Oval-shaped Canals Research Articles

Impact of Contracted Endodontic Cavities on Root Canal Disinfection and Shaping

IntroductionThe impact of minimally invasive endodontic procedures on root canal disinfection has not been determined. This ex vivo study compared root canal disinfection and shaping in teeth with contracted or conventional endodontic cavities. MethodsMandibular incisors with oval-shaped canals were selected and anatomically matched based on micro–computed tomographic (micro-CT) analysis and distributed into 2 groups. Conservative and conventional access cavities were prepared, and the canals were contaminated with a pure culture of Enterococcus faecalis for 30 days. Root canal preparation in both groups was performed using the XP-endo Shaper instrument (FKG Dentaire, La Chaux-de-Fonds, Switzerland) and 2.5% sodium hypochlorite irrigation. Intracanal bacteriologic samples were taken before and after preparation, and DNA was extracted and subjected to quantitative polymerase chain reaction. Micro-CT scans taken before and after preparation were used for shaping evaluation. Bacteriologic data were analyzed by the Poisson regression model and the chi-square test with Yates correction. Micro-CT data were analyzed by the Wilcoxon, Mann-Whitney, and Student t tests with the significance level set at 5%. ResultsAll initial samples were positive for E. faecalis. After preparation, the number of bacteria-positive samples was significantly higher in the contracted cavity group (25/29, 86%) than in the conventional cavity group (14/28, 50%) (P < .01). Intergroup quantitative comparison showed that the reduction in bacterial counts was also significantly higher in the group of conventional cavities (P < .01). Micro-CT data revealed no significant difference in the amount of unprepared areas between groups. ConclusionsOur findings showed that although shaping using an adjustable instrument was similar between groups, disinfection was significantly compromised after root canal preparation of teeth with contracted endodontic cavities.

Micro–computed Tomographic Evaluation of the Shaping Ability of WaveOne Gold, TRUShape, EdgeCoil, and XP-3D Shaper Endodontic Files in Single, Oval-shaped Canals: An In Vitro Study

IntroductionThis study evaluated and compared the shaping ability of the WaveOne Gold (Dentsply/Tulsa Dental Specialties, Tulsa, OK), TRUShape 3D Conforming File (Dentsply/Tulsa Dental Specialties), EdgeCoil (EdgeEndo, Albuquerque, NM), and XP-3D Shaper (Brasseler USA, Savannah, GA) endodontic file systems on oval-shaped canals using micro–computed tomographic (micro-CT) technology. MethodsThirty-two oval-shaped, single-canal extracted human teeth were decoronated 1 mm coronal to the cementoenamel junction and scanned via a micro-CT scanner (μCT100; Scanco Medical, Bassersdorf, Switzerland). Teeth were divided into 4 groups (n = 8) and instrumented according to the manufacturer's instructions. Coregistered images, before and after root canal preparation, were evaluated for morphometric measurements of the surface area, volume, structure model index (SMI), conicity, and percent of walls untouched using the manufacturer's evaluation software (IPL Register, Scanco Medical). Data were statistically compared between groups using 1-way analysis of variance and within groups using a paired sample t test. ResultsInstrumentation with all file types increased the surface area, volume, and conicity between and within groups. There was no statistically significant difference between the groups for any of the rotary instruments used (P < .05). ConclusionsInstrumentation of oval-shaped canals with WaveOne Gold, TRUShape, EdgeCoil, and XP-3D Shaper rotary endodontic instruments similarly increase the volume, surface area, and conicity. None of the file systems were capable of contacting all of the surface area in any canal.

Ex vivo ability of a noninstrumentation technique to disinfect oval-shaped canals.

Context:Oval-shaped canals represent a challenge in endodontics. Infected tissue may remain in their recesses. This concern may be more critical with minimally instrumentation techniques.Aims:The present study evaluated the disinfection ability in oval-shaped canals of a noninstrumentation technique using ultrasonic agitation and intracanal heating of sodium hypochlorite (NaOCl) compared to rotary canal preparation and ultrasonic agitation with and without heating of NaOCl.Settings and Designs:Sixty extracted mandibular incisors were included. The teeth had pulp necrosis and apical periodontitis and oval-shaped canals. They were divided into three groups depending on the treatment protocol: (1) IHAN: intracanal heating and ultrasonic agitation of NaOCl only, (2) R-IHAN: Rotary preparation followed by IHAN, and (3) R-passive ultrasonic agitation (PUA): Rotary preparation and ultrasonic agitation of NaOCl.Methods:Root canal samples were taken before (S1) and after (S2) the endodontic procedures were completed and cultured anaerobically.Statistical Analysis Used:Wilcoxon tests were performed to compare colony-forming units (CFUs) before and after the endodontic procedures for the three groups. The percentage of variation of CFUs was compared among the three groups using Kruskal–Wallis tests, followed by Mann–Whitney U-tests.Results:All S1 samples were positive. All S2 samples showed bacterial growth in R-PUA compared to 17 in R-IHAN. None of the S2 samples in IHAN were positive. Bacteria reduction was significant in each group (P < 0.001). The percentage of bacteria reduction was highest for IHAN and lowest for R-PUA (P < 0.001).Conclusions:Intracanal heating and ultrasonic agitation of NaOCl without instrumentation completely eliminated bacteria from infected oval-shaped canals.

Adaptation and Retention of Conventional and Digitally Fabricated Posts and Cores in Round and Oval-Shaped Canals.

To compare the adaptation of conventional cast posts and cores to digitally milled counterparts in round and oval-shaped canals and to evaluate the retention of the milled posts. One cast post and one milled post were fabricated for each of the 26 selected teeth, which had either round or oval-shaped canals. The apical gap was evaluated with radiography, and coronal adaptation was evaluated by weighing the silicon wash trapped between the post and canal wall and also by comparing the volumes of the stereolithographic models. The milled posts were cemented with self-curing glass-ionomer, and the pullout test was performed to evaluate retention. A two-way analysis of variance and independent t test were used for statistical analyses, with α = .05. Conventional cast posts and cores revealed significantly higher coronal adaptation and less apical gap than the milled groups (P < .001), irrespective of the type of canal. Within the milled groups, there was no significant difference between the coronal adaptation of posts in the round and oval canals. On the contrary, the apical gap of milled posts was the least in the round canals (P = .024). The pull-out test revealed no statistically significant difference between the milled posts in the round and oval canals (P = .0864). Conventional cast posts and cores revealed significantly better adaptation compared to the milled group. However, the adequate adaptation of the milled posts to the coronal portions of the canals provided tolerable retention. Nevertheless, clinicians should be cautious with the application of the scan posts, particularly in oval canals, as they could result in a large apical gap.

Evaluation of apical extrusion and cone-beam computed tomography assessment of irrigant penetration in oval-shaped canals, using XP Endo Finisher and EndoActivator.

Background:Thorough cleaning of the pulp space is a challenging task. The mechanical instrumentation alone is usually not sufficient to completely debride the canals, and therefore, it requires the chemical action of irrigants also to disinfect the difficult to reach areas.Aim:The purpose of this study was to determine apical extrusion and assess irrigant penetration through cone-beam computed tomography (CBCT) for EndoActivator (EA) and XP Endo Finisher (XP).Materials and Methods:Sixty single-rooted mandibular premolars with oval-shaped canals were equally divided into three groups after instrumentation, based on the final irrigation: Group-1 syringe needle (30G Max-I-probe), Group-2 EA, and Group-3 XP. After the final irrigation, the weight of the extruded sodium hypochlorite was calculated. The prepared canals were then irrigated with a radiopaque contrast medium, which was activated according to the group of the sample (Group-1, 2, or 3). The volume of irrigant filled in the canal, especially in the apical third was determined through special tools in CBCT imaging.Statistics:One-way ANOVA test was used to compare the different groups.Results and Conclusion:Significantly more apical extrusion was seen in XP (P < 0.001). Both XP and EA have shown complete penetration of irrigant in the canal (100%).

In vitro comparative evaluation of efficiency of XP-endo shaper, XP-endo finisher, and XP-endo finisher-R files in terms of residual root filling material, preservation of root dentin, and time during retreatment procedures in oval canals - A cone-beam computed tomography analysis.

Background:In an oval-shaped canal, no single instrumentation systems were effective in absolute removing obturation.Aim:The aim of the study was to evaluate the performance of ProTaper Universal Retreatment (PTUR) system, XP-endo Shaper (XPS), XP-endo Finisher (XPF), and XP-endo Finisher-R (XPF-R) in removing root-canal filling material and preservation of sound dentin during retreatment procedure.Methodology:Root-canal preparation was performed on 60 mandibular premolars with oval-shaped canals using the ProTaper Gold file system. Preobturation scans were performed to measure canal volume of the canal and recorded. Obturation was performed and the samples were randomly assigned into four groups according to the retreatment protocol used (n = 15): H-file, PTUR files, PTUR followed by XPF file, and XPS supplemented with XPF-R file. After retreatment, the specimens were re-scanned and volumetric analysis of remaining root filling material, volume of the canal space were measured using EZ-3Di Software Version 5.0.0.2. All the data were subjected to one-way ANOVA and post hoc Tukey's test with a significance of 5%.Results:XPS + XPF-R showed promising results in the removal of obturating material and preservation of root dentin than any other group. The difference is statistically significant.Conclusion:XPS + XPF-R removed gutta-percha more significantly without sacrificing the sound dentin along with instrumentation.

Comparative evaluation of retreatment techniques by using different file systems from oval-shaped canals.

Introduction:Endodontic failure resolves after complete removal of obturating material followed by disinfection, cleaning, shaping and three-dimensional obturation.Materials and Methods:Seventy single-rooted mandibular premolars, with single oval-shaped root canal were included. They were decoronated at a length of 16 mm from the apex. Shaping and cleaning were performed, and obturation was done using the warm lateral compaction technique. The teeth were divided into seven groups according to retreatment procedures (Hand files; ProTaper Universal retreatment files; MTwo® Retreatment system; R-Endo® Retreatment system; ProTaper Universal retreatment files with solvent and ultrasonics; MTwo® R with solvent, and ultrasonics and R-Endo® with solvent and ultrasonics). The data were obtained and subjected to the statistical analysis.Results:All instrumentation techniques left obturating material with least in Group 6 and maximum Group 5. The mean time taken for complete retreatment procedure was minimum in Group 2 and maximum with Group 1.Conclusion:MTwo® R with solvent and ultrasonics, R-Endo®, and R-Endo® with solvent and ultrasonics were effective in gutta-percha removal from coronal third, middle third, and apical third, respectively. Significance: Nonsurgical endodontic retreatment using rotary files helps in gaining access to infected teeth. During retreatment procedure, this helps disinfectant to reach in critical areas of the root canal system, thereby decreasing the microbial load, leading to achieve healthy periradicular tissues.

Arrowhead design ultrasonic tip as a supplementary tool for canal debridement.

To investigate the shaping and cleaning performance of the Clearsonic ultrasonic tip as a supplementary tool during the preparation of long oval-shaped root canals through micro-computed tomographic (micro-CT) imaging technology. TheReciproc M-Wire R40 instrument was used as a reference instrumentation technique for comparison. Twenty mandibular incisors with single, straight and long oval-shaped canals were selected and pair-matched by micro-CT scanning. The root canals were prepared with Reciproc R25 and R40 instruments, scanned again in a micro-CT device and randomly allocated into one of the two experimental groups (n=10), according to the supplementary debridement protocol used: Clearsonic or Reciproc R40 used in abrushing motion against buccal and lingual walls. Noninstrumented canal areas, accumulation of hard-tissue debris (AHTD) and volume of removed dentine were assessed using micro-CT imaging following the supplementary debridement protocols. Data were analysed statistically in two phases using a t-test with a significance level of 5%. In phase-1, there was asignificant similarity between the samples regarding the evaluated micro-CT baseline parameters (P>0.05), validating the anatomical similarity between the toothpairs. In phase-2, there was asignificant difference between the groups for canal volume, surface area, noninstrumented root canal walls and the amount of removed dentine for both absolute and percentage values (P<0.05), but not for AHTD (P=0.759). The Clearsonic tip outperformed the Reciproc R40 instrument as a supplementary debridement protocol as it was associated with significantly greater reduction of noninstrumented root canals walls and consequently a larger amount of removed dentine. Both groups performed similarly regarding the AHTD.

3-dimensional Ability Assessment in Removing Root Filling Material from Pair-matched Oval-shaped Canals Using Thermal-treated Instruments

IntroductionThe purpose of this study was to evaluate the ability of the XP-endo Shaper instrument (FKG Dentaire, La Chaux-de-Fonds, Switzerland) during the removal of root fillings from oval-shaped canals. M-Wire Reciproc and Reciproc Blue systems (VDW, Munich, Germany) were used as reference instruments for comparison, and micro–computed technology was used as an analytical tool. MethodsThirty mandibular incisors with oval-shaped canals were matched based on similar anatomic features of the canal (eg, volume, aspect ratio, and 3-dimensional configuration) after scanning procedures. The canals were prepared with M-Wire Reciproc R25 instruments and filled with gutta-percha and AH Plus sealer (Dentsply DeTrey, Konstanz, Germany) using the continuous wave of condensation technique. Then, the sample was allocated into 3 experimental groups (n = 10) according to the retreatment protocol used: M-Wire Reciproc, Reciproc Blue, and XP-endo Shaper. M-Wire Reciproc R25, Reciproc Blue R25, and XP-endo Shaper instruments were used to remove the root fillings. Apical enlargement was performed with M-Wire Reciproc R40, Reciproc Blue R40, and BioRace BR5 (FKG Dentaire) instruments. Each sample was scanned after each endodontic procedure. The volume of remaining root filling material was quantified before and after apical enlargement. The percentage volumes of root filling reduction in relation to the instrumented canals at both time points (before and after apical enlargement) were calculated and considered for statistical analysis. Data were analyzed statistically with a significance level of 5%. ResultsReciproc Blue presented significantly lower removal of filling material compared with the XP-endo Shaper (Tukey test, P < .05). No difference was detected either between M-Wire Reciproc and Reciproc Blue (Tukey test, P > .05) or M-Wire Reciproc and XP-endo Shaper (Tukey, P > .05). The increase of apical enlargement significantly improved the removal of root fillings from the root canals (P < .05); this effect was similar for all systems (time point × file system, P > .05). ConclusionsThe XP-endo Shaper instrument showed a higher percentage of root filling removal, but no differences were observed comparing M-Wire Reciproc with the XP-endo Shaper or Reciproc Blue. The increase of apical enlargement improved the removal of root fillings in all groups. None of them was able to render root canals completely free from root fillings.

Microscopic and Chemical Assessments of the Filling Ability in Oval-Shaped Root Canals Using Two Different Carrier-Based Filling Techniques.

Objectives The aim of this study was to assess the filling ability in oval-shaped canals using two different carrier-based filling techniques. Materials and Methods Twenty-four human mandibular premolars with one oval canal were selected. Canals were shaped using WaveOne Gold Primary and ProGlider. Samples were divided into two groups and filled as follows: Thermafil and GuttaCore. The proportions of gutta-percha-filled areas (GPFAs), sealer-filled areas (SFAs), and void areas (VA), at 2 and 5 mm, were analyzed using optical numeric microscope, scanning electron microscope, and energy-dispersive X-ray. Statistical Analysis Data were compared by Kruskal–Wallis one-way analysis of variance on ranks, with statistical significance set at α = 0.05. Results At 2 and 5 mm distances from the apex, this study discloses no statistically different filling ability for the two techniques. Concerning each sample treated using both filling systems, the presence of tags was visualized. At working length (WL)-5, and WL-2, the maximum tag penetration depth for the GuttaCore group into the dentinal tubules was, respectively, 96 μm and 48 μm, whereas the values in the thermafil group were 109 μm, and 55 μm, respectively. Conclusions Our results clearly show that Thermafil and GuttaCore can fill oval-shaped canals in appropriate way. Furthermore, we can state that the GuttaCore obturator allows to preserve the same filling ability than Thermafil obturator, in view of the fact that there was no difference, in terms of GPFA, SFA, and VA between the two different carrier-based obturation techniques.

XP-endo Finisher R instrument optimizes the removal of root filling remnants in oval-shaped canals.

To evaluate the performance of XP-endo Finisher R instruments when removing root filling remnants from oval-shaped canals using microcomputed tomographic (micro-CT) imaging as the analytical tool. Passive ultrasonic irrigation (PUI) was used as a reference technique for comparison. Twenty mandibular incisors with oval-shaped canals were matched based on similar anatomic features of the canal (volume, aspect ratio and 3D configuration) after scanning procedures. The canals were prepared with Reciproc R25 instruments, filled with gutta-percha and AH Plus sealer using the single-cone technique and retreated up to a Reciproc R40 instrument. After retreatment procedures, the specimens were rescanned, and the homogeneity between the specimens, the oval-shaped anatomy and the remaining filling material were confirmed. The pair-matched samples were assigned to two experimental groups (n=10), according to the supplementary approach used: XP-endo Finisher R or PUI. Each sample was scanned after each endodontic procedure. The volume of remaining root filling material was quantified before and after the use of each supplementary approach. This analysis was performed considering the total canal (Student t-test) and also by thirds (anova procedure followed by a Bonferroni correction). Data were analysed statistically with a significance level of 5%. The volume of root filling material at baseline was similar between the groups (t-test, P=0.787). XP-endo Finisher R removed significantly more root filling material compared to PUI (t-test, P=0.015), as it removed a mean of ≅32% material compared to 12% for the PUI. There was no difference in the amount of root filling material removed in the root canal thirds after using both supplementary approaches (one-way anova, P=0.07 for XP-endo Finisher R and P=0.886 for PUI). Both supplementary approaches significantly reduced the volume of remaining root filling material from oval-shaped canals. The XP-endo Finisher R instrument removed significantly more root filling material than PUI. None of the supplementary approaches was able to render oval-shaped canals completely free from remaining root filling material.

Application of XP-Endo finisher files in the reduction of microbial load in oval-shaped root canals - An ex vivo study

The present study evaluated the effectiveness of XP-Endo Finisher (XPF) associated with XP-Endo Shaper (XPS) or Reciproc Blue (RB) files in the reduction of Enterococcus faecalis in oval-shaped root canals. Eighty mandibular incisors with single oval-shaped root canals were contaminated with E. faecalis for 10 days at 37°C with centrifugation on alternate days. The teeth were randomly assigned to eight experimental groups (n=10) as follows: G1 – XP-Endo Shaper, G2 – XP-Endo Shaper + XP-Endo Finisher, G3 – Reciproc Blue, and G4 – Reciproc Blue + XP-Endo Finisher. Chemomechanical preparation was performed with saline solution (NaCl) or 2.5% sodium hypochlorite (NaOCl). Microbial reduction was assessed by colony forming units (CFU/mL) count before (S1) and after (S2) CMP by using sterile paper points. ANOVA, Tukey’s test and Bonferroni’s post-hoc tests were used at 5% significance level. Bacteria were present in all initial samples (P&gt;.05). All instrumentation techniques reduced bacteria, irrespective of the irrigating solution (P&lt;.05). With the use of NaCl, Reciproc Blue was more effective than XP-Endo Shaper (P=.035). The association of XP-Endo Finisher improved the cleaning efficacy of both systems (P=.239). With the use of NaOCl, XP-Endo Shaper and Reciproc Blue presented similar effectiveness (P=.779). XP-Endo Finisher enhanced the bacterial reduction of both systems tested (P&lt;.05). The use of NaOCl improved the CMP, irrespective of the instrumentation technique used (P&lt;.05).

Root canal preparation in mandibular premolars with TRUShape and Vortex Blue: A micro-computed tomography study.

A comparison of the preparation ability of two root canal instrumentation systems in oval-shaped canals using micro-computed tomography was undertaken. Thirty extracted, single-rooted, human mandibular premolars with radiographically similar canal morphology were selected, allocated to two groups (N=15) and prepared with TRUShape or Vortex Blue (VB). Each sample was subjected to three scans (20μm resolution): pre-preparation and after preparation to sizes #30 and #40. Three-dimensional data sets were evaluated for canal volume, surface area and surface treatment. Matched axial slices in apical, middle and coronal root thirds were evaluated for cross-sectional area, roundness and transportation. Preparation with both instruments increased canal volumes and surface areas similarly and significantly (P<0.001) with no significant difference between groups. TRUShape significantly enhanced surface treatment at both apical sizes (P<0.05). Transportation exceeded 100μm in only eight out of 90 cross sections. Both instruments performed similarly during preparation. TRUShape, however, significantly enhanced surface treatment.

Analysis of Mandibular Premolars Root Canal Morphology Using Radiographic and Cross-Sectional Techniques in Malaysian Population

Introduction: Aberrant root canal morphology of mandibular premolars has always been associated with high endodontic treatment failures. This study was conducted to assess the canal morphology of the mandibular premolars in the Malaysian population using periapical radiographs and cross-sections of the premolar teeth. Materials and Methods: One hundred extracted permanent mandibular premolars with intact apex were randomly collected from various clinics across Malaysia. Radiographs were taken both in mesiodistal (MD) and buccolingual (BL) views to examine the presence of a second canal and to evaluate the type of canal configuration. The roots were then stained and perpendicularly resected to the long axis at three levels (cervical, middle, and apical one third). Digital photographs were taken for each of the cross-section sample and analyzed according to the number and shape of canals. Results: It was found that 78% of the mandibular premolars had single canal in BL radiographic view and 65% in MD view. Seventy-one percent of the single-canal premolars were observed in all three cross-sectional views (1-1-1 configuration). Furthermore, 37% showed oval-shaped canals and 34% showed irregular-shaped canals mainly found at cervical one third; 20% of the teeth showed the canals to be rounded in shape, most prevalent at the apical one third. Two canals with isthmus were observed in 5% of the all cross-sectional views. Conclusion: The majority of mandibular premolars in Malaysian population have a single canal, and there are a few possibilities of two or more canals in these teeth.

Micro-CT comparison of XP-endo Finisher and passive ultrasonic irrigation as final irrigation protocols on the removal of accumulated hard-tissue debris from oval shaped-canals.

To compare the effectiveness of the XP-endo Finisher instrument and passive ultrasonic irrigation (PUI) as final irrigation protocols on the removal of accumulated hard-tissue debris (AHTD) from oval-shaped canals using micro-computed tomographic (micro-CT) analysis. Twenty mandibular incisors were anatomically pair-matched based on similar morphological dimensions (length, volume, aspect ratio, and configuration) through micro-CT analysis, prepared with Reciproc R25 instrument, scanned again, and assigned to one of the two experimental groups (n = 10), according to the final irrigation protocol: XP-endo Finisher and PUI. After the final irrigation protocols, the specimens were rescanned and the registered datasets were examined to quantify the amount of AHTD. Data were statistically analyzed using Student's t test with a significance level of 5%. The final irrigation protocols were highly similar in terms of volumetric percentage reduction of AHTD (P = 1.000). XP-endo Finisher and PUI showed the same effectiveness on the removal of AHTD. None of the tested final irrigation protocols completely removed the AHTD from oval-shaped root canals. AHTD may be considered clinically relevant because it could harbor bacterial contents away from the disinfection procedures. Both final irrigation protocols were effective on the removal of AHTD.

Effectiveness of complementary irrigation routines in debriding pulp tissue from root canals instrumented with a single reciprocating file.

To compare histologically the debridement efficacy of four irrigation techniques in root canals instrumented with a reciprocating single file. From recently extracted premolars with vital pulp, 68 were selected and classified as having round canals (mesiodistal diameter similar to buccolingual) or oval-shaped canals (mesiodistal diameter 2.5 times larger than buccolingual) (n=32, each) by means of bidirectional radiographs. Four additional uninstrumented samples served as histological controls. The root canals of the specimens were accessed and then instrumented with Reciproc R25® and further assigned to one of four experimental groups according to the complementary irrigation technique: Group I, conventional syringe; Group II, passive ultrasonic irrigation; Group III, manual dynamic activation (MDA); and Group IV, EndoActivator® . Roots were then demineralized and the apical 3mm was multi-sliced and processed for histologic examination. The percentage of residual pulp tissue was calculated at each cross section. Kruskal-Wallis and Mann-Whitney tests were used to evaluate the effects of irrigation technique, root canal shape and level of cross section on the percentage of residual pulp tissue (P<0.05). Irrigation technique and root canal shape significantly influenced the percentage of residual pulp tissue (P<0.05) of canals instrumented with the R25 instrument. Percentage of residual pulp tissue was significantly less using ultrasonic irrigation (P<0.05), but there was no difference between other irrigation techniques (P>0.05). Round canals retained significantly less percentage of residual pulp tissue compared to oval-shaped canals (P=0.001). At 3mm, there was less pulp tissue compared to levels 2 and 1mm (P<0.05). In canals instrumented with R25 files, ultrasonic irrigation was more effective in removing pulp tissue in the apical level, especially for the debridement of oval-shaped canals.

Oval Versus Circular-Shaped Root Canals: Bond Strength Reached with Varying Post Techniques.

The aim of this study was to compare the bond strength (BS) of glass fiber posts (GFP) luted to oval and circular-shaped root canals rehabilitated using varying post techniques, at different intraradicular levels. Ninety 16-mm-long roots of human mandibular premolars, classified either as having oval or circular-shaped canals, were endodontically treated and prepared for restoration using one of three different post techniques (n=15): 1) single GFP; 2) resin-relined GFP; 3) main GFP associated with accessory posts. GFPs were luted with a dual polymerizing resin cement (RelyX ARC) after the canal had been treated with a 3-step etch-and-rinse adhesive system (Adper Scothbond Multipurpose). The samples were sectioned into three 1-mm-thick sections, which were differentiated by the root level (cervical, middle and apical) and tested for push-out BS. Assessment of failure mode was made under a stereomicroscope. Data were analyzed using repeated measures three-way ANOVA and Tukey's test. The root canal cross-section had a significant influence on BS (p<0.001), with the lowest values being observed in oval-shaped canals. The post technique also significantly affected the BS (p=0.018), with the resin-relined GFPs providing the highest BS values in both oval and circular-shaped canals. Irrespective of the cross-section of the root canal and post technique, there was no significant difference in BS in the cervical, middle and apical third of the root canal (p=0.084). In oval-shaped canals, the BS to intraradicular dentin at cervical, middle or apical level could be increased when the GFPs posts were relined.

Evaluation of the time required to perform three retreatment techniques with dental microscope and ultrasonic activation for removing filling material from the oval root canal.

BackgroundWhen endodontic treatment fails, retreatment consists of the complete removal of the root canal filling material for thorough cleaning and reobturation. Various techniques are available for the filling removal procedure, which present varying degrees of efficacy, and take a varying length of time to perform. The aim of this study was to compare the time required to carry out reciprocating, rotary, and manual techniques with dental microscope and ultrasonic activation for removing filling material from root canals.Material and MethodsNinety-nine extracted single-rooted teeth with straight and oval-shaped canals were selected. The samples were instrumented with ProTaper Gold System up to file F2 and obturated with AH Plus sealer and GuttaCore. The teeth were randomly divided into three groups (n=33) according to the instruments used for removal of filling material: Group (1) Reciproc blue R50 instrument; Group (2) ProTaper Retreatment instruments; Group (3) manual (Hedstrom files and Gates-Glidden drills), under dental microscope at X10 magnification with Ultrasonic retreatment tip. The time required to remove the filling materials was measured with a chronometer. Data were analyzed statistically applying the Kruskal-Wallis test followed by the Mann-Whitney U-test (p<0.05).ResultsThe time required to remove filling material was significantly shorter in Group 1, followed by Group 2, the slowest being Group 3 (P<0.05).ConclusionsThe reciprocating technique was the fastest method for removing root canal filling material. Key words:Endodontic retreatment, hedstrom file, ProTaper retreatment, reciproc blue.

Evaluation of Cutting Efficiency by Rotary and Hand Files in Oval-shaped Canals

Evaluation of Cutting Efficiency by Rotary and Hand Files in Oval-shaped Canals

Micro–computed Tomographic Evaluation of the Shaping Ability of XP-endo Shaper, iRaCe, and EdgeFile Systems in Long Oval-shaped Canals

IntroductionThis study evaluated the shaping ability of the XP-endo Shaper (FKG Dentaire SA, La Chaux-de-Fonds, Switzerland), iRaCe (FKG Dentaire SA), and EdgeFile (EdgeEndo, Albuquerque, NM) systems using micro–computed tomographic (micro-CT) technology. MethodsThirty long oval-shaped canals from mandibular incisors were matched anatomically using micro-CT scanning (SkyScan1174v2; Bruker-microCT, Kontich, Belgium) and distributed into 3 groups (n = 10) according to the canal preparation protocol (ie, XP-endo Shaper, iRaCe, and EdgeFile systems). Coregistered images, before and after preparation, were evaluated for morphometric measurements of the volume, surface area, structure model index (SMI), untouched walls, area, perimeter, roundness, and diameter. Data were statistically compared between groups using the 1-way analysis of variance post hoc Tukey test and within groups with the paired sample t test (α = 5%). ResultsWithin groups, preparation significantly increased all tested parameters (P < .05). No statistical difference was observed in the mean percentage increase of the volume (〜52%) and surface area (10.8%–14.2%) or the mean percentage of the remaining unprepared canal walls between groups (8.17%–9.83%) (P > .05). The XP-endo Shaper significantly altered the overall geometry of the root canal to a more conical shape (SMI = 2.59) when compared with the other groups (P < .05). After preparation protocols, changes in area, perimeter, roundness, and minor and major diameters of the root canals in the 5 mm of the root apex showed no difference between groups (P > .05). ConclusionsThe XP-endo Shaper, iRaCe, and EdgeFile systems showed a similar shaping ability. Despite the XP-endo Shaper had significantly altered the overall geometry of the root canal to a more conical shape, neither technique was capable of completely preparing the long oval-shaped canals of mandibular incisors.