimed to compare the diagnostic accuracy of two cone-beam computed tomography (CBCT) systems for detection of strip perforation in the mesiobuccal canal of mandibular molars after root canal treatment. Methodology: The curved mesiobuccal canals of mandibular first and second molars were instrumented as part of endodontic treatment. The canals were strip-perforated using #2 and #3 Gates-Glidden drills in distoaxial direction at 1 to 3 mm distance from the furcation. The canals were filled with gutta-percha and AH26 sealer with lateral compaction technique. The teeth were then mounted in dry bovine mandible and underwent CBCT using Acteon and NewTom CBCT systems. The CBCT scans were evaluated by two observers, and the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of the two CBCT systems for detection of strip perforation were determined and compared using the Chi-square test. Results: The sensitivity and specificity for detection of strip perforation were 51.3 and 46.3 for Acteon, and 55 and 38.8 for New -Tom CBCT system, respectively. The difference between the two CBCT systems for detection of strip perforation was not significant (Chi-square test, P>0.05). Conclusions: The accuracy of Acteon and New -Tom CBCT systems for detection of strip perforation is low, and no significant difference was noted between the two systems in this respect.

Assessment of shaping ability of rotary and reciprocating file systems using cone-beam computed tomography in mandibular molars: An in vitro study

Aim: The purpose of this study was to compare the canal transportation, centering ability, canal curvature, dentin removal, the volume of the curved root canals, and time taken during and after instrumentation with Wave One, Reciproc, F360, and One shape (OS) by using cone-beam computed tomography (CBCT). Materials and Methods: According to the file systems used for canal preparation, eighty mesiobuccal canals of mandibular molars were distributed into four groups (20 samples each): OS (Group 1), F360 (Group 2), Wave One (Group 3), and reciproc (Group 4). According to the manufacturer's instructions, all groups were prepared until size 25 taper. Canals were scanned using CS three-dimensional CBCT scanner (Carestream) before and after preparation at 2 mm, 5 mm, and 8 mm from the apex. The data collected were evaluated using SPSS software with ANOVA and post hoc for a significant difference. Results: Significant difference was found between the entire group at 2 mm and 5 mm (P = 0.021) and at 8 mm (P = 0.037), where F360 showed the least canal transportation. The mean values for centering ability were not found significant at 2 mm and 5 mm. OS proved to remain more centered than the other groups. Curved canals were instrumented better with minor canal straightening by using Reciproc. The dentin was removed more by using Wave One, whereas least dentin was removed by F360. During pre- and post-instrumentation scans the change in volume of the root canal were not found statistically significant. Wave One showed the maximum increase in the volume of the canal after instrumentation. For the preparation of the canal, the time taken was less with reciproc as compared to other groups. Conclusion: Therefore, according to the study single-file rotary instrument like F360 used in the continuous rotation is suitable instrument for the root canal preparation followed by Reciproc, OS, and Wave One.

Radiographic evaluation of root canal curvature in mesiobuccal canals of mandibular molars by different methods and its correlation with canal access angle in curved canals: An in vitro study

Aims:The aim of this study is to compare three different methods of measuring root canal curvature and its correlation with canal access angle (CAA) in curved mesiobuccal canals of permanent mandibular first molars.Materials and Methods:Sixty human mandibular first molars were used in this study. Standardized access cavities were prepared. After endodontic access, a size 10 K-file was placed in the mesiobuccal canal extending to the apical foramen, and radiographs were taken. Radiographs of each root canal were taken in buccolingual direction with the long axis of the root perpendicular to the central X-ray beam. After that, the radiographs were scanned with a computer Scanner. The angles were measured using the Schneider method, Weine's method, Lutein's method, and correlated with the CAA method. The angular and linear values used in this study were plotted, and the pertinent measurements were made using the program AutoCAD R12.Statistical Analysis:The resultant values were evaluated statistically using ANOVA test and Pearson correlation and multiple regression analyses (P = 0.001).Results:Lutein's method is as effective as the Schneider's method, Wein's method and CAA. method in evaluating root canal curvature.Conclusions:Scheider/Wein/Luiten method, together with CAA method, may be considered as a reliable guideline for preoperative assessment of canal curvature.

Influence of motion pattern on apical transportation and centering ability of WaveOne single-file technique in curved root canals.

Background:The aim of this study was to evaluate apical transportation and centering ability of single-file instruments, WaveOne primary, with full rotation versus reciprocation movement using cone-beam computed tomography (CBCT) analysis in curved mesiobuccal (MB) root canal of human mandibular molars.Materials and Methods:Thirty MB canals of mandibular molars were randomly divided into two groups according to the instrument motion (n = 15): Group 1, reciprocation/WaveOne primary; Group 2, continuous rotation/WaveOne primary. After preparation, the amount of apical transportation and centering ability were assessed by evaluating pre- and post-instrumentation CBCT scans in three section (1, 3, and 5 mm from apical foramen). Statistical analysis of the data was performed using Mann-Whitney U-test and Friedman test (α = 0.05).Results:There was no statistically significant difference between two experimental groups in terms of apical transportation and centering ratio at 1, 3, and 5 mm from apical foramen (P > 0.05).Conclusion:Apical transportation and centering ability of WaveOne primary reciprocating instrument did not significantly differ between two motion patterns.

Comparative Analysis of Canal Centering Ability of Different Single File Systems Using Cone Beam Computed Tomography- An In-Vitro Study

The ability of an endodontic instrument to remain centered in the root canal system is one of the most important characteristic influencing the clinical performance of a particular file system. Thus, it is important to assess the canal centering ability of newly introduced single file systems before they can be considered a viable replacement of full-sequence rotary file systems. The aim of the study was to compare the canal transportation, centering ability, and time taken for preparation of curved root canals after instrumentation with single file systems One Shape and Wave One, using cone-beam computed tomography (CBCT). Sixty mesiobuccal canals of mandibular molars with an angle of curvature ranging from 20(o) to 35(o) were divided into three groups of 20 samples each: ProTaper PT (group I) - full-sequence rotary control group, OneShape OS (group II)- single file continuous rotation, WaveOne WO - single file reciprocal motion (group III). Pre instrumentation and post instrumentation three-dimensional CBCT images were obtained from root cross-sections at 3mm, 6mm and 9mm from the apex. Scanned images were then accessed to determine canal transportation and centering ability. The data collected were evaluated using one-way analysis of variance (ANOVA) with Tukey's honestly significant difference test. It was observed that there were no differences in the magnitude of transportation between the rotary instruments (p >0.05) at both 3mm as well as 6mm from the apex. At 9 mm from the apex, Group I PT showed significantly higher mean canal transportation and lower centering ability (0.19±0.08 and 0.39±0.16), as compared to Group II OS (0.12±0.07 and 0.54±0.24) and Group III WO (0.13±0.06 and 0.55±0.18) while the differences between OS and WO were not statistically significant. It was concluded that there was minor difference between the tested groups. Single file systems demonstrated average canal transportation and centering ability comparable to full sequence Protaper system in curved root canals.

Comparative evaluation of shaping ability of different rotary NiTi instruments in curved canals using CBCT

Aim:The aim of this study was to compare the canal transportation, canal centering ability, and time taken for preparation of curved root canals after instrumentation with ProFile GT Series X (GTX) files, Revo-S files, twisted files, and Mtwo files by using cone-beam computed tomography (CBCT).Materials and Methods:Forty mesiobuccal canals of mandibular molars with an angle of curvature ranging from 20 to 40 were divided according to the instrument used in canal preparation into four groups of 10 samples each: GTX (group I), Revo-S (group II), twisted file (group III), and Mtwo (group IV). The teeth were instrumented according to manufacturer's guidelines, with all groups being prepared to size 30, 0.06 taper master apical file. Canals were scanned using an i-CAT CBCT scanner (Imaging Science International, Hatfield, PA, USA) before and after preparation to evaluate the transportation and centering ratio at 3 mm, 5 mm, 7 mm, 9 mm, and 11 mm from the apex. The data collected were evaluated using one-way analysis of variance (ANOVA) with Tukey's honestly significant difference (HSD) test.Results:Twisted file system showed significantly least canal transportation and highest canal centering ability values as compared to GTX, Revo-S, and Mtwo file systems. Overall, GTX, Revo-S, and Mtwo showed comparable results with respect to canal transportation and centering ability.Conclusion:The innovative method of manufacturing the TF system resulted in superior shaping ability in curved canals, with the instruments remaining more centered and producing less canal transportation than GTX, Revo-S, and Mtwo file systems.

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.

Effect of Altering the Reciprocation Range on the Fatigue Life and the Shaping Ability of WaveOne Nickel-Titanium Instruments

IntroductionThe purpose of this study was to investigate the effect of altering the reciprocation range of the WaveOne instrument (Dentsply Maillefer, Ballaigues, Switzerland) on its fatigue life and shaping ability regarding tendency for canal transportation, the canal centering ratio, and preparation time. MethodsThirty primary WaveOne instruments were divided into 3 equal groups according to the reciprocation range used: G1: 150 counterclockwise (CCW)–30 clockwise (CW), G2: 120 CCW–30 CW, and G3: 90 CCW–45 CW. They were activated in a cyclic fatigue testing device until fracture. The time to fracture and the length of the fractured tip were recorded and registered. To assess the shaping ability, 30 mesiobuccal canals of mandibular molars were prepared using the same reciprocation ranges. Canals were scanned using cone-beam computed tomography scanning before and after preparation to evaluate root canal transportation and the canal centering ratio at 1, 4, and 7 mm from the apex. The time taken to complete canal preparation was also recorded. The mean ± standard deviation values were analyzed using analysis of variance and the Tukey post hoc test. The significance level was set at P < .05. ResultsThe time to fracture recorded increased as the reciprocation range decreased, and this was significant for the 90 CCW–45 CW group (P < .05). Regarding preparation time, it increased significantly as the reciprocation range was decreased (P < .05). Results for canal transportation and the canal centering ratio showed that at 1 mm from the apex there were no significant differences between the experimental groups. For the other studied levels, the 150 CCW–30 CW group had the highest mean for canal transportation and the lowest mean for the canal centering ratio, which was statistically significant in comparison with the other experimental groups (P < .05). ConclusionsDecreasing the reciprocation range of WaveOne instruments resulted in an increased cyclic fatigue resistance with less canal transportation and more centered preparations but with longer preparation times.

Geometric Analysis of Root Canals Prepared by Four Rotary NiTi Shaping Systems

IntroductionA great number of nickel-titanium (NiTi) rotary systems with noncutting tips, different cross-sections, superior resistance to torsional fracture, varying tapers, and manufacturing method have been introduced to the market. The purpose of this study was to evaluate and compare the effect of 4 rotary NiTi preparation systems, Revo-S (RS; Micro-Mega, Besancon Cedex, France), Twisted file (TF; SybronEndo, Amersfoort, The Netherlands), ProFile GT Series X (GTX; Dentsply, Tulsa Dental Specialties, Tulsa, OK), and ProTaper (PT; Dentsply Maillefer, Ballaigues, Switzerland), on volumetric changes and transportation of curved root canals. MethodsForty mesiobuccal canals of mandibular molars with an angle of curvature ranging from 25° to 40° were divided according to the instrument used in canal preparation into 4 groups of 10 samples each: group RS, group TF, group GTX, and group PT. Canals were scanned using an i-CAT CBCT scanner (Imaging Science International, Hatfield, PA) before and after preparation to evaluate the volumetric changes. Root canal transportation and centering ratio were evaluated at 1.3, 2.6, 5.2, and 7.8 mm from the apex. The significance level was set at P ≤ .05. ResultsThe PT system removed a significantly higher amount of dentin than the other systems (P = .025). At the 1.3-mm level, there was no significant difference in canal transportation and centering ratio among the groups. However, at the other levels, TF maintained the original canal curvature recording significantly the least degree of canal transportation as well as the highest mean centering ratio. ConclusionsThe TF system showed superior shaping ability in curved canals. Revo-S and GTX were better than ProTaper regarding both canal transportation and centering ability.

The Quality of Apical Canal Preparation Using Hand and Rotary Instruments with Specific Criteria for Enlargement Based on Initial Apical File Size

The aim of this study was to compare the quality of apical enlargement of mesiobuccal canals of mandibular molars using conventional stainless steel hand files (K files) and nickel-titanium (Ni-Ti) rotary instruments (LightSpeed). Thirty freshly extracted mandibular molars were randomly assigned to three equal groups (n = 10 each group). The mesiobuccal canals were instrumented with K file using step-back technique without coronal flaring (control; group 1), K file using step-back technique after coronal flaring (group 2), and LightSpeed instrumentation (group 3). Specific criteria for apical enlargement based on initial apical size were used. For step-back techniques, the master apical file sizes were based on the Grossman criterion of three sizes larger than the first file that bound at working length, without coronal flaring (group 1) and with flaring (group 2). For the LightSpeed (LS) group, the master apical rotary sizes were based on the manufacturer's recommendation. Canal cleanliness, canal transportation, and final canal shapes were determined histologically at 1-mm and 3-mm levels short of the working length. Canals were prepared to significantly larger sizes using LS instrumentation than with either hand instrumentation techniques (15-17 ISO units, p < 0.001). LS instrumentation allowed greater apical enlargement with significantly cleaner canals, less apical transportation, and better canal shape than both hand instrumentation groups at both levels (p < 0.05). None of the three techniques was totally effective in cleaning the apical canal space. It was concluded that greater apical enlargement using LS rotary instruments is beneficial as an attempt to further debride the apical third region in mesiobuccal canals of mandibular molars. Instrument designs, alloy properties, and canal curvature are important factors that determine the feasibility of greater apical enlargement in narrow canals.