Canal Taper Research Articles

Does reduced taper canal preparation increase the load capacity of endodontically treated teeth?

Objectives: The aim of this in-vitro study is to assess and compare the load capacity of teeth with canals prepared using progressive taper versus regressive taper. Methods: Twenty-seven extracted mandibular molars were categorized into three equal groups. The negative control group involved teeth that were accessed and restored with composite resin without canal preparation. The regressive canal preparation group used the TruNatomy file system, while the progressive canal preparation group employed the ProTaper Gold system. Subsequently, all samples underwent loading using a universal testing machine until tooth fracture occurred. The force required to fracture each tooth was recorded in Newton. Results: The highest value was found in samples without preparation 1009.68±57.28 N, followed by TN group 979.04±31.16 N, while the lowest value was found in PTG 966.47±17.51N. There was no significant difference between different groups (p=0.118). Conclusions: The root canal taper did not exert a significant influence on the longevity or fracture resistance of the tooth.

Impact of using single-file reciprocating system on the quality of root canal treatment treated by undergraduate students

BackgroundThis study aimed to evaluate the use of a single-file reciprocating system on the technical quality of root canal filling and treatment by radiographic assessment of cases treated by undergraduate dental students. Materials and methodsThis was a retrospective cross-sectional clinical study of endodontically treatments conducted by fourth-year undergraduate students during the academic year 2021–2022. Root canal preparation was performed using the WaveOne Gold system with matching single-cone gutta-percha. The collected data included sex, tooth position, number of canals, and treatment time (first or second semester). The quality of the root canal filling was assessed based on the root canal filling length, density, and taper. The presence of ledges, apical transportation, perforation, and instrument separation were recorded. Data were analyzed using SPSS version 28. Chi-square tests were used, and the statistical significance level was set at P < 0.05. ResultsA total of 601 teeth were included. The length of the root canal filling was adequate in 93.51 % of the teeth, underfilled in 2.82 %, and overfilled in 3.66 %. The density and taper were adequate in 96.5 % and 98.16 % of the teeth, respectively. There were no significant differences among the parameters of length, taper, density, or procedural errors relative to the arch type. However, there was a significant difference between the anterior and premolar teeth in terms of taper, density, and overall quality of the root canal filling. The overall quality of root canal treatment was acceptable in 527 teeth (87.68 %), with no significant difference between teeth (P = 0.256). ConclusionThe quality of root canal treatment performed by undergraduate students using a single-file reciprocating system is good or acceptable.

Cone-beam computed tomography evaluation of shaping ability of kedo-S square and fanta AF™ baby rotary files compared to manual K-files in root canal preparation of primary anterior teeth

BackgroundPediatric rotary file systems were developed to solve manual file limitations. With many systems available, it may be tricky to select the most appropriate one.Aimto assess & compare Kedo-S Square, Fanta-AF™-Baby rotary files with manual K-file concerning removed dentin amount, canal transportation, centric ability & root canal taper using CBCT in primary anterior teeth.DesignExtracted Seventy-five upper primary anterior teeth with intact 2/3 root length were collected and divided into three groups based on root canal instrumentation, group-I: prepared using K-file, group-II: prepared using Kedo-S Square, and group-III: prepared using Fanta AF™ Baby file. The teeth were imaged with CBCT before & following canal instrumentation. Then, the removed dentin amount was calculated at each root-canal level. The Kruskal-Wallis test was utilized to statistically analyze study data.ResultThe difference among the three groups was highly statistically significant at cervical & apical thirds concerning dentin thickness changes on both mesial & distal sides following canal preparation with the least removed dentin in the Kedo-S Square group(P < 0.0001). Regarding transportation & centering ability, a non-significant difference between the three groups was found. 80% of the Fanta AF™ Baby group had good-tapered preparation compared to the Kedo-S Square (72%) and K-file (40%) groups(P < 0.05).ConclusionKedo-S Square was preferable to Fanta-AFTM-Baby & manual K-files in primary root canal preparation.

