Oval-shaped Canals Research Articles

Comparison of the Bond Strength of Circular and Oval-Shaped Fiber-Reinforced Composite Posts in Oval Shaped Canals

Background: Fiber reinforced composite resin (FRC) posts are used to restore endodontically treated teeth. Many factors affect the bond strength of posts; however, there is a concern regarding the mismatch between the posts and oval root canals and its effect on posts retention. Aim: To compare the bond strength of circular and oval-shaped fiber-reinforced composite posts in oval shaped canals. Materials and Methods: Forty Five extracted single rooted human premolars with single oval-shaped root canals were decorated, endodontically treated and prepared to receive quartz reinforced composite resin posts, then they were randomly assigned to three groups, the posts in the first group (control) (n=15) were parallel with circular cross section (Match post, RTD, France), the posts in the second group (n=15) were taper with circular cross section (DtLight Illusion post, RTD, France), The posts in the third group were oval shaped (Macro lock oval post, RTD, France). The posts in the three groups were cemented with dual cure resin cement (Permflo DC Composite Luting, Ultra dent, USA). All samples were then stored in 100% relative humidityat at room temperature for 24 hours then pull-out test was performed and data were analyzed using one-way analysis of variance (ANOVA) followed by Bonferonni's post hoc test (a = 0.05). Results: Oval shaped posts showed higher bond strength values than circular posts, whether the circular posts were conical(taper)or parallel (control) (p<0.05).Conclusions: The bond strength of fiber reinforced composite resin posts in oval root canals increased when the posts were oval-shaped.

A micro-computed tomographic assessment of oval-shaped root canals obturated with bioceramic sealer using different obturation techniques

Background/Aim: To evaluate void volumes in oval-shaped root canals obturated with three different obturation systems using microcomputed tomography (micro-CT). Material and Methods: Twenty-four distal roots of mandibular molar teeth canals were prepared and randomly divided into three groups (n = 8 in each group). The canals were obturated using single cone (SC), GuttaCore (GC), and warm vertical compaction (WVC) techniques. Each specimen was scanned using a micro-CT device. The volumes of the voids were calculated, and the data were statistically analyzed using a one-way analysis of variance and post hoc Tukey's (P < .05). Results: The void volumes in the WVC group were significantly lower than those in the other groups (P < .05). When different root canal parts were examined, the void volumes increased significantly from the apical to the coronal level in the GC and SC groups (P < .05). In the WVC group, most voids were observed in the middle part (P < .05), whereas there was no significant difference in void volumes in the coronal and apical parts (P > .05). Conclusions: None of the systems provided void-free root filling. However, the void volume using the WVC system was significantly lower than that observed using the other systems.

Evaluation of irrigation techniques in the removal of root canal filling material: Micro-CT and SEM study

Background/Aim: This study aimed to compare the different irrigation activation methods in retreatment of oval-shaped root canals. Material and Methods: Forty distal canals from mandibular molars were filled. After the removal of filling material, specimens were assigned to four groups as follows; control, passive ultrasonic irrigation (PUI), self-adjusting file (SAF), and XP-endo Finisher (XPF). The amount of residual filling material was assessed by micro-computed tomography (micro-CT) and root canal walls were examined by using scanning electrom microscopy (SEM). Data were analyzed using the Kruskal-Wallis and Dunn test. Results: None of the activation techniques removed root canal remnants completely. The amount of filling material significantly decreased in all activation techniques compared to the control group (p<0.05). There was no significant difference between the PUI, SAF, and XPF groups in the micro-CT analysis (p>0.05). SEM evaluation showed higher scores in the apical region in all groups (p<0.05). Conclusions: The use of activation methods reduces the amount of residual filling material.

Influence of pecking frequency at working length on the volume of apically extruded debris: A micro-computed tomography analysis

Background/purposeThere is no consensus to date on how many repetitive pecking motions at working length (WL) should be regarded as optimal during instrumentation. Therefore, this study aimed to evaluate the effect of pecking frequency at WL on the volume of apically extruded debris using three single-file systems in curved, oval-shaped canals. Materials and methodsForty-five single-rooted mandibular premolars with curved, oval-shaped canals were prescanned by micro-computed tomography, anatomically paired-matched, and randomly divided among three groups (n = 15 each): Reciproc Blue (RB), WaveOne Gold (WOG) and XP-endo Shaper (XPS). Samples were embedded in agarose gel to collect extruded debris. After preparation to the WL, each sample was rescanned after one, two, four, 10, and 20 pecking motions at WL, respectively. The debris volume was innovatively calculated by a modification of an existing method using micro-computed tomography. The apical preparation size was also measured. Data were compared using a two-way repeated-measures analysis of variance. ResultsAll single-file systems extruded debris apically, irrespective of the pecking frequency at WL. The extruded debris volume correlated positively with the minor foramen size (P < 0.05); both increased with pecking frequency for each single-file system (P < 0.05). The minor foramen size corresponded to the instrument tip size when reaching the WL once. ConclusionTo produce less debris extrusion and obtain a predictable foramen size corresponding to the instrument tip size, a single pecking motion may be preferred when using single-file systems. Caution should be exercised when applying the current results to clinical situations.

Comparison of the efficacy of three different supplementary cleaning protocols in root-filled teeth with a bioceramic sealer after retreatment-a micro-computed tomographic study.

The present study evaluated the efficacy of three different supplementary cleaning protocols on the removal of bioceramic-based root canal filling materials from oval-shaped canals. A total of 36 human mandibular premolars were instrumented and obturated with gutta-percha and iRoot SP using the single-cone technique. Retreatment was performed with ProTaper Universal retreatment files. The samples were randomly divided into the following supplementary cleaning protocols: conventional syringe irrigation (CSI), passive ultrasonic irrigation (PUI), and XP-endo Finisher R (XPR). The samples underwent micro-CT scanning to quantify the amount of residual filling materials after retreatment and after performing the cleaning protocols. The volume of filling material removal was analyzed by one-way analysis of variance and post hoc Bonferroni and Games-Howell tests (P < 0.05). There were significant differences in the amount of root canal filling material removal in every comparison group (P < 0.05). The XPR removed significantly more residual filling materials (P < 0.01) followed by PUI and CSI (P < 0.05). Similar efficacy was found in the total root canal and all root thirds. The additional use of XP-endo Finisher R and passive ultrasonic irrigation effectively removed the bioceramic-obturated root filling materials from the oval-shaped canals. However, none of the techniques completely removed the filling materials. The XP-endo Finisher R and passive ultrasonic irrigation exhibited greater efficacy compared with syringe irrigation in the reduction of residual filling materials after retreatment in root-filled teeth with a bioceramic sealer.

Shaping ability of reciprocating and rotary systems in oval-shaped root canals: a microcomputed tomography study.

This study compared the shaping ability of single-file reciprocating (WaveOne Gold) and multifile rotary (Mtwo) systems on mandibular oval-shaped canine root canals, using microcomputed tomography (micro-CT). Thirty mandibular canines were scanned by micro-CT and assigned to one of two groups (n=15) according to the system used for root canal preparation: WaveOne Gold or Mtwo. After preparation, the teeth were rescanned, and the percentage of untouched canal area, apical transportation and centering ability were analyzed. The data was evaluated using Kruskal and Mann- Whitney tests (p<0.05). No difference was found in percentage of unprepared canal area between groups in the entire root canal or the apical third, or in centering ability (p>0.05). WaveOne gold had less canal transportation than MTwo at the 5 mm section (p<0.05). WOG and Mtwo systems presented similar shaping ability and centering ability in oval-shaped canals. However, WOG presented less transportation than Mtwo at 5 mm from the apex.

Adaptation of the single-cone in prepared long oval-shaped canals: a micro-computed tomography study

The present study aimed to evaluate adaptation of the single gutta-percha cone on root canal walls prepared with the two systems, the XP-endo Shaper (XPS; FKG Dentaire, La Chaux-de-Fonds, Switzerland) and ProTaper Next systems (PTN; Dentsply Sirona, Ballaigues, Switzerland) by using micro-computed tomography (micro-CT) technology. Twenty long oval-shaped canals in mandibular incisors were scanned by micro-CT (Skyscan 1172; Bruker microCT, Kontich, Belgium). Two groups were divided into (n = 10) according to the canal preparation protocol: XPS group with an extra 45 s of instrumentation and PTN group. A gutta percha cone, with respect to the protocol used for each group (size 40, .04 taper, XPS and size 40, .06 taper, PTN) was adapted to the canal at the working length of all the samples, and all root canals were filled, using the single-cone technique. The mean values for volume of voids and percentage relative to the mentioned space were correspondingly higher in XPS group than they were PTN group, mean values for volume of voids (3.61 mm3 - 1.92 mm3) and for percentage of voids (39.25% - 23.28%), respectively, significant differences were recorded (p &lt; 0.05) between the two groups (XPS and PTN, Student’s-t test for homogenous variances and Mann–Whitney test). The canals prepared with XPS, in the procedure performed with an extra 45 s of instrumentation, showed a higher volume of voids than those prepared with the PTN system, in obturation of the root canal with the single cone technique.

Scope of Preparation of Oval and Long-Oval Root Canals: A Review of the Literature.

Successful endodontic treatment depends on cleaning and disinfecting the root canals, in order to provide conditions for three-dimensional filling, which should prevent root canal reinfection. However, anatomical complexities pose a challenge during endodontic treatment. The present study was a literature review carried out in the following databases: PubMed, SciELO, and MEDLINE, which were searched for articles published from 2017 to 2021. Micro-CT studies published in English, which analysed the capacity for preparation of oval and long-oval root canals, were included. The following keywords were used: “oval-shaped canals,” “long-oval-shaped canals,” “endodontics,” and “micro-CT.” The aim of this study was to carry out a literature review of micro-CT studies on the scope of the capacity for preparation performed in oval and long-oval root canals with rotary and reciprocating instruments.

Long-term porosity and retreatability of oval-shaped canals obturated using two different methods with a novel tricalcium silicate sealer.

To evaluate the percentage volume of voids and gaps in oval-shaped canals obturated using two different methods with a tricalcium silicate-based sealer after short- or long-term storage. The long-term effect of storage on the efficiency of removing filling material was also investigated. Forty premolar teeth with oval-shaped canals were instrumented to Reciproc R25 and obturated using single cone obturation (SCO) or warm vertical compaction (WVC) techniques with gutta-percha and HiFlow sealer. The specimens were stored at 100% humidity and 37°C for 2 weeks or 6 months and scanned using micro-computed tomography. Initial retreatment was performed up to a Reciproc R40, and the operating time was recorded. The residual material in the canal received a supplementary procedure using XP-endo Finisher R (XPFR) files. After each retreatment procedure, the specimens were rescanned. The percentage volume of voids and gaps in the SCO group was higher than that of the WVC group at both 2 weeks and 6 months (P < 0.05). The percentage volume of the filling material removed after initial retreatment and XPFR cleaning was significantly higher in the 6-month group than in the 2-week groups (P < 0.05). The proportion of the residual material decreased significantly when XPFR files were used, compared to the initial retreatment group (P < 0.05) in both storage times. The efficiency of retreatment in the oval-shaped canal was closely related to the storage time rather than the filling technique using a tricalcium silicate sealer. The XPFR instrument proved effective in the removal of the remaining materials from the oval-shaped canal. Obturation of the oval-shaped canal with TSBS using the SCO technique in the coronal area needs to be optimized. The retreatment was less efficacious in freshly filled canals than aged filled canals.

The prevalence of oval-shaped root canals: A morphometric study using cone-beam computed tomography and image analysis software.

This study aimed to evaluate the prevalence of oval-shaped root canals at the apical, medial and coronal cross sections of all tooth groups using CBCT and image analysis software. Based on the diameter values, the long/short diameter ratio was calculated and each root canal was classified regarding its shape. Oval-shaped canals were present in 45% at the apical, 50% at the medial and 56% at the coronal level of all teeth. The mandibular central incisors presented oval canals in 24%, long oval in 28% and flat in 2% at the apical level. Mandibular molars showed a statistically significant difference (P < 0.05) in the distribution of oval-shaped canals between cross-sectional levels. Analysis of CBCT scans with an image analysis software could be a reliable and reproducible method and a valuable tool for objective determination of root canal shape in further research.

3D CBCT evaluation of root filling quality of two sealers in oval-shaped canals

Aim: The oval canals may be associated with inadequate debridement, which can affect the quality of the root canal filling, thus the treatment outcome. The aim of the present work was to compare the quality of oval canals fillings using EndoSequence BC sealer and Bio Root RCS with the single-cone technique.Materials and Method: In total, 20 freshly extracted human single-rooted maxillary premolars were used. Specimens instrumented with the Protaper gold rotary instruments were assigned randomly into two groups. In each group, root canals were filled with single-cone gutta-percha and one of the tested sealers. Each specimen was then scanned using. CBCT at a voxel resolution of 100 mm. Proportions of sections with voids in cross-sectional images and void volumes for each sealer were calculated in the apical, middle, and coronal thirds. Differences according to root canal sealers were evaluated statistically using the Kruskal–Wallis test and the Mann– Whitney U-test at a significance level of 5%.Results: The analysis showed a decrease in void formation in the apical third, with a significant difference between the apical and coronal thirds among bioceramic sealers The bioceramic sealers (EndoSequence BC Sealer, Bio Root RCS) produced similar voids which had the fewest in the apical third of root canals among the sealers tested which can be related due to root canal anatomy variations

Efficiency of Supplementary Contemporary Single-file Systems in Removing Filling Remnants from Oval-shaped Canals: An In Vitro Study

This study investigated the performance of supplementary three single-file systems for eliminating root filling residue from oval-shaped canals utilizing cone-beam computed tomography (CBCT). Thirty single-rooted human mandibular premolars with oval-shaped canals were chosen. After decoronation and working length determination, ProTaper Universal (PTUR) rotary files were used to prepare canals up to F3. Irrigation was fulfilled by 2.5% sodium hypochlorite (NaOCl), 17% ethylenediaminetetraacetic acid (EDTA), and lastly distilled water. By utilizing the lateral compaction technique, canals were filled by gutta-percha and Endosequence BC Sealer. The PTUR retreatment system (D1, D2, and D3) eliminated the primary filling material sequentially. Subsequently, specimens were categorized into three groups at random: group I: WaveOne Gold (WOG) primary file, group II: TruNatomy (TRN) medium file, and group III: XP-endo Finisher R (XPF-R). The volume of residual left from filling material was quantified utilizing CBCT imaging before and after the supplementary retreatment. Statistical analyses were done by one-way analysis of variance (ANOVA) and Tukey's test at a 5% significance level. The volume of removed root filling after using XPF-R was significantly higher than using WOG in all sections and TRN in the coronal third, while nonsignificantly higher than using TRN in the apical and middle. XPF-R as a supplementary technique revealed the highest percentage reduction of root filling material (73.13%) in comparison with the other systems (37.39% WOG and 44.16% TRN) in oval-shaped canals. Neither one of the methods and tools used to remove filling material from oval-shaped root canals is perfectly efficient. The performance of supplementary techniques using contemporary single-file systems improves the cleaning and reshaping of root canal space that permits a proper disinfection to optimize the outcome of retreatment option.

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

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

Shaping ability of two root canal instrumentation systems in oval-shaped canals: A microcomputed tomography study.

The objective was to evaluate the shaping ability of XP-endo Shaper and Mtwo systems in oval-shaped canals preparation by microcomputed tomography (micro-CT) along the entire canal. The volume, surface area and percentage of unprepared area were evaluated by image processing in entire canal and apical third (5mm). Apical transportation and centring ability were evaluated at 3, 5 and 7mm from the apex. Forty single-canal oval canines were paired in two groups (n=20) according to the instrumentation system: XP-endo Shaper and Mtwo. The teeth were scanned by micro-CT before and after instrumentation, using a thermal vat at 37°C. The XP-endo Shaper system was more effective in the instrumentation of oval-shaped canals when compared to Mtwo system, resulting in greater volume increases and lower percentage of unprepared canals walls in apical region. Regarding apical transportation and centring ability, no statistical difference was observed.

Apical extrusion of bacteria following the use of reciprocating single-file and rotary multi-file instrumentation systems in oval root canals

Objective: All instrumentation techniques and instruments are associated with apical extrusion during chemomechanical preparation, and this causes postoperative pain and flare-up. However, it is controversial whether reciprocal systems or rotary systems cause more apical extrusion. The objective of this in vitro study was to determine the differences in the amounts of apically extruded bacteria (AEB) associated with nickel-titanium rotary and reciprocating systems when used in oval-shaped root canals. Material and Methods: Seventy human mandibular premolar teeth with oval-shaped canals were randomly assigned to four experimental groups (15 teeth in each group) and one control group (10 teeth). The root canals were contaminated with Enterococcus faecalis and instrumented using two full-sequence rotary instruments (ProTaper Universal [PTU] and ProTaper Next [PTN]) and two reciprocating single-file instruments (Reciproc [R] and WaveOne [WO]). A 0.9% NaCl solution was used as an irrigant, and the bacterial extrusion was quantified as the number of colony-forming units for each sample. The results were statistically analyzed using the Kruskal-Wallis one-way analysis of variance and the Mann-Whitney U test, and the statistical significance level was set at p &lt;0.05. Results: The R system was associated with the highest amount of bacterial extrusion (p &lt;0.05). The PTU system caused more bacterial extrusion than the PTN and WO systems (p &lt;0.05). There was no significant difference between the PTN and WO systems (p &gt;0.05). Conclusions: All instrumentation techniques caused apical bacterial extrusion. The instrument design and preparation techniques affect the number of extruded bacteria.KEYWORDS Apical extrusion; Bacteria; Endodontics; Root canal preparation.

Quantitative Assessment of the Efficacy of Two Different Single-file Systems in Reducing the Bacterial load in Oval-Shaped Canals: A Clinical Study

IntroductionThis randomized clinical study compared the in vivo antibacterial efficacy of Reciproc Blue (RB), XP-endo Shaper (XP-S), and XP-endo Shaper associated with XP-endo Finisher (XP-F) systems in infected oval-shaped root canals with primary apical periodontitis. MethodsIn this study, 28 human teeth with a single root and a single canal were randomly assigned to 2 groups according to the instrumentation technique: group 1, RB (n = 14) and group 2, XP-endo (XP-S and XP-F, n = 14). The single-rooted teeth were prepared by reciprocating and rotary nickel-titanium instruments with 5.25% sodium hypochlorite irrigation. Samples were collected from the canal at the baseline (S1), after chemomechanical preparation (S2), and after XP-F instrumentation (S3). The DNA extracts were subjected to quantitative analysis for total bacterial counts by quantitative real-time polymerase chain reaction. The data were analyzed using the analysis of variance test, and the level of significance was set at 5%. ResultsAll samples tested positive for the presence of bacteria at baseline, and the bacterial counts substantially reduced after treatment procedures (P < .01). The results showed no statistical difference between RB and XP-S instrumentation with respect to the bacterial reduction (P > .05). A marked bacterial reduction was observed after the use of the XP-F instrument (P < .01). ConclusionsThe XP-S and RB systems sharply reduced the bacterial load in oval-shaped root canals with primary apical periodontitis. XP-F used as a supplementary instrument to chemomechanical preparation promoted a significantly higher bacterial reduction.

Evaluation of Passive Ultrasonic Irrigation and GentleWave System as Adjuvants in Endodontic Retreatment

IntroductionNonsurgical endodontic retreatment continues to be a challenge in endodontics, particularly when dealing with a complex tooth anatomy. This study evaluated the efficacy of passive ultrasonic irrigation (PUI) and the GentleWave system as supplementary techniques to remove remaining filling materials from oval-shaped root canals. MethodsTwenty distal roots of human mandibular molars with single and oval-shaped canals were shaped with R40 (40.06) instrument and filled with gutta-percha and AH Plus sealer using warm vertical obturation. Initial filling material removal was performed with R50 (50.05) instrument, followed by the use of PUI (n = 10) or GentleWave system (n = 10). Micro-computed tomographic images were obtained after obturation, initial material removal, and after the use of PUI and GentleWave. The volume of remaining filling material was calculated for the entire canal as well as for the coronal, middle, and apical thirds. Statistical analyses were performed by using analysis of variance, Kruskal-Wallis and Mann-Whitney tests. P ≤ .05 was considered significant. ResultsThe use of PUI and GentleWave as supplementary techniques significantly reduced the volume of remaining filling material after initial instrumentation (P < .05). However, none of these techniques was able to render canals free from filling materials. PUI showed better performance by removing 18% of the remaining filling material, whereas the GentleWave system was able to remove approximately 10% (P = .02). ConclusionsThe use of supplementary techniques optimized filling material removal after initial instrumentation. PUI enhanced the overall cleaning of the root canal system during endodontic retreatment in oval-shaped canals.

Root Canal Shape of Human Permanent Teeth Determined by New Cone-Beam Computed Tomographic Software

IntroductionThe purpose of this study was to determine root canal cross-sectional shapes (RCCSSs) of human permanent teeth using new cone-beam computed tomographic (CBCT) software. MethodsRCCSS was determined on CBCT scans of 1400 teeth (422 patients) as follows:(1) circular,(2) conical/pyramidal,(3) oval/long oval,(4) flat/ribbonlike,(5) 8 shaped,(6) C shaped,(7) calcified,(8) trapezoidal,(9) drop shaped, and(10) other shapes. Root canal shapes were evaluated in the coronal and middle thirds, 2 mm below their beginning, and in the apical third, 1 and 2 mm short of the apical foramen. Categoric variables were described as frequencies and percentages and analyzed using the chi-square test. The level of significance was set at P = .05. ResultsMaxillary anterior teeth and maxillary first and second premolars had a circular RCCSS at 1 and 2 mm from the apical foramen in more than 45% of the cases. The most frequent RCCSS in the buccal canal of maxillary first premolars at 1 mm from the apical foramen was circular (71%) followed by flat/ribbonlike (10%) and oval/long oval (6%). In mesiobuccal roots of maxillary and mandibular first molars at 1 mm from the apical foramen, the circular shape was found in 52% and 49%, respectively. ConclusionsThe RCCSSs in human permanent teeth are variable according to the tooth group and root thirds. The highest frequency of the circular-shaped canal at 1 and 2 mm from the apical foramen was found in maxillary central incisors and mandibular first and second premolars. Oval-shaped canals were detected in practically all tooth groups and root thirds.

Retreatability of BC Sealer and AH Plus root canal sealers using new supplementary instrumentation protocol during non-surgical endodontic retreatment.

The aim of this study was to evaluate the efficacy of supplementary techniques (ultrasonic tip/XP-endo Finisher R) in removing remaining filling materials (gutta-percha/AHPlus/BCSealer) from oval-shaped root canals during non-surgical endodontic retreatment. Twenty-eight distal roots of human mandibular molars with single and oval-shaped canals were initially shaped with a R40 instrument and filled with gutta-percha points and AH Plus (n= 14) or BC Sealer (n= 14) followed by an initial micro-CT scanning. Initial filling material removal was performed in all 28 samples with an R50 instrument, and all samples submitted to a second micro-CT. Supplementary techniques with ultrasonic tips or XP-endo Finisher R instruments were performed in each sealer group, and all samples submitted to a third micro-CT. The volume of remaining filling material was calculated for the entire canal as well as for the coronal, middle, and apical thirds. Statistical analyses were performed using T, ANOVA 3-way, and Tukey tests. Lower values of remnant filling material were found for BC Sealer (16.06 ± 14.34) compared to AH Plus (28.30 ± 10.54) (P < 0.001), and considering the supplementary technique, lower values of remnant filling material were found for the ultrasonic tip (18.95 ± 11.05) compared to XP-endo Finisher R (25.41 ± 15.81) (P = 0.025). Ultrasonic instruments significantly reduced the percentage of remaining filling material for both AH Plus (P = 0.04) and BC Sealer (P = 0.02) while XP-endo Finisher R was effective for AHPlus only (P = 0.04). The remaining filling material was observed in all samples regardless the filling material or the supplementary technique employed. Supplementary techniques increased filling material removal; however, none of them was able to render root canals completely free from root fillings. Ultrasonic tips should be considered a good option for endodontic retreatment, especially for bioceramic cases. Supplementary instrumentation techniques are effective tools to reduce the amount of filling materials during root canal retreatment.

Shaping ability of XP-endo Shaper and ProTaper Next in long oval-shaped canals: a micro-computed tomography study.

To evaluate the shaping ability of the single-file XP-endo Shaper system (XP-S; FKG Dentaire, La Chaux-de-Fonds, Switzerland) employing a different working time and of the multiple-file ProTaper Next system (Dentsply Sirona, Ballaigues, Switzerland) using micro-computed tomography (micro-CT) technology. Twenty long oval-shaped canals in mandibular incisors were matched anatomically and scanned by micro-CT (Skyscan 1172; Bruker micro-CT, Kontich, Belgium). The canals were divided into two groups (n=10) according to the canal preparation protocol: XP-endo Shaper (XP-S) with an extra 45s of instrumentation and ProTaper Next (PTN X4). The images recorded before and after preparation were evaluated for morphometric measures of volume, surface area, structure model index and untouched walls. The data were compared statistically (Student's t-test for homogenous variances and Mann-Whitney test) between the two groups (XP-S and PTN X4) at α=5%. Root canal preparation significantly increased all parameters (volume, surface area, structure model index and untouched walls) tested in each group (P<0.05). There was no significant difference (P>0.05) in the percentage increase of volume (107.50%-93.13%), surface area (27.74%-29.68%) or untouched canal wall (13.08%-11.74%) between XP-S and PTN X4, respectively. The XP-endo Shaper system (single-file) with an extra 45s of instrumentation and the ProTaper Next system (multiple files) had a similar root canal shaping ability. Neither technique was able to fully prepare the long oval-shaped canals of mandibular incisors.