Micro-computed tomographic evaluation on the quality of single-cone obturation using a modified passive-deflation sealer injection needle: an in vitro study.

This study aimed to design a modified passive-deflation sealer injection needle and investigate its ability to improve obturation quality of single-cone technique through assessing the distribution of voids in root canals using micro-computed tomography (micro-CT). Forty-eight mandibular incisors were divided into eight groups (n = 6), according to the taper of root canal preparation (0.06 or 0.04), the needle used for sealer injection (modified or commercial iRoot SP injection needle), and the obturation method (iRoot SP sealer-only or single-cone obturation). After obturation, each specimen was scanned by micro-CT. The volumetric percentage and distribution of all voids were first analyzed and compared among groups, then the open and closed voids were separately analyzed and compared among single-cone obturation groups. Compared to commercial needle groups, modified needle groups showed much less voids, especially in the apical root canal part (P < 0.05). Besides, the modified needle groups produced much less open voids than commercial needle groups despite the root canal taper (P < 0.05). The modified passive deflation sealer injection needle could effectively improve the quality of single-cone obturation through reducing intra-canal voids, especially open voids throughout the root canal, thus might possibly be developed as an effective intra-canal sealer delivering instrument.

Influence of root canal taper on the measurement of two different electronic apex locators.

This research aimed to analyze the influence of root canal taper on the accuracy of two Electronic Apex Locators (EALs). Twenty-five disto-vestibular roots from extracted human upper molars belonging to the tooth bank were used in this study. To determine the File Position (FP), access was made using a spherical diamond tip #1014, and the crowns were sectioned using a diamond tip #3080. The initial anatomic file used was a size K #10, which was introduced into the root canal until its tip was visualized (foraminal patency) with the aid of a clinical microscope (16X magnification). Teeth without foraminal patency and calcifications were excluded from the study. Odontometric readings were performed using two different EALs (Root ZX II and Romiapex A-15), considering the electronic reference point 0.0 (apex) for each device. All measurements were taken in triplicate, and the arithmetic mean of the three values was used. Digital calipers were used to record the measurements, which were then entered into an Excel spreadsheet. After visual verification using file K #10, the canals were instrumented with a #25.01 file to standardize the apical region, then successively instrumented with files #25.02, #25.04, #25.06, #25.08, #25.10, and #25.12, with electronic odontometry checked after each instrumentation using #25.02. Measurement 0.0 was adopted, with error margins of ±0.5 and ±1.0. Discrepancies between visual and electronic readings were statistically analyzed using ANOVA and Bonferroni tests, with significance considered when P<0.05. Using the 0.0 mark and a ±1.0 error margin, it was observed that readings from the devices were similar in canals with different tapers (P>0.05), showing a tendency towards underestimation. However, when using the measurement variation margin of ±0.50, a statistically significant difference was found in the Romiapex A-15 group (P=0.0248) when comparing the results of the two EALs. Therefore, it was concluded that the canal taper did not significantly influence the accuracy of the evaluated EALs, using the reference point 0.0. When using the ±0.5 variation margin, the Romiapex A-15 device showed greater accuracy, and finally, at the ±1.0 error margin, both EALs exhibited excellent precision. Key words:Endodontics, Odontometry, Eletronic Apex Locator, Root Canal Preparation.

Comparative evaluation of the fracture resistance of endodontically treated premolars after different access cavity designs-root canal taper combinations

Comparative evaluation of the fracture resistance of endodontically treated premolars after different access cavity designs-root canal taper combinations

Impact of Access Cavity Design and Root Canal Taper on Fracture Strength of Endodontically Treated Mandibular Premolars (An In-Vitro Study)

Impact of Access Cavity Design and Root Canal Taper on Fracture Strength of Endodontically Treated Mandibular Premolars (An In-Vitro Study)

A comparison of online and face-to-face modalities in endodontic preclinical education: A retrospective study.

The aim of this study was to evaluate the competency of undergraduate students in following the principles of access cavity preparation and the radiographic quality of root canal filling in maxillary molar teeth in either online or face-to-face education courses during the novel coronavirus disease 2019 (COVID-19) pandemic. A total of 178 extracted maxillary molar teeth that underwent endodontic dental treatment by undergraduate students who completed the endodontic preclinical practice course online or face-to-face during the COVID-19 pandemic were retrospectively analyzed. A visual access cavity examination determined the form, width of the cavity, deroofing of the pulp chamber, and the presence of a perforation. Root canal fillings were examined radiographically on periapical radiographs for length, homogeneity, taper, and the presence of iatrogenic defects. Statistical analysis was performed using the chi-square test. The incidence of incorrect form, wide cavities, and perforation was statistically higher in the online group than in the face-to-face group (p<0.05). It was determined that root filling length and homogeneity were more successful in the face-to-face group (p<0.05). When evaluated for iatrogenic errors, the presence of broken instruments was found to be significantly higher in the online group (p<0.05). There was no significant difference between the groups in other iatrogenic errors and the taper of the root canal filling (p>0.05). The students who underwent face-to-face education were more successful in accessing cavity preparation and root canal fillings than the students who undertook online education.

Effect of Root Canal Taper on the Ability of Endodontically Treated Teeth using the TruNatomy and Protaper Next File Systems to Resist Fracture.

This research was done to evaluate how the root canal taper affects the Endodontically Treated Teeth (ETT) prepared with the TruNatomy and Protaper Next file systems in terms of fracture resistance. Forty recently extracted mandibular premolar teeth were used in this research, which was classified into four groups at random. Groups 1a and 1b used TruNatomy 4% and 6%, respectively, while groups 2a and 2b used the Protaper Next 4% and 6% file systems, respectively. The root canals were cleaned, shaped, and sealed using cold lateral compaction. The root canals were then fixed in standardized autopolymerizing acrylic resin blocks and tested for vertical root fracture using a universal testing machine. Newtons were used to measure the forces needed to cause fractures. Data were statistically analyzed. In comparison with other groups, group 1a (TruNatomy 4%) displayed greater fracture resistance (423.322.43 Newtons), and group 2b (Protaper Next 6%) displayed the least fracture resistance (264.512.76 Newtons). Protaper Next file system had lower fracture resistance than TruNatomy file system. With the use of greater taper instruments, a notable decrease in the fracture resistance of ETT was observed.

Optimum Shaping Parameters of the Middle Mesial Canal in Mandibular First Molars: A Finite Element Analysis Study

IntroductionThis study investigated the effect of shaping parameters of 2 different configurations of middle mesial canals (MMCs) on the biomechanical behavior and life span of a mandibular first molar using finite element analysis (FEA). MethodsA mandibular molar with an independent MMC and another with a confluent MMC were scanned via micro-computed tomography, and FEA models were produced. For each tooth, an intact model and 5 experimental models were produced that differed by parameters of how the MMC was shaped: unshaped MMC, 25/.04, 25/.06, 30/.04, and 30/.06. Cyclic loading of 50 N was applied on the occlusal surface in vertical and oblique scenarios, and the number of cycles until failure (NCF) was compared with the intact models. In addition, mathematical analyses evaluated the stress distribution patterns and calculated maximum von Mises and maximum principal stresses. ResultsFor both the independent and confluent MMC models, shaping the MMC reduced the NCF. The lifelog percentage of models was inversely proportional with radicular shaping parameters during the vertical and oblique loading scenarios. The shaping size of 30/.06 resulted in lower lifelog percentage than the cases with shaping size of 25/.04 in both of the independent and confluent MMC models. For all models, oblique loading reduced NCF more than vertical loading. ConclusionShaping the MMC should be kept as conservative as 25/.04. Also, whether the MMC is independent or confluent is a deciding factor in whether to increase the apical diameter or the root canal taper when larger shaping parameters are needed.

Impact of Root Canal Taper on Fracture Resistance of Endodontically Treated Teeth Prepared by Hero Shaper and RaCe File Systems: An In-vitro Study

Introduction: Tooth fracture is one of the most undesirable phenomena in Endodontically Treated Teeth (ETT) and usually leads to tooth extraction. Basically, removal of any hard tissue from the canal walls raises the chance of root fracture. Aim: To evaluate the impact of root canal taper on fracture resistance of ETT prepared by two different file systems (Hero Shaper and RaCe file systems). Materials and Methods: This in-vitro study was conducted in the Department of Conservative Dentistry and Endodontics at Bharati Vidyapeeth (Deemed to be University) Dental College and Hospital, Sangli and Praj Metallurgical Laboratory Pune, Maharashtra, India, frome February 2021 to November 2021. The study included 44 freshly extracted mandibular premolar teeth were randomly divided into four groups. Group 1a had Hero Shaper 4%, group 1b had 6% Hero Shaper, group 2a had RaCe 4% and group 2b had RaCe 6% file system. After cleaning and shaping the root canals, obturation was completed using cold lateral compaction and root canals were embedded in standardised autopolymerising acrylic resin blocks, subjected to a vertical load in universal testing machine to cause vertical root fracture. The forces required to induce fractures were measured in Newtons. Data was analysed by using independent t-test and two-way Analysis of Variance (ANOVA) test for intergroup comparison. A p-value≤0.05 was considered as statistically significant. Results: Among instrumented groups, group 1a (Hero Shaper 4%) showed higher fracture resistance of 372.5 Newtons and group 2b (RaCe 6%) showed lowest fracture resistance of 314.56 Newtons as compared to other groups. Statistically significant difference (p-value=0.026) was seen in the mean fracture resistance among the group 1a and 1b, and group 2a and 2b. At pair wise comparison there was statistically significant difference in group 1a and group 2a (p-value=0.016). Conclusion: Amongst the instrumented groups, Hero Shaper file system showed the higher fracture resistance, than RaCe file system. Marked reduction in fracture resistance of ETT was seen with the use of greater taper instruments.

Variations in the morphology of apical constriction affecting electronic readings: An in vitro investigation using 3D-printed tooth models.

We investigated the interference of apical constriction position and diameter on the accuracy of electronic apex locators using 3D-printed tooth models. Single-rooted tooth models with the same length, canal taper and major foramen, but variation in apical constriction position or size, were designed and 3D-printed. A mounting model was custom-made for precise measurement of both marks (0.5 and APEX/0.0) of two electronic apex locators. The electronic measurements of both devices were correlated significantly to the major foramen rather than apical constriction. The mean measurements of the group with 0.45 mm in apical constriction width were significantly shorter than those of the other groups for both marks of the two devices (p < 0.05). The variations in apical constriction position and width negatively affected the precision of the 0.5 mark of the tested devices. The 0.0 or APEX mark was consistently located the major foramen.

Kök kanal geometrisinin ve iğne tipinin apikalden irrigan taşmasına etkisi: ex vivo çalışma

Objective: The aim was to evaluate the effect of root canal geometry on the amount of apical extrusion of irrigant, by testing different tapers and needle types. Materials and Method: Forty-three extracted single-rooted human mandibular premolar teeth were accessed. Experimental groups were instrumented to produce increasing amounts of taper in each successive group: Group 1 (#25/.02), Group 2 (#25/.04), Group 3 (#25/.06), and Group 4 (#25/.08) (n=43, each). Irrigation was done sequentially by using a 30-G open-ended flat needle, 30-G close-ended side-vented needle, and 27-G open-ended beveled needle. Flat and side-vented needles were each placed 3 mm short of the apex, while the beveled needle was placed as far as possible in the canal without binding. Extruded irrigant was collected in preweighed foam cubes. Statistical significance was set at p&amp;lt;0.05. Results: An increase in canal taper led to a decrease in the amount of extruded irrigant for the flat needle (p&amp;lt;0.05; Groups 1 and 2 versus 3 and 4) and side-vented needle (p&amp;lt;0.05; Groups 1 and 2 versus 4), but no significant effect was found for the beveled needle. The amount of extruded irrigant was greater with the flat than with the side-vented needle at all tapers and with the beveled needle at most tapers (p&amp;lt;0.05). The side-vented needle was generally associated with the least amount of extrusion. Conclusion: Given a constant needle insertion depth, the amount of apically extruded irrigant decreased as canal taper increased. The greatest and least amounts of extrusion were generally observed with the flat and side-vented needle, respectively.

Impact of Access Cavity Design and Root Canal Taper on Fracture Resistance of Permanent Mandibular Molars: An In-vitro Study

Introduction: Minimal invasive endodontics in the form of conservative access designs and minimal root canal taper preparation have been devised to preserve tooth structure and increase fracture resistance. Aim: To assess the influence of two different access cavity designs and two different final preparation tapers on fracture resistance of mandibular molars. Materials and Methods: In this in-vitro study, performed over a period of two months, a total of 54 extracted human permanent mandibular first and second molar teeth with completely formed apices were selected and for infection control, the teeth were stored in 10% buffered formalin solution for two weeks before the experiment. The teeth were then randomly allocated into three groups, Group C where no tooth preparation was carried out, Group TAC in which traditional access cavity design was performed and Group TREC where Truss access cavity was performed. The groups TAC and TREC were further subdivided into subgroup A and B with two different tapers 0.04 and 0.06 taper preparations. Mesial canals of the teeth were chosen for testing the minimal root canal taper preparations. After apical gauging the distal canals, obturation and postendodontic restoration was carried out in all teeth of both the test groups. The teeth in all three groups were subjected to fracture testing in a universal testing machine. The data were recorded. Oneway Analysis of Variance (ANOVA) and Tukey Post-hoc test were used for statistical analysis. Results: The fracture resistance between group C and groups TAC and TREC and their subgroups were found to be statistically significant (p&lt;0.05). However, there was no statistically significant difference (p&gt;0.05) observed between the two test groups TAC and TREC and their subgroups. Conclusion: The conservative truss access design in combination with a reduced root canal taper preparation has shown to have produced better fracture resistance values in comparison to other groups and their subgroups although the results were not statistically significant.

Technical Quality of Endodontic Treatment Performed by Underperforming Undergraduate Dental Students

Objectives: This study aimed to evaluate the technical quality of root canal treatment performed by fifth-year underperforming students, in the extra sessions of the 2018–2019 academic year.&#x0D; Methods: Periapical radiographs of teeth endodontically treated by underperforming undergraduate students at King Abdulaziz University Faculty of Dentistry, were collected. The quality of obturation was evaluated radiographically in relation to the length of obturation to root apex, homogeneity and density of obturation, root canal tapering, and incidence of mishaps (such as perforation, ledge, missed canal, separated instruments). The data were subjected to descriptive analysis.&#x0D; Results: The periapical radiographs of 70 treated teeth showed acceptable length, filling density and root canal taper in 96 (80%),50 (41.7%) and 66 (55%) root canals, respectively. Only four teeth were subjected to mishaps.&#x0D; Conclusion: Under the circumstances of this study, the quality of endodontic treatment performed by underperforming students at the extra session was low. More studies are needed to address the student underperformance source and hence amend the quality of root canal filling.

The antibacterial efficacy of photon-initiated photoacoustic streaming in root canals with different diameters or tapers

BackgroundIn recent years, the concept of minimally invasive endodontics has been proposed, which could be described as preventing or treating diseases by preserving more dental tissue and creating minimal damage. In the process of root canal preparation, it was recommended to use instruments with a smaller taper to preserve more tooth tissue and improve the preservation rate of the affected teeth. Photon-induced photoacoustic streaming (PIPS) was a new type of laser-activated irrigation technology, which was now widely used in endodontic treatment. The purpose of this article was to evaluate the bactericidal effect of PIPS with NaOCl in root canals with different widths or tapers.MethodsTwenty-three maxillary first molars with three independent root canals were included in this study. The mesiobuccal (MB), distobuccal (DB), and palatal (P) root canals were prepared at sizes of #10/.02, #25/.02, and #25/.06, respectively. After being incubated with a bacterial suspension for 4 weeks, the specimen were irrigated with 2% NaOCl activated by conventional needle irrigation (CNI) (n = 10) or PIPS (n = 10). Three specimen were not treated (control group). Before and after irrigation, the presence of bacteria was assessed with an adenosine 5'-triphosphate (ATP) assay kit and biofilms were assessed using confocal laser scanning microscopy and scanning electron microscopy.ResultsIn specimen prepared using PIPS irrigation, the ATP was reduced by more than 98%. When the root canal taper was 0.02, the size #25 root canals had a higher percentage of dead bacteria than the size #10 root canals in all regions (P < 0.05) in the PIPS group. When the root canal width was #25, the 0.02 taper group had a higher percentage of dead bacteria than the 0.06 taper group in the apical region (P < 0.05), except coronal and middle regions (P > 0.05). PIPS irrigation results in a greater percentage of dead bacteria and reduction of ATP in size #10/.02 root canals than CNI in size #25/.06 root canals in three regions (P < 0.05).ConclusionIncreasing the width from #10 to #25 improves the bactericidal effect of PIPS in the root canal. Increasing the taper of the root canal from 0.02 to 0.06 at size #25 did not affect the bactericidal effects of PIPS. PIPS resulted in more dead bacteria in specimen with smaller tapers and root canal widths than CNI. PIPS can be used to clean the smear layer in the coronal region and open the dentin tubules.Clinical significance: Activation of irrigants with PIPS brought about significant bacterial reduction smaller tapers and width root canals compared to CNI, which was beneficial to prevent excessive loss of tooth tissue and conserve the structural integrity of teeth.

Impact of Canal Taper and Access Cavity Design on the Life Span of an Endodontically Treated Mandibular Molar: A Finite Element Analysis

IntroductionThis study investigated the impact of different canal tapers and access cavity designs on the life span of endodontically treated mandibular first molars using the finite element method. MethodsFinite element analysis was performed on simulated models with 3 access cavity designs (traditional, conservative, and truss). The mesial canals were prepared to either constant tapers of 25/.04 and 25/.06 or a variable taper corresponding to the cumulative canal preparation shapes of TruNatomy Prime (Dentsply Sirona, Charlotte, NC) and ProTaper Gold F2 (Dentsply Sirona). The distal canals in all models had a 40/.04 preparation. Using occlusal fingerprint analysis, all models were subjected to cyclic occlusal loading until model failure. The number of cycles until failure, the location of failure, stress distribution patterns, and the maximum von Mises stresses were assessed. ResultsThe traditional access models showed a lower life span than the conservative and truss models regardless of the canal taper, whereas there was not a notable difference in the conservative and truss models. The stresses migrated apically along the root surface and remarkably on the mesial aspect of the mesial root and the furcation area’s outer surface. After root canal preparation with different tapers, there were no evident changes in the pattern and magnitude of the stresses distributed along the root surface. ConclusionsThe life span of the tooth is affected more significantly by the access cavity design than the root canal preparation taper. Because stress patterns migrate apically rather than concentrate in the pericervical area, crack initiation and propagation might occur anywhere on the root surface.

Effectiveness of photon-initiated photoacoustic streaming in root canal models with different diameters or tapers

BackgroundThis study aimed to compare the use of photon-initiated photoacoustic streaming (PIPS) and conventional needle irrigation (CNI) in conjunction with different concentrations of sodium hypochlorite (NaOCl) to remove Enterococcus faecalis (E. faecalis) suspended bacteria and biofilms from root canal systems with different diameters or tapers.MethodsArtificial root canal samples (n = 480) were randomly divided into three groups (n = 160/group). The canals were prepared to fit file sizes #10/.02, #25/.02, or #25/.06. The size #10/.02 group was incubated for seven days. The size #25/.02 or #25/.06 group was incubated for 2 days. A stable biological model of E. faecalis infection was established. The root canals were washed with distilled water or with 1%, 2%, or 5.25% NaOCl combined with CNI or PIPS. Bacterial suspensions and biofilms were assessed using an ATP assay kit and fluorescence microscopy. Image-Pro Plus was used to analyse the average fluorescence intensity to determine the most suitable root canal irrigation solution.ResultsIn the CNI and PIPS groups, the ATP value of the 5.25% NaOCl subgroup was the lowest, followed by that of the 2% and 1% NaOCl subgroups. The ATP value of the distilled water subgroup was the highest (P < 0.05). When the root canal taper was 0.02, the ATP value of the #10/.02 + PIPS group was significantly lower than that of the #25/.02 + CNI group (P < 0.05). The average fluorescence intensity of the #10/.02 + PIPS group was lower than that of the #25/.02 + CNI group (P < 0.05). When the apical diameter was #25, the ATP value of the 0.02 taper in the PIPS group was lower than that of the 0.06 taper in the CNI group (P < 0.05), and the average fluorescence intensity of the 0.02 taper + PIPS group was lower than that of the 0.06 taper + CNI group (P < 0.05). PIPS combined with 2% and 5.25% NaOCl effectively improved the long-term antibacterial effect after irrigation and re-culture for 6 h.ConclusionsCompared with CNI, PIPS has greater ability to remove bacteria in root canals with a small preparation diameter and a small taper. PIPS with 2% and 5.25% NaOCl exhibited superior antibacterial and bacteriostatic effects.

The Effect of Different Preparation Times on The Taper and Shape of Simulated Root Canals Using The XP-Endo Shaper Rotary File

ABSTRACT Objective: This study evaluated the effect of different preparation times on the taper and shape of simulated root canals using the XP-endo Shaper rotary file Materials and methods: A total of 54 resin blocks made of clear polyacrylic resin with simulated root canals were used in this study. They were photographed using a stereomicroscope. They were prepared using the XP-endo Shaper instrument up to the working length (WL) according to the manufacturer’s recommendation for 30 seconds (s), 60 s and 90s. Postoperative photographs were performed after canal preparation at each time-point. Then, the registered pre and postoperative datasets were examined to evaluate the canal taper and apical tip diameter. Repeated measures general linear model was used to compare the differences in either the increase or the reduction of the parameters amongst the time-points. Alpha-error was set at 5%. Results: Extending the period of XP-endo Shaper active instrumentation at WL significantly influenced several parameters such as apical tip diameter (P < 0.05) and canal taper (P < 0.05) of the instrumented canal. Conclusions: Extending the activation time of XP endo Shaper instruments at WL resulted in a more comprehensive root canal preparation, increasing the canal taper and the apical tip diameter.

Fuerza de unión por micro-expulsión del sellador de conductos radiculares a base de minerales en conductos con diferentes ahusamientos

Objective: The aim of this study was to assess the micro-push-out bond strength of a mineral-based root canal sealer, BioRoot RCS in canals prepared by K3XF rotary systems of two different tapers. Material and Methods: Eighty caries free maxillary central incisors were used in this study. The samples were allocated into 4 groups (n=20) according to the root canal sealer and taper of the rotary instruments. The samples were obturated using single cone obturation technique. From each root 1mm thick slices at coronal, middle and apical thirds were collected using hard tissue microtome under continuous water coolant. Push-out tests were done for these sections using a Universal testing machine (INSTRON 8801) at a crosshead speed of 1mm/min. One-way analysis of variance (ANOVA) was used to compare the bond strengths within groups and Tukey’s multiple post hoc analysis was used for pair-wise comparison of bond strengths. Results: AH Plus exhibited higher micro-push-out bond strength than BioRootRCS though they did not differ significantly (p&gt;0.05). Preparation of root canals with 6% taper rotary instruments showed higher bond strength than 4% though they did not differ significantly (p&gt;0.05). Conclusion: There was no significant difference between micro-push-out bond strength values of BioRoot RCS and AH Plus. The bond strength values were high in 6% taper canals than 4% canals though the difference was not significant statistically